HomeMy WebLinkAboutAPA398a-----------.
3.,<i
rJ<
{Lid
,.5 5
('",iE EO',
n fo.i39.
Ii
,'-0"•••"r ~~
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
ENVIRONMENTAL STUDIES PHASE I FINAL REPORT
o
o
o SUBTASK 7.11
BIRDS AND NON-GAME MAMMALS
(Baseline Studies)
April 1982
o
by
Brina Kessel,Principal Investigator
Stephen O.MacDonald
Daniel D.Gibson
Brian A.Cooper
and
Betty A.Anderson
)
ir..f1I\
-:-~.,..\
\
I
~;~-:(},
f
University of Alaska Museum
Fairbanks,Alaska 99701
)
)
)
)
)
)
)
)
SUMMARY
To aid in determining the potential effects that the proposed Susitna
Hydroelectric Project might have on the fauna of the upper Susitna River
Basin,field studies on birds and small (non-game)mammals were con-
ducted from 6 July to 4 October 1980,8 to 10 February 1981,and
17 April to 23 October 1981.The overall study area extended from near
Sherman on the west to the mouth of the Maclaren River on the east and
for approximately 15 km (10 miles)on either side of the Susitna River
channel.Within this region,we 1)established twelve 10-ha (25-acre)
bird census plots and 49 small mammal trapline transects and sampled
populations on them,2)flew aerial waterfowl surveys in spring 1981 and
in falls 1980 and 1981,and conducted ground surveys of 28 waterbodies
(20.5 km 2 wetlands)in July 1981,3)flew surveys of cliff habitat along
the Susitna River and its tributaries to determine use by raptors and
ravens in July 1980 and May 1981,and made ground visits during 1981 to
the vicinity of all 1980 and 1981 active sites,4)undertook frequent
general surveys to obtain supplemental information about the birds and
small mammals of the region,and 5)measured up·to 60 habitat variables
on the bird census plots and small mammal trapline transects for
subsequent analyses of animal species-habitat relationships.Sites for
the bird census plots and small mammal trapl ine transects were selected
to represent as broad a spectrum as possible of the various vegetation
types used by small mammals and terrestrial birds in the region.
During the study period,135 species of birds were recorded in the
region;the Common Redpoll,Savannah Sparrow,White-crowned Sparrow,
Lapland longspur,and Tree Sparrow were the most numerous.Fifteen
species were ranked as rare in the region,mostly birds at the periphery
of their geographic ranges or for which appropriate habitat was lacking.
All are represented by larger populations in other portions of Alaska.
Population levels among the different habitats varied greatly.
Generally,the forest and woodland habitats supported higher densities
co
cocococo
C'l
ooo
l!)
l!)
r--
C'l
C'l
i
ARLIS
Alaska Resources
Library &Information Services
Anchorage.Alaska
)
and/or biomasses of birds than the shrub communities.Highest densities
in forests were found at the downstream (Sherman)Cottonwood Forest
plot,the lowest in the White Spruce Forest plot at the mouth of Kosina
Creek.Of the shrub habitats,Low-Medium Willow Shrub had the highest
densities and the Dwarf Shrub-Alpine Tundra,the lowest.Tall Alder
Shrub also had low densities.Alpine tundra areas had the lowest bird
usage,but supported some bird species generally not found in other
habitats.
The wetlands of the region supported relatively few waterbirds,both
during summer and during migratory periods.Densities of 23.8 adults/km 2
of wetlands in July 1981 were one-fifth those of the upper Tanana River
Valley,east-central Alaska.The region was of less importance to
migratory waterfowl in spring than fall,primarily because ice breakup
did not occur until after the main spring migratory movement of many
ducks;during both seasons,most waterbodies received far less use than
those in the upper Tanana Valley.
The two most important waterbodies in the immediate vicinity of proposed
impoundments were Stephan and Murder lakes.In addition to supporting
relatively high numbers of species and individuals,the~had the longest
ice-free season and thus were important to early spring and late fall
migrants.Swans used these lakes until late October.
During 1980 and 1~81,43 raptor/raven nest sites were found,20 of which
were inactive in both years.Of the 23 active sites,five were used
both years,each year by the same species.These active sites included
ten of Golden Eagle,six of Bald Eagle,four of Common Raven,one,
perhaps two,~of Gyrfalcon,and one of Goshawk.A single observation of
an Osprey was reported during the two seasons of study.There were no
confirmed sightings of Peregrine Falcons.
Of the 16+members of the Susitna River Basin's small mammal fauna,the
most abundant and widespread were masked shrew,northern red-backed
ii
)
)
)
)
)
)
)
)
)
)
)
vole,and arctic ground squirrel.The last two are probably the most
important prey species for bird and mammal predators.Trapline capture
information indicated considerable temporal variation in population
levels for most shrews and voles,-but their relative abundance rankings
remained the same.Patterns of habitat occupancy among these species
indicated that shrews and red-backed voles were habitat generalists,
exploiting a wide range of vegetation types,while Microtus and lemmings
were habitat specialists,using a narrow range of tundra and herbaceous
vegetation types.Meadow voles and singing voles were the most selec-
tive,the former preferring wet-mesic sedge-grass meadows and the
latter,herbaceous shrub tundra.Habitat occupancy patterns were
affected by changes in density and probable species interactions.
Collared pikas and hoary marmots were locally common in the alpine zone
of the region,while red squirrels,snowshoe hares,and porcupines were
fairly common to uncommon in forest and shrubland at lower elevations.
The major impacts of the Susitna Hydroelectric Project would be from
habitat destruction due to flooding and from a range of habitat altera-
tions due to various construction and operational factors.Flooding
would destroy a :arge percentage of the riparian cliff habitat used by
nesting raptors and ravens.It would also inundate most of the major
forest habitats upriver of the Devil Canyon dam site,habitats that
support the highest avifaunal occupancy levels in the region and support
bird and mammal species unable to use non-forested habitats.In all,
the breeding habitat used by over 40,000 pairs of small-and medium-
sized upland birds would be inundated.Flooding of the fluviatile
shorelines and alluvia,both along the Susitna River and up the mouths
of tributary creeks,would destroy breeding habitat of a few bird
species and wintering habitat of the Dipper.It would also deprive
early spring migrant waterfowl of one of the first sources of open water
~n the region--the rapidly flowing waters of the Susitna River.The new
impoundments could provide habitat for waterbirds,but the degree of
iii
)
)
J
utilization would depend upon the rate and kind of development of food
resources in the lakes.The drawdown zone would be an ecological desert
for small mammals,but would probably be used in May by migrant
shorebirds.
Impacts of other habitat alterations would depend on the type of altera-
tion,i.e.,which habitats would be destroyed or altered or which
replacement habitats developed.Birds and small mammals dependent on
the destroyed or altered habitats would disappear,whereas new habitats
formed would increase populations of species that favor the newly
created habitats.The construction zones for building and operation and
the access road right-of-way and.borrow areas would destroy (or alter in
the case of borrow areas)the breeding habitat used by about 60,000
pairs of small-and medium-sized upland birds.Generally,impacts on
regional populations from forest destruction would be greater than those
from destruction of shrub habitats.Other than eliminating entire
communities.through habitat destruction,some of the most striking
anticipated impacts of habitat changes would be increased populations of
ground squirrels,Mew Gulls,ravens,and magpies about human habitations
and/or refuse sites and increased populations of ground squirrels,
tundra and meadow voles,and several sparrow species along the edges of
access roads.
Impacts would also result from direct disturbance to animals by various
human activities.The most prominent of these would be ground and
aerial activity too close to raptor nest sites during the breeding
season,and too close to wetlands during the ·ice-free season.Estab-
lishment of habitations near wetlands would also improve human access to
these areas and increase various types of disturbance,including
hunting.
iv
)
)
)
J
)
PROPOSED DEVELOPMENT
Two major reservoirs would be formed in the full-basin development plan
for the proposed Susitna Hydroelectric Project.The larger reservoir
would extend 77 km (48 miles)upstream of the Watana site and have an
average width of about 2 km (1 mile)and a maximum width of 8 km (5 miles).
The Watana re~ervoir would have a surface area of 154 km 2 (38,000 acres)
and a maximum depth of about 207 m (680 ft)at normal operating level.
The Devil Canyon reservoir would be about 42 km (26 miles)long and 1 km (0.5
mile)wide at its widest point.A surface area of 32 km 2 (7,800 acres)and
a maximum depth of about 168 m (550 ft)would exist at normal operating level.
Staged development is planned.An initial installation of 680-MW of capacity
at Watana would be available to the system in 1993 and 340 MW would be added
in 1994.If the mid-range forecast in growth in energy demand were realized,
Devil Canyon would be completed by 2002 and would have an installed capacity
of 600 MW.
The Watana dam would be an earth-fill structure,with a maximum height of
270 m (885 ft),a crest length of 1250 m (4,100 ft),and a total volume of
about 47,400,000 m3 (62,000,000 yd 3).During construction,the river would
be diverted through two concrete-lined diversion tunnels,each 11.5 m (38 ft)
in diameter,in the north bank of the river.·Upstream and downstream
cofferdams would protect the dam construction area.The power intake would
include an approach channel in rock on the north bank.A multilevel,
reinforced concrete,gated intake structure capable of operating over a
full 43-m (140-ft)drawdown range would be constructed.
The Devil Canyon dam would be a ·double-curved arch structure with a maximum
height of about 197 m (645 ft)and a crest elevation of 446 m (1463 ft).The
crest would be a uniform 6-m (20-ft)width and the maximum base width,27 m
(90 ft).A rock-fill saddle dam on the south bank of the river would be
constructed to a maximum height of about 75 m (245 ft)above foundation
v
)
)
)
)
)
)
)
)
)
J
level.The power intake on the north bank would include an approach
channel in rock,leading to a reinforced concrete gate structure,which
would accommodate a maximum drawdown of 17 m (55 ft).Flow construction
would be diverted through a single 9-m-diameter (30-ft-diameter)concrete-
lined pressure tunnel in the south bank.Cofferdams and the diversion
tunnel would provide protection against floods during construction.
About 2.5 yr of average streamflow would be required to fill the Watana
reservoir.Filling would commence after dam construction had proceeded
to a point where impoundment concurrent with continued construction
could be accommodated.Post-project flows would be lower in summer and
higher in winter than current conditions.Downstream of the project,
differences between pre-and post-project flow conditions would be
progressively less pronounced,because the entire upper basin contributes
less than 20%of the total discharge into Cook Inlet.
The selected access plan consists of a road from a railhead at Gold
Creek to Devil Canyon on the south side of the river.At Devil Canyon
the road would cross the Susitna and proceed east to the Watana site on
the north side of the river.The plan also includes access by road
connecting Gold Creek to the Parks Highway.Construction of a limited
access between Gold Creek and the Watana site,by way of a pioneer road,
would commence in mid-1983.Road access from the Parks Highway would be
deferred until after award of a federal license for the project.The
pioneer road would be ren~ered impassable if the project did not proceed.
The selected transmission line route associated with the Susitna project
would roughly parallel,but not be adjacent to,the access route between
Gold Creek and the Watana dam site.At Gold Creek,the line would
connect with the Railbelt Intertie.Between Willow and Anchorage,the
route would extend in a southerly direction to a point west of Anchorage,
where undersea cables would cross Knik Arm.Between Willow and Healy,
the route would utilize the transmission corridor previously selected by
the Alaska Power Authority for the Railbelt Intertie.
vi
)
)
)
)
)
)
)
)
)
)
)
TABLE OF CONTENTS
1 -INTRODUCTION
1.1 -Historical Literature Review
1.2 -Objectives
1.3 -Study Area
1.4 -Acknowledgments
2 -METHODS
2.1 -Selection and Configuration of Bird Census Plots
2.2 -Measurement of Habitat Variables
2.3 -Bird Censusing
2.4 -Waterbird Surveys
2.5 -Raptor Surveys
2.6 -Avifaunal Survey
2.7 -Small Mammal Sampling
2.8 -Analytical Techniques
3 -BIRDS -RESULTS AND DISCUSSION
3.1 -Habitat Descriptions of Census Plots
3.2 -Species Composition and Relative Abundance
3.3 -Breeding Bird Densities
3.4 -Waterbird Use of Wetlands
3.5 -Breeding by Cliff-nesting Raptors,Ravens,and Eagles
3.6 -Avifauna/Habitat Relationships
3.7 -Annotated List of Species
vii
1
1
3
4
4
8
8
9
12
12
14
16
17
19
23
23
40
40
48
58
65
76
)
)TABLE OF CONTENTS (Continued)
Page
4 -NON-GAME (SMALL)MAMMALS -RESULTS AND DISCUSSION 105
)
4.1 -Species Composition and Relative Abundance 105
4.2 -Small Mammal/Habitat Relationships 112
)5 -LITERATURE CITED 130
)
)
)
)
)
)
viii
)
)LIST OF TABLES
Table
)
1.Measured habitat variables used to describe bird and small
mammal intensive study plots,upper Susitna River Basin,
Alaska,July-August 1980-81 10
)
2.Summary of values of habitat variables from each 10-ha
intensive study plot,upper Susitna River Basin,July-
August 1980-81
3.Frequencies (%)of shrub and herb species in the ground
cover of intensive study plots,upper Susitna River Basin,
Alaska,July-August 1980-81
26
30
)
4.Relative abundance of loons,grebes,and waterfowl,upper
Susitna River Basin,Alaska 41
5.Relative abundance of large landbirds ~nd cranes,upper
Susitna River Basin,Alaska 42
:)
6.Relative abundance of shorebirds and gulls,upper Susitna
River Basin,Alaska 43
7.Relative abundance of small landbirds,upper Susitna River
Basin,Alaska 44
49
45
8.Avian habitat occupancy levels,upper Susitna River Basin,
Alaska,breeding season 1981
9.Number of territories of each bird species on each 10-
hectare census plot,upper Susitna River Basin,Alaska,1981 46
10.Number of adult waterbirds (or independent youn~)and
broods found on 28 waterbodies (total =20.5 km of
wetlands),upper Susitna River Basin,Alaska,July 1981:)
:)
53
)
11.Summary of total numbers and species composition of water-
birds seen on surveyed waterbodies during aerial surveys
of the upper Susitna River Basin,fall 1980 52
12.Summary of total numbers and species composition of water-
birds seen on surveyed waterbodies during aerial surveys
of the upper Susitna River Basin,fall 1981
)
13.Summary of total numbers and species composition of water-
birds seen on surveyed waterbodies during aerial surveys
of the upper Susitna River Basin,spring 1981 54
ix
:)
)
)
)
LIST OF TABLES
14.Seasonal population statistics for the more important of
·surveyed waterbodies of the upper Susitna River Basin,
1980-81 56
15.Location of active raptor and raven nest sites,upper
Susitna River Basin,Alaska,1980 and 1981,and their
proximity to potential adverse disturbance from construc-
tion activities .62
)16.Breeding chronologies of eagles,Gyrfalcon,and Common
Raven in interior Alaska 66
17.General types of impacts to raptors (from Roseneau et al.
1981)67
)18.Factors that affect the sensitivity of raptors to di s-
turbances (from Roseneau et al.1981)68
70
)
19.Influence of timing of disturbance on the possible effects
on raptors (from Roseneau et al.1981)69
20.Linear distances of cliffs in vicinity of propo~ed
impoundments,and distances that would be inundated,
Susitna Hydroelectric Project .
)
)
)
)
)
21.Number of known raptor or raven nest sites in upper
Susitna River Basin,Alaska,that would be inundated by
Devil Canyon and Watana reservoirs
22.Species of small mammals found in the upper Susitna
River Basin,Alaska,1980 and 1981
23.Standardized habitat niche breadth values for ten small
mammal species sampled by snap and pitfall trapping at
43 sites,upper Susitna River Basin,fall 1981
24.Standardized habitat niche breadth values for six small
mammal species captured on 22 trapping sites during
three sampling periods,upper Susitna River Basin,1980-81
x
71
106
120
122
:)
)
)
)
)
LIST OF FI GURES
Fi gure
1.Map of the upper Susitna River Basin,Alaska,showing
locations of the 12 bird census plots and the waterbodies
included in the waterfowl surveys.
2.Locations of small mammal trapline sites in the upper
Susitna River Basin,Alaska,1980-81.
3.Relative importance of 20 waterbodies for migrant loons,
grebes,and waterfowl in the upper Susitna River Basin,
Alaska,compared to 3 waterbodies in the upper Tanana
River-Scottie Creek area of eastern Alaska in fall 1980.
4.Relative importance of 34 waterbodies for migrant loons,
grebes,and waterfowl in the upper Susitna River Basin,
Alaska,in spring 1981 compared to 9 waterbodies in the·
upper Tanana River Valley of eastern Alaska in spring
1980.
5
7
59
60
108)
5.Habitat ordination of 22 bird species in the upper Susitna
River Basin,Alaska,based on a three-dimensional plot of
mean factor scores from subplots on which the species
occurred at least once during 1981 censuses.74
6.Temporal variation in numbers of small mammal captures
at 22 trapline sites in the upper Susitna River Basin,
Alaska,1980-81.
7.Seasonal chronologies of the arctic ground squirrel,
Talkeetna Mountains near Anchorage,Alaska (after Hock
and Cottini 1966).110
)
)
J
8.Clustering of 42 small mammal trapline sites into similar
vegetative groupings,based on an analysis of frequency
counts of 81 plant taxa in the ground cover.113
9.Abundance of eight small mammal species relative to
vegetation types at 42 trapline sites in the upper Susitna
River Basin,Alaska,29 July-30 August 1981.115
10.Two-dimensional ordination of 43 small mammal trapline
sites trapped in fall 1981,upper Susitna River Basin,Alaska,
based on principal component analyses of ground-level
structural habitat variables.The two principal components
accounted for 41%of total variance in measured variables
among sites.Vegetation types that correspond to the
groupings of mean factor score centroids are indicated.116
xi
)
)
)
)
)
)
)
)
)
J
1 -INTRODUCTION
The bird and non-game or small mammal studies of the upper Susitna River
Basin were undertaken to aid in determining the potential effect that
the proposed Susitna Hydroelectric Project might have on the fauna of
the region.More specifically,we learned what species of birds·and
small mammals were present·in the upper Susitna River Basin and,on a
seasonal basis,the manner and extent of their use of the region,in-
cluding the general habitats in which they occurred.These data,while
not definitive after only 1~field seasons,can be used with care to
1)evaluate habitat potential in the area,2)provide a basis .for pre-
dicting faunal changes based on·habitat changes caused by environmental
alterations,including changes in water level,and 3)evaluate possible
mitigative measures.
The bird and small mammal studies were composed of three interrelated
work packages:1)Bird community-habitat study,2)Avifaunal survey,
and 3)Small mammal studies.Field studies were conducted during the
following periods:6 July-4 October 1980,8-10 February 1981,and
17 April-23 October 1981.
1.1 -Historical Literature Review
Prior to the initiation of this study,almost nothing was known about
the birds and small (non-game)mammals of the upper Susitna River Basin.
The only published bird information from the region was a report of
birds seen by Hinckley (1900)while he was with a U.S.Geological Survey
party in the Susitna Valley in 1898.In the surrounding regions,
Abercrombie (1899)in ·summer and Bailey (1926)in winter both visited
the upper Copper River Basin and provided sketchy accounts of birds
seen.More recently,Williamson and Peyton (1959)reported inland
breeding of ~ouble-crested Cormorants (Phalacrocorax auritus)at Lake
Louise,and Schaller (1954)reported on summer birds seen in the
1
)
)
)
)
J
)
}
)
)
J
Talkeetna Mountains.More data were available from the vicinity of
Denali (Mt.McKinley)National Park,where O.J.Murie (1923,1924),
A.Murie (1946,1956),Dixon (1927a,1927b,1933a,1933b,1933c,1938),
and Sheldon (1909,1930)spent extended periods of time.
A.Murie (1963)prepared a generalized summary of occurrence of birds in
Denali National Park,and a recent checklist of the birds of the Park
was compiled by Kertell (1981).In the Alaska Range,directly north of
the Susitna study area,a study of the nesting and hunting behavior of
the Gyrfalcon*has just been completed (Bente 1981).All pertinent
pre-1978 data from the above citations have been consolidated and sum-
marized by Gabrielson and Lincoln (1959)and Kessel and Gibson (1978).
Between 10 and 15 June 1974,White (1974)carried out a raptor survey on
the Susitna River upstream of the proposed Devil Canyon dam site;and,
between 12 and 15 July 1975 and on 18 July 1975,White and Cade (1975)
conducted a raptor survey on the proposed Susitna powerline corridors,
.but not in the current study area.
The small mammals of the upper Susitna River Basin had never been sur-
veyed prior to this study and hence were essentially unknown except by
inference.Published species lists for nearby areas of central Alaska
~
came from a small/number of studies and surveys:Denali National Park
area (Sheldon 1930,Dixon 1938,Viereck 1959,A.Murie 1962),several
collecting sites on the Denali and Richardson highways (Baker 1951,
Strecker et al.1952,Baker and Findley 1954,Pruitt 1968),and the
upper Cook Inlet area (Osgood 1901,Wilber 1946,Hock and Cottini 1966).
General distributional information has been summarized by Manville and
Young (1965)and Hall (1980).
*See Annotated List of Species (Section 3.7)for scientific names of
birds,Table 22 for scientific names of small mammals.
2 .
)
)
)
)
)
)
)
)
)
)
Historically,little attention has been paid to bird and mammal species-
habitat relationships in Alaska,although generalized,descriptive
accounts of species habitats can be found scattered throughout the
1i terature.
1.2 -Objectives
Over the two-year period of this study,the general objectives of the
three work packages were as follows:
(a)Bird community-habitat study
(i)Determine,for as many of the major upland avian habi-
tats of the region as feasible,the type and degree of
use by birds,and compare these habitats relative to
species composition,density,etc.
(ii)Obtain data relative to species habitat use that can be
used in later analyses on habitat selection by specific
speci es (1982).
(b)Avifaunal survey
(i)Determine all species of birds using the region.
(ii)Determine,on a seasonal basis,each species'relative
abundance and general habitat use.
(iii)Determine spring and fall migration dates (earliest,
latest,peak)and,insofar as time permits,the seasonal
chronologies of each species.
3
)
)
)
)
)
(iv)Determine the extent and type of use of the area by the
Peregrine Falcon,Bald Eagle,and Osprey.
(v)Determine,generally,the use of the region by water-
birds,including shorebirds and waterfowl.
(c)Small (non-game)mammal studies
(i)Determine all species of small and medium-sized mammals
occurring in the region.
(ii)Determine,for the major vegetation types of the region,
species composition,relative abundance,and habitat
use.
1.3 -Study Area
Geographically,the overall study area extended from near Sherman,
adjacent to the Alaska Railroad,up the Susitna River to the mouth of
the Maclaren River,and out to approximately 15 km (10 miles)on either
side of the river.Survey work included habitats throughout this vast
area,but intensive work was located within a few kilometers of the
present river channel.Except for the Cottonwood Forest plot at
Sherman,the intensive sites are located between the Devil Canyon dam
site and the southeast-facing slopes east of Kosina Creek (Fig.1 and
2).
1.4 -Acknowledgments
..'.
'project of the scope of these bird and small mammal studies could not
~conducted without the assistance of many competent field and labora-
ry personnel,and we are pleased to acknowledge and express apprecia-
ln for all such help we have received.Kevin C.Cooper participated
4
)
)
)
)
)
)
)
)
)
:)
5
l>,/"·:;
I:.~.i '"a:
UI
l-
UI:;
g
>::
'"-
o-
'"
o
~
0
~
Vl+>0
~a.
Vl::s
Vl
I::
OJ
U
-0
~
.~
.0
'"~
OJ
..<::+>
4-
0
Vl Vl
I::>,
0 OJ
.~>+>~
'"::suVl
0
~~:;:
0>0
1::4-
.~~:;:OJ
0 +>..<::'"Vl :;:
OJ
'"..<::..><:+>
Vl
'"I::
~.~«:
-0•OJ
1::-0
.~::s
Vl ~
'"ucoI::
.~
~
OJ~
>Vl
.~~
0::OJ
.0
'"E
I::::s+>I::
.~~
Vl::s Vl
Vl OJ
.~
~-o
OJ 0o..c
o.~::s OJ+>OJ '"..<:::;:
~+>
OJw4-..<::
0::o+>::>
'"0.-0
~'"I::u...::;:'"
(/la:w
)I-w
:;g.
~
III
~
)0
~
}
~
-0
QJ
::>s::
.~
+'s::
0u
~
W
0::=><!l
~
)LL.
}
}
}
6
u u u u u u u u u u u
<;7
"\
\
1
\
\
I
~-~,-
,..J--
~
SUSITNA
Lm
HIGHWAY
-....._,-....""\.-",
I
I
~
"
"\,
",
I
I
\.,"tR[.(K
p
1
,>';,.------"__UJ
.t IoI
"I/--...1 ...._--"""/
oJ
TO CANTWElL ____
/FOO CREEK(-....~
.r-V ~-"\WATANA
.17 ,DAMSITE,
1.,
\"
''''l
t
\
I
(,......,-
(
I(
\
\
SCALE
(
B.ASIN BOUNDARY I_J'",..
f"1....,./..",""J>---_-J
/...._~......".....
,-~
I
.J
g S 10 20 --;'0 KILOMETERS
=-----.o 1I 10 1111 20MlLES
I
....,
FIGURE 2
Locations of small mammal trapline sites in the upper Susitna River Basin,
Alaska,1980-81.
)
)
)
)
)
)
)
in all field aspects of the study during 1981 and shouldered the major respon-
sibilities for all the 1981 waterfowl surveys.Alan M.Springer in 1980 and
David G.Roseneau in 1981 shared their raptor-hunting expertise with us by
participating in aerial raptor surveys.Brian E.Lawhead,in 1980,helped
monitor fall bird migration and flew all of the fall waterfowl surveys.A
,number of other field assistants also made significant contributions to our data-
gathering efforts,including Susan R.Lucachick,Michael K.MacDonald,Donald A.
Williamson,Jan Overturf,and Maurice L.Ward.Edward C.Murphy and Douglas P.
Pengilly provided statistical advice and assistance,and Catherine H.Curby
compiled and manipulated all of our massive habitat and animal computer data files.
We also appreciated all the contributions made to our studies by various members
of the Furbearer study group:Philip S.Gipson,Steven W.Buskirk,T.Winston
Hobgood,David P.Vol sen,William H.Busher,and Richard F.Morse.We thank
John Ireland,resident at Murder Lake,for his hospitality and for sharing his
many bird observations with us.And we laud the fine logistics provided by all
the field support personnel at Watana and High Lake,especially Onnalie Logsdon
of Terrestrial Environmental Specialists and the helicopter pilots from ERA
Helicopters,Akland Air,and Air Logistics.
Our studies were conducted under a contract between the University of Alaska
and Terrestrial Environmental Specialists,Inc.,for Acres American,Inc.,and
the Alaska Power Authority.
2 -METHODS
2.1 -Selection and Configuration of Bird Census Plots
Twelve square 10 ha (25 acres)bird census plots were established in the
study area.This plot size is above the minimum recommended by the Inter-
national Bird Census Committee (1970)and is one that can be adequately
censused in 4 h,the approximate period of maximum bird activity each
morning.Except for the Alpine Tundra plot,sites were selected in
relatively uniform patches of vegetation that represented each of the
8
)
)
)
)
)
J
J
J
)
J
J
major woody avian habitats (after Kessel 1979)present in the region.
The Alpine Tundra plot was selected to include several of the widespread
avian habitats found at the higher elevations of the study area.Each
of the 10-ha plots was divided by a 7 x 7 grid to aid in animal census-
ing procedures and in analysis of habitat variables.
2.2 -Measurement of Habitat Variables
The variables chosen to describe the habitats (Table 1)were those
judged most likely to affect,either directly or indirectly,the animal
community structure,species composition,and habitat occupancy levels
of these habitats.Some of these variables had already been tested in
central Alaska by Spindler (1976),Wolff (1977),West (1979),MacDonald
(1980),and Spindler and Kessel (1980).
The gridded subplots and small mammal trap stations were used as sample
units in vegetation analyses.Systematically located points were
sampled,using the point-centered quarter method of Cottam and Curtis
(1956),but including more detailed sampling of ground cover,under-
story,and shrub vegetation.Sampling was vertically stratified into
six layers (after Kessel 1979):ground cover (~0.25 m),dwarf shrub
«0.4 m),low shrub (0.4-1.1 m),medium shrub (1.2-2.4 m),tall shrub
(2.5-4.9 m),and tree (~5.0 m).
Non-vegetative variables measured included litter depth,microrelief,
distance to nearest standing water,if any,in subplot,and character-
istics of that water (fluviatile or lacustrine,depth,surface area),
distance to habitat edge and the length of that edge if any,in a sub-
plot,and the slope and aspect of the 10-ha study plot (Table 1).Age
of stands was determined by taking 10-20 auger core samples from the
largest trees on a plot,or,in the case of the tall shrub plot,by
cutting the largest stems from alder shrubs and counting the growth
.rings.
9
)
)
TABLE 1
MEASURED HABITAT VARIABLES USED TO DESCRIBE BIRD AND SMALL MAMMAL INTENSIVE STUDY PLOTS,UPPER
SUSlTllA RIVER BASHI,ALASKA,JULY-AUGUST 19BO-81.
)
)
Habitat Variable
Distance between trees
Distance between shrubs/shrub clumps*
Canopy area of shrub/shrub clump
Height of trees and shrubs
Diameter of tree trunk
Method
Average distance to nearest tree l~5 m height),in
quarters (Cottam and Curtis 1956)
Average distance to center of nearest shrub/shrub clump
(1.2-4.9 m hi9h),in quarters (Cottam and Curtis 1956)
Average area of shrub/shrub clump canopy,in quarters
(Cottam and Curtis 1956).Calculated as area of ellipse
from length and width measurements)
Average height of nearest tree and nearest shrub,in
quarters (Cottam and Curtis 1956)
Average diameter (dbh)of trunk of nearest tree,in
quarters (Cottam and Curtis 1956)
)
Canopy thickness of tree layer and shrub
layer
Average canopy thickness of nearest tree and
shrub,in quarters (Cottam and Curtis 1956).
from distance between lowest live branch and
tree or shrub.
nearest
Derived
top of
)
)
)
)
)
)
Foliage height density profile
Canopy coverage
Ground cover
Species frequency in ground cover
Dwarf shrub cover
Low shrub cover
Tree and shrub importance values
Litter depth
Microre1 ief
Distance to water
Average number-of 645.0 x 5.0 em coverboard squares
contacted,3 m from centerpoint in quarters (Cottam
and Curtis 1956),at heights 0-0.4 m,0.6-1.0 m,
1.6-2.0 m,3.5-3.9 m
Percent of 20 sightings (10 at 1 m intervals
along each of two perpendicular lines centered on
centerpoint)showing vegetation contact at cross-hairs
of a vertical ocular tube.Tree and shrub as well as
total canopy coverage obtained.
Percent each of sedge,grass,forb,microshrub
«0.25 m),litter,moss,lichen,water,and bare soil
in a 1.0 x 1.0 m plot with corner on centerpoint.
Occurrence of specific plant species in the 1.0 x 1.0 m
plot at small mammal trap stations.
Percent of shrub cover <0.4 m high in 3.0 x 3.0 m plot
with corner on centerpoint.
Percent of shrub cover 0.4-1.1 m high in the 3.0 x 3.0 m
plot.
Sum of'relative frequency,relative density,and
relative dominance of species,nearest tree and
nearest shrub species in quarters (Curtis and
McIntosh 1951)
Average depth of five random samples in the 1.0 x 1.0 m
plot,using calibrated probe
Maximum vertical range of topography in the 3.0 x 3.0 m
plot
.Distance to nearest perennial water,if any,on subplot
from centerpoint
10
)
)
)
)
)
TABLE 1 (Continued)
Habitat Variable
Size and type of waterbody
Depth of waterbody
Distance to habitat edge
Length of habitat edge
Slope
Aspect
Age of stand
Method
Area and edge of waterbody within a subplot,calculated
as area and circumference of an ellipse,respectively,
from length and width measurements.Type differentiated
as lacustrine or fluviatile .
Maximum depth of water
Distance to nearest edge,if any,on subplot from
centerpoint.Defined as edge of forest opening at
least 30 mx 30 m,or edge of shrub thicket opening
at least 15 mx 15 m.
Length of edge within a subplot
Degree of slope of 10-ha plot as measured with Abney
level
Direction of slope exposure of IO-ha plot measured
wi th a compass
Number of growth rings ,obtained from cut stems or._.
wi th tree auger
)
)
}
)
*Clumps of intertwining shrubs were treated as a single shrub for the purposes of habitat analyses
11
)
)
)
)
)
)
)
)
)
)
)
2.3 -Bird Censusing
A modification of the territory mapping census method (International
Bird Census Committee 1970)was used to determine the densities of
breeding birds on each of the twelve 10-ha bird census plots.The 7 x 7
gridding of each plot resulted in forty-nine 0.2-ha subplots,which were
used in censusing and in the subsequent plotting of territories and
analyses of avian-habitat relationships.In all,588 subplots were
censused in 1981.
Three field parties conducted a total of eight censuses on each 10-ha
plot between 20 May and 3 July 1981.Each census took approximately
4 h,usually between 03:00 and 08:00 (Alaska Standard Time),which is
generally within the time of greatest singing activity.Censuses were
conducted in pairs of two consecutive days at each plot,partly to
minimize the effects of changing territorial boundaries and partly to
alleviate transportation problems between plots.During a census,the
observer stopped at the center of each subplot f~r 2-7 minutes,depend-
ing upon avian activity,and recorded on a field map of the plot all
birds seen or heard.For birds seen,sex and age,activity,spatial
location (height above ground and positioning within a shrub or tree),
and substrate used (including plant species)were also recorded.
2.4 -Waterbird Surveys
Data on the use of wetlands by waterbirds were obtained primarily from
two types of surveys of the lacustrine waterbodies of the region:
ground censuses during the breeding season and aerial surveys during
migration.Generally,we examined most of the large lakes near the
proposed impoundments,plus a number of smaller lakes and ponds that
were near proposed access routes or that were efficiently examined
because they were either near the large lakes or were located on the
route between two of the larger lakes.
12
)
)
)
)
)
)
)
)
)
Ground censuses of 28 waterbodies,involving 53 party-hours of field
work,were conducted between 8 and 29 July 1981.Each waterbody was
censused once.A census consisted of two or more people either walking
around the shoreline of a waterbody or paddling the edges in an inflat-
able Sea Eagle canoe,or sometimes both simultaneously,and enumerating
all waterbirds and broods present.The efficacy of this method of
censusing individual waterbodies and its'usefulness for comparing water-
bird population characteristics over time and for determining the rela-
tive importance of different waterbodies to waterbirds is discussed by
Spindler et al.(l981).
Aerial surveys to monitor waterbody use during migration were also based
on counts from individual waterbodies.Surveys were conducted 7 September-
4 October 1980,3-26 May 1981,and 15 September-23 October 1981.We
began aerial surveys earlier and conducted more of them in fall 1980
than in 1981,because it was necessary to familiarize ourselves with the
use patterns in the region during the first year.In fall 1981 the
surveys were not as extensive or intensive.We began them later in
September,but continued them until most of the waterbodies were frozen.
We tried to time our first survey in 1981 to catch the peak of waterfowl
migration,but apparently missed it because of a somewhat earlier move-
ment of wigeon,Pintail,and scaup in 1981.The pattern of migration
and waterbody use during both fall periods was similar,however.
An average of 34 waterbodies was included in each survey,but the number
varied as we developed our sampling scheme and in response to 100%ice
cover.Brian E.Lawhead flew all the surveys during fall 1980,and
Kevin C.Cooper flew them all during 1981.All but the 3 October 1980
survey were made from a Bell 206B "Jet Ranger"hel icopter,with the
observer seated in the left front seat beside the pilot.The other
survey was made in an Aerospatiale AS350 "A-Star."
13
)
)
)
)
)
)
)
)
)
)
)
In searching for birds,usually a single pass was made over small water-
bodies.With larger waterbodies,the helicopter followed the shoreline,
usually in a counterclockwise direction so that the observer was on the
water side.Diving ducks in particular were less disturbed when the
helicopter flew over the shore instead of over water.Large lakes
containing scattered birds were surveyed in sections.Flights during
counts were at about 80 km/h (50 mph)and between 30 and 75 m (100-
250 ft)above ground level.When flocks of birds were encountered,the
helicopter circled widely and slowly around the birds while the observer
counted and identified them,sometimes with the aid of 7X,35 binoculars.
Hovering or circling directly over waterfowl was avoided,because it
unnecessarily disturbed the birds,causing them to scatter and dive and
making enumeration difficult.
As with most aerial surveying,accuracy of results was subject to many
foibles,including weather-caused factors (sun glare,choppy water),bird
behavior (diving,flushing,hiding in vegetation),differences in heli-
copter performance and pilots'flying styles,etc.Generally,however,
we feel that results were a reasonably accurate indication of the
species and numbers present on the respective waterbodies at the time of
the surveys.
2.5 -Raptor Surveys
Information on use of the region by breeding raptors and ravens was
derived from 1)helicopter surveys on 6 July 1980 and 16 and 17 May 1981
of all cliff habitat along the Susitna River ~nd its tributaries (but
not the upland cliffs and tors),from Portage (1980)and Indian (1981)
creeks to the mouth of the Tyone River,and,on 3 and 5 July 1981,of
habitats along the proposed access routes,2)ground visits to all 1980
and 1981 active nest sites,3)special ground and aerial searches of
vegetated cliff habitat (potential Peregrine habitat?),4)supplemental
observations made whenever flying over or working near raptor habitat,
and 5)from miscellaneous observations made throughout the study period.
14
)
)
)
)
)
)
)
)
)
)
)
Aerial surveys of raptor cliff-nesting habitat were conducted from Bell
206B "Jet Ranger"hel icopters.Three observers in addition to the pilot
took part in each survey.Brian A.Cooper participated in all surveys;
he was accompanied in July 1980 by A.M.Springer and O.Logsdon,in May
1981 by D.G.Roseneau and K.C.Cooper,and in July 1981 by K.C.
Cooper and S.R.Lucachick.Because of the ability and accumulated
experience of the observers,we feel that our surveys were as accurate
as most aerial surveys of this type.
During the surveys,the helicopter moved slowly past cliff faces as
close as the pilot deemed safe,usually at a distance of about 30-40 m.
When necessary for better observation,the helicopter hovered for short
periods or made more than one pass past a site.All active and inactive
nest sites were recorded and briefly described on 1:63,000 USGS quad-
rangle maps.All nest sites found in earlier surveys,including those
by White (1974),were relocated and checked for activity.
Between 20 May and 13 July 1981,we visited all 1980 and 1981 active
cliff sites from the ground,taking photographs of each site and record-
ing data on nest site characteristics and cliff habitat in proximity of
eQ~h site (data on file at University of Alaska Museum).Several times
during early summer and at least once from the ground in June 1981,we
examined all potential Peregrine-type habitat (vegetated cliffs).In
all,some 44 party-hours were spent in these ground examinations of
raptor habitat.
Over the course of the summer,we roughly delineated all cliffs in or
near the impoundment area on 1:63,000 USGS quadrangle maps and classi-
fied cliffs according to their structure and apparent quality for nest
sites."A"cl iff habitat had cl iffs large enough to support a nest,had
ledges and nooks for nest placement,and had little loose material;"B"
cliffs had these same attributes,but were smaller and perhaps not large
15
)
)
)
)
)
)
)
)
)
)
)
enough to support a nest;and "G"cl iffs had loose substrates (dirt and
rock banks or loose talus)and probably would not have been used by
raptors.
2.6 -Avifaunal Survey
In addition to,·data gathered during the intensive activities described
above,we accumulated general data on the avifauna through several other
means:
(a)A daily checklist enumerating all independent individuals (as
opposed to dependent broods)of all species observed was
maintained while we were in stationary camps.
(b)Whenever time permitted,we walked cross-country at various
locations throughout the upper basin,recording all indivi-
duals of all species seen and,whenever feasible,the habitats
utilized.Hours in the field and distance traveled were
recorded,broken down by habitat when possible.In all,over
630 party-hours were spent.in this form of survey.
(c)All observations related to breeding chronologies were re-
corded,e.g.,nests and their contents,and age and activity
of dependent broods.
(d)Observations were solicited,either verbally or through posted
data sheets,from others working in the region.
16
)
)
}
}
}
:)
J
2.7 -Small Mammal Sampling
(a)Shl'ews and Voles
To sample shrew and vole populations,we used a modification of the
North American Census of Small Mammals (Calhoun 1948).Trapline tran-
sects cons i sted of 20 trap stati ons,spaced every 15.2 m.Two "Museum
Special"snap-traps and one pitfall trap (primarily for shrews)were set
within a 1-m radius of each trap station centerpoint for three consecu-
tive nights.Snap-traps were baited with a mixture of peanut butter,
rolled oats,and ground walnuts or sunflower seeds.Pitfalls,which
were heavy galvanized sheetmetal cones measuring 155 mm in diameter and
260 mm in depth,were pressed into the ground so that the cone opening
was flush or slightly lower than ground level;they were not baited.
Two trapline transects,treated as independent samples in analyses,were
set up along grid lines number three and five of each 10-ha bird census
plot (except on the multihabitat Alpine Tundra plot).In addition,we
established a number of traplines at other locations in the study area,
on vegetationally-homogeneous sites that represented the wide range of
vegetation types present in the upper Susitna River Basin.By fall
1981,the number of trapline transects in operation totaled 49.
During each sampling period we recorded the following data for each
animal trapped:date,location,trap type (snap-trap or pitfall),
species,sex,weight (using 10 g,50 g,and 100 g Pesola scales),and
reproductive condition (males--testes abdominal or scrotal;females--
pregnant,number and size of embryos,lactating).Representative
samples of study skins and skeletal material ·were pres~rved and
deposited in the University of Alaska Museum.-
17
)
)
)
)
)
}
J
(b)Other Small Mammals
Systematic enumeration of small mammals other than shrews and voles
proved to be impractical,largely because each species required a·dif-
ferent,time-consuming census technique,the application of which was
impossible within time and manpower constraints.Also,some of these
other small mammals,while common and widespread throughout central
Alaska,were present in relatively low densities in the upper Susitna
River Basin (snowshoe hare and porcupine)or were in locations unlikely
to be impacted by activities related to the Susitna Hydroelectric
Project (collared pika and hoary marmot).
Attempts to census ground squirrels in 1981 failed,largely because of
inconsistencies among inexperienced observers in the recording of
squirrel sign and habitat variables.With four observers,we conducted
transect censuses at eight fox den sites and.20 non-fox den sites above
treeline between 9 August and 17 September 1981.Each census consisted
of an observer walking a north-south transect and then an adjoining
east-west transect,each 500 paces long (approx.365 m),and stopping to
record at every 20 paces (approx.15 m)the number of ground squirrel
burrow holes encompassed by a 2 m-radius circle centered at the
recorder's feet.Also recorded at each stop were vegetation type,slope,
aspect,and one of three substrate moisture categories--wet,moist,dry.
In addition,the number of squirrel calls heard during a census was
tallied.
Red Squirrel counts are still to be made.These will be done in con-
junction with bird censusing in 1982,when observers will map active
squirrel middens on the bird census plots.Densities will be determined
by assuming one squirrel per midden (after Wolff and Zasada 1975).
Lacking more concrete data,relative abundance information given in
discussions below on these other small mammals is based on general
18
)
)
)
)
)
)
survey information gathered by our field parties and from observations
contributed by others.
2.8 -Analytical Technigues
(a)Importance Values
In an attempt to identify the waterbodies most significant to waterbirds
(loons,grebes;and waterfowl),we derived a relative "Importance Value"
for each season for each waterbody surveyed,i.e.,we calculated an
Importance Value of a waterbody to breeding waterbirds compared to all
others surveyed during July 1981 (a total of 28 waterbodies),another
for 20 waterbodies surveyed during fall 1980,and another for 34 water-
bodies surveyed during spring 1981.The importance value of each water-
body at a given season was the sum of relative·mean abundance (number of
birds)from the several censuses,the relative mean density (birds/km 2),
and the relative mean species richness (number of species)(after Curtis
and McIntosh 1951):
mean number of birds
)IMPORTANCE VALUE of per census on waterbody
a waterbody =+
sum of mean number of
birds per census on all
waterbodies
)mean density of birds mean number of species
per census on waterbody ~er census on waterbody
+
sum of mean densities of sum of number of species
birds per census on all per census on all
wa terbod i es wa terbod i es
19
)
)
)
)
)
)
)
)
(b)Avian Communities
The avian communities in the major terrestrial habitats of the region,
represented by the 12 bird census plots,were compared relative to
species composition,species richness (number of species),breeding
density,breeding biomass,and species diversity (H').
Breeding density was determined by estimating the number of territories
of each species,based on repeated observations of territorial males,
females,or breeding pairs (International Bird Census Committee 1970).
Partial territories were also determined and added to the number of
whole territories.Species that had only a small fraction of a terri-
tory on a plot were given a "+,"which was counted as 0.1 territory in
calculations of breeding density,species diversity,and breeding bio-
mass.The breeding densities of early season nesters,such as Gray Jay
and.chickadees,were estimated,based on repeated observations of adults
or immatures on the plot.
Species diversity was calculated using the diversity index,H'(Pielou
1975).Species diversity h~s two components:number of species
(species richness)and the evenness (species equitability)with which
the individuals of the community are apportioned among these species
(Pielou 1975).H'reaches its maximum value in communities with many
species of nearly equal abundance.A community with many species dis-
tributed evenly may have the same diversity index as a community with
fewer species that are distributed evenly.
Breeding biomass was calculated for each plot as the sum of breeding
biomass for each species breeding on the plot.Breeding biomass for
each species was calculated as the product of the density of breeding
birds and average weight of the species.Species weights used were an
average weight for all adult specimens in the University of Alaska
Museum that had been collected in Alaska during the breeding season.If
20
)
)
)
the sample size in the museum was too small,or variability too high,we
consulted published literature (Carbyn 1971,West and DeWolfe 1974)for
values determined from northern populations.Large-bodied breeding
birds,such as grouse or ptarmigan,were omitted from biomass calcula-
tions,because they tended to skew the total biomass disproportionately.
Breeding biomass was expressed as grams breeding birds per 10 ha.
(c)Statistical Procedures and Data Presentation
Two procedures were used to organize the small mammal trapline sites
into groups,based on their similarities:cluster analysis and princi-
pal component analysis (PCA).Variables used in the analyses were our
measurements of ground-level habitat structure and plant taxa frequen-
cies,thus emphasizing the stratum used by small mammals and allowing
expression of variation among sites.The resultant groups of trapline
sites corresponded to vegetation types (see Section 4.2),which were
used to document patterns of small mammal habitat distribution,abun-
dance,and coexistence.
The cluster analysis (Biomedical Computer Program BMDP2M:Chi-Square
Procedure [Dixon and Brown 1979J)was performed using the plant taxa
frequencies.This technique is a method for organizing a data array,
based on a measure of similarity among variables,into groups or
clusters that are more similar within groups than among groups.In this
instance,trapline sites with the most similar composition of plant taxa
were clustered first (subgroups),and those less similar clustered
progressively later (major groups).
The principal component analysis (Biomedical Computer Program BMDP4M
[Dixon and Brown 1979J)was performed using measured structural habitat
variables.PCA is a statistical technique that reduces multivariate
data into a few dimensions,uncorrelated with each other,that are
linear combinations ("principal components")of the original variables
21
)
)
)
)
)
)
)
)
)
)
)
(Morrison 1976).The first new composite set of linear variables (PC I)
accounts for more of the variance (information)in the data set than any
other linear combination and thus provides the best summary of linear
relationships exhibited in the data.PC II accounts for the most
variance in the data set not accounted for by PC I,and each successive
component or dimension accounts for successively less variance.From
our PCA analysis of habitat variables,we used PC I and PC II as axes on
which to ordinate the trapline sites (using'mean factor scores),in
order to examine their interrelationships and to provide a base from
which to look at habitat occupancy patterns.
A PCA,based on measured habitat variables,was also used to ordinate
the breeding distribution of bird species relative to habitat character-
istics.A mean PCA factor score from all subplots on which a given
species was recorded at least once during censuses was calculated for
species that occurred on 10 or more subplots.These scores were plotted
on a three-dimensional diagram,using the first three principal com-
ponents of habitat characteristics as axes.
Distribution patterns of small mammals relative to groupings of vegeta-
tion types were further shown through the use of a three-dimensional
display technique (Surface II Graphics System Programs [Sampson 1978]).
The percentage of total number of captures of a given small mammal
species per trapping site was added as a vertical axis to the two-
dimensional PCA ordination of trapline sites.Block or "fishnet"
diagrams of each species,created by connecting contours of equal abun-
dance,give three-dimensional illustrations of a species'distributional
"topography."
22
)
)
)
)
)
)
)
)
)
)
)
To quantify the variation in range of habitat use by small mammals,we
calculated values for habitat niche breadth for each species,using the
formula (after Krebs and Wingate 1976)
1
B =
where B=habitat niche breadth and Pi =proportion of species total
density at trapline site i;p is defined from average density estimates:
Pi =
where di =number of individuals per 100 trap nights at trapline site i.
Habitat niche breadth was then standardized by dividing by the total
number of sites.
3 -BIRDS -RESULTS AND DISCUSSION
3.1 -Habitat Descriptions of Census Plots
Twelve intensive study plots were established in the shrub and forest
vegetation types of the upper Susitna River Basin (Fig.1).Plot sites
within these vegetation types were chosen to represent each of the major
woody avian habitats (Kessel 1979)present in the region in sufficient
size and uniformity to accommodate a square 10-ha (25-acre)study plot.
Below,in capital letters,are listed the avian habitats represented by
our plots,followed in parentheses by their most distinguishing habitat
characteristics and in brackets by the approximate vegetative equiva-
lents of Viereck and Dyrness (1980).Classified thereunder are the
twelve bird census plots.
23
)
)
)
)
)
)
)
)
)
)
)
DWARF SHRUB MAT (<0.4 m high),DWARF SHRUB MEADOW,AND BLOCK-FIELD
[Mat and Cushion Tundra,Mesic Sedge-grass]
Alpine Tundra
LOW (0.4-1.1 m high)AND/OR MEDIUM (1.2-2.4 m high)SHRUB THICKETS'
[Low and/or Tall Shrubland,separated at 1.5 m]
Dwarf-Low Birch Shrub Thicket
Medium Birch Shrub Thicket
Low-Medium Willow Shrub Thicket
TALL (2.5-4.9 m high)SHRUB THICKET [Tall Shrubland,>1.5 m]
Tall Alder Thicket
DECIDUOUS (90%of canopy)FOREST [Deciduous Forest,75%of canopy]
Cottonwood Forest
Paper Birch Forest
MIXED (10-90%of Canopy)DECIDUOUS-CONIFEROUS FOREST [Mixed Conifer
and Deciduous Forest,25-75%of canopy]
White Spruce-Paper Birch Forest I
White Spruce-Paper Birch Forest II
CONIFEROUS (90%of Canopy)FOREST [Conifer Forest,75%of canopy]
White Spruce Forest
24
)
)
)
)
)
)
)
J
)
J
)
SCATTERED WOODLAND (~5 m high)AND DWARF FOREST «5 m high)
(Stunted growth of 0.2-20%canopy)
[Conifer and Deciduous Woodlands,
10-24%tree canopyJ
White Spruce Scattered Woodland
Black Spruce Dwarf Forest
There are two problems in the upper Susitna River Basin studies in using
the vegetative classification of Viereck and Dyrness (1980)to describe
avian habitats.One is the fact that their Tall Shrubland supports two
more or less distinct bird communities (medium and tall shrub birds of
Kessel [1979J).The other is that their definition of coniferous and
deciduous forests is not restricted enough for birds,since only about
10%of either vegetation type will attract the respective bird species
into these forests.
A brief description of each of the 10-ha study plots is provided below.
Table 2 presents a summary of the various habitat variables measured on
each of the 10-ha plots,and Table 3 gives the frequencies of shrub and
herb species in the ground cover of these ·plots.Generally,we have
used common names for the most important tree and shrub species
(Table 2)and major plant groups (e.g.,sedges,lichens),but only
scientific names for the less common species and ground cover plants.
Nomenclature follows Hulten (1968),except for willows,which follow
Argus (1973).
(a)Alpine Tundra
The Aipine Tundra plot contained three distinct avian habitats,all
typical of and widespread in the high country of the region:Dwarf
Shrub Meadow,Dwarf Shrub Mat,and Block-field (rock scree).Vegetation
.was all less than 0.4 m high,mostly less than 0.25 m.The Dwarf Shrub
25
u u u u u u u u u u \,.J
TABLE 2
SUMMARY OF VALUES OF HABITAT VARIABLES FROM EACH 10-HA INTENSIVE STUDY PLOT.UPPER SUSITNA RIVER BASIN.JULY-AUGUST 1980-81.SEE TABLE 1 FOR
DESCRIPTION OF METHODS.
Dwarf-Low Medium Low-Medium Tall White Spruce-1·lhite Spruce-White Black
Birch Birch Willow Alder Paper Paper Paper White Spruce Spruce
Alpine Shrub Shrub Shrub Shrub Cottonwood Birch Birch Birch Spruce Scattered Dwarf
Habitat variable Tundra Thicket Thicket Thicket Thicket Forest Forest Forest I Forest II Forest lIoodland Forest
GROUND COVER (X)
Grass 3.4 22.0 4.1 16.0 21.1 19.3 12.5 28.7 8.2 2.5 4.8 3.4
Se dge 34.6 3.3 7.3 37.7 0.1 0.7 0.0 0.0 0.7 0.0 1.0 8.9
Forb 3.5 3.0 0.7 3S.2 15.4 45.8 30.0 40.2 43.7 1.9 2.7 11.7
Microshrub «0.25 m)47.7 49.9 57.7 34.6 16.0 0.8 32.2 26.3 55.9 47.2 79.5 54.0
Litter 9.9 4.3 4.7 39.6 81.8 97.5 88.3 73.3 57.4 5.3 5.5 3.1
Moss 34.5 53.4 85.7 59.4 9.6 4.1 13.8 17.0 41.8 82.5 74.3 79.2
Lichen 41.9 47.3 9.8 0.0 0.2 0.0 0.6 0.5 0.4 25.7 3.1 9.6
lIater 3.0 0.0 0.8 4.4 0.0 0.0 0.0 0.0 0.0 0.0
0.3 1.9
Bare soil 16.3 2.3 1.1 0.0 6.4 9.4 6.2 7.7 0.0 0.1 0.2 1.I
N MICRORELIEF (m)0.23 0.27 0.37 0.25 0.13 0.22 0.32 0.28 0.30 0.24 0.32 0.33
'"
LITTER DEPTH (em)0.05 0.04 0.9 7.8 8.6 10.6 10.5 9.5 4.7 0.4 0.9 7.0
DIIARF SHRUB COVER «0.4 m)(X)53.4 54.0 61.8 44.4 27.7 1.7 38.4 7.5 58.2 60.6 81.5 64.3
LOW SHRUB COVER (0.4-1.1 m)(X)0.0 28.2 22.3 47.7 19.9 28.1 3.9 33.4 12.0 19.8 34.0 34.5
MEDIUM-TALL SHRUBS/SHRUB CLUMPS
(1.2-4.9 m)
Distance between shrubs (m)--(1.1)"1.5 4.6 3.6 1.4 5.1 2.7 3.7 5.9 2.0 2.5
Shrub height (m)--(0.5)1.4 1.3 3.8 2.6 3.7 3.2 2.4 2.8 1.5 2.9
Height to canopy bottom (m)----0.1 0.3 0.2 0.6 0.2 0.1 0.4 0.2 0.2 0.2
Canopy thickness (m)----1.3 1.1 3.6 2.0 3.5 3.1 2.0 2.6 1.4 2.7
Canopy area (m 2 horizontal
pI ane)----1.3 0.9 12.3 2.6 8.3 7.5 1.8 0.9 1.8 1.4
Shrub heterogeneity (100 SO/x)--(61.4)37.1 101.3 47.8 29.4 45.4 50.0 39.1 56.1 50.1 60.2
()()()u u u u u v v u
TABLE 2 (Continued)
Dwarf-Low Medium Low-Medium Tall flh ite Spruce-Wh ite Spruce-White Black
Birch Birch Willow Alder Paper Paper Paper White Spruce Spruce
Alpine Shrub Shrub Shrub Shrub Cottonwood Birch Birch Birch Spruce Scattered Dl'/arf
Habitat variable Tundra Thicket Thicket Thicket Thicket Forest Forest Forest I Forest II Forest Woodland Forest---TREES (>5.0 m)
Distance between trees (m)-------- --
6.2 5.6 8.0 3.8 4.6 20.6
Tree height (m)----------17.6 13.5 13.5
12.9 10.4
g.O
Height to canopy bottom (m)---- -- -- --
7.4 4.2 1.3 1.5 0.6 0.1
Canopy thickness (m)-- -- -- -- --
10.1 9.3 12.2 11.4 9.8 8.9
Tree diameter (m dbh)---- ------0.34 0.21 0.23 0.18 0.16 0.22
Tree heterogeneity (100 SO/x)------ --
--54.0 57.7 30.3 29.4 34.0 44.4
CANOPY COVERAGE (%)
Trees 0.0 0.0 0.0 0.0 0.0 56.5 55.0 25.5 57.5 19.5 3.0 1.5
Medium-tall shrubs 0.0 0.0 18.0 5.0 74.5 70.0 30.0 64.5 9.5 3.5 14.5 15.0
N Total (trees &shrubs)0.0 0.0 18.0 5.0 74.5 87.5 74.0 79.5 62.5 21.5 17.5 16.5
"
FOLIAGE DENSITY PROFILE (number
of coverboard squares contacted)
Woody stems:
0.0-0.4 m 5.6 44.7 62.3 57.8 46.1 53.0 35.7 43.1 38.5 53.2 59.8 54.1
0.6-1.0 m 0.0 5.3 58.0 40.0 34.0 47.7 27.0 38.7 16.5 20.9 51.5 29.6
1.6-2.0 m 0.0 0.0 2.7 0.0 44.1 37.0 27.0 42.9 16.9 15.0 8.7 15.3
3.5-3.9 m 0.0 0.0 0.1 0.0 40.5 42.3 29.4 36.1 21.3 15.5 2.5 7.7
Graminoid stems:
0.0-0.4 m 10.0 18.9 12.1 40.1 33.1 41.0 42.5 50.3 25.5 6.2 12.1 16.7
0.6-1.0 m 0.0 0.2 1.7 7.2 7.2 13.5 14.5 18.6 2.8 0.3 1.0 0.7
1.6-2.0 m 0.0 0.0
0.0 0.0 0.0 0.1 0.9 0.3 0.3 0.0 0.0 0.2
u u u u u u u u u u u
TABLE 2 (Continued)
Dwarf-Low Medium Low-Medium Tall White Spruce-White Spruce-White Black
Birch Birch Willow Alder Paper Paper Paper IIhite Spruce Spruce
Alpine Shrub Shrub Shrub Shrub Cottonwood Birch Birch Birch Spruce Scattered D\'/arf
Habitat variable Tundra Thicket Thicket Thicket Thicket Forest Forest Forest I Forest II Forest lIoodland Forest
Forb stems:
0.0-0.4 m 0.6 1.1 0.4 20.2 22.7 42.4 24.7 33.4 24.9 3.4 5.3 10.5
0.6-1.0 m 0.0 0.2 0.0 0.0 1.0 16.B 5.2 3.0 2.4 0.0 0.0 0.1
1.6-2.0 m 0.0 0.0 0.0 0.0 0.0 0.2 0.3 0.0 0.0 0.0 0.0 0.0
TREE HIPORTANCE VALUES
White spruce,Picea glauca 0 0 0 0 0 15 61 163 129 202 293 0
Black spruce,Picea mariana 0 0 0 0 0 0 0 0 2 90 7 0
Cottonwood,Populus
balsamifera 0 0 0 0 0 220 0 0 0 2 0 0
Quaking aspen,Populus
N tremuloides 0 0 0 0 0 0 9 0 0 0 0 0
0>lIillow,Salix spp.0 0 0 0 0 1 0 0 0 4 0 0
Paper birch,Betula ".
papyri fera 0 O.0 0 0 2 223 135 169 2 0 0
Alder,Alnus spp.0 0 0 0 0 62 7 2 0 0 0 0
14EOIUM-TALL SHRUB IMPORTANCE
VALUES
Ilhite spruce,Picea glauca 0 0 0 0 0 0 37 IB 91 lIB 0 B
Black spruce,Picea mariana 0 0 0 0 0 0 0 0 2 141.4 284
Ilillow,~spp.0 0 0 124 5 13 5 0 14 2 3 8
Shrub birch,Betula
glandulosa/hybrids 0 0 300 164 5 0 0 0 0 13 289 0
Paper birch,Betula
papyrifera 0 0 0 0 O.0 30 37 54 13 0 0
Alder,~spp.0 0 0 12 2B9 195 211 240 95 13 4 0
Raspberry,Rubus idaeus 0 0 0 0 0 2 0 0 0 0 0 0
u v
TABLE 2 (Continued)
v v u v v u v '-''-'
Dwarf-Low Medium low-Medium Tall White Spruce-White Spruce-White Black
Birch Birch Willow Alder Paper Paper Paper White Spruce Spruce
Alpine Shrub Shrub Shrub Shrub Cottonwood Birch Birch Birch Spruce Scattered Dwarf
Habitat variable Tundra Thicket Thicket Thicket Thicket Forest Forest Forest I Forest II Forest Woodland Forest
Alaska spiraea,Spiraea
beauverd i ana 0 0 0 0 0 0 0
5 '1 0 0 0
Greene mountain ash,
Serbus scopul ina 0 0 0 0 0 0 16 0 24 0 0 0
Prickly rose,Rosa
acicularis 0 0 0 0 0 0 0 0 5 2 0 0
Devil's club.E~hinopanax
horridum 0 0 0 0 0 20 0 0 0 0 0 0
High bush cranberry,
Viburnum edule 0 0 0 0 0 71 0 0 13 0 0 0
'"<0 TOTAL LENGTH OF EDGE (m)160 gO 233 IBO 0 0 0 0 90 79 0--
AVERAGE SLOPE (degrees)7.1 .2.2 5.4 6.0 22.2 0 21.8 20.B 0 1.0 5.0 1.0
MEAN ASPECT (degrees)311 150 215 356 143 0 159 144 0 276 195 16B
ELEVATION (m)1300 1100 900 B80 1200 180 600 600 260 520 820 730
*Low Shrubs
v v v v u <...'v u v v v
TABLE 3
FREQUENCIES (%)OF SHRUB AND HERB SPECIES IN THE GROUND COVER OF INTENSIVE STUDY PLOTS,UPPER SUSITNA RIVER BASIN,ALASKA,JULY-AUGUST 1980-81.BASED
ON OCCURRENCE IN 40 1.0 mx 1.0 m SAMPLE PLOTS LOCATED AT THE MAMMAL TRAPSITES ON LINES THREE AND FIVE OF THE 10-IIA STUDY PLOTS,EXCEPT ON THE ALPINE
TUNDRA AND DWARF-LOW BIRCH SHRUB THICKET PLOTS,WHERE THE 1.0 mx 1.0 m PLOTS WERE LOCATED AT THE SINGLE VEGETATION SAMPLING SITE IN EACH OF THE 49
SUBPLOTS OF THE 10-HA PLOT.
Dwarf-Low Medium Low-Medium Tall White Spruce-Wh ite Spruce-White Black
Birch Birch Willow Alder Paper Paper Paper
White Spruce Spruce
.Alpine Shrub Shrub Shrub Shrub Cottonwood Birch Birch Birch Spruce Scattered Dwarf
Plant species Tundra Thicket Thicket Thicket Thicket forest Forest Forest I Forest II Forest Woodland Forest
--
SHRUB
Alnus crispa 13 3
Andromeda polifolia 3
Arctostaphylos rubra 13 10 5
Betula glandulosa/hybrids 88 100 97 17 63 85 95
Cassiope tetragona 63
Cornus suecica/canadensis 70 95 33 93 73 100 53 100 15
w Diapensia lapponica 43
0 Dryas octopetala 53
Echinopanax horridum 33
Empetrum nigrum 94 100 67 3 7 40 37 100 97
Ledum palustre 6 29 97 20 16 6 85 97 93
Linnaea borealis 7 37 90 85 97 40 43
Loiseleuria procumbens 4 6
Oxycoccos microcarpus 3 3 45
Potent!lla fruticosa 10 3 3
Ribes glandulosum 7 55
Ribes triste 57 27 10
Ribes spp.25
Rosa acicularis 10 27 33 3 10 55 27 17
Rubus idaeus 5 30 5 40
Salix arctica 73 45
Sa 1i x bebbi ana 3
S.myrtillifolia 3
S.novae-angliae 3
S.planifolia I1018973 20
S.reticulata 28 2 40 3 3
Salix spp.14 15 5 3 5 33
u u u u u u u ,;;u u u
TABLE 3 (Continued)
Dwarf-Low Medium Low-Medium Tall White Spruce-Wh i te Spruce-White Black
Birch Birch Willow Alder Paper Paper Paper
White Spruce Spruce
Alpine Shrub Shrub Shrub Shrub Cottonwood Birch Birch Birch Spruce Scattered Dwarf
Plant species Tundra Thicket Thicket Thicket Thicket Forest Forest Forest I Forest II Forest Woodland Forest
I
Sorbus scopulina 2
Sp1raea beauverdfana 8 85 27 33 55 27 65 60 17
Vaccinium ovalifolium 3
Vaccinium uliginosum 55 96 40 63 27 17 55 50 97 100
Vaccinium vitis-idaea 33 94 100 57 35 43 13 92 100 97 100
Viburnum edule 10 3 55 7 10
FORB
Achillea spp.40 3 6
Aconitum delphinifolium 30 13 5
w Actaea rubra 17.....Anemone spp.45 82 35
Antennaria sp.6
Arnica latifolia 3
Art~nisia arctica 2 24 20 20
Artemi s ia sp.33
Boykinia richardsonii 12
Campanula lasiocarpa 2
Ci rcaea a1pi na 3
Delphinium glaucum 5
Dodecatheon frigidum 2
Epilobium an9ustifolium 23 93 47 13 50 47 7 17
Erigeron·peregrinus 10
Gal ium boreale 23 3 3
Gal ium tri fidum 90
Gentiana spp.12 29 23
Geocaulon lividum 5 20
Geranium erianthum 3
Geum rossi i 6
Hedysarum alpinum 10
Heracleum lanatum 10
u v v u v v u v v v u
TABLE 3 (Continued)
Dwarf-Low Medium Low-fled i um Tall Wh ite Spruce-White Spruce-White Black
Birch Birch Will ow Alder Paper Paper Paper White Spruce Spruce
Alpine Shrub Shrub Shrub Shrub Cottonwood Birch Birch Birch Spruce Scattered Dwarf
Plant species Tundra Thicket Thicket Thicket Thicket Forest Forest Forest 1 Forest II Forest Woodland Forest
Hieracium gracile 35
Listera cordata ID 17
Lloydia serotina ID
Lupinus nootkatensis 7
Mertensia paniculata 55 35 2D ID 15
Oxytropis nigrescens 10
Parrya nudicaulis 22 ID
Pedicularis spp.36 12 3 33 5 5
Petasites hyperboreus 27 ID 3 43
Platanthera dilitata 3
w Polemonium acutiflorum 57 23 3 7
N Polygonum bistorta 24 6
Potentilla palustris 20 3
Pyrola spp.4 2 5 27 83 10 7 50 3 15 3
Ranunculus sp.3
Rubus arcticu5 17 30 5 5 10
Rubus chamaemorus 47 83 5 17 7 35 75
Rubus pedatus 83 70 95
Rumex arcticus 10 7
San9uisorba stipulata 3 73 ID 45 ID
Saussurea angustifolia 7
Saxifraga spp.10
Sedum ro'sea 7
Senecio spp.8 13 3
Solidago multiradiata 2 5 10 3
Stellaria spp 10 7 ID 5
Streptopusamplexifol ius 3 60 5 7
Thalictrum sparsiflorum 3
Thalictrum alpinum 40
Trientalis europaea 3 10 17 27 90 80 65 3
Valeriana capitata 2 15
(J \..;u u u u u u u v u
TABLE 3 (Continued)
Dwarf-Low Medium Low-fledi um Tall White Spruce-White Spruce-White Black
Birch Birch Willow Alder Paper Paper Paper White Spruce Spruce
Alpine Shrub Shrub Shrub Shrub Cottonwood Birch Bi rch Birch Spruce Scattered Dwarf
P1~nt species Tundra Thicket Thicket Thicket Thicket Forest Forest Forest r Forest II Forest Uood1and Forest
-
GRASS
Calamagrostis canadensis B3 B7 80 95 95 15 23 7
Deschampsia spp.7 57
Festuca a1 taica 2 51
Hierochloe a1pina 59 53
Grass.unidentified 6 77 93 57 10
SEDGE
Carex microchaeta 88 59
Carex spp.6 65 5 5 5 5 15 85
w Eriophorum ca11atrix 6wEriophorumsp.3
Sedge.unidentified 6 100 12
.
HORSETAIL
Equisetum spp.7 95 17 70 20 73 50 27 43 40
FERN
Dryopteris di1atata 47 17 40 2
Gymnocarpium dryopteris 55 33 60 67
Natteuc·cia struthiopteris 7
The1ypteris phe90pteris 7
CLUB MOSS
Lycopodium spp.10 17 20 3 50 33 100 7 20 3
Se1a9ine11a sibirica 8
MOSS 98 98 100 100 77 83 97 95 97 100 100 100
LICHEN 90 100 100 15 63 3 35 35 7 97 100 83
)
)
)
)
)
)
}
}
Meadow was dominated by Carex microchaeta and contained significant
quantities of dwarf shrub (up to 50%of ground cover),primarily
Cassiope tetragona,Dryas octopetala,Salix arctica,~.reticulata,
Vaccinium uliginosum,and some~.planifolia.The drier Dwarf Shrub Mat
habitat was dominated by mosses (Pleurozium schreberi and Polytrichum
commune),fruticose lichens,and Cassiope tetragona,with considerable
Carex microchaeta and Dryas octopetala and some Vaccinium uliginosum.
The block-field habitat was predominantly rock detritus,with varying
amounts of crustose and fruticose lichens (20-40%cover)and mosses (up
to 60%cover).The plot was on a northwest-facing terrace,sloping an
average of 7°,on a north shoulder of r~t.Watana at 62°44'37"N,
148°05'42"W,and.at about 1300 m (4300 ft)elevation.
The vegetation reflected the harsh environmental conditions at this
plot.In 1981,an extensive snowbank still covered the southern edge of
the plot on 15 May and lasted most of the summer.Vegetation began to
turn green rapidly on 29 May,after a rain,although a few plants were
in bloom earlier.High winds were frequent,and a cold snap during the
second week of June brought nightly temperatures to _4°C.Fresh snow
blanketed the plot with a 10 cm layer on 9 June,and about 7 cm fell
again 28-30 June and may have been responsible for nesting failures.
By late July,vegetation was already browning again;and,beginning on
14 August,regional precipitation fell mostly as autumnal snows at this
high elevation.
(b)Dwarf-Low Birch Shrub Thicket
The plot consisted of a relatively uniform stand of shrub birch (Betula
glandulosa/nana),with interspersed open patches where snow lingered in
spring.Average shrub height was 0.5 m.The ground cover was fairly
uniform throughout,even in the open patches;it was dominated by micro-
shrubs (Empetrum nigrum,Vaccinium vitis-idaea,~.uliginosum),moss,
and fruticose lichens.Birch and moss generally contributed less and
34
J
J
J
J
J
)
)
grass (Hi erochl oe al pina and Festuca altaica)more to the ground cover
in the open patches than in the shrubby areas.The plot was located on
a 4°south-southeast-facing slope near the top of a dry,broad knoll
east of Kosina Creek,at 62°42'47"N,147°53'50"W,and at 1100 m
(3600 ft)elevation.
(c)Medium Birch Shrub Thicket
A dense,homogeneous stand of 1.4 m-high shrub birch characterized this
plot.Ground cover consisted of thick moss and a dense mat of micro-
shrubs,especially Empetrum nigrum,Vaccinium vitis-idaea,Ledum
palustre,and lesser amounts of Spiraea beauverdiana.The plot was
along a broad,relatively dry ridge that sloped slightly to the
southwest.It was located west of Tsusena Creek,at 62°52'17"N,
148°37'05"W,and at 900 m (3000 ft)elevation.
(d)Low-Medium Willow Shrub Thicket
Although a rather heterogeneous plot,the vegetation was dominated by
willow,primarily Salix planifolia pulchra and 1.barclayi.Dense low
shrubs,predominantly willow,occurred throughout the plot,with inter-
spersed wet sedge meadow openings present on the upper third of the
plot.Medium-height shrubs of shrub birch and willow grew on the lower
two-thirds of the plot.Ground cover consisted of about equal percent-
ages of microshrubs (especially Cornus sp.,Empetrum nigrum,Vaccinium
uliginosum,and 1.vitis-idaea,with lesser amounts of Salix
reticulata),sedges,many species of forbs (including relatively high
frequencies of Eguisetum arvense,Rubus chamaemorus,~anguisorba
stipulata,Polemonium acutifolium,and Mertensia paniculata),and
litter.The substrate was moist to wet,and the above-mentioned ground
cover vegetation was underlain by moss.The plot was on the north-
facing 6°slope of a draw west of Tsusena Creek,at 62°51'10"N,
148°45'50"W,and at 880 m (2900 ft)elevation.
35
)
)
)
)
)
)
)
)
)
)
)
(e)Tall Alder Shrub Thicket
The plot was dominated by dense,tall Sitka alder (Alnus crispa
sinuata),averaging 88 yr old (oldest 158 yr)and 3.6 m in height.The
upper half to two-thirds of the plot was dense alder,whereas the lower
portion had some openings and intrusions of small groups of white spruce
trees (x=60 yr;oldest 134 yr).Ground cover was predominantly leaf and
grass litter,with moderate amounts of dwarf and microshrubs (Linnaea
borealis,Vaccinium vitis-idaea,Spiraea beauverdiana,Cornus sp.,
1.uliginosum,Rosa acicularis,and Ribes spp.),grass,and forbs.The
plot was on a steep,southeast-facing slope east of Watana Creek,at
62°50'40"N,147°59'00"W,at approximately 1200 m (4000 ft)elevation.
(f)Cottonwood Forest
A dense stand of tall,mature cottonwoods or balsam poplar (Populus
balsamifera),averaging 133 yr old (oldest 176 yr),17.6 m tall,and
34 cm dbh,dominated this plot.The forest was homogeneous,except for
an old,overgrown river channel that intruded into the northern edge,
resulting in a narrow strip of only dense alder and no trees.There was
a two-level understory--an alder (Alnus spp.)layer with a canopy top at
about 6 m,and a medium shrub layer of high bush cranberry (Viburnum
edule)and devil 's club (Echinopanax horridum).A 28%low shrub cover
consisted primarily of Ribes triste,Rosa acicularis,and Rubus idaeus;
and the g~ound cover was composed of more than 97%litter and many
forbs,most commonly Galium trifidum,Pyrola spp.,Streptopus
amplexifolius,and Epilobium angustifolium.Eguisetum spp.and the
ferns Dryopteris dilatata,Gymnocarpium dryopteris,and Matteuccia
struthiopteris were frequent,and there were many fallen logs.The plot
was located on the Susitna River floodplain near Sherman,at
62°42'10"N,149°49'45"W,and at 180 m (600 ft)elevation.
36
)
)
)
)
)
)
)
)
)
)
)
(g)Paper Birch Forest
The plot was composed predominantly of mature paper birch (Betula
papyrifera)that averaged 66 yr old (oldest 90 yr),13.5 m tall,and
21 cm dbh,although patches of white spruce (x=101 yr,oldest 194 yr)
intruded into the southwest corner.There were patches of heavy under-
growth of tall alder,and this was one of only two plots in which Greene
mountain ash (Sorbus scopulina)occurred.The forest floor had a high
cover (88%)of litter,and a moderate cover (30 and 38%,respectively)
of forbs and of dwarf and microshrubs,including Cornus sp.,Linnaea
borealis,Spiraea beauverdiana,and Vaccinium vitis-idaea.The plot was
on a steep south-southeast-facing,rocky,terraced slope,with rock
cliffs 3 m to 6 m high.It was located on the north wall of the Susitna
River canyon 8 km downstream from Devil Creek,at 62°48'46"N,
149°11'30"H,arid at 600 m (2000 ft)elevation.
(h)White Spruce-Paper Birch Forest I
An open,uniform stand of mature white spruce (Picea glauca)and paper
birch (Betula papyrifera)dominated this mixed deciduous-coniferous
forest.The spruce trees were older and larger than the birch,the
former averaging 139 yr old (oldest 185 yr),14.3 m tall,and 24 cm dbh
and the latter averaging 103 yr old (oldest 145 yr),11.3 m tall,and
20 cm dbh.Similar to the deciduous forest plots,this one had a dense
undergrowth of tall alder.There was a moderate cover (33%)of low
shrubs (especially Ribes spp.,Rubus idaea,and Spiraea beauverdiana)
and microshrubs (Cornus sp.,Linnaea borealis,and Vaccinium vitis-
idaea).Ground cover was dominated by litter,with lesser amounts of
forbs,especially,as in the paper birch forest,Trientalis europaea and
Rubus pedatus.The ground cover had the highest percentage of grass of
any 10-ha plot,28.7%.The plot was located a little northeast of the
Paper Birch Forest plot and was on a steep slope of a tributary drainage
on the north side of the Susitna River (62°49'10"N,149°08'25"W,600 m
[2000 ft]elevation).
37
)
)
)
)
)
)
)
)
)
)
)
(i)White Spruce-Paper Birch Forest II
Paper birch and white spruce dominated this mature mixed forest also,
but in this stand the birch,even though younger,were larger than the
spruce.The birches averaged 73 yr old (oldest 98 yr),14.0 m tall,and
22 cm dbh,and the spruce averaged 126 yr old (oldest 140 yr),12.2 m
tall,and 16 cm dbh.Tree density and canopy coverage were twice those
in Mixed Forest I and,concomitantly,the heavy understory of alder
found in Mixed Forest I was absent in Mixed II.In fact,except for the
dwarf shrub layer «0.4 m),which exceeded that of Mixed I,other shrub
layers lacked the coverage and density of Mixed I.The dominant ground
cover species,both woody and herbaceous,were similar in the two mixed
plots,although Mixed II had a higher moss cover and higher frequencies
of Cornus sp.,Vaccinium spp.,Pyrola secunda,Rubus pedatus,and
Lycopodium annotinum.The plot was located on a flat terrace on the
south bank of the Susitna River,at 63°49'05"N,149 0 32'26"W,and at
260 m (850 ft)elevation.
(j)White Spruce Forest
Mature white spruce trees (Picea glauca)dominated this plot,but a few
black spruce (Picea mariana)were scattered throughout and increased in
frequency toward the southwest corner.The white ~pruce averaged 127 yr
.old (oldest 145 yr),10.1 m tall,and 19 cm dbh,whereas the black
spruce averaged 83 yr old (oldest 122 yr),8.1 m tall,and 12 cm dbh.
There were many dead spruce snags of both species standing on the plot,
with an average distance between snags of 11.3 m.Thirteen snags with
complete tops and identifiable as white spruce averaged 13.3 m tall,and six
identifiable as black spruce averaged 10.8 m tall.Many small spruce
indicated continued regeneration by both species.The deciduous shrub
understory consisted primarily of shrub birch,paper birch,and alder •.
Ground cover was predominantly moss,with considerable interlacing of
lichens and of dwarf and microshrubs,especially Vaccinium vitis-idaea,
38
)
)
)
Ledum palustre,Cornus sp.,and 1.uliginosum.
absent.The plot was located on an old outwash
Kosina Creek,at 62°47'00"N,147°57'16"W,and
elevation.
(k)White Spruce Scattered Woodland
Litter was essentially
plain at the mouth of
at 520 m (1700 ft)
)
)
)
)
)
)
J
)
The dominant trees on the plot were mature,but relatively short,white
spruce (Picea glauca),averaging 146 yr old (oldest 310 yr),9.0 m tall,
and 22 em dbh.They were widely scattered throughout the plot,becoming
somewhat denser toward the southeast corner;average distance between
trees was 20.6 m.Amid the spruce was a relatively dense medium and
low shrub cover of shrub birch,averaging about 1.5 m high.Beneath
this layer was a dense'cover (80%)of dwarf and microshrubs,especially
Cornus sp.,Empetrum nigrum,Ledum palustre,Vaccinium uliginosum,and
1.vitis-idaea,and a relatively high ground cover of moss.The plot
was located on a south-southwest-facing slope just north 'of the mouth of
Tsusena Creek,at 62°51'47"N,148°35'50"W,and at 820 m (2700 ft)
elevation.
(1)Black Spruce Dwarf Forest
An open stand of stunted black spruce (Picea mariana)composed this
plot.The spruce averaged 80 yr old (oldest 98 yr),but averaged only
2.9 m high and 4 em dbh (and hence are treated as "shrubs"in Table 2).
They were somewhat clumped in distribution and became more dense toward
the west edge of the plot.There was a moderate cover (35%)of low
shrubs,composed mostly of shrub birch and black spruce,and a denser
cover (64%)of dwarf shrubs,primarily Vaccinium uliginosum,1.vitis-
idaea,Empetrum nigrum,Ledum palustre,and shrub birch.The predomi-
nant ground cover was moss (79%).There was an extensive area of water
seepage through this slightly sloping plot and some hummocky ground.
The plot was located in the Fog Lakes area,at 62°47'48"N,
148°28'15"W,at 730 m (2400 ft)elevation.
39
)
)
)
)
)
)
)
)
)
)
)
3.2 -Species Composition and Relative Abundance
To date,135 species of birds have been recorded in the upper Susitna
River Basin study area.A complete annotated list of these species is
included in Section 3.7.The relative abundance of these species (see
Tables 4-7)is largely a function of habitat availability,with Common
Redpoll,Savannah Sparrow,White-crowned Sparrow,Lapland Longspur,and
Tree Sparrow being the most abundant species.Redpolls are habitat
generalists,while the other abundant species are birds of the shrublands
(dwarf,low,and medium shrubs),vegetation types that cover 70%of the
region (Plant Ecology report,APA 1982).
Fifteen species are ranked as rare in the region on the basis of current infor-
mation:four raptors (Osprey,American Kestrel,Snowy Owl,Boreal Owl),three
.species of prairie ducks (Gadwall,Blue-winged Teal,Ring-necked Duck),four
shorebirds (Upland Sandpiper,turnstone sp.,Surfbird,Sanderling),three small
land birds (Black-backed Three-toed Woodpecker,Western Wood Pewee,Yellow
Warbler),and Ruffed Grouse.Most of these birds are at the periphery of their
geographic ranges,although lack of appropriate habitat may limit a few.All
are represented,however,by larger populations in other portions of Alaska.
An Eastern Kingbird on 11 July 1980 is considered accidental in the
region.In Alaska this species is a regular visitant only in South-
eastern;it is casual elsewhere in the state (Kessel and Gibson 1978).
3.3 -Breeding Bird Densities
Avian population levels varied greatly among the different habitats
(Table 8),as,of course,did the level of use of each habitat by dif-
ferent species (Table 9).The presence or absence of a given species in
a habitat is largely a function of species'habitat preferences,but
habitat occupancy levels are affected by a number of factors,including,
in interior AJaska,habitat strUctural complexity and primary produc-
tivity (Spindler and Kessel 1980).
40
u
TABLE 4
v u v u v u u u u v
iRELATIVEABUNDANCEOFLOONS,GREBES,AND WATERFOWL,UPPER SUSITNA RIVER BASIN,ALASKA.BASED PRIMARILY ON TOTAL NUMBER OBSERVED ON 198D AND 1981
AERIAL SURVEYS AND 1981 GROUND SURVEYS.
Sprin9 Mi9ration Fall Migration
(Aerial &Ground,(Aerial:7 Sept-3 Oct 8D Summer
1981)15 Sept-23 Oct 81}(Ground,1981)
110.Species No.Species No.Species
802 Scaup spp.
}COf1MON
2658 Scaup spp.}COMMON 94 Scaup (incl.41 L,27 G)
394 Mallard 81 White-winged Seater
366 Pintail 905 Mallard (incl.flock of 65)
874 American Wigeon 60 Pintail
262 Pmeri can Wi gean 718 Goldeneye spp.FAIRLY COMMON 59 Trumpeter Swan*
215 Green-winged Teal 551 Seater spp.55 01 dsquaw
210 Seater spp.FAIRLY COMMON 514 Bufflehead 47 Mallard
140 Goldeneye spp.33 Surf Seater
102 01 dsquaw 299 Mer9anser spp.32 American Wigeon
277 Swan spp.28 Green-winged Teal
"""52 Mer9anser spp.233 Pintail 26 Black Seater......
51 Snow Goose (=1 flock)142 Green-winged Teal 25 Cornman Loon.
46 Canada Goose 111 01 dsquaw 24 Harlequin Duck
43 Northern Shoveler 71 Canada Goose UNCOMMON
43 Swan spp.35 Horned Grebe (1980)16 Northern Shoveler
31 Redhead 33 Red-necked Grebe 11 Red-breasted Mer9anser
23 Buffl ehead 28 Northern Shoveler 8 Red-throated Loon
11 COlTVllon Loon UNCOf·IMON 17 Conunon Loon 8 Barrow's Goldeneye
8 Arctic Loon 7 Red-necked Grebe
6 White-fronted Goose 14 Ring-necked Duck (1980)J.7 Common Goldeneye
5 Red-necked Grebe 1 8lue-winged Teal (1980)RARE 5 Ilorned Grebe
4 Canvasback 5 Common Merganser
3 Red-throated Loon 4 Arctic loon
3 Horned Grebe
3 Blue-winged Teal
}RARE3Gad"a 11
2 Rin9-necked Duck
*40 fr~n aerial survey
FAIRLY COflMON
UNCOMHON
)
)
)
42
J
TABLE 6
)
RELATIVE ABUNDANCE OF SHOREBIRDS AND GULLS,UPPER SUSITNA RIVER BASIN,
ALASKA.BASED PRIMARILY ON TOTAL NUMBER OBSERVED 17 APRIL-23 OCTOBER 1981,
BUT SUPPLEMENTED BY DATA FROM LATE SUMMER AND FALL 1980 FOR RARE SPECIES.
J No.Species
163 Mew Gull
146 American Golden Plover
)114 Common Snipe COMMON
103 Spotted Sandpiper
78 Northern Phalarope
)69 Arctic Tern
58 Lesser Yellowlegs FAIRLY COMMON
55 Long-tailed Jaeger
51 Least Sandpi per
)
44 8onaparte's Gull
34 Baird's Sandpiper
22 Semipalmated Plover
)20 Herring Gull
19 Greater Yellowlegs
17 Whimbrel UNCOMMON
12 Semipalmated Sandpiper
)09 Wandering Tattler
09 Pectoral Sandpiper
06 Solitary Sandpiper
03 Long-billed Dowitcher
)
06 Upland Sandpiper (1980)
02 Turnstone sp.
01 Su rfbi rd (l980 RARE
01 Sanderling (1980)
43
v v v v v v '-'v v v v
TABLE 7
RELATIVE ABUNDANCE OF SI1ALL LANDBIRDS,UPPER SUSITNA RIVER BASIN,ALASKA.BASED PRIMARILY ON TOTAL NUMBER OBSERVED 17 APRIL-23 OCTOBER 1981,
SUPPLEMENTED BY DATA FROM LATE SU~I~IER AND FALL 19BO FOR THE LESS NUMEROUS SPECIES.
1161 Common Redpoll
669 Savannah Sparrow
631 llhite-cra>med Sparrow
588 Lapland Lon9spur
5B3 Tree Sparrow
420 Horned Lark
398 Dark-eyed Junco
343 Ruby-crowned Kinglet
316 Yellow-rumped Warbler
288 Water Pipit
~258 Varied Thrush
~257 Gray Jay
249 Wilson's Warbler
225 Bohemian Waxwing
211 American Robin
195 Hermit Thrush
179 White-winged Crossbill
163 Fox Sparrow
146 Swainsonls Thrush
145 Blackpoll Warbler
129 Boreal Chickadee
98 Snow Bunting
71 Arctic Warbler
64 Tree Swa 11 ow
62 Violet-green Swallow
55 Northern Waterthrush
54 Gray-cheeked Thrush
No.Specie's
ABUNDANT
COMMotl
FAIRLY COMMON
No.Species
53 Bank Swallow
46 Cliff Swallow
45 Gray-crowned Rosy Finch
42 Black-capped Chickadee
41 Golden-crowned Sparrow
35 Lincoln's Sparrow
33 Rusty Blackbird
29 Dipper
26 Pine Siskin
23 Northern Three-toed Woodpecker
23 Wheatear
22 Black-billed Magpie
16 Belted Kingfisher
16 Olive-sided Flycatcher
14 Alder Flycatcher
13 Common Flicker
11 Brown Creeper
10 Hairy Woodpecker
10 Orange-crowned Warbler
09 Pine Grosbeak
05 Say's Phoebe
02 Townsend's Solitaire (+4 in 1980)
03 Northern Shrike (+27 in 1980)
02 Smith's Longspur (+5 in 1980)
01 Downy Woodpecker (+8 in 1980)
01 Golden-crowned Kinglet (+11 in 1980)
UNCOMMON
No.Species
I Black-backed Three-toed
Woodpecker (1980)
4 Western Wood Pewee (1980)
2 Yellow Warbler (+3 in 1980)
1 Eastern'Kingbird (1980)
}..
}-ACCIDENTAL
)
TABLE 8
)AVIAN HABITAT OCCUPANCY LEVELS,UPPER SUSITNA RIVER BASIN,
BREEDING SEASON,1981
Density
No.species (No.Biomass Species
)(No.breeding territories/(Grams/diversity
Avian Census Plot species)10 hal 10 hal (H ')
Cottonwood Forest 21(16)60.9 3653 2.55
White Spruce-Paper
)Birch Forest II 22(13)34.6 1836 2.07
White Spruce-Paper
18(14)Birch"Forest I 41.8 1709 2.47
Paper Birch Forest 18(10)38.1 1814 2.05
)
Wh ite Spruce
Scattered Woodland 23(16)43.8 1775 2.29
Black Spruce
Dwarf Forest 23(13)24.8 1166 2.43
)
Low-Medium
Willow Shrub 14(6)45.4 1413 1.56
White Spruce Forest 18(8)15.7 1059 1.83
)Medium Birch Shrub 10(5)32.5 952 1.48
Ta 11 Al der Shrub 15(10)12.5 888 2.05
Dwarf-Low Bi rch
)
"Shrub 11(6)10.6 355 1.29
Alpine Tundra 8(7)3.9 211 1.73
)
)
45
)
v v v v v v v v 'wi v v
TABLE 9
NUMBER OF TERRITORIES OF EACH BIRO SPECIES ON EACH 10-HECTARE CENSUS PLOT,UPPER SUSITNA RIVER BASIN,ALASKA,19BI.(+=SMALL PORTION OF A BREEDING
TERRITORY ON CENSUS PLOT,COUNTED AS 0.1 IN DENSITY AND DIVERSITY CALCULATIONS;V =VISITOR TO PLOT.)
Dwarf-Low Medium Low-Medium Tall Wh 1te Spruce-White Spruce~Whi te Black
Birch Birch Willow Alder Paper Paper Paper White Spruce Spruce
Alpine Shrub Shrub Shrub Shrub Cottonwood 81 rch Birch Birch Spruce Sea ttered Dwarf
Species Tundra Thicket Thicket Thicket Thicket Forest Fares t Forest I Forest Jl Fares t Woodland Forest
---
Pintail v
Goshawk v v
r·larsh Hawk v
Spruce Grouse v v v 1.0 I.D v v
Ruffed Grouse +
Willow Ptarmigan 0.5 v v
Rock Ptarmigan 0.7
White-tailed Ptanmlgan +
~American Golden Plover v
Greater Yel10wlegs +
Canman Sn i pe v v 0.5 1.0
Baird's Sandpiper 0.8 v
Long-tailed Jaeger v
Short-eared Owl v v
Convnon Fl icker v
Hairy Woodpecker 1.0 1.0
Downy Woodpecker 0.5
N.Three-toed Woodpecker v 0.3 1.0 v v..,.Alder Flycatcher 1.0en01fve-sided Flycatcher v v
Horned lark 0.3 v
Tree Swa 11 ow v v v
Gray Jay 1.0 v 0.5 0.5 1.0 +v
Black~bil1ed Magpie v
CO/OOlon Raven v
Black-capped Chickadee 1.8 v v v
Boreal Chickadee v 1.7 1.0 v v 1.0
Brown Creeper 2.0 1.0
American Rob;n 0.5 v v 0.5 0.5
Varied Thrush 1.5 10.0 3.5 2.5 3.3 2.9 v v
Henni t Thrush 2.2 v 6.1 3.8 v
Swa foson IS Thrush 6.9 5.5 5.4 8.0 3.0 v v
Gray-cheeked Thrush 3.8 v v 3.9 2.5
Arctic Warbler 4.8 3.6 2.8
Ruby-crowned Kinglet v v 3.3 1.0 4.2 0.8 4.0
Water Pipit 0.5
Bohemian Waxwing v
Orange-crowned Warbler v
Yel1ow-rumped Warbler +7.0 9.8 7.5 9.5 I.D 0.8 2.5
Blackpoll Warbler v 4.4 3.9 1.8 0.5 2.0 1.5
..Northern Waterthrush 6.1 +2.5 v
Wilson's Warbler 8.8 9.2 1.2 4.0 3.8 4.0 9.4RustyBlackbird vCOll1T1oflRedpollv v 1.5 v 2.5 2.0 2.0 3.0 v 0.5 1.0PineSiskinvvWhite-winged Crossbill v v v v v v vSavannahSparrow1.0 5.8 3.0 12.3 v 2.5 0.8Dark-eyed Junco 2.8 1.8 2.5 3.9 4.5 2.5 2.0 2.0TreeSparro~1 2.5 11.8 15.0 1.5 7.9 2.6White-crowned Sparrow 0.3 4.1 3.8 +3.5 6.5 2.5FoxSparrowv1.6 4.6 1.0 1.9 v 3.5 2.9Lincoln's Sparrow v
Lapland longspur 1.0 0.8
Snow Bunting 0.2
}
}
)
}
J
)
}
)
)
)
)
Generally,in the upper Susitna River Basin,the forest and woodland
habitats ·supported higher densities and/or biomasses of birds than the
shrub communities.Highest densities in forests were found at the
downstream (Sherman)Cottonwood Forest plot,which supported 60.9 bird
territories/l0 ha,and lowest densities were found in the White Spruce
Forest plot at the mouth of Kosina Creek (15.7 territories/l0 hal.Of
the shrub habitats,Low-Medium Willow Shrub had the highest densities
(45.4 territories/l0 hal and Dwarf Shrub-Alpine Tundra the lowest (11
territories/l0 hal.Bird density was also low in Tall Alder Shrub (12.5
territories/l0 hal.Alpine tundra areas of upland cliffs and block-fields
and of mat and cushion tundra had the lowest bird usage,but supported
some bird species generally not found in other habitats,e.g.,White-tailed
Ptarmigan,Horned Lark,Wheatear,Water Pipit,Gray-crowned Rosy Finch,
and Snow Bunting.
Preliminary comparisons between occupancy levels in habitats of the'
upper Susitna River Basin and those in similar habitats in the upper
Tanana River Valley (Spindler and Kessel 1980)show many parallels.In
both regions Paper Birch Forest and the Mixed Deciduous-Coniferous
Forest supported intermediate levels of bird populations and Coniferous
Forest the lowest.The Scattered Woodland and Dwarf Forest habitats,
with their openness and added shrub components,also supported inter-
mediate occupancy levels,however,even with major coniferous components.
The lower-height shrub thickets had low numbers of species,apparently
because of relatively simple habitat structure,and there were dif-
ferences in occupancy levels between plots with a dry substrate and ones
with high substrate moisture.Habitat diversity and a wet substrate
probably allowed higher occupancy levels on the Susitna Low-Medium
Willow Shrub plot compared to other shrub plots.
The most conspicuous difference between the upper Susitna and Tanana
valleys was in the Tall Shrub Thickets.Tall shrubs in interior Alaska
supported the highest avian occupancy levels of any habitat (Spindler
47
)
)
)
)
)
)
J
)
)
)
and Kessel 1980),but,unlike in the Susitna study area,these thickets
were dominated by willow,thinleaf alder (Alnus tenuifolia),and balsam
poplar (Populus balsamifera),which have average to above average levels
of primary productivity.The tall shrub thickets of the Susitna study
area were composed almost entirely of Alnus crispa,which has relatively
low levels of primary productivity (Spindler and Kessel 1980)and which,
in interior Alaska and on the Seward Peninsula,also supports relatively
few birds (Kessel,pers.obs.).
3.4 -Waterbird Use of Wetlands
(a)Summer Populations
The wetlands of the region supported relatively few waterbirds during
the summer,both in respect to number of species and number of indivi-
duals.The relative abundance of loons,grebes,and waterfowl as deter-
mined from all observations is shown in Table 4.The number and density
of adults and broods of waterbirds observed during the intensive ground
surveys of 28 ponds and lakes during July 1981 are shown in Table 10.
The density of adult birds derived from the intensive ground survey of
20.5 km 2 of wetlands was 23.8 adults/km 2•By comparison,a similar
census of 13 of the more productive waterbodies of the upper Tanana
River Valley,east-central Alaska,in 1977 and 1979 showed,respec-
tively,183.3 and 110.9 adults/km 2 of wetlands (Spindler et al.1981)*•
..'The number of broods was correspondingly low,with 2.9 broods/km 2 of
wetlands in the upper Susitna River Basin in 1981,
*Regional comparisons of densities obtained by the waterbody census
method can only be made if the distribution of waterbody size classes is
similar between regions (Spindler et al.1981),which was the case for
the sets of sampled waterbodies used here.
48
)
)
TABLE 10
NUMBER OF ADULT WATERBIRDS (OR 2INDEPENDENT YOUNG)AND BROODS FOUND ON 28
WATERBODIES (TOTAL =20.5 KM OF WETLANDS),UPPER SUSITNA RIVER BASIN,
ALASKA,JULY 1981.ARRANGED IN DECREASING ORDER OF ADULT NUMBERS.
)
)
)
)
)
)
}
)
)
Species
White-winged Scoter
Arctic Tern
01dsquaw
Mew Gull
Lesser Scaup
scaup sp.
Surf Scoter
B1 ack Scoter
scoter sp.
Greater Scaup
Northern Phalarope
Common Loon
Trumpeter Swan
Mall ard
Red-throated Loon
American Wigeon
Red-necked Grebe
Pintail
Northern Shoveler
Go1 deneye·sp.
Horned Grebe
Bonaparte I s Gull
Bald Eagle
Arctic Loon
Green-winged Teal
Red-breasted Merganser
Merganser sp.
TOTAL
No./km 2
No.adults
81 (incl.flock 65)
48
47
43
36
9
33
26
6
25
23
22
16
10
8
8
7
7
7
6
5
5
3
2
2
1
1
487
23.8
49
No.broods
o
o
11
7
4
1
2
11
1
o
o
3
1
1
o
6
1.
2
1
1 (=Common)
5
o
o
o
1
1
o
60
2.9
)
)
)
)
)
)
)
)
)
)
)
compared to an average of 6.2 broods/km 2 in the upper Tanana River
Valley (ibid.).Productivity in the eastern portion of the upper Tanana
River Valley study area in 1979 was 30-40%lower than historically at
Minto lakes and the Yukon Flats (Kessel et al.1980).Minto lakes,
Tetl in lakes,and portions of the Yukon Flats are considered among the
most productive wetlands in Alaska (J.G.King,U•.S.Fish and Wildlife
Service,pers.comm.).Thus,the waterbodies of the upper Susitna River
Basin appear to support a relatively impoverished population of water-
fowl during the summer.
The species composition of waterfowl in the region showed some differ-
ences from that of central Alaska as a whole,in part reflecting the
subalpine nature of much of the study area.Oldsquaw and Black Scoter
were the most productive of the waterfowl in 1981 (Table 10).Both
species are primarily tundra nesters,and the Alaska Range is the only
inland nesting location known for the Black Scoter in Alaska (Gabrielson
and lincoln 1959).On the other hand,the Pintail,which is one of the
most numerous ducks in central Alaska,occurred in relatively small
numbers in the study area,in spite of the fact that both.1980 and 1981
were high population years for Pintails in Alaska,due to severe drought
in the Canadian prairie provinces (King and Conant 1980,Conant and King
1981).
Trumpeter Swans bred commonly at the eastern end of the study area,from
the vicinity of the Oshetna River at least to the Maclaren River.On a
random flight over the ponds of this area on 4 August 1981,we had
19 observations of Trumpeter Swans.We counted 40 adult birds,includ-
ing 9 pairs with broods,totaling 28 cygnets.This area is the western
edge of the Gulkana Basin Trumpeter Swan population,which has more than
doubled during the past five years (King and Conant 1981).
50
)
)
)
)
)
)
)
)
)
)
)
(b)Populations During Migration
Summaries of the numbers and species composition of loons,grebes,and
waterfowl enumerated during aerial surveys in fall 1980 and 1981 and
spring 1981 are given in Tables 11-13,and relative abundance rankings
for species in fall and spring are given in Table 4.Based on these
data,the upper Susitna River Basin,which is on a high plateau between
the Alaska Range and the Talkeetna Mountains,does not appear to be a
major migration route for waterbirds (contra U.S.Corps of Engineers
1977).
Scaup,including both Lesser and Greater scaup,were the most numerous
species group during both spring and fall.Relatively large numbers of
Mallards and American Wigeon also moved through during both seasons
(although we missed peak wigeon numbers in fall 1981 surveys).Pintails
were common during spring migration but uncommon in fall.Few geese or
cranes were seen at either season.
The upper Susitna River Basin was less important to migratory waterfowl
in spring than fall.The difference was probably due largely to the
time of ice breakup,which occurred after "he main spring migratory
movement of many species,especially the dabbling ducks and Common
Goldeneye.Early migrants used the Susitna River itself and the thawed
edges of lakes.Use of the region's waterbodies increased toward the
end of May,concurrent with the availability of more open water and the
influx of the later-arriving loons,grebes,scaup,Oldsquaw,scoters,
and mergansers.The relatively high Importance Values (see below)of
the large lakes of the region in spring reflect their use after thaw by
these later-arriving species.
The pattern of fall movement in the region was similar to that known for
the rest of central Alaska;That is,peak numbers of American Wigeon,
Pintail,and Green-winged Teal occurred during the first half of
51
u u u u v u u u u v v
TABLE 11
StlflMARY Of TOTAL NUMBERS AND SPECIES COMPOSITION Of WATERBIRDS SEEN ON SURVEYED WATERBODIES DURING AERIAL SURVEYS Of THE UPPER
SUSITNA RIVER BASIN,FALL 19BO
DATE Of SURVEY
Species 7 Sept 11 Sept 16 Sept 20 Sept 26 Sept 3 Oct TOTAL
Loon spp.4 1 5.
Common Loon 3 2 3 8
Red-necked Grebe 2 3 4 5 3 17
Horned Grebe 1 4 17 9 2 2 35
Swan spp.34 29 9 12 20 104
Canada Goose 1 20 21
American Wigeon 155 325 97 88 56 721
Green-winged Teal 30 83 9 1 2 125
01 Mallard 10 64 14 116 110 124 438'"Pintail 60 60 53.21 3 4 201
Blue-winged Teal 1 1
Northern Shoveler 8 20 28
Rin9-necked Duck 2 12 14
Scaup spp.165 347 499 370 293 180 1854
01 dsquaw 7 4 13 13 16 4 57
81 ack Scoter 8 38 25 24 10 105
Scoter spp.*6 56 72 134
Surf Scoter 5 4 2 11
White-winged Scoter 10 1 6 1 18
Bufflehead 33 40 95 127 101 396
Goldeneye spp.15 36 68 124 95 133 471
Mer9anser spp.8 30 36 68 19 161
TOTAL BIRDS 270 803 1241 953 .927 731 4925
Total wetland area surveyed (km 2)13.11 22.08 25.76 27.53 29.00 24.25
Density (birds/km 2 of wetlands)20.6 36.4 48.2 34.6 32.0 30.1
*Surf or Yhite-winged seater
u u \.)\.)u u u u u u u
TABLE 12
SUMMARY OF TOTAL NUMBERS AND SPECIES COflPOSITION OF WATERBIRDS SEEN ON SURVEYED WATERBODIES DURING AERIAL SURVEYS OF THE UPPER
SUSITNA RIVER BASIN,FALL 1981
'--r DATE OF SURVEY
Species 15-16 Sept 26 Sept 26 Sept-9 Oct 12-19 Oct 20-23 Oct TOTAL
Common Loon 2 3 3 1 9
Arctic loon
Red-throated Loon
Loon spp.
Red-necked Grebe 12 3 1 .16
Horned Grebe
IIhist1 ing Swan 18 24 42
Trumpeter Swan 6 10 14 30
Swan spp.41 25 22 13 101
Canada Goose 50 50
Mallard 41 153 131 142 467
Pintail 32 32
Green-winged Teal 13 3 16
<n Northern Shoveler
w .American Wigeon 133 14 5 152
Canvasback
Redhead
Scaup,Greater and Lesser 479 166 51 gO 786
Goldeneye,Common and Barrow's 18 125 68 36 247
8ufflehead 17 20 29 52 118
01dsquaw 15 31 7 1 54
White-winged Seater 69 13 82
Surf Seater 29 29
8lack Seater 1 6 2 1 10
Seater spp.69 1 92 162
Common Merganser 1 2 3
Red-breasted Merganser.
Merganser spp.77 3D 18 133
TOTAL BIRDS'915 607 436 568 13 2539
Total wetland area surveyed (knh 25.68 25.68 21.31 11.57 .6.62
Km 2 of 100%frozen waterbadies
surveyed*0 1.41 3.91 3.76**2.00
Density (birds/km 2 of wetlands)35.6 .23.6 20.5 49.1 1.96
*Other waterbodies had at least some open water.
**An additional 9.22 km 2 of 100%frozen waterbadies were not surveyed in mid-October because they were known to be frozen.
By late October only Stephan and Murder lakes still had sorne open water.
u u v v u u u u u u v
TABLE 13
SUMMARY OF TOTAL NUMBERS AND SPECIES COMPOSITION OF WATERBIRDS SEEN ON SURVEYED WATERBODIES DURING AERIAL SURVEYS OF THE UPPER
SUSITNA RIVER BASIN,SPRING 1981
DATE OF SURVEY
Species 3 May 10 r~ay 26 Nay TOTAL
Common Loon 4 4
Arctic Loon 5 5
Red-throated Loon 2 2
Loon spp.3 4 7
Red-necked Grebe 4 4
Horned Grebe 1 1 2
Whistlin9 Swan
Trumpeter Swan 2 6 8
Swan spp.11 10 21
Canada Goose
Mallard 97 78 121 296
Pi nta il 71 70 116 257
01 Green-winged Teal 67 47 38 152
*'"Northern Shoveler 12 28 40
American Wigeon 5 94 99 198
Canvasback 1 1
Redhead 28 28
Scaup,Greater and lesser 103 513 616
Goldeneye.Common and Barrow's 51 38 89
Bufflehead 2 10 12
Oldsquaw 2 84 86
White-winged Seater 16 16
Surf Seater 4 35 39
81 ack Seater 1 42 43
Seater spp.12 74 86
Common Merganser 7 7
Red-breasted Merganser 2 2
Merganser spp.25 25
TOTAL BIRDS 242 492 1312 2046
Total wetland area surveyed (km 2)25.68 25.68 25.68
Km 2 of 100%frozen waterbodies
surveyed*14.31 1.97 0
Density (birds/km 2 of wetlands)9.4 19.2 51.1
*Other waterbodies had at least some open water.
)
)
)
)
)
)
)
)
)
)
)
September;of loons,grebes,and scaup during the second and third weeks
of September;of Oldsquaw and mergansers during the last half of
September;and of Mallards,scoters,BUffleheads,and goldeneyes from
the last third of September to mid-October.Swan migration,which·
included both Trumpeter and Whistling swans,occurred between the last
week of September and the end of October.
(c)Relative Importance of Waterbodies
Use by birds of the various waterbodies*of the region differed con-
siderably.Waterbodies included among the six highest Importance Value
(I.V.)ratings (see Section 2.8)for at least one season are listed with
seasonal population statistics in Table 14.
Of these more important waterbodies,WB 106 and 107,Stephan and Murder
lakes,respectively,were among the top three in Importance Values for
all seasons.Stephan Lake received twice the use in fall as in spring,
but both waterbodies consistently had relatively high levels of species
richness,while large Stephan Lake had high numbers of birds and smaller
Murder Lake,high densities.These lakes assumed additional importance
in early spring and late fall because of ice conditions.Murder Lake,
which reportedly has some open water all winter,provided some of the
first open water for early spring migrants,as did the inlet of Stephan
Lake;Green-winged Teal,Mallard,and Pintail were using this open water
on 3 May 1981.Likewise,these lakes provided the last open water in
fall and were used by the late migrants.Swans used these lakes during
October as other lakes in the region became ice-covered.Between 9 and
.11 Trumpeter Swans frequented Murder Lake between 10 and 18 October 1981
.(J.Ireland,pers.comm.),11-22 unidentified swans were on Stephan Lake
from 9 to 23 October 1981,and 120 swans were there on 10 October 1980.
*See Figure 1 for location of specific waterbodies.
55
.'-
u u u ,-,J u u u u u u v
TABLE 14
SEASONAL POPULATION STATISTICS FOR THE MORE IMPORTANT OF SURVEYED WATERBOOIES OF THE UPPER SUSrTNA RIVER BASIN.1980-81.INCLUDED ARE WATER800rES
THAT WERE AMONG THE SIX HIGI1EST INPORTANCE VALUE RATINGS IN AT LEAST ONE SEASON.
Fall 1980**Fall 1981**++Summer 1981Sprin91981
Mean Mean Mean Mean Mean Mean Mean Mean Mean Density
Size no.density no.no.density no.no.density no.No.of No •.No.
WaterbodY (km 2)birds (no./km 2)species birds (no./km2)species'birds (no./km 2)species adults adults species broods
WB 107 0.15 39.0 260.0 4.3 38.0 253.3 3.0 51.3 342.2 5.0 23 153.3 5 1
(Nurder Lake)
WB 106 3.55 156.0 43.9 9.5 168.5 47.5 5.0 99.7 28.1 7.3 B7 24.5 9 2
(Stephan Lake)
WB 140 0.90 53.5 59.4 5.0 30.5 33.9 2.5 48.3+53.7+3.7+75 83.3 11 4
01 WB 131 1.04 212.8 204.6 6.5 123.0 llB.3 5.0 54.7+52.6+3.7+C'I
WB 145 1.60 103.B 64.8 7.0 42.5 26.6 4.5 58.7 36.7 7.0 35 21.9 8 6
WB 059 1.44 72.8 50.5 6.5 55.0 3B ..2 3.0 21.3 14.8 4.7 54 37.5 11 5
WB 148 1.25 95.8 76.6 3.8 34.5 27.6 2.0 21.3+17.1+3.0+8 6.4 3 0
(Watana Lake)
WB 067 0.76 19.0* 17.9*4.0*4.0+5.3 1.5+85.0 111.8 6.0 15 19.7 8 5
(Pistol Lake)
WB 032 0.07 -- -- -- -- -------- --
8 114.3 4 6
WB 150 0.57 ------11.5 20.2 0.5 4.7+8.2+o.l 33 57.9 5 4
(Swimmin9 Bear Lake)
*Combines WB 064-067
**11.16.20.and 26 September 1980;15 and 26 September 1981+.100%frozen on at least one survey
++3.10.and 26 Nay 1981
--Not surveyed
)
)
)
)
)
)
)
)
)
)
)
WB 131,near the mouth of the MacLaren River,was another of the most
important lakes on the study area,because it consistently supported
high levels of waterfowl abundance,density,and species richness.Its
I.V.in spring was lessened by the fact that it was still frozen during
two (3 and 10 May)of the three spring surveys.Because it was so far
from the main proposed construction sites,we did not census it for
breeding birds in July,but a flight over the lake on 4 August 1981
revealed a flock of some 100 molting ducks,mostly scaup,as well as a
pair of Trumpeter Swans.This and WB 134 were the only duck-molting
lakes we found in the basin.A flock of 22-42 Trumpeter Swans congre-
gated to feed on this lake throughout the first half of September 1980.
WB 140,east of the Oshetna River,had the highest I.V.of the 28 water-
bodies censused during the breeding season.Not only did it have a high
species richness (11 species),but it also supported a large number of
birds and an above average density.It was also of above average impor-
tance during migration,although it thawed late and froze early.
WB 145,Clarence Lake,had the fourth highest I.V.during spring and
fall migration,but was less important during the summer.It had a
relatively high species richness at all seasons,being used by both
diving and dabbling ducks during migration,but primarily by divers in
summer.A flock of 51 migrant Snow Geese flew west over this lake on
30 April 1981 (T.W.Hobgood,pers.comm.).
WB 148,Watana Lake,was used in fall,especially in 1980,by migrant
scaup,goldeneyes,and mergansers during the last half of September.
Otherwise it was of little importance to birds.
WB 067,Pistol Lake,had a relatively high I.V.in spring because of the
number and diversity of birds it contained after it began to thaw toward
the end of the first week of May.This relatively large lake was only
of average importance during summer,however,and was little used in
fall.
57
)
)
)
)
)
)
)
)
WB 059,the southernmost Fog Lake,supported high levels of abundance
and species richness at all seasons.It received less use in spring
than at other seasons,probably because of ice cover,which was still
extensive as late as 17 May 1981.On this date,ducks were heavily
concentrated in the open water at the inlet end of the lake.This lake
and WB 140 had the highest species richness (11 species)during summer.
WB 032,a small lake at the west end of the Fog Lakes,supported a high
density of birds in summer and showed high productivity (at least four
broods of Horned Grebe and two of American Wigeon seen on 28 July 1981).
It was not monitored during migration.
WB 150,Swimming Bear Lake,an alpine lake,received its primary use
during summer.After it thawed in late May,it was occupied by at least
five species of waterbirds (scaup,Oldsquaw,scoter,Mew Gull,and
Arctic Tern),three of which had broods on 29 July 1981.Flocks of
scaup and White-winged Scoters were seen on the lake during the last
half of September 1981.
None of the waterbodies in the upper Susitna River Basin had Importance
Values as high as those calculated for some of the better wetland sites
of eastern interior Alaska from data obtained during fall 1980 by
Ritchie and Hawkings (1981)(Fig.3)and during spring 1980 by Ritchie
(1980)(Fig.4).
)
3.5 Breeding by Cliff-nesting Raptors,Ravens,and Eagles
(a)Summer Populations
)
)
In all,43 raptorjraven nest sites were located during 1980 and 1981,20
of which were inactive in both years.Presumably these inactive sites
58
)
75 ...------_-----_
)Scottie-Desper Creek
#'s 15,16,17,''3 01 20
70
)-----ir-------------ir-----
-----~------------~-----Moon Lake area
30 Midway lake
)
f/)
W
Co
III
a:
W
I-
<t:::
25
W8131·
)
)
)
)
U
LL
U
W
0-
f/)
LLo
f/)
w
=>
..J
<t>
w
U
Z
<t
I-a:o
0-
::;;
20
15
10
5
we 106 Stephan Lake ~
we 059 Fog Lakes.
we lOS
WB 130 Deadman Lake
we 135
we 121-128
Delusion Creek Group
we 107 Murder Lake
we 145 Clarence l.ake
we 148 Watana Lake
WaG69
WB064 -067
Pistol Lake .Group
W8134
we 104
WBI03
WB 129 Big Lake
)
)
)
we 06fr~=g~:Fog Lakes
we 037Ol....-L..;;.;.~____I
FIGURE 3
Relative importance of 20 waterbodies for migrant
.loons,grebes,and waterfowl in the upper Susitna
River Basin,Alaska,compared to 3 waterbodies in
the upper Tanana River-Scottie Creek area of eastern
.Alaska in fall 1980.
59
)
)
35-r-------or-------_
30-Cathedral Bluff lakes
)
Quartz Lake
Shaw Creek Flats Moon Lake &Vicinitr
III
111 25-
C
)0
IIIa:
111
I--WB107-Murder Lake..:::
0 20-
Dry Lake-
)U.
0
111a.
III Dot Lake-Sam Crk area
U.
0 15'
)III
111
::l.....:
l..--WB De7-Pistol Lake>
111
0 10-
Bear Chief Creek·
Z
)..:I---1B 106-Stephan LakeI-a:
0 Robertson River-I.-WS145-Clarence Lakea.:;;Johnson Slough ~t"'B'3'WB140
5-'::::::i B 133WaD6S
)Deadman Lake-WEI 13~.::WB103
WB 059 .;..WB06Qwe135WS132we105:::.-..::~B 148-Watana lake~~~3:;~~fB038WB139we104WB114
WB03 WB037~~g3~WaD66
WB 150 ~~~~~-Hlgh Lake
we 015 w~;!.~~0 we 016
)
FIGURE 4
J
J
Relative importance of 34 waterbodies for migrant loons,
grebes,and waterfowl in the upper Susitna River Basin,
Alaska,in spring 1981 compared to 9 waterbodies in the
upper Tanana River Valley of eastern Alaska in spring 1980.
60
)
)
)
)
)
)
)
)
)
J
)
function either as alternative sites or are used in year~of higher
population levels.Of the 23 nests that were active in at least one
year,at least 5 were used both years,each by the same species (Table
15).Active sites during the two years of study included ten of Golden
Eagle,six of Bald Eagle,four of Common Raven,one,perhaps two,of
Gyrfalcon,and one of Goshawk.
In 1974,White (1974)found ten active nests within this same geographic
area:two Gyrfalcon,one Bald Eagle,and seven Common Raven.He reported
14 inactive nests,ascribing 8 to ravens and 3 each to Golden and Bald
eagles.The reason for the substantially different species composition
between the two sets of surveys,i.e.,more ravens and fewer eagles in
1974,is unknown.
The concentration of active Golden Eagle nests in both 1980 and 1981
(one pair per 14.8 km [9.2 miles])was similar to that along the Dalton
Highway through the Brooks Range in 1979 (one active nest per 15.7 km
[9.7 miles])(D.G.Roseneau,pers.comm.)--the Brooks Range having one
of the largest populations of Golden Eagles in Alaska.A.Murie (1944),
in Denali (Mt.McKinley)National Park,found active nests as close as
1.6 and 2.4 km (1-1.5 miles)to each other in 1941 and 1939,respectively.
Pairs of Golden Eagles regularly build and maintain a number of simul-
taneous nests,which they use as alternative sites in various years
(Brown and Amadon 1968),some several kilometers apart (D.G.Roseneau,
pers.comm.).It has been suggested (White et al.1977)that local
populations increase during years of high hare populations,but hares
were relatively scarce on the upper Susitna in 1980 and 1981.A.Murie
(~944)found that ground squirrels were a major prey of Golden Eagles in
Denali National Park in 1939-1941,and this species was abundant in the
Susitna area during our study.
Bald Eagle densities found in the upper Susitna River drainage appear
slightly lower than those of interior Alaska,where Roseneau et al.(1981)
61
u u '...c l u v v v v v '...!v
TABLE 15
LOCATION OF ACTIVE RAPTOR AND RAVEN NEST SITES,UPPER SUSITNA RIVER BASIN,ALASKA,19BO AND 19B1,AND THEIR PROXIMITY TO POtENTIAL ADVERSE DISTURBANCE
FROM CONSTRUCTION ACTIVITIES
Substrate
elevation Active Active
Nest Species m (feet)19BO 19BI Nest location ·Potential disturbance
A Bald Eagle 490 (1600)X 0
B.O km up Susitna River from the mouth of Watana Creek.On Inundation
wooded island in live,15 m white spruce.
B Bald Eagle 690 (2260)X X 4.5 km up Oshetna River from its confluence with the Susitna River.
Nest 4 m from edge of west river bank in a 22 m white spruce.
C Golden Eagle 750 (2450)X 0 3.5 km upriver frrnn V-Canyon and 0.7 km up a narrow canyon on the
north side of the Susitna River.Nes t 26 m up a 33 mel iff,
100 m back from and 6.7 m above unnamed creek.
D Golden Eagle 700 (2300)X 0 4.0 km up the Susitna River from the mouth of Jay Creek and in
canyon on north side of the Susitna.Nest 5 m up 13 m cliff,
10 m back from and IB m above unnamed creek.
en E Golden Eagle 640 (2100)X X 2.5 km up Jay Creek from its junction with Susitna River.Nest Inundation
N 5 m up 30 m c1 iff,150 m from west bank and 115 m above Jay Creek.
F Golden Eagle 550 (lBOO)X 0 1.0 km down Susitna River from the mouth of Kosina Creek.Nest Inundation
32 m up 3B m cliff on north riverbank.
G Golden Ea9le 490 (1600)X 0 4.0 km down Susitna River from the mouth of Watana Creek.Nest Inundation
13 m up 23 mc1iff,40 m back from and 34 m above the north
bank of the river.
H Unknown 490 (1600)X 0 6.B km down Susitna River from mouth of Devil Creek and 4.0 km up 0.5 km from road and rail-
a gorge on south side of the Susitna.Nest 100 m up 105 m cliff road,east end Corridor 2*
of creek canyon.Occupied by a Gyrfalcon in 1974 (White 1974).
I Golden Eagle 365 (1200)X X 0.5 km up Devil Creek from its mouth.Nest 30 m up 45 m Inundation
vegetated cliff,100 m back from and 120 m above Devil Creek,
on west bank.
J Raven 520 (1700)X ?1.0 km up Devil Creek from its mouth.Nest near top of
cliff of west bank.Could not relocate nest in 19B1.
K Bald Eagle (2500)X X 9.0 km up Deadman Creek from its mouth.Nest on top of 15 m Approximately 50 m from
broken-topped cottonllOod,25 m from north side of Deadman Creek.Corridor 3
L Bald Eagle 275 (gOO)X X 1.0 km up Susitna River frrnn confluence with Indian River.0.5 km from road and rail-
Nest on top of 23 m broken-topped Cottonwood,4 m from north road,west end Corridor 2*
river bank.'I
'-i u
TABLE 15 (Continued)
v v .......v v \-I v v v
Nest Species
Substrate
elevation Active Active
m (feet)19BO 19BI Nest location Potential disturbance
Golden Eagle 305 (1000)
Bald Eagle 540 (1775)
Golden Eagle 685 (2250)
Golden Eagle 975 (3200)
0\
W
H
N
o
P
Q
R
5
T
u
Bald Eagle
Raven
Raven
Raven
Gyrfalcon
580 (1900)
470 (1550)
550 (1000)
625 (2050)
715 (2350)
o
o
x
x
x
x
x
x
x
x
• X
2.0 km up Susitna River from the mouth of Portage Creek.
Nest on moderate-sized cliff on north bank.but not relocated
on ground check.
On south shore of WB 105,1.0 km east of NE end of Stephan
Lake.Nest on top of 13 m broken-topped cottonwood.
2.0 km up Fog Creek from mouth.Nest g m up 23 m cliff on
west bank,17 m back from and 23 In above creek.
5.0 km up Tsusena Creek from mouth.Nest on cliff on east
bank of creek.
1.0 km up Deadman Creek from mouth.Nest 13 m up 32 m cliff
on east bank of creek.
8.0 km down Susitna River from the mouth of Kosina Creek.
Nest 7 m up 12 m cliff on tor above south bank of river.
2.0 km up Susitna River from the mouth of Kosina Creek.
Nest 25 m up 33 m cliff on north bank of river.
4.0 km up Susitna River from the mouth of Jay Creek,in
canyon on north side of river.Nest 1 m up 5 m vegetated
cliff.14 m back from and 33 m above unnamed creek.
At V-Canyon.Nest 100 m up 113 m cliff at south bank of
Susitna River.
On alternate b of road and
railroad,east end Corridor 2
0.7 km from alternate b of
road and railroad,east end
Corridor 2
0.5 km from road.east end
Corridor 1
Inundation
Inundation
Inundation
00 Goshawk
V Golden Ea9le 750 (2450)
55D (1800)
o X
X
3.5 km up Susitna River from V-Canyon and 0.7 km up narrow
canyon on north side of Susitna River.Nest 8 m up 12 m cliff.
81 m back from and 67 m above unnamed creek.
2.0 km southeast of Devil Canyon Dam site.100 m from road and 200 m
from ra i 1road J eas t end of
Corridor 2
o =inactive
- •site not located in 1980• =east and west ends of Corridor 2 divided at Devil Canyon dam site
)
)
)
)
)
)
)
)
)
reported 44 nests,25 active in 1980,in the vicinity of the Alaska
Highway and Tanana River between Fairbanks and the U.S.-Canada border,
a distance of approximately 480 km (300 miles).
Compared to eagles,Gyrfalcons are uncommon in central Alaska,but they
nest throughout the Alaska Range.Cade (1960)estimated the total
Alaska population at about 200-300 pairs,whereas Roseneau et al.(1981)
thought there were more,but fewer than 500 pairs.Numbers in a given
area may vary considerably between years (Cade 1960,Roseneau 1972),but
probably not over large geographic regions (Roseneau 1972).Gyrfalcons
in northern and western Alaska have low site fidelity from year to year
(Cade 1960,Roseneau 1972),but in the Alaska Range most sites are used
every year (Bente 1981).
There were no confirmed sightings of Peregrine Falcons in the region
during our study,in spite of the many hours spent in ornithological
field work and in raptor habitat.White (1974),however,saw two indi-
vidual Peregrines during his 10-15 June 1974 survey,but found no sign
of nesting.One bird was a "single adult male •••roosting on a cliff
about 4 miles upriver from the Devil Canyon Dam axis,"and the other was
"a sub-adult ••.about 15 miles upriver from the Devil Canyon Darn axis."
White (ibid.)stated that the Yentna-Chulitna-Susitna-Matanuska drainage
basin "seemingly represents an hiatus in the breeding range of breeding
peregrines •••,"and Roseneau et al.(1981)stated that "The Susitna and
Copper rivers both provide •••[very few]•••potential nesting areas for
Peregrines ."
. A single observation of an Osprey was reported during the two seasons of
.study,a bird seen on 23 May 1981 by J.Ireland at Murder Lake (pers.
comm.).
64
J
)
)
)
J
)
.J
.J
J
)
(b)Breeding Chronologies
No special effort was made to obtain data on the breeding biology of
raptors and ravens on the Susitna study area.Because the breeding
season is a period when most birds are relatively sensitive to distur-
bance,however,we show in Table 16 the breeding chronologies of eagles,
Gyrfalcon,and Common Raven in interior Alaska.
(c)Potential Disturbance Factors
The general types of impacts on raptors that can result from development
activities have been well-described by Roseneau et al.(1981),and
Tables 17-19,which summarize disturbance factors,are taken from their
report.
Inundation is an additional potential impact from hydroelectric pro-
jects.In the upper Susitna River Basin,the total length of good
potential raptor cliffs (type "A")that would be inundated by the pro-
posed reservoirs is 42.5 km (26.4 miles)(Table 20).Almost all "A"
quality habitat in the Watana reservoir will be inundated,but only
about half of that in the Devil Canyon reservoir.Currently,however,
the number of raptor nests (active and inactive)is considerably greater
in the proposed Watana reservoir area than in that for Devil Canyon dam
(Table 21),with densities of 0.6 nest sites/km and O.l/km,respec-
tively.For some reason,in spite of cliffs with good structural char-
acteristics,Devil Canyon is little used for raptor nesting.Possibly
the deep,narrow canyon,with its often strong and buffeting winds,
makes this area undesirable for raptors •
3.6 -Avifauna/Habitat Relationships
A general overview of bird habitat preferences in the upper Susitna
River Basin can be obtained by examining the density of territories of
65
u u \..)......)\".'.1-1 u u v u u
TABLE 16
BREEDING CHRONOLOGIES OF EAGLES,GYRFALCON,AND COMMON RAVEN IN INTERIOR ALASKA
DATES OF PfiASES OF BREEDING CYCLE
Species Status+Arrival/courtship Egg-laying Incunation
Golden Eagle"M 5 Mar-3D Apr 1 Apr-l0 May 15 Apr-20 June
Bald Eagle"M/R 10 Mar-l May 20 Mar-l0 Hay 31 Apr-3D June
0>Gyrfal can"R 1 11ar-ID Apr 1 Apr-2D May 5 Apr-25 June0>
Raven**R 1 Mar-15 Apr 1 Apr-5 May 5 Apr-25 Hay
+M=migrant t R =resident
"Data summarized from Roseneau et al.(1981)
""Based on calculations from Kessel (unpubl.data)and Brown (1974)
Nestlings
1 June-l Sept
20 May-15 Sept
15 Hay-15 Aug
25 Apr-25 June
Fledging/dispersal
1 Aug-25 Sept
1 Aug-3D Sept
10 July-3D Sept
25 May-15 July
)
)
)
)
)
)
J
)
)
J
TABLE 17
GENERAL TYPES OF IMPACTS TO RAPTORS (FROM ROSENEAU ET AL.1981)
Disturbance
Construction and Operation Activities
sudden loud noises (e.g ••blasting.gas venting.etc.)can lead to panic flights
and damage to nest contents
-noise,human presence,etc.can lead to disruption of daily activities
Aircraft Passage
-sudden appearance and noise can lead to panic flights and damage to nest contents
Human Presence Near Nests
-inadvertent -chance occurrence of people (and dogs)near nests;people may be
unaware of nest,raptors,or raptor alarm behavior
-deliberate -curious passersby,naturalists,photographers,researchers can have
impacts if safeguards are not taken
Direct Impacts
Intentionally Oestructive Acts (as a result of increased public access)
-shooting
-legal or illegal removal of eggs,young,or adults
-rolling of rocks off cliff tops
-cutting of nest trees
Man-made Structures and Obstructions
-raptors may be struck on roads where they may perch or feed
-may strike wires,fences,etc.
-may be electrocuted on power poles
-raptors sometimes attack aircraft,or may accidentally strike aircraft
Environmental Contaminants
-deliberate application and accidental release of insecticides,herbicides,petro-
chemicals,and toxic industrial materials can affect raptors and prey by affecting
hormones,enzymes,shell thickness,bird behavior,egg fertility and viability,and
survival rates of nestlings,fledglings,immatures and adults
Changes in Prey Availability
-decrease in prey abundance or loss of nearby hunting areas may affect territory
size,efficiency of hunting,nest occupancy,nesting success,conditio~of adults
and young
-changes may result from aircraft overflights,construction and maintenance activi-
ties,public access,etc.
Habitat Loss
Abandonment of area due to destruction of nest,perch or important hunting habitat
67
)
J
}
)
)
TABLE 18
FACTORS THAT AFFECT THE SENSITIVITY OF RAPTORS TO DISTURBANCES (FROM
ROSENEAU ET AL.1981)
Characteristics of the disturbance
type of disturbance
-severity (speed,loudness,suddenness,persistence,etc.)
-frequency of occurrence
Characteristics of the bird
the individual (individual differences in response)
-sex
-age
'mood'(a factor of recent activities,weather)
-territorial status (breeder,territorial non-breeder,or non-
territorial floater)
stage of annual life cycle (winter,migration,courtship,egg-
laying,rearing young,etc.)
-occurrence of other disturbances or natural stresses at the same
time
previous experience with this type of disturbance (habituation may
occur)
Topography
-nearness of disturbance to raptor or nest
-relative elevations (is nest or raptor above or below the distur-
bance?by what distance?)
-presence of screening features (trees,intervening hill)
-direction faced by nest relative to sun,wind,disturbance
-type of nest (exposed ledge,overhung ledge,cave)
-distance of nest above foot of cliff and below lip of cliff (i.e.,
'security'of nest)
Time of day
Weather at time of disturbance
Potential predators nearby
Type of prey utilized by the bird (species,location,abundance)
68
)TABLE 19
INFLUENCE OF TIMING OF DISTURBANCE ON THE POSSIBLE EFFECTS ON RAPTORS
(FROM ROSENEAU ET AL.1981)
)Timin9
Winter
)Arriva 1 and
courtship
Egg-laying
);
Incubation
Nestl i ng
phase
)
Fledgling
phase
:;
Night
General
)
)
)
Possible effects of disturbance
Raptor may abandon nest,roosting cliff,or hunting area
(e.g.,Gyrfalcon)
Migrant raptor may be forced to use alternative nest
site (if available),may remain but refuse to breed or
may abandon nest site
Partial clutch may be abandoned and remainder (or full
clutch)laid at alternative nest;breeding .effort may
cease or site may be abandoned
Eggs may be chilled,overheated,or preyed upon if
.parents are kept off nest too long;sudden flushing from
nest may destroy eggs;male may cease incubating;clutch
or site may be abandoned
Chilling,overheating,or predation of young may occur
if adults are kept off nest;sudden flushing of parent
may injure or kill nestlings;malnutrition and death may
result from missed feedings;premature flying of nest-
lings from nest may cause injury or death;adults may
abandon nest or site
Missed feedings may result in malnutrition or death;
fledglings may become lost if disturbed in high winds;
increased chance of injury due to extra moving about;
parents may abandon brood or site
Panic flight may occur and birds may become lost or
suffer injury or death
Undue expense of energy;increased risk of injury to
alarmed or defending birds;missed hunting opportunities
69
}TABLE 20
LINEAR DISTANCES OF CLIFFS IN VICINITY OF PROPOSED IMPOUNDMENTS,AND
DISTANCES THAT WOULD BE INUNDATED,SUSITNA HYDROELECTRIC PROJECT
Length above
Type of Length inundated waterline
cliff (km)(km)
Devil Canyon Reservoir
J A 27.4 24.9
B 8.3 7.9
C 2.4 1.6
)Watana Reservoir
A 15.1 0.9
B 5.1 0
C 1.6 0.3
}
)
J
)
70
)
u u u u u u v v v ,j u
TABLE 21
NUMBER OF KNOWN RAPTOR OR RAVEN NEST SITES IN UPPER SUSITNA RIVER BASIN,ALASKA,THAT WOULO BE INUNOATED BY DEVIL
CANYON AND WATANA RESERVOIRS
Species
Total no.
active nests
Total no.
inactive nests
Active nests that
would be flooded
Devil Canyon Watana
Inactive nests that
would be flooded
Oevil Canyon Watana
Tota 1 flooded
nests
Golden Eagle 10 g 1 4 2 3 10
..........Bald Eagle 6 1 0 2 0 1 3
Gyrfalcon 1 0 0 0 0 0 0
Goshawk 1 0 0 0 0 0 0
Common Raven 4 7 1 0 1 2 4
Unknown 1 3 0 0 0 0 0
.'TOTALS 23 20 2 6 3 6 17
J
J
J
various species in the habitats represented by the bird census plots
(Table 9),the assumption being that species occur in greatest densities
in their preferred habitats.Similarily,some information on habitat
preferences was obtained from our general surveys,in which we recorded
the number of individuals of each species seen per kilometer in various
habitats (data not shown).
J
Following,based on data from the bird censuses and the general bird
surveys,is a list of the four or five most abundant species found
during the summer in each of the major avian habitats of the upper
Susitna River Basin:
)(a)Lacustrine Waters and Shorelines:Arctic Tern,Mew Gull,
Lesser and Greater scaup,Common Loon.
)
(b)Fluviatile Waters,shorelines,and alluvia:Spotted Sand-
piper,Mew Gull,Violet-green Swallow,and Harlequin Duck.
)
(c)Upland Cliffs and Block-fields:Gray-cr_owned_Rosy Finch,
Common Redpoll,Horned Lark,cAmerican Golden Plover,~Water-=-----Pi pi t.
-----------
Go 1denPlo~-eh Horned----------Dwarf Shrub Mat:Water Pipit,~~~~an
Lark,Lapland Longspur,Rock Ptarmigan.
(d)
)
(e)Low Shrub:Savannah Sparrow,Tree Sparrow,Lapland Longspur,
White-crowned Sparrow.
J (f)Medium Shrub:Tree Sparrow,White-crowned Sparrow,Savannah
Sparrow,Arctic Warbler,Wilson's Warbler.
)(g)Tall Shrub:Hermit Thrush,Wilson's Warbler,Fox Sparrow,
White-crowned Sparrow,Tree Sparrow.
72
)
(h)Scattered Woodland and Dwarf Forest:White-crowned Sparrow,
American Robin,Bohemian Waxwing,Tree Sparrow,Ruby-crowned
Kinglet.
(i)Mixed Deciduous-Coniferous Forest:Hermit Thrush,Dark-eyed
Junco,Yellow-rumped Warbler,Swainson's Thrush,Varied
Thrush.
(j)Deciduous Forest:
Swainson's Thrush,
Yellow-rumped Warbler,
Blackpoll Warbler.
Common Redpoll,
)
)
)
(k)Coniferous Forest:Ruby-crowned Kinglet,Varied Thrush,
Dark-eyed Junco,Yellow-rumped Warbler,Swainson's Thrush.
A more detailed examination of species-specific habitat selection during
the breeding season,based on the more than 60 habitat variables
measured on the 588 subplots (Table 1),is still incomplete because of
time constraints.A principal component analysis was performed,however,
using 31 structural habitat variables that were present across
the full range of the 12 bird census plots,i.e.,from tundra through
forests.This procedure provided statistically uncorrelated axes
(principal components),each representing a combination of habitat
characteristics,along which to ordinate each bird census plot (using
mean factor scores from each plot's 49 subplots)(not shown)and to
ordinate the habitat data for individual bird species (using mean factor
scores from subplots on which the species was recorded at least once
during the eight 1981 censuses)(Fig.5).
An examination of how each habitat variable "loaded"onto each of the
first four principal components allowed an interpretation of the meaning
of these axes.PC I corresponded to a gradient of openness,ranging
from open treeless to heavy-canopied habitats,a primarily deciduous
component;it accounted for 33.8%of the total variation (information)
73
u u u u v v v u u u u
ElESS,
OH SHRUB CANOPY;
GRASS,lEDGE,LITTER
"•MOSS
1.50 1.75
HEAVY CANOPY,LAnGE TREES;
MEDIUU-TALL SHRUBS;
LITTER,FORB,GRASS
1,251.000.750.500.25
PC I
o0.250.50
NO CANOPY,TREELESS;
DWARf SHRUB,MOSS,LICHEN
THICK,"U
PENSE SHRUBBERV,
MOSS
O,S
0
GTH
PC III ~O.5 RCK
WCS WWR JA.V FOXTSPARC
JCO BPW aOR
-1.0 STH VTH HWT
CRP 'RW SGR HTH
LESS SHRUBBERY;aCR
LICHENS ~l.S SAV acc
1.5/
//-,"-LARGE CONIFERS;
10 ./\'\""""-LESS SHRUDBEII
II 0.5 -'./LAP //I "-'\"'""'DWARF SHRU
'7 //I I \"-'""-"-0
-O,S ./'///-J 7 \\"-'\."-"-YR
/"/'/'///I \\\."""'"".--1.0
PC
........
FIGURE 5
Habitat ordination of 22 bird species in the upper Susitna River Basin,Alaska,based on a three-
dimensional plot of mean factor scores from subplots on which the species occurred at least once
during 1981 censuses (lAP =Lapland Longspur,SAV =Savannah Sparrow,TSP =Tree Sparrow,
ARC =Arctic Warbler,WCS =White~crowned Sparrow,RCK =,Ruby-crowned Kinglet,WWR =Wilson's
Warbler,JAY =Gray Jay,GTH =Gray-cheeked Thrush,FOX =Fox Sparrow,JCO =Dark-eyed Junco,
BPW =Blackpoll Warbler,CRP =Common Redpoll,BOR =Boreal Chickadee,YRW =Yellow-rumped Warbler,
STH =Swainson's Thrush,SGR =Spruce Grouse,HTH =Hermit Thrush,BCR =Brown Creeper,
VTH =Varied Thrush,NWT =Northern Waterthrush,BCC =Black-capped Chickadee).
.'
)
J
)
J
J
J
)
J
)
)
)
in the data set.PC II,which accounted for 10.6%of the variation,
linearly combined two relatively independent habitat gradients,one
ranging from treelessness to woodlands and forests with conifers,and
the other from high deciduous shrub canopy (tall and medium shrubs,
.primarily alder)to less shrubbiness.PC III corresponded to thickness
and density of shrub cover and accounted for 8.8%of the variation.
PC IV represented a substrate moisture gradient,ranging from bare soil
and lichens to low shrubs with a ground cover of forbs,grasses,sedges,
and water,and accounted for 7.0%of the variation.In all,60.2%of
the variation in the data set was accounted for by these four principal
components.
The ordination of the habitat data for 22 bird species along the first
three principal components is shown in Figure 5.The height of each
vertical bar represents the factor score along PC III,whereas the dot
at the bottom of the bar shows the species'ordination relative to PC I
and II.Although this ordination presents some problems of interpreta-
tion that have yet to be addressed,the species on the left end (-)of
PC I were selecting treeless habitats with varying amounts of shrubbery;
those on the right (+),forest habitats;and those in the middle,either
open forests (Ruby-crowned Kinglet and Gray Jay)or medium-tall shrub-
bery that mayor may not have a forest overstory.The Northern Water-
thrush is in an anomalous position along this axis,reflecting the
phytogeography of the region.Generally,the species favors tall shrub
thickets near water (Kessel,pers.obs.).This habitat occurred almost
entirely along the major rivers.at the lower elevations of the Susitna
River Basin,at the same sites where the major forests were found.Six
of the nine Northern Waterthrush territories found in 1981 were on the
Cottonwood Forest plot and 2.5 were on the Mixed I plot,both adjacent
to fluviatile waters.Thus,habitat data from the subplots on which
Northern Waterthrushes occurred manifest this riverine association in
the region of tall shrub and forest habitats.
75
)
)
)
)
)
)
).
)
)
)
)
Interpretation of species'habitat ordinations along PC .11 is more
difficult,because the two trends of habitat characteristics combined in
this component influence bird distribution differently.The Hermit
Thrush falls at the lower (-)end of PC II because of its apparent
selection of habitats with high importance values of medium-tall alder
shrubs (cf Table 9 and Table 2).Other bird species at this end of the
axis were selecting treeless habitats.At the upper end (+)of PC II,
Gray Jays appear to have been selecting habitats with large spruce
trees.An understanding of the positioning of the other species along
this composite axis must await application of further statistical
procedures,however.
Along PC III,the Lapland Longspur (shortest vertical bar)shows selec-
tion of open habitats;in actuality,it often occurred where only a
ground cover of prostrate,dwarf shrub was present.Species with the
tallest bars (Gray-cheeked Thrush and Fox Sparrow)were birds of the
tall shrubs,which in this area were primarily alders or short spruce,
both of which have thick (deep)canopies and also often grow in associa-
tion with shrubbery of lower-height canopies.'Other species with tall
bars (Arctic Warbler,Tree Sparrow,and White-crowned Sparrow)show
their selection of habitats with dense,low-and medium-height shrub
birch.The Wilson's Warbler occurred in both types of shrub habitats,
with or without a forest canopy.
3.7 -Annotated List of Species
A list of the 135 species of birds recorded in the upper Susitna River
Basin during the study,with species-specific information for the region.
(abundance and status,habitat,phenological data),follows.Informa-
tion for these species accounts was drawn from above Sections 3.1-3.6
and from the collective field observations gathered by our group and
others throughout the study.Breeding by some birds in the study area
has not yet been confirmed.In the annotated list,a species is called
76
J
J
)
)
)
)
)
)
)
a breeder only if we have a substantiated breeding record.Suspected
breeding--based on such things as breeding or territorial behavior of
adults,breeding status in closely adjacent areas,or persistent
abundance of certain species in breeding habitats--is indicated as
"probable"or "possible"breeding,depending on the strength of the
evidence.
Common Loon.Gavia immer.Uncommon breeder on lacustrine waters.
Species occurred 16 May (1981)through 19 October (1981).Four
birds each on 26 May 1981 and on 20 September 1980 was maximum day
count.Three broods totaling five young were seen 28-29 July
1981;the oldest chick was about two-thirds adult size,with
juvenal feathering in the dorsal and scapular feather tracts.
Arctic Loon.Gavia arctica.Uncommon spring migrant and probable
breeder on lacustrine waters.Species was observed from 16 May
(1981),when a dead bird was found on a pond just north of Watana
Camp,through 27 July (1981),when a pair was observed on WB 015.
A total of 12 birds was seen in 1981.
Red-throated Loon.Gavia stellata.Uncommon probable breeder on
lacustrine waters,occurring between 9 May (1981)and 21 August
(1980).Few birds were seen,six in 1980 and 12 in 1981.
Red-necked Grebe.Podiceps grisegena.Uncommon breeder on lacustrine
waters,occurring from 16 May (1981)through 12 October (1981),
maximum eight birds on 15 September 1981.An adult flushed from a
nest north of Watana Camp on 18 July 1980,and a pair with two
juvenal-feathered,non-flying young was.on WB 036 on 27 July 1981.
77
J
J
J
J
J
J
J
)
)
)
Horned Grebe.Podiceps auritus.Uncommon breeder on lacustrine waters.
Species occurred 10 May (1981)through 3 October (1980),maximum
17 bi rds on 16 September 1980.Five broods total ing eight large
downy young were seen on 28 July 1981;.four broods were on WB 032
and the other was on WB 033.
Whistling Swan.Olor columbianus.Fairly common migrant.Two birds
on 9 May 1981,14 on 17 May 1981,and two on 22 May 1981 were the
only records in spring.The first Whistling Swans identified in
fall were 18 birds on WB 134 on 26 September 1981.Others (up to
23)were identified at WB 103 and HB 104 on 8-9 October 1981.The
144 swans reported by George Nissen,helicopter pilot,on Stephan
lake and nearby WB 105 on 10 October 1980 were probably also
mostly Whistling Swans,based on the size of the aggregations and
the fact that they occurred during the known period of peak move-
ment of this species through central Alaska (Kessel,unpubl.
da tal •
Trumpeter Swan.Olor buccinator.Common breeder on lacustrine
waters,especially in the wetlands east of the Susitna,between
the Oshetna and Maclaren rivers.Earliest in spring was a sighting
on 29 April 1981 on Murder lake by J.Ireland;he also reported
7-11 Trumpeters there between 10 and 18 October 1981,the latest
birds identified as this species.However,small groups of swans,
composed of 6-13 adults and juvenal s,on Stephan lake between 20
and 23 October 1981,were probably of this species.Maximum count
was 42 Trumpeters on WB 131 on 7 September 1980.Single pairs
were at their nests on WB 132 and WB 138 on 26 May 1981.Nine
broods (2-5 cygnets each)were counted during a l~-hour random
survey over the ponds of the Oshetna-Maclaren region on 4 August
1981.
78
)
)
)
}
Canada Goose.Branta canadensis.Uncommon migrant.In spring this
species occurred from 20 April (1981)to 18 May (1981),maximum
35 birds on 1 May 1981.It was observed in fall from 16 August
(1980)to 22 October (1981);high count was 27 flying over Watana
Creek on 23 September 1981.
White-fronted Goose.Anser albifrons.Uncommon spring migrant.Six
birds seen 1 May 1981 at Watana Camp Lake constituted the only
record.
}
Snow Goose.Chen caerulescens.
record was of 51 birds seen
Hobgood on 30 April 1981.
Uncommon spring migrant.The only
flying over Clarence Lake by T.W.
}
)
}
Mallard.Anas platyrhynchos.Common sprin9 and fairly common fall
migrant and uncommon breeder on lacustrine waters.Species
occurred from 23 April (1981)to 19 October (1981),with the main
fall passage occurring from late September to mid-October.Maxi-
mum count in spring was 121 birds on 26 May 1981 and in fall 153
birds on 26 September 1981.Single broods were seen on 13 July
1980 and 27 July 1981,the latter of four flying juvenals.
Gadwall.Anas strepera.Rare spring migrant and summer visitant.A
male at Pistol Lake and a pair at WB 059,all 17 May 1981,and a
male on WB 032 on 3 July 1981 provided the only records in the
study area.This species is normally scarce north of the Pacific
coast of Alaska (Kessel and Gibson 1978).
Pintail.Anas acuta.Common spring and uncommon fall migrant and
uncommon breeder on lacustrine waters.Pintails were recorded
from 24 April (1981)to 3 October (1980),with the main fall
passage over by mid-September.Spring maximum was 116 birds on
79
)
)
)
)
)
)
)
)
26 May 1981,and high count in fall was 60 birds on both 7 and
11 September 1980,all during aerial surveys.Two broods were
found in 1981,one on 8 July and the other,of nearly-fledged
juvenals,on 29 July.
Green-winged Teal.Anas crecca.Fairly common spring migrant and
uncommon breeder and fall migrant on lacustrine waters.Species
occurred from 29 April (1981)through 3 October (1980),although
the main fall exodus occurred by mid-September.Maximum count in
spring was 67 birds on 3 May 1981,in fall 83 birds on 16 September
1980.Single broods of 2-to 3-week-old chicks were recorded on
12 July 1980 and 8 July 1981.
.Blue-winged Teal.Anas discors.Rare migrant •.In spring blo birds
were seen at WB 067 on 6 May 1981,and one was seen at Murder Lake
on 25 May 1981 by J.Ireland.In fall one male at Stephan Lake on
11 September 1980 was the only record.
Northern Shoveler.Anas clvpeata.Uncommon migrant and breeder on
lacustrine waters.Species was recorded from 9 May (1981)to
16 September (1980).Maximum count in spring was 28 birds on
26 May 1981,in fall 20 birds on 16 September 1980.A brood of
six downy young seen on 12 July 1981 on Murder Lake was the only
evidence of breeding.
American Wigeon.Anas americana.Fairly common migrant and breeder on
lacustrine waters.Species occurred from 2 May (1981)through
19 October (1981).The main fall passage occurred during the
first half of September,with a maximum single-day count of 325
wigeon on the aerial survey of 16 September 1980;maximum count in
spring was 102 on the aerial survey of 26 May 1981.Six broods of
downy young were seen 13-28 July 1981,and a brood of ten large
young was noted on 2 September 1980.
80
)
)
)
)
}
J
)
}
)
)
Redhead.Aythya americana.Uncommon spring migrant.The only records
were of 31 Redheads seen in spring 1981.Three birds were seen on
17 May on W8 059,Fog Lakes.The rest were observed during the
aerial survey of 26 May:eight birds on WB 067 (Pistol Lake),
seven on WB 106 (Stephan Lake),two on WB 130 (Deadman Lake),
three on WB 148 (Watana Lake),and eight on WB 145 (Clarence
Lake).
Ring-necked Duck.Aythya collaris.Rare migrant on lacustrine waters.
The only records were of two birds on WB 059 on 16 September 1980,
a group of seven males and five females on Clarence Lake on
20 September 1980,and two birds seen on Murder Lake in early May
1981 by J.Ireland.
Canvasback.Aythya valisineria.Uncommon spring migrant.One bird on
WB 067 on 6 May 1981,one on WB 037 on 10 May 1981,and a pair at
WB 059 on 17 May 1981 were the only records in the study area.
Greater Scaup and Lesser Scaup.Aythya marila and Aythya affinis.Common
migrants and breeders on lacustrine waters.Although both species
were identified,it was often impossible to separate them under
many field conditions;thus they are treated together.Scaup
occurred from 9 May (1981)through 19 October (1981);their main
fall passage occurred during the second and third weeks of
September.Maximum count in spring was 513 birds on 26 May 1981,
in fall 499 on 16 September 1980.Four broods of downy Lesser
Scaup,totaling 14 young,were seen between 16 and 28 July 1981;
three broods totaling 29 young were seen at Stephan Lake on
21 August 1980.Although Greater Scaup were present throughout
the summer,no broods were found;they were somewhat less numerous
in summer than Lesser Scaup.
81
)
)
)
)
)
)
J
J
)
)
)
Common Goldeneye and Barrow's Goldeneye.Bucephala clangula and
Bucephala islandica.Fairly common spring migrants and uncommon
breeders and fall migrants on lacustrine and fluviatile waters.
Both species were identified and Barrow's appeared to be more
numerous,but females and eclipse males were usually impossible to
identify to species dur.ing summer and early fall,so the species
are treated here together.Goldeneyes occurred from 29 April
(1981)(Barrow's Goldeneye at mouth of Watana Creek)through
17 October (1981)(12 unidentified goldeneyes on Stephan Lake).
Maximum in spring was 51 goldeneyes on 10 May 1981;maxima in fall
were 133 birds on 3 October 1980,125 on 26 September 1981,and
124 on 20 September 1980.One brood of three downy Common Goldeneyes
was seen on WB 060 (Fog Lakes)on 27 July 1981.
Bufflehead.Bucephala albeola.Uncommon spring migrant and fairly
common fall migrant on lacustrine waters.Species occurred in
spring from 29 April (1981)to 26 May (1981)and in fall from
8 September (1981)to 19 October (1981).Maximum count in spring
was 10 birds on 26 May 1981,in fall 127 birds on 26 September
1980,both during aerial surveys.None was recorded in summer.
Oldsquaw.Clangula hyemalis.Fairly common spring migrant and breeder
and uncommon fall migrant on lacustrine waters.Species occurred
17 May (1981)to 12 October (1981),maximum 84 birds during the
aerial survey on 26 May 1981.Oldsquaws and Black Scoters were
the "most productive waterfowl on the study area,with 0.54 broods/km 2
of wetlands surveyed during July 1981.Eleven broods,mostly
downy young,were counted between 8 and 28 July 1981,three broods
each on Pistol Lake (WB 067),Clarence Lake (WB 145),and WB 140.
Harlequin Duck.Histrionicus histrionicus.Fairly common breeder on
suitable fluviatile waters.Species occurred from 13 May (1981)
through 24 September 1981 and 2 October 1980;maximum single-day
82
)
)
)
)
)
)
)
)
)
)
)
count was seven adults in the vicinity of Kosina Creek on 2 June
1981.A few-day-old downy was found dead on Kosina Creek on
17 July 1980,and a brood of four was seen on the Susitna River
above the mouth of Watana Creek on 25 July 1980.
White-winged Scoter.Melanitta deglandi.Uncommon migrant and summer
visitant on lacustrine waters.This scoter occurred from 26 May
(1981)to 17 October (1981),maxima 16 birds on 26 May 1981'and 39
on 29 September 1981.A flock of up to 63 birds was present at
Stephan Lake 12-16 July 1981.
Surf Scoter.Melanitta perspicillata.Uncommon migrant and breeder on
lacustrine waters.Species occurred 17 May (1981)to 12 October
(1981).Maximum count in spring was 37 birds on 26 May 1981,in
fall 29 birds on 12 October 1981.Two broods of downy young were
recorded on the Fog Lakes on 27 and 28 July 1981.A flock of 12
Surf Scoters,mostly males,was on Watana Lake on 13 July 1980.
Black Scoter.Melanitta nigra.Fairly common migrant and breeder on
lacustrine waters.Species occurred 17 May (1981)to 12 October
(1981).Maxiu,jm counts were during aerial surveys:38 bi rds on
16 September 1980 and 30 birds on 26 May 1981.It was one of the
most productive ducks on the study area (0.54 broods/km 2 of
wetlands).Eleven broods totaling 55 downy young were recorded
between 24 and 29 July 1981.
Common Merganser and Red-breasted Merganser.Mergus merganser and
Mergus serrator.Uncommon migrants and breeders.Common
Mergansers may have bred along the Susitna River proper,where we
regularly saw adults off our camps at the mouth of Kosina Creek
and off the Mixed II plot;Red-breasteds occupied lacustrine and
.smaller fluviatile waters in the study area.Because of diffi-
culties in identification from aircraft,these species are
83
)
discussed together.They occurred from 4 May 1980 and 8 May 1981
(Red-breasted Merganser)and 7 May (1981)(Common Merganser)
through 12 October (1981)(Common Merganser).Maximum count was
68 mergansers (sp.)on 26 September 1980.Three broods of Red-
breasted Mergansers were recorded:one of six young on Portage
Creek on 23 July 1980,one of four young at High Lake on 5 August
1980,and one of ten newly~hatched young on WB 023 on 6 July 1981.
Molting Red-breasted Mergansers were observed using the wetland
system west of Deadman Mt.and upper Deadman Creek on 3 and
28 July and 24 August 1981.
Goshawk.Accipiter gentilis.
uous and mixed forests.
found 6 m up in a birch
Uncommon resident and breeder in decid-
A nest with at least one large young was
tree,in paper birch forest,27 July 1981.
J
)
)
)
)
)
Sharp-shinned Hawk.Accipiter striatus.Uncommon probable breeder in
mixed and-coniferous forests.Three birds were seen in 1980 and
two in 1981.
Red-tailed Hawk.Buteo jamaicensis.Uncommon migrant;uncommon breeder
in coniferous or mixed forests,occurring from 26 April (1981)
through 16 September (1980).A pair was seen about a nest on the
Susitna River near the mouth of Portage Creek on 1 May 1981 but
not subsequently.Both ~.1.harlani and ~.1.calurus were seen.
Golden Eagle.Aguila chrysaetos.Fairly common breeder on cliffs.
Observed 20 April (1981)through 19 October (1981)in the study
area,and a bird was reported in the northern foothills of the
Alaska Range on 20 March 1981 (Kessel,unpubl.notes).Six pairs
nested along the upper Susitna River and its tributaries each
year,using a total of ten nest sites during both years.Young
birds rangeq from almost 3 weeks old to over 4 weeks old at the
time of the aerial survey on 6 July 1980.
84
)
)
)
)
J
)
)
)
Bald Eagle.Haliaeetus leucocephalus.Uncommon breeder.Species was
recorded from 10 March (1981)through 30 October (1980).A pair
was observed at a cliff nest near the mouth of Kosina Creek on
28 April 1981.Four active aeries were found in the study area in
both 1980 and 1981;three nests failed in 1981.One nest con-
tained 5-week-old young on 6 July 1980.Nests were in the tops of
cottonwoods and white spruce trees and on riverine cliffs.
Marsh Hawk.Circus cyaneus.Fairly common migrant;uncommon probable
breeder in meadows,occurring as early in spring as 25 April
(1981)and as late in fall as 16 September (1981).
Osprey.Pandion haliaetus.Rare spring migrant.One bird seen at
Murder Lake on 23 May 1981 by J.Ireland was the only record in
the study area.
Gyrfalcon.Falco rusticolus.Uncommon resident and breeder on cliffs.
One aerie in V-Canyon was occupied in 1981.White (1974)found
two active nests in steep draws on the south side of the Susitna
River,just above the proposed Devil Canyon dam site,10-15 June
1974.The species is known to occur in the Alaska Range during
winter (Bente 1981),and two were seen near the mouth of Watana
Creek on 11 March 1980.
Merlin.Falco columbarius.Uncommon probable breeder in scattered
woodland and forest edge.Ten birds were recorded in 1980,but
only three in 1981.A pair exhibited defensive behavior at
Deadman Falls Canyon on 5 June 1981,and a bird was seen there
again on 28 July 1981.
American Kestrel.
Stephan Lake
Falco sparverius.Rare fall migrant.
on 23 August 1980 was the only record.
85
One male at
)
J
Spruce Grouse.Canachites canadensis.Fairly common resident and
breeder in mixed and coniferous forests 'throughout the study area.
First chicks were seen on 23 June (1981).Maximum breeding den-
sity in 1981 was 1.0 territory/10 ha in each of two White Spruce-
Paper Birch Forest plots.
Ruffed Grouse.Bonasa umbellus.Rare visitant.One bird observed
20 May 1981 at the edge of an open white spruce forest at Kosina
Creek was the only record of the species in the study area.It is
a common resident in interior Alaska.
Willow Ptarmigan.Lagopus laqopus.Common resident and breeder in low
shrub thickets.Young were first ,observed on 9 July (1981).
Maximum breeding density in 1981 was 0.5 territory/10 ha in the
Dwarf-Low Birch Shrub plot.
Rock Ptarmigan.Laqopus mutus.Common resident and breeder in dwarf
and low shrub and in block-fields throughout the study area.
Chicks were first seen on 24 June (1981).Maximum breeding den-
sity in 1981 was 0.7 territory/10 ha in the Dwarf-Low Birch Shrub
plot.
White-tailed Ptarmigan.Laqopus leucurus.Uncommon resident and
breeder in dwarf shrub mat and block-fields.Species occurs at
higher elevations than jts congeners,although at least several
hundred altitudinal feet of overlap was seen with Rock Ptarmigan.
No nests were found,but broods were seen at Mt.Watana beginning
on 10 August (1981).
Sandhill Crane.Grus canadensis.Uncommon migrant.Two flocks of cranes
were observed on 19 September 1980,one of 30 birds flying north-
east up Devil Creek and one of 105 birds flying northeast up
86
)
)
}
)
)
J
:1
)
)
Tsusena Creek.Fifteen birds seen flying northwest over lower
Watana Creek by W.H.Busher on 15 May 1981 provided the only
additional record of the species.
Semipalmated Plover.Charadrius semipalmatus.Uncommon breeder on
alluvial bars.Species occurred from 5 May (1981)to 8 September
(1980).Two nests with full clutches of four eggs were found,one
on 6 June and the other on 16 June 1981;both were along shorelines
of the Susitna River.
American Golden Plover.Pluvialis dominica.Common breeder in dwarf
shrub mat and dwarf shrub meadows.Species occurred in the study
area from 15 May (1981)through 22 August (1980).Three nests
with four eggs each were found in 1981,the earliest on 12 June.
Maximum breeding density in 1981 was 1.5 territories/10 ha ·in the
Alpine Tundra plot.
Whimbrel.Numenius phaeopus.Uncommon probable breeder in dwarf shrub
meadow,occurring from 9 May (1981)to 6 August (1981).
Upland Sandpiper.Bartramia lonqicauda.Rare probable breeder in dwarf
shrub meadow near scattered spruce woodlands.This shorebird was
observed only in 1980,when two birds were seen near Watana Camp
on 8 July,at least three birds were seen west of Kosina Creek on
13 July,and one was seen east of Kosina Creek on 19 July.It is
known to breed in the Alaska Range and along the Den!!li Highway
".."
(Kessel and Gibson 1978).
Greater Yellowlegs.Tringa melanoleuca.Uncommon probable breeder in
wet meadows,foraging on fluviatile and lacustrine shorelines.
Species occurred from 29 April (1981)to 31 July (1980).Defen-
sive pairs were present near High Lake in mid-July 1980 and near
the White Spruce Scattered Woodland plot on 1 July 1981,but no
nests or young were found.
87
)
)
)
}
)
)
J
Lesser Yellowlegs.Tringa flavipes.Fairly common spring migrant;rare
summer visitant.In spring species occurred 6 May (1981)to
24 May (1981).Single birds were seen on 16 June 1981,13 July
1980,and 23 July 1981.
Solitary Sandpiper.Tringa solitaria.Uncommon probable breeder in
scattered woodland or forest edge near lacustrine waters;rare
spring migrant.One migrant was seen 9 May 1981 •.At least one
courting male was observed regularly about a beaver pond at
Sherman in June 1981.
Spotted Sandpiper.Actitis macularia.Common breeder on alluvial
shorelines,especially along the larger creeks and rivers,
occurring from 19 May (1981)to 10 September (1980).Earliest
nest,with full clutch of four eggs,was found on a Susitna
riverbar on 6 June (1981).A brood of Juvenal-plumaged young with
some down was seen on Kosina Creek on 17 July 1980,and an
independent juvenal was seen at Clarence Lake on 24 July 1981.
Wandering Tattler.Heteroscelus incanus.Uncommon possible breeder and
fall migrant.The species was recorded 7-30 June 1981 and on
14 August and 8 September 1980.The June birds were in appro-
priate habitat for breeding,i.e.,along tundra streams,but the
species is secretive and we noted no breeding behavior.Tattlers
breed in the Alaska Range (Kessel and Gibson 1978)and likely do
so in the study area.
)
:)
)
Turnstone.Arenaria sp.
were flushed from a
on 14 May 1981.
Rare migrant.Two unidentified turns tones
Susitna riverbar by an approaching helicopter
88
)
)
)
)
)
Northern Phalarope.Phalaropus lobatus.Fairly common probable
breeder,occurring in wet meadow pond areas from 9 May (1981)to
13 July 1981 and 12 July 1980.Maximum count was 24 birds seen
17 May 1981.
Common Snipe. Gallinago gallinago.Common breeder in wet meadows,
where it occurred from 28 April (1981)to 31 July (1981).One
bird on 16 September 1981 was the only fall migrant recorded.A
clutch of four eggs found on 1 June 1981 hatched on 15 June.
Long-billed Dowitcher.Limnodromus scolopaceus.Uncommon spring
migrant.Two observations totaling three birds on 17 May 1981
constituted the only records.
Surfbird.Aphriza virgata.Rare possible breeder in dwarf shrub mat.
One bird seen 13 July 1980 west of Kosina Creek was the only
record,but the species is known to breed in the Alaska Range
(Kessel and Gibson 1978).
)
Sanderling.Calidris alba.
Tyone 'River mouth on 5
Rare fall migrant.
September 1980 was
One juvenile at
the only record.
the
J
)
)
Semipalmated Sandpiper.Calidris pusilla.Uncommon spring migrant,
recorded 6-20 May 1981,and rare summer visitant,recorded 25 and
30 June and on 23 July 1981.
Least Sandpiper.Calidris minutilla.Fairly common probable breeder in
wet and dwarf shrub meadows,occurring 9 May (1981)to 25 July
(1980).Aerial courtship displays were prominent May-July.
Baird's Sandpiper.Calidris bairdii.Uncommon breeder in dwarf shrub
mat,occurring 15 May (1981)to 18 July (1980).A nest,with full
clutch of three eggs,was found 19 June 1981,and three downy
89
)
)
)
)
)
)
)
)
young were seen the same date.In 1981,the species was last seen
on the Alpine Tundra plot on 2 July,and on 7 July one individual
moved through and fed at lower elevations at the Dwarf-Low Birch
Shrub plot.
Pectoral Sandpiper.Calidris melanotos.Uncommon migrant in wet
meadows and at water edges.Three birds on 12 May 1981,six on
17 May 1981,and one on 16 September 1980 were the only records.
Long-tailed Jaeger.Stercorarius longicaudus.Fairly common probable
breeder in dwarf shrub meadow and dwarf shrub mat.Earliest seen
in spring was 26 May (1981),latest 10 August (1981).
Herring Gull.Larus argentatus.Uncommon spring migrant and summer
visitant,occurring 3 May-14 June 1981;maximum was 15 birds seen
on 3 May 1981 during aerial survey.
Mew Gull.Larus canus.Common summer visitant and breeder about lacus-
trine and fluviatile waters;also flocked to refuse dump at High
Lake.Species occurred 30 April (1981)through 24 August (1980).
Large downy young were found at High Lake on 10 July 1980 and
6 July 1981;a brood of large,flightless chicks was on a pond
south of High Lake on 12 July 1980;and seven families of fledged
juvenals were enumerated 27-29 July 1981.
Bonaparte's Gull.Larus philadelphia.Uncommon summer visitant about
fluviatile and lacustrine waters,breeding in adjacent scattered
spruce woodlands.A fledged juvenal on WB 059 on 27 July 1981 was
the only evidence of breeding in the region.
Arctic Tern.Sterna paradisaea.Fairly common probable breeder about
lacustrine water shorelines.Species occurred from 6 May (1981)
to 16 August (1980).Maximum was seven scattered birds seen by
90
)
)
)
)
)
}
)
)
several field parties on 17 May 1981.No eggs or young were
found,but territorial ism and aggressive behavior indicated
breeding.
G~eat Horned Owl.Bubo virglnlanus.Uncommon resident and probable
breeder in forests and.woodlands.Heard calling in the upper
Basin 12 February 1981 and 6-7 March 1980.A probable family
group of three birds was present near Kosina Creek at least
between 20 May and 13 June 1981.
Snowy Owl.Nyctea scandiaca.Probably rare migrant.Two birds were
seen about 18 November 1981 by Craig Gardiner.
Hawk Owl.Surnia ulula.Uncommon resident and probable breeder in
mixed woodlands.Records of single birds were made from
22 February (1981)through early November (1981).
Short-eared Owl.Asio flammeus.Uncommon migrant,summer visitant,and
possible breeder,occurring in all open habitats.Earliest in
spring were one on 27 April 1980 and one on 3 May 1981,and latest
in fall was on 21 October (1981).
Boreal Owl.Aegolius funereus.Rare resident and probable breeder
in mixed forests.Single observations,probably of the same bird,
on 18 April 1981 and 5 May 1981,were the only records.
Belted Kingfisher.Megaceryle alcyon.Uncommon probable breeder in
cutbanks.Species was recorded from 13 May (1981)through
11 September 1980 and 14 September 1981,primarily along the large
watercourses.A pair was observed flying regularly between Kosina
Creek and a canyon across the Susitna River during July 1980,
apparently to a nest site in the canyon.
91
)
)
}
)
J
)
)
Common Flicker.Colaptes auratus.Uncommon breeder at forest edge.
This species was present as early as 6 May (1981)and as late.as
11 September (1980).A pair was seen at a nest with young at
Kosina Creek on 20 June 1981.
Yellow-bellied Sapsucker.Sphyrapicus varius.No sapsuckers were seen,
but old sapwells on many of the large paper birches in the study
area attested their presence in earlier years.Most of the work-
ings were many years old,but some at the mouth of Kosina Creek
were relatively fresh,perhaps no older than about five years.
Similar old sapwells are numerous in the Tanana River Valley,and
in recent years a few sapsuckers have been seen in extreme eastern
interior Alaska (Kessel,pers.obs.).
Hairy Woodpecker.Picoides villosus.Uncommon resident and breeder in
mixed and deciduous forests.Most were seen in the vicinity of
Sherman or along Portage Creek.A female and fledged young were
seen together on the Cottonwood Forest plot at Sherman on 13 June
1981.
Downy Woodpecker.~lcoides pubescens.Uncommon resident and probable
breeder in open mixed and deciduous forests.Single birds were
observed at irregular intervals during the 1980 study period,and
there was a portion of a breeding territory on the Cottonwood
Forest plot at Sherman during June 1981.
Black-backed Three-toed Woodpecker.Picoides arcticus.Probably rare
resident.in coniferous forest.One male seen along Watana Creek
on 29 September 1980 was the only record.
Northern Three-toed Woodpecker.Picoides tridactyl us.Uncommon resi-
.dent and breeder in coniferous forests.A pair at a nest with
young was observed at Kosina Creek on 13 and 20 June 1981.The.
nest was 8 m up in a 12-m black spruce.
92
)
J
)
)
)
)
)
)
)
Eastern Kingbird.Tyrannus tyrannus.Accidental.One bird observed
near High Lake on 11 July 1980 was the only record.In Alaska
this species is a regular visitant only in Southeastern;it is
casual elsewhere in the state (Kessel and Gibson 1978).
Say's Phoebe.Sayornis saya.Uncommon breeder on upland cliffs and in
buildings.A few birds were seen,mostly at Mt.Watana and in
mountains east of Watana Creek,from 28 May (1981)through 20 July
(1980).A pair was feeding young at a cliff on Mt.Watana on
13 July 1980,a bird was flushed from a nest in an old cabin on
Gilmore Creek on 29 June 1981,and a pair was present at V-Canyon
on 5 June 1981.
Alder Flycatcher.Empidonax alnorum.Uncommon probable breeder in
medium and tall shrub thickets.A late spring migrant,this
species was recorded first on 3 June (1981),when at least four
singing males were present in the vicinity of the Sherman camp-
site.Two juveniles at Stephan Lake on 21 August 1980 were fall
migrants,the latest individuals seen.
Western Wood Pewee.Contopus sordidulus.Rare possible breeder in
deciduous forest.Four birds at Watana Creek on 25 July 1980
provided the only record.
Olive-sided Flycatcher.Nuttallornis borealis.Uncommon migrant and
probable breeder,occurring in open forest and scattered woodland.
One singing bird at Watana Creek on 15 May 1981 was earliest seen,
and one bird at Stephan Lake on 23 August 1980 was latest.
Horned Lark.Eremophila alpestris.Common migrant and fairly common
breeder,occurring on passage in most open habitats and as a
breeder in Qlock-fields and dwarf shrub mat.Three birds at
Watana Creek on 30 April 1981 were earliest in spring.Two nests
93
)
)
)
were found in 1981,both in high alpine dwarf shrub mat;one had
five eggs on 31 May,the other four eggs on 3 June.The first
fledgling was seen 20 June 1981.Postbreeding flocks were forming
16-21 August 1981,some shifting to lower elevations;four flocks
totaling 70 birds were seen at 1100 m in dwarf-low shrubs north-
west of Clarence Lake on 16 August 1981.Five birds on 23 September
1981 were latest fall migrants observed.
Violet-green Swallow.Tachycineta thalassina.Fairly common spring
migrant and summer visitant;probable breeder in riparian cliffs.
One bird on 16 May (1981)about Watana Camp was earliest in
spring,and none was seen after 25 July (1980),when two were
noted over Watana Creek.
Swall ow.
probable
wa ters.
.spring,
)
Tree Iridoprocne bicolor.Fairly common spring migrant and
breeder,occurring widely over lacustrine and fluviatile
Two on 3 May (1981)over Watana Creek were earliest in
and none was seen after 23 July (1980)•
)
)
)
)
)
Bank Swallow.Riparia riparia.Uncommon local breeder and fall
migrant,occurring about riparian cutbanks and over fluviatile
waters.There was a nesting colony of 25 pairs along upper Watana
Creek on 25 July 1980,the only evidence of breeding in the area.
The species was recorded no earlier than 4 June (1981)nor later
than 21 August (1980).
Cliff Swallow.Petrochelidon pyrrhonota.Uncommon local summer V1Sl-
tant and breeder,occurring about fluviatile and lacustrine
waters.The species was recorded only in the month of July (1980,
1981).Twenty birds in two colonies of five pairs each were seen
nesting under the eaves of two small cabins on the Watana Lake
shore on 9 July 1981,and a colony of seven pairs was seen at
Clarence Lake on 24 July 1981.
94
J
J
}
Gray Jay.Perisoreus canadensis.Common resident and breeder in coni-
ferous and mixed forests and woodlands throughout the study area.
Densities on four census plots in 1981 ranged from 0.5 to 1.0
fledged family/10 ha.One bird was observed in flight over low
shrub thickets northwest of Clarence Lake on 5 September 1981,the
only occurrence noted far from timber.
}
Black-billed Magpie.Pica pica.
and fall;possible resident
scattered woodlands.
Uncommon visitant in spring,summer,
and breeder in open tall shrubs and
)
)
)
}
}
}
}
Common Raven.Corvus corax.Common resident and breeder,nesting on
riparian and upland cliffs.Widespread,this species foraged in
or near most habitats and fed on game carcasses and about refuse
dumps in winter.Nests contained downy young at the time of the
aerial survey on 16-17 May 1981.
Black-capped Chickadee.Parus atricapillus.Uncommon resident and
probable breeder in deciduous forests.Breeding territories were
found only on the Cottonwood Forest plot,where there were 1.8
territories/10 ha in 1981.
Boreal Chickadee.Parus hudsonicus.Fairly common resident and breeder
in coniferous and mixed forests.A pair was found feeding young
in a nest in the hollow.top of a leaning 15 cm dbh spruce snag on
the Black Spruce Dwarf Forest plot on 16 June 1981.Maximum
breeding density in 1981 was 1.7 territories/10 ha in mixed white
spruce-paper birch forest.
.Brown Creeper.Certhia familiaris.Uncommon breeder and fall visitant
in deciduous and mixed forests.A singing bird on 20 May (1981)
was earliest record,and one seen 21 October (1981)was latest in
fall.On 3.June 1981 a pair was seen entering a vertical cleft in
95
)
)
)
)
)
)
)
)
)
)
the bark 10 m up the trunk of an 18-m cottonwood at Sherman.This
nest could not be examined,and no others were found.There were
two breeding territories in 1981 on the Cottonwood Forest plot and
one on the mixed White Spruce-Paper Birch Forest II plot.
Dipper.Cinclus mexicanus.Uncommon resident and probable breeder on
suitable fluviatile waters throughout the study area.We have no
observations from mid-wint~r,but between 17 and 23 April 1981,
before spring thaw,birds were observed at open water sites along
creeks and rivers.Most were seen along the Susitna River at the
mouths of Watana,Deadman,and Tsusena creeks,and in Devil
Canyon.
American Robin.Turdus migratorius.Common spring migrant and breeder
and uncommon fall migrant,occurring from 25 April (1980)to
11 October (1981),although few were seen after August.Species
occurred in forests and medium and tall shrub thickets.Two nests
with eggs were found,one in a paper birch near Sherman on 13 June
1981 and the other in high alpine tundra southeast of the Devil
Canyon dam site on 20 June 1981.The latter nest was on the
ground at the base of a I-m high rock face.Maximum breeding
,density in 1981 was 0.5 territory/l0 ha on each of three census
plots:Tall Alder Shrub Thicket,White Spruce Scattered Woodland,
and Black Spruce Dwarf Forest.
Varied Thrush.Ixoreus naevius.Common spring migrant and.breeder and
uncommon fall migrant,occurring in all forest types and in tall
alder shrub thickets.Species was recorded in spring as early as
24 April (1981)and in fall as late as 20 September 1980 and
30 September 1981.Four nests were found,the earliest,with four
eggs,on 21 May (1981).Nests were located in a spruce tree,an
alder shrub,and on an old stump.First nestlings were seen
13 June (1981),first fledglings on 20 June (1981).Most forest
96
)
)
)
)
)
)
)
)
)
)
plots supported breeding densities in 1981 of 2.5-3.5 territories/
10 ha,but there were 10 territories on the 10-ha Cottonwood
Forest plot.
Hermit Thrush.Catharus guttatus.Common breeder in forests on steep
slopes and in tall alder shrub thickets;uncommon fall migrant.
Species was first seen in spring on 14 May (1981),last in fallon
7 September 1981 and 12 September 1980.Five nests were found in
1981,the earliest with a full clutch of four eggs on 25 May and
with nestlings with closed eyes but emerging primaries on 11 June.
A clumsy juvenal was seen in woods along Portage Creek on 31 July
1981.Maximum breeding density in 1981 was 6.1 territories/10 ha
in the Paper Birch Forest plot.
Swainson's Thrush.Catharus ustulatus.Fairly common breeder in all
forest types.Species occurred from 18"May (1981)to 27 August
(1980).A bird carrying nesting material in mixed forest on
20 May 1981,an adult carrying food in spruce forest on 17 July
1980,one feeding a fledgling on 15 July 1980,and many defensive
pairs observed at various times constituted breeding evidence.
Maximum breeding density in 1981 was 8.0 territories/10 ha on the
mixed White Spruce-Paper Birch Forest II plot.
Gray-cheeked Thrush.Catharus minimus.Fairly common breeder in scat-
tered woodland,in dwarf black spruce,and in the Cottonwood
Forest plot.Species occurred 20 May (1981)to 4 September
(1980).Earliest nest,on a 0.6 m hi9h stump in the Cottonwood
Forest plot,had a full clutch of four eg9s on 3 June 1981.
Maximum breeding densities in 1981 of 3.9 and 3.8 territories/
10 ha were on the White Spruce Scattered Woodland and the Cotton-
wood Forest plots,respectively.
97
)
)
)
)
)
)
)
)
)
)
)
Wheatear.Oenanthe oenanthe.Uncommon breeder in block-fields.
Earliest sighting was of one male west of Tsusena Creek on 31 May
(1981);none was seen after 30 August (1980),when one juvenile
was seen east of Devil Creek.No nests were found,but defensive
adults were encountered in mid-July (1980,1981),and bob-tailed
young were noted at the summit between Devil Creek and Watana Camp
on 18 July 1980.
Townsend's Solitaire.t{Yadestes townsendi.Uncommon spring migrant;
uncommon breeder on cliffs.One bird at Tsusena Butte on 17 May
1981 was our only record of a migrant.One was seen about a cliff
northeast of Jay Creek on 20 June 1981,and a pair at a nest with
young was observed at a rock outcrop in mountains northeast of
Watana Creek on 22 July 1980.Single birds seen 13 and 23 July
1980 were the only other records of the species.
Arctic Warbler.Phylloscopus borealis.Fairly common breeder in scat-
tered woodlands and medium shrub thickets as far east as the
slopes northwest of Clarence Lake;not detected on passage except
on 22 August 1980,when four birds were seen west of Watana Camp.
Earliest record in spring was 11 June (1981).Twelve singing
males were counted on 11 July 1980 at High Lake,and food-carrying
adults were seen there on 1 August 1980.An adult feeding fledged
young was observed at WB 023 on 29 July 1981.Maximum breeding
density in 1981 was 4.8 territories/l0 ha on the Medium Birch
Shrub Thicket census plot.
Golden-crowned Kinglet.Regulus satrapa.Uncommon spring and fall
visitant,occurring in coniferous and mixed forests.One bird
along the Susitna River on 24 April 1981 was the only spring
record;one bird was seen at Cache Creek mouth on 9 September
1980;one was seen near the mouth of Tsusena Creek on 14 September
98
)
J
J
J
)
)
)
)
J
1980;two were seen on 12 September,four on 19th,and two on
25th--all in 1980 at Portage Creek;and two were observed at Gold
Creek on 4 October 1980.
Ruby-crowned Kinglet.Regulus calendula.Common migrant,and common
breeder in coniferous forests.Species was recorded in spring as
early as 3 May (1981),a singing male at Watana Creek,and in fall
as late as 25 September (1980).Four fledglings fed and begged
from their parents in the white spruce forest at Kosina Creek on
15-17 July 1980.Maximum breeding density in 1981 was 4.2 terri-
tories/l0 ha in the White Spruce Forest plot.
Water Pipit.Anthus spinoletta.Common breeder about block-fields and
dwarf shrub mat,and common migrant,less conspicuous in spring
than in fall.Earliest sighting in spring was of eight birds
along the Susitna River on 1 May (1981)and latest in fall was on
30 September (1981),except for a very late bird on 21 October
1981.Three nests were found on Mt.Watana in 1981,all in dwarf
shrub mat,the earliest with six eggs on 10 June.A nest on
19 June had three nestlings.Postbreeding flocking was first
noted in alpine areas on 10 August 1981,and small groups (two to
five birds)began to move to lower elevations at this same time.
Bohemian Waxing.Bombycilla garrulus.Common migrant and uncommon
probable breeder in scattered spruce woodland.A flock of about
25 birds at the mouth of Watana Creek on 21 March 1980 and a
single bird at the same place on 22 March 1981 were the earliest
seen;latest in fall was a flock of 12 birds along Watana Creek on
24 September (1980).Maximum number was 38 birds counted on a
5-km transect through scattered dwarf black spruce in the Fog
Lakes area on 9 May 1981.Late summer flocks included family
groups of recently fledged juvenals.
99
)
)
)
)
)
J
)
)
)
Northern Shrike.Lanius excubitor.Uncommon breeder in tall shrub
thickets and scattered spruce woodlands.Although probably
resident,species was first recorded on 25 April (1980);on
passage it occurred in all open vegetated habitats.A family
group of four birds,including at least two fledged young,was
seen near High Lake on.9 July 1980.One immature was observed
northwest·of Clarence Lake on 16 September 1981,and an adult was
seen near Deadman Lake on 5 October 1981.
Orange-crowned Warbler.Vermivora celata.Uncommon breeder in medium
and tall shrub thickets and scattered woodlands.Earliest in
spring was a singing male at Sherman on 21 May (1981)and latest
in fall was one bird at High Lake on 7 September (1980).A nest
placed in moss under a dwarf shrub contained six eggs when first
found on 11 June 1981;the young hatched on 21 June.
Yellow Warbler.Dendroica petechia.Rare migrant and summer visitant.
A male singing at 04:20 on 15 June 1981 in riparian willows along
the Susitna River,between Sherman and Devil Canyon,was not
present there hours later or subsequently.One male was observed
at Sherman on 30 July 1981,and three juveniles were seen there on
30 August 1980.There were no other records.
Yellow-rumped Warbler.Dendroica coronata.Common breeder in forests.
Earliest in spring was one on 8 May (1981)and latest in fall were
two on 24 September (1980).No nests were found,but food-
carrying adults were observed along the Susitna,below Watana
Creek,on 7 July 1980.Independent juvenals were recorded on
14 July 1980.Maximum breeding densities in 1981 were 9.8 terri-
tories/10 ha on the Paper Birch Forest plot and 9.5 territories/
10 ha on the mixed White Spruce-Paper Birch Forest II plot.
100
)
)
)
J
J
J
Blackpoll Warbler.Dendroica striata.Fairly common breeder in tall
shrub thickets,scattered woodlands,and in understory within
forests.Earliest in spring were two males on 18 May (1981).A
nest 1 m up in a tall alder shrub of the understory of the Cotton-
wood Forest plot held six eggs when found on 13 June 1981;the
eggs hatched sometime between 14 and 19 June.Also,adults were
observed carrying food below Watana Camp on 7 July 1980.Maximum
breeding densities in 1981 were in the deciduous forests:4.4
territories/10 ha in the Cottonwood Forest plot and 3.9 terri-
tories/10 ha in the Paper Birch Forest plot.A juvenile at Gold
Creek on 5 September 1980 was the latest record.
Northern Waterthrush.Seiurus noveboracensis.Fairly common probable
breeder in tall shrub thickets near water,often at deciduous and
mixed forest edges along the banks of the Susitna River.Earliest
in spring was a singing male bn 15 May (1981),and latest in fall
was one bird on 6 September (1980).Maximum breeding density in
1981 was 6.1 territories/10 ha on the Cottonwood Forest plot.
Wilson's Warbler.Wilsonia pusilla.Common breeder in medium shrub
thickets,with'or without a forest overstory.Earliest in spring
was a male on 14 May (1981).A bird on 25 September (1981)was
latest in fall.A nest on the ground at the base of a willow in
scattered woodland contained six eggs on 14 June 1981 and five
young on 1 July.A defensive,food-carrying pair was observed on
7 July 1980.Maximum breeding densities in 1981 ranged from 8.8
to 9.4 territories/10 ha on the Low-medium Willow Shrub Thicket
and Medium Birch Shrub Thicket plots.
Rusty Blackbird.Euphagus carolinus.Uncommon migrant and possible
rare breeder.Earliest in spring were sightings on 27 April 1980
,and 2 May 1981;none was seen in spring after 24 May (1981).In
fall the species was recorded from 13 August (1980)thro~gh
101
)
)
)
)
)
)
)
)
)
)
25 September (1980).A bird seen on 29 July 1981 at WB 059 (Fog
Lakes)was the only midsummer record.
Pine Grosbeak.Pinicola enucleator.Uncommon spring,summer,and fall
visitant and possible breeder.A pair of birds on 16 May 1981,
two birds on 21 May 1981,three on 3 June 1981,one on 4 June
1981,one on 18 June 1981,··three on 18 September 1980,and two
birds on 4 October 1980 were the only records.
Gray-crowned Rosy Finch.Leucosticte tephrocotis.Uncommon probable
breeder in cliffs and block-fields.A pair on 23 May (1981)was
earliest record;one bird on 23 September (1981)was latest.
Large postbreeding flocks (15-35 birds)were present on alpine
tundra from 10 August through 11 September 1981.
Common Redpoll.Carduelis flammea.Abundant and widely distributed at
all seasons;the most numerous passerine species recorded,but
bred in low densities.Four nests were found.Three pairs were
building nests 7-21 m up in 21-26 m cottonwoods on the Cottonwood
Forest plot on 21 and 22 May 1981.On 4 June 1981 a female incu-
bating four eggs was found 1.2 m up in a 1.5 m alder on a river
bar;the eggs hatched on 15 June.A flock of 200+birds at High
Lake on 4 September 1980 was the largest flock seen.
Pine Siskin.Carduelis pinus.Irregularly uncommon summer visitant and
probable breeder;fairly common in summer 1980 and distinctly
uncommon in summer 1981 (when the species was numerous from Kodiak
and Anchorage to Southeastern and when it bred as far north as
Fairbanks).Seen in mixed deciduous-coniferous forests and in
tall alder shrub thickets.Itinerant and irruptive and near the
northern limits of its range,this species probably breeds in the
study area in some years.
102
)
)
)
)
J
)
)
)
)
)
J
White-winged Crossbill.Loxia leucoptera.Fairly common summer visi-
tant and possible breeder in coniferous forests.Like those of
siskins and redpolls,numbers of this species fluctuate markedly
from year to year.Maximum counts were a flock of 65 crossbills
that landed briefly in cottonwoods near the Mixed II plot on
2 August Ig81 and 36 birds seen at the Cottonwood Forest plot on
4 June 1981.
Savannah Sparrow.Passerculus sandwichensis.Abundant breeder through-
out the study area in open low shrub thickets with grass-sedge
ground cover.Earliest in spring was on 2 May (1981)and latest
in fallon 14 September (1981).Five nests were found,from
alpine tundra to scattered woodlands.Eggs were found in nests
from 7 June through.1 July 1981.First barely-fledged young was
recorded on 29 June (1981).Maximum breeding density in 1981 was
12.3 territories/l0 ha on the Low-Medium Willow Shrub Thicket
plot.Postbreeding Savannah Sparrows did not form flocks.They
began gradually to disappear from the Dwarf-Low Birch Shrub plot
in mid-August 1981,and few were left by 25 August.
Dark-eyed Junco.Junco hyemalis.Common breeder,occurring throughout
forest and woodland habitats.It was recorded as early as 2 May
(1981)and as late as 29 September (1981),with an exceptionally
late bird on 30 October 1981.Maximum breeding densities in 1981
were 3.9-4.5 territories/l0 ha in the White Spruce-Paper Birch
Forest plots.
Tree Sparrow.Spizella arborea.Abundant breeder in low shrub thickets,
Earliest record in spring was 6 May (1981)and latest records
in fall were 4 October 1980 and 6 October 1981.First observation
of nesting was on 27 May (1981),when a pair was lining its nest
with ptarmigan feathers.Nine nests were located,with eggs
present·from 7 June to 9 July.The first nestlings were found on
103
)
)
)
)
)
)
)
)
)
)
15 June (1981)and first fledglings on 28 June (1981).Maximum
breeding densities in 1981 were 15.0 territories/l0 ha on the
Low-Medium Willow Shrub plot and 11.8 territories/l0 ha on the
Medium Birch Shrub plot.Tree Sparrows did not form postbreeding
flocks,but gradually left the Dwarf-Low Birch plot from 20 to
25 August 1981.Few birds remained on this plot after 25 August
1981.
White-crowned Sparrow.Zonotrichia leucophrys.Abundant breeder,
widely distributed in low and medium shrub habitats.Species
occurred from 6 May (1981)to 29 September (1981).Eight nests
were found,the earliest,with four eggs,on 29 May (1981).
Nestlings were present in three nests on 15 June (1981),and some
had fledged by 29 June (1981).Average clutch size of five com-
pleted clutches in 1981 was 4.8 eggs.Maximum breeding density in
1981 was 6.5 territories/l0 ha on the White Spruce Scattered
Woodland plot.
Golden-crowned Sparrow.Zonotrichia atricapilla.Uncommon probable
breeder in low shrub thickets and dwarf spruce forests.Species
was seen as "early as 16 May (1981)and as late as 3 September 1981
and 6 September 1980.
Fox Sparrow.Passerella iliaca.Fairly common probable breeder in
medium and tall shrub thickets and in forest understory.Species.
occurred from 8 May (1981)through 7 September (1981).Maximum
breeding densities in 1981 were 4.6 territories/l0 ha on the
Cottonwood Forest plot and 3.5 territories/l0 ha on the White
Spruce Scattered Woodland plot.
Lincoln's Sparrow.Melospiza lincolnii.Uncommon probable breeder in
low and medium shrub thickets near water.Species occurred from
26 May (1981)through 7 September 1981 and 9 September.1980.
104
)
)
)
)
)
)
)
)
)
)
Lapland Longspur.Calcarius lapponicus.Abundant breeder in dwarf
shrub meadow and dwarf shrub mat.Species occurred from 24 April
(1981)through 16 September (1981),with an extremely late indivi-
dual seen 2 October 1981.Earliest nest,containing five eggs,
was seen 26 May (1981)and had four downy nestlings on 7 June
(1981).Longspurs began forming flocks on 25 July 1981 and were
still moving through dwarf-low shrub habitat in large flocks
(15-70 birds)on 26 August 1981.
Smith's Longspur.Calcarius pictus.Uncommon probable breeder in dwarf
shrub meadow/mat.A pair north of Watana Camp on 8 July 1980,two
birds near Watana Lake on 13 July 1980,one male northwest of
Clarence Lake on 7 July 1981,and one male at the last location on
24 August 1981 were the only records of the species.The species
is known to breed along the Denali Highway (Kessel and Gibson
1978).
Snow Bunting.Plectrophenax nivalis.Fairly common probable breeder at
high elevations in cliffs and block-fields,feeding in dwarf shrub
mat.Species was observed from 15 May (1981)to 19 October
(1981).
4 -NON-GAME (SMALL)MAMMALS -RESULTS AND DISCUSSION
4.1 -Species Composition and Relative Abundance
During the study period we confirmed the presence of sixteen species of
small mammals in the upper Sus.itna River Basin (Table 22).In addition,
there was evidence of two other species in the region:a bat (two
separate sightings of what were probably little brown bats,Myotis
lucifugus,near High Lake and Tsusena Creek,August 1980,by J.Wilson
105
)
)
)
)
)
)
)
)
)
)
TABLE 22
SPECIES OF SMALL MAM~lALS FOUND IN THE UPPER SUSITNA RIVER BASIN,ALASKA,
1980 AND 1981
Order INSECTIVORA
Family Soricidae
Sorex cinereus,masked shrew
Sorex monticolus,dusky shrew
Sorex arcticus,arctic shrew
Sorex hoyi,pygmy shrew
Order LAGOHORPHA
Family Ochotonidae
Ochotona collaris,collared pika
Family Leporidae
Lepus americanus,snowshoe hare
Order RODENTIA
Family Sciuridae
Marmota caligata,hoary marmot
Spermophilus parryii,arctic ground squirrel
Tamiasciurus hudsonicus,red squirrel
Family Cricetidae
Clethrionomys rutilus,northern red-backed vole
Hicrotus pennsYlvanicus,meadow vole
Microtus oeconomus,tundra vole
Hicrotus miurus,singing vole
Lemmus sibiricus,brown lemming
Synaptomys borealis,northern bog lemming
Family Erethizontidae
Erethizon dorsatum,porcupine
106
7
)
)
).
)
)
j
J
)
)
)
and S.W.Buskirk);and water shrew,Sorex palustris (tracks of a small
mammal between ice openings on Watana Creek,March 1980,by S.W.
Buskirk).
Comparison of our species list with the literature and several
unpublished sources shows few distributional surprises.Our discovery
of arctic shrews in the study area constitutes a minor range extension;
the closest previous record was from Denali National Park (Murie 1962).
To inventory the shrews and voles of the upper Susitna Basin,we con-
ducted one spring and two fall trapline surveys,involving a total of
16,776 trap nights of effort.This effort resulted in the capture of
1752 microtine rodents (6 species)and 1747 shrews (4 species).The two
most abundant animals,constituting 76%of total captures,were northern
red-backed voles,represented by 1382 specimens,and masked shrews,
represented by 1286 specimens.Other shrews captured were arctic shrews
(297 specimens),dusky shrews (153),and pygmy shrews (11).Microtus
specimens included 203 tundra voles,68 meadow voles,and 75 singing
voles.Small numbers of brown lemmings (20)and northern bog lemmings
(4)were also taken.
Capture results from sites sampled during all three trapping periods
indicated a pronounced temporal difference in small mammal abundance
(Fig.6).Trapping in fall 1980 resulted in 941 animal captures,com-
pared to 125 the following May and 1231 in fall 1981.Comparison of
fall numbers shows that tundra voles were twice as abundant in 1981 as
.~.~
in 1980,red-backed voles 1.7 times more abundant,and masked shrews 1.3
times more abundant.Fall capture numbers of meadow voles,arctic
shrews,and pygmy shrews were about equal,while dusky shrews declined
sharply.We captured brown lemmings (6 specimens)and bog lemmings (3)
in 1981 only.Regardless of the temporal differences in population
107
J
)
)
)
)
)
600
500
400
en
LUex:
::J
f-300
0-
ct
U
u..o
ex:
LU 200
·Ill
:E
::J
Z
100
600
500-
400
300
200
100-
o
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
R-bV :o I
\I
\I
\I
\:
\I
\I
\I
\I
\I
\I
\I
\I
\I
\I
\I
\I
\I
\ I
\ I
\ I
\ I
\ I
\ I
\ I
\ I
\ I
\ I
b
J
"::l<
a;
C>
~g
<
TV•
o
<Xl
C>
~
"::l<
)FIGURE 6
SHREWS VOLES
J
)
Temporal variation in numbers of small mammal captures at 22 trapline
sites in the upper Susitna River Basin,Alaska,1980-81 (MS =masked
shrew,AS =arctic shrew,DS =dusky shrew,PS =pygmy shrew,R-bV =
northern red-backed-vole,TV =tundra vole,MV =meadow vole).
108
7
)
)
}
)
)
)
)
)
)
)
levels,the relative abundance ranking among species remained the same,
i.e.,the common species remained common and the rare continued to be
rare.
Six small mammal species not sampled on our traplines also occurred in
the study area:arctic ground squirrel,hoary marmot,collared pika,
red squirrel,porcupine,and snowshoe hare.
The arctic ground squirrel was a numerous and ecologically important
mammal of the region.Although the largest numbers were found on the
drier slopes,knolls,and ridges above treeline,small numbers occurred
at lower elevations:one near the mouth of Tsusena Creek,several along
the railroad sidings at Sherman and Curry,and one 0.8 km below treeline
in mixed forest near Portage Creek.
Duri ng the snow-free months ground squirrel s provi de an abundant,rel i-
able food source for a number of mammalian and avian predators (Carl
1962,Murie 1962,Bente 1981,Olendorff 1976).At High Lake in 1981 the
first ground squirrel emerged from hibernation the third week of April;
the last squirrel seen here in fall was 4 October 1981 (E.Powell,pers.
comm.).These emergence and entrance dates are essentially the same as
those reported by Hock (1960)and Hock and Cottini (1966)in the
Talkeetna Mountains near Anchorage,and by Carl (1962)at Ogotoruk
Creek,northwestern Alaska.Seasonal chronologies (after Hock 1960)in
ground squirrels in the Talkeetna Mountains,approximately 120 km south
of the study area,are shown in Figure 7.
General observations indicated that the Susitna study area supports a
relatively high and stable population of ground squirrels,probably
comparable to densities reported elsewhere in the State.For example,
in the Talkeetna Mountains to the south,Hock and Cottini (1966),on
20 June 1951,removed 27 squirrels from an area about 100 mx 50 m with
little apparent decrease in numbers;the squirrel population in this
109
)
}
,0'
FATTENING ALL FATTENING
J
HIBERNATION
LACTATION-YG EMERGE-...BREEDING BIRTH
-ENTER HIBERNACULA
H IBERHATION
J CARE OF YOUNG
1 I
GESTATION
J
JA FE MR AP MY IN JL AU SE OC NO OE
J
)
J
FIGURE 7
Seasonal chronologies of the arctic ground squirrel,Talkeetna
Mountains near Anchorage,Alaska (after Hock and Cattini 1966).
1,10
J
)
)
area remained high throughout four years of study.In the eastern
Brooks Range,Bee and Hall (1956)counted 175 ground squirrels along a
1-km ridge,and,in another location nearby,70 squirrels on approxi-
mately 1.5 ha of hillside.At Ogotoruk Creek,near the extreme western
end of the Brooks Range,Carl (1962,1971)estimated a maximum number of
220 animals on his 29-ha (72-acre)study plot during the month of July
1961.
Hoary marmots were locally common residents of the alpine zone.We
found scattered colonies above treeline above 1000 m.None was seen
within proposed impoundment areas.Marmots hibernate longer than ground
sqUirrels;in the Talkeetna Mountains near Anchorage,marmots emerge
from hibernation during the first third of May and begin entering
hibernacula in early September (Hock and Cottini 1966).
Hock and Cottini (1966)suggested that a portion of their marmot popula-
tion underwent seasonal shifts in altitude,moving down from high rocky
slopes in fall to sites having better soil conditions for winter denning
and having an available food supply in early spring.An opposite
seasonal movement apparently occurs in some Montana hoary marmot
colonies (Barash1974).The only suggestion of fall movement in the
upper Susitna River Basin was the observation of several marmot trails
and a single marmot traversing the 1067 m-high valley near Swimming Bear
Lake (WB 150)in about 8 cm of snow on 10 October 1980 (T.W.Hobgood,
pers.comm.).
Another locally common alpine species was the collared pika.It
occurred regularly in talus slopes at higher elevations.As in the case
of marmots,no pikas were seen below treeline.
Densities of pikas varied from five animals/ha in large rock slides,to
25/ha on small,isolated rock piles at Denali National Park jn 1962
(Broadbooks 1965).
111
)
)
}
J
)
J
)
:)
Active throughout the year (Sheldon 1930,Broadbooks 1965,Hock and
Cottini 1966),pikas store large quantities of dried plant material in
late summer for use during the winter months.
Evidence of avian predation on this species was our discovery of pika
bones in a raptor "pellet"(bird species unknown)near the edge of montane
alder thickets in fall 1981.Observations in other areas suggest that the
short-tailed weasel (Mustela erminea)is an important mammalian predator of
the pika (S.O.MacDonald pers.obs.,Rausch 1961,Broadbooks 1965).
In contrast to the three alpine species,red squirrels,porcupines,and
snowshoe hares were generally confined to the forested areas of the
Basin.IHthin these areas red squirrels were fairly common,while
porcupines and snowshoe hares were uncommon.Snowshoe hares,a major
source of food for predators over much of central Alaska,were generally
restricted to areas east of Watana Creek.Local ized "pockets"occurred
primarily in the vicinities of Jay Creek,Goose Creek,and the lower
Oshetna River.Long-term information on overall hare abundance,pro-
vided by several local residents,indicated that the low number of hares
during our study is a chronic situation and not just a low stage of a
population cycle.
4.2 -Small Mammal/Habitat Relationships
(a)Shrews and Voles
Forty-two trapping sites were organized into floristically similar groups
by using a cluster analysis of frequency counts of 81 plant taxa in the
ground cover (Fig.8).The major groups that emerged from this analysis
corresponded to the following vegetation types of Viereck and Dyrness 1980:
1)herbaceous and dwarf and low shrub,2)coniferous forest and woodland,
and 3)mixed forest,deciduous forest,tall shrub,and tall grass.Within
major groups,clustered subgroups roughly corresponded to sedge-grass
112
)
)
J
MIXED &
HERBACEOUS-FOREST DECIDUOUS FOREST-
c:::::D=W=A=R:::F=&==L:::O=W=:::S=H=R=U=B==,C,C=O=N=IF=E=R=O=U=S====.=.:::::JI!TAL L SH RUB,
I lea •I
I I I~:I
:SEOGE-GRASS':SEDGE-GRASS'LOW ~OPEN t>WOOOLANO t>BOG:BIRCH-".COTTON-....TALL ...TALL;
ISHRUB TUNDRA:WilLOW SHRUB I~SPRUCE SPRUCE I SPRuce""WOOD ""'ALOER""'GRASS,
I'I~~I I
~f~EPLI ~6.2 II 7 2 2 1 6 2 1 1 1 2 2 1 1 5 1 4 4 4 3 2 2 2 2 4 4 4 9 3 3 4 3 3 3 4 4 4 3 3 1 1
40958103267445676798789 3409651231232
100
J
*>...
J cc
<t
..J
:;50--en
w
>
)...
<t
..J
W
CC
J
o
••J L J 1J 1J 1I ~jLJ
....~
r-
...,..
~J .......
'--
I .
J
)
FIGURE 8
Clustering of 42 small mammal trapline sites into similar vegetative groupings,
based on an analysis of frequency counts of 81 plant taxa in the ground cover.
113
)
)
)
)
J
)
)
and shrub tundra,sedge-grass and low willow shrub;herbaceous-mixed low
shrub meadow,open white spruce forest to black spruce bog (low birch
shrub sites also clustered with this group);and paper birch-white
spruce forest,cottonwood forest,tall alder shrub,and tall grass
meadow (the last with a tall shrub component).The number of captures
of each small mammal species relative to these vegetation types is shown
in Figure 9.
Trapline site ordination by principal component analyses (PCA)provided
essentially the same general groupings as the clustering technique,
despite use of structural habitat variables instead of plant taxa counts.
This approach also tends to emphasize habitat continuity.The resultant
ordinations of 43 trapline sites trapped in fall 1981 are shown in
Figure 10,and those of 22 sites trapped during all three sampling
periods are shown in Figure 12 (p.124).
By using the relative abundance of a given small mammal species at each
trapping site as a vertical axis on the PCA ordinations (see Section
2.8),a general habitat occupancy pattern becomes visible (Fig.11).
Shrews and red-backed voles in the upper Susitna River Basin displayed a
relatively broad and uniform distribution pattern across the habitat
landscape.Masked shrews,the numerically dominant shrew species,
occurred at all trapping sites.They were most numerous in deciduous
forest (particularly cottonwood),grassland,and tall shrub sites.
Arctic shrews occurred at 29 trapline sites,with peaks of abundance on
the drier non-forested sites,particularily grassland (at low eleva-
tions)and low shrub (above treeline).Dusky shrews were thinly distri-
buted across the vegetation types of the study area.Although we captured
them at 23 sites,no.particular preferences were apparent;however,they
may have avoided the wettest sites.The few captures of pygmy shrew in
cottonwood forest (3 specimens),white spruce forest (1),and grassland
(1)during the fall 1981 trapping,and open spruce forests (5)and
cottonwood forest (1)during fall 1980,suggest a possible restriction
of this species to forest.
114
v V \.J V U U V V V IJ \.-.J
"MEADOW VOLE
"1 MASKED SHREW •
:'0 ·..
«
•
~50 (I·•..,•
u
:30 •••
•
."
••••
0
o •
d;tO •
d 20 •••
Z
~10.••••••••••••
I •
•••
-.-.-.-......•
•••
"TUNDRA VOLE
"1 ARCTIC SHREW...«..
•g so
•«..
•
,
:c 40
t:40
U
-
~"••~'"
0"•~"L::-•
z
"••
10 •••
•••
o •e_••••••••••••••••
,••••••..•
•
"SINGING VOLE
"1 DUSKY SHREW
."
...
~••::l so',
~§50 ~40-1
01 •:c 40
U
~Jo-
."•
0
0"
CPO g 10'
Z
"0'-·"'····•••••••••••••••••••••••
."•~50
~..O
U."og20
"OI'~"~I'tli"'ii ;'!i1~""'''ii 'i1"
:HERBACEOU8~:CONIFEROUs :M'XED ..,
I DWARF ..LOW SHRUB I FOREST I DECIDUOUS FOR.-I:~-----_·_----~--l:-----·_-------~---_TAI:.L_~!'!'Y.!l_J'$loc;E.OIlAWS(IIGE·aR~sSlLow ·OrE,...WO/XllA"D ..I.OG'IIRCH...conO~T"l.L"'T~LL:~JlUllTf,I_"':W'UOW '""III &PR\lC.f.SPRUCE ,IPRUCl WOOD "UlDI""ASS..'". .:.::
~-------------~----------~-~---------~
,,
I HERBACEOUS-I CONIFEROUS I MIXED a I
•DWARF ..LOW SHRUB I FOREST I DECIDUOUS FOR.-:!~IDc1:oiiAS;;'SEDcii:GA";;iiow~jOP£N~-.;~;~D-;-.Oo~il;C:.-:-t;;;~;;~T;~~~~L"L ~.""AlJalll~DA":WIUow SHIIUII ~&PIIUCE SPIIUCI ,"III1CE WOOII O\UlUI·......n.L ~~j~_~j
NORTHERN RED-BACKED VOLE
•
•••
•
•••
••
••••
••
•
••••
•
•
•
••••
••e.-•
••
"
::60
«
'"~-.,
U."o
6 20
Z
"
BROWN LEMMING"
FIGURE 9
Abundance
the upper
of eight small mammal species relative to vegetation
Susitna River Basin,Alaska,29 July-3D August 1981.
types at 42 trapline sites in
)
)
)
)
)
).
)
)
)
)
GROUPINGS OF 43 TRAPLINE SITES
MASKED SHREW
DUSKY SHREW
FIGURE 11
ALL SPECIES
ARCTIC SHREW
NORTHERN RED-BACKED VOLE
Habitat occupancy patterns of small mammals captured at 43 trap1ine sites,
upper Susitna River Basin,Alaska,29 Ju1y-30 August 1981.Species relative
abundance has been added as a vertical axis to the two-dimensional PCA
ordination shown in Figure 10 (see Methods,Section 2.8).
"'7
)
)
)
)
)
)
)
)
)
)
MEADOW VOLE
SINGING VOLE
FIGURE 11 (Continued)
TUNDRA VOLE
BROWN LEMMING
118
)
)
)
)
)
)
)
)
)
)
)
Red-backed voles,the dominant microtine of the region,occurred on all
but five trapping sites.Although red-backed vole abundance levels were
roughly similar across most forest and shrub types,greatest numbers
occurred in open and woodland spruce and cottonwood forest sites.
Herbaceous meadows,particularly in wet situations,harbored lower
red-backed vole densities,as did paper birch forest •.
In contrast to the more general habitat occupancy patterns of most
shrews and of red-backed voles,the three Microtus species displayed
stronger habitat specificity,as evidenced by their general restriction
to open,non-forested sites (Fig.11).Singing vole colonies were found
in open low shrub,herbaceous tundra,and mat and cushion tundra above
treeline.Captured on only 10 trapline transects,they were most abundant
in open low willow-birch shrub on relatively dry soils.Tundra voles
and meadow voles occurred primarily in sedge and grass-forb meadows and
bogs.We captured tundra voles on 22 sites (primarily grass-forb,but
also sedge-grass),compared to 10 for meadow voles (primarily wet sedge-
grass).Small numbers of brown lemmings were captured on 11 sites at or
above treeline,usually in wet herbaceous and low shrub situations.80g
lemmings were taken at lower elevations in mesic sedge-grass/low shrub
meadow (2 captures),grass meadow (1),and near a seepage in white
spruce forest (1).
Some of the small mammal species occupied a broad range of vegetation
types,while others were more restricted.We quantified these differ-
ences by calculating a standardized habitat niche breadth measure for
each species captured during fall 1981 (Table 23).The ubiquitous
masked shrew and red-backed vole had the broadest habitat niche breadth,
followed closely by dusky shrew and arctic shrew.Microtus species,and
particularly singing voles,had the narrowest habitat niche breadths,
along with the rare or uncommon pygmy shrew,bog lemming,and brown
lemming.
119
)
)
)
TABLE 23
STANDARDIZED HABITAT NICHE BREADTH VALUES FOR TEN SMALL MAMMAL SPECIES
SAMPLED BY SNAP AND PITFALL TRAPPING AT 43 SITES,UPPER SUSITNA RIVER
BASIN,FALL 1981.(SEE SECTION 2.8 FOR CALCULATION OF Ed.AND HABITAT
NICHE BREADTH VALUES.)1
)
)
)
)
)
)
)
)
Species (Sum of captures/100 TN [Ed i ])
Masked shrew (464.7)
Northern red-backed vole (454.8)
Dusky shrew (28.3)
Arctic shrew (96.3)
Brown lemming (10.2)
Tundra vole (87.7)
Northern bog lemming (2.2)
Meadow vole (43.8)
Pygmy shrew (2.8)
Singing vole (42.7)
120
Standardized
habitat niche breadth value·
0.60
0.59
0.45
0.38
0.21
0.17
0.09
0.08
0.08
0.05
)
)
)
)
)
As population densities fluctuate over time,a species might be expected
to expand its range into suboptimal habitat during periods of high
density and contract its range to optimal habitat during periods of low
density (Guthrie 1968,others).Changes in habitat niche breadth for
species captured in the upper Susitna River Basin generally reflect such
changes (Table 24).Variation in habitat niche breadth between periods
seems to parallel changes in abundance for masked shrews,red-backed
voles,and dusky shrews.In masked shrews and red-backed voles,niche
breadth varied little,despite large variations in abundance.Range
contraction did not occur in arctic shrews,however,which increased in
niche breadth despite a slight decline in abundance.The habitat niche
breadth of the tundra vole remained essentially constant, despite a
two-fold population increase from fall 1980 to fall 1981.The opposite
occurred with the meadow vole,in which abundance levels were constant
from fall to fall,yet niche breadth increased.
Interspecific interactions,particularly among ecologically similar
species,can playa major role in determining intraspecific habitat
utilization (MacArthur and Wilson 1967)and may help explain the
apparent anomalies we witnessed in shifts of habitat niche breadth
values.,'0 avoid competing for 1imited resources,species may occupy
different habitats,or may occupy the same habitat but exploit its
resources (food,den sites,etc.)in different ways and/or at different
times.Closely related species,similar in size and broadly overlapping
in food requirements,should display the greatest degree of habitat
segregation (Grant 1978).Discrete habitat distribution patterns among
the Basin's three Microtus species (Fig.11)supports this conjecture:
Singing voles and meadow voles occupied a narrow and non-overlapping
range of habitats,suggestive of species having strong and different
habitat preferences.Tundra voles,in contrast,displayed a more
diffuse and overlapping pattern of habitat occupancy,suggestive of a
more ecologically flexible species,although their peak densities
occurred on sites essentially devoid of either congener •.
121
) .TABLE 24
STANDARDIZED HABITAT NICHE BREADTH VALUES FOR SIX SMALL MAMMAL SPECIES
CAPTURED ON 22 TRAPPING SITES,DURING THREE SAMPLING PERIODS,UPPER
SUSITNA RIVER BASIN,1980-81.(SEE SECTION 2.8 FOR CALCULATION OF
).HABITAT NICHE BREADTH VALUES.)
)
)
)
122
)
)
)
)
)
)
)
)
)
)
)
A comparison of the habitat occupancy patterns of the tundra and meadow
voles between fall 1980 and fall 1981 (Fig.13)shows that while the
tundra vole population increased substantially the second year,spill-
over into other meadow habitats was not evident (breadth values remained
constant).Also,while meadow vole abundance was similar between years,
habitat shift and expansion occurred the second year (breadth values
increased)--but into habitats not occupied by its congener.Habitat
segregation between two similar species was thus maintained and the
possibility for overt competitive interactions reduced.
There was no clear pattern of habitat segregation between red-backed
voles and Microtus species.Capture information on sites with low
numbers of Microtus in fall 1980 and high numbers the following year
showed an inverse relationship in red-backed vole numbers (in spite of
the fact that this vole was also more abundant the second year).West
(1979),noting a similar situation for red-backed voles and Microtus in
the Yukon-Tanana Highlands,attributed it to competitive exclusion.
Other studies (Morris 1969,Turner et al.1975)also have shown that
Microtus and red-backed voles tend to exclude each other from certain
·s i tes.
Among members of the Susitna River Basin's diverse microtine fauna,
then,red-backed voles were the most abundant and widespread.A habitat
generalist,the species dominated the forest and shrublands of the area.
Open herbaceous-dominant habitats,left vacant by declining Microtus
populations,were quickly colonized and dominated by this adaptable
vole,which has a relatively unspecialized tooth structure (Guthrie
1965)and generalized feeding habits (Guthrie 1965,·Grodzinski.1971,
Bangs 1979,West 1979).Although red-backed vole numbers can vary
considerably from year to year,the magnitude of change is usually less
dramatic (and also less predictable)than that of such open country
species as Microtus and Lemmus (Pitelka 1967,Whitney 1976,West 1979).
123
}
)
)
)
)
)
)
)
)
)
)
)
)
)GROUPINGS OF 22 TRAPLINE SITES
)
)
)
FALL 1980
TUNDRA VOLE
FALL 1981.
)
)
)
FIGURE 13
FALL 1980
MEADOW VOLE
..~
FALL 1981
,.~
)
)
Changes in habitat occupancy patterns of tundra voles and meadow voles
between fall 1980 and fall 1981,upper Susitna River Basin,Alaska.Species
relative abundance has been added as.a vertical axis to the two-dimensional
PCA ordination shown in Figure 12 (see Methods,Section 2.8).
125
)
)
)
)
)
)
)
)
)
)
Members of the genus Microtus were restricted to,and specialized in,
meadow and meadow/shrub habitats found scattered about the Basin's
landscape.All have more specialized tooth morphologies and diets than
have red-backed voles (Guthrie 1965,West 1979).The similarity of
habitat and trophic requirements among Microtus is most pronounced in
tundra voles and meadow voles (West 1979),and the impact of competition
probably plays a major role in determinin9 the dynamic spatial relation-
ships between the two.Among Microtus,tundra voles appear the most
ecologically flexible,in that they have a somewhat simpler tooth struc-
ture (Guthrie 1965),broader food habits (West 1979),and wider toler-
ance to differing vegetation types (West 1979,this study)than have
their congeners.As suggested by West (1979),such flexibility probably
accounts for the fact that among the three Microtus species occurring in
the SusitnaBasin,tundra voles seemed better able to find and exploit
isolated "pockets"and border patches of suitable habitat.This flexi-
bility might also explain why tundra voles were the only Microtus found
on the two Susitna River islands sampled during 1981.
Northern bog lemmings and brown lemmings did not appear to be major
microtine constituents in the study area.Bog lemmings are generally
uncommon throughout their range,and little is known of their ecological -
requirements (Banfield 1974,West 1979,MacDonald 1980).In other areas
of the State,small numbers have been taken primarily in shrub bogs and
marshes (Osgood 1900,Dice 1921,West 1979,MacDonald 1980)--not unlike
the few sites where we found them during this study.Their diet is
apparently restricted to sedges,grasses,some forbs (Cowan and Guiguet
1956)and mosses (West 1979).
Although the high country of the upper Susitna Basin has an apparent
abundance of suitable brown lemming habitat,we captured only small,
scattered numbers during our study •.They have been found in fairly
large numbers in other montane areas of central Alaska (R.L.Rausch
pers.comm.),so perhaps we failed to sample the right habitat,or,more
126
)
)
)
)
)
)
)
)
)
)
)
likely,sampled during a period of low population levels.Brown
lemmings are usually associated with wet sedge-grass tundra above tree-
line,but are also found locally at lower elevations in spruce bogs and
wet meadows (Buckley and Libby 1957,Banfield 1974).This species is
almost completely dependent on a diet of sedges and grasses (Guthrie
1968),although mosses may be important at times (West 1979).
Among the insectivorous shrews,habitat occupancy patterns indicated
considerable spatial overlap between species and only weak habitat
preferences.Hence,competition could help explain the apparent inverse
relationship of masked shrew abundance and the abundance of the other
shrew species,particularly the similarly-sized dusky shrews and pygmy
shrews.Confounding factors,not obvious from our data,could also be
involved (Terry 1981):(1)Shrews coexist in the same habitats,and
their environmental requisites are less similar than assumed (Disparity
in body size between masked shrews and arctic shrews suggests the ability
to coexist [see Brown 1975],which might explain why arctic shrew
abundance appeared least affected by masked shrew abundance in fall
1981);(2)they occupy distinct subdivisions of the habitats (i.e.,
microhabitats);or (3)habitat coexistence (macro-and micro-)is
occurring because critical resources are not limited.
(b)Other Species
Arctic ground squirrels inhabit herbaceous tundra and open shrub"
habitats above treeline (Guthrie 1967,Kurten and Anderson 1980,this
study).At lower elevations they also colonize riverbanks,lakeshores,
moraines,eskers,road sidings,and other disturbed sites with subclimax
vegetation (Banfield"1974,Guthrie 1968,this study).Our observations
corroborate Bee and Hall's (1956)conclusion for the Brooks Range that
the optimum conditions for ground squirrel colonies are (1)loose
permafrost-free soils on well-drained slopes,(2)vantage points from
which the surrounding terrain can be observed,and (3)bare soils
127
J
)
)
)
)
)
)
)
)
)
surrounded by vegetation that is in an early xerosere stage of succes-
sion.Carl (1962)found ground squirrels avoided sites where tall
vegetation (greater than 20 em)impaired vision.The effects of
squirrel activity--e.g.,burrowing,mound buildin9,feeding,feces
deposition--within areas of established colonies tends to maintain
vegetation at an early successional stage (Carl 1962,Youngman 1975)•.
Hoary marmots and collared pikas are generally restricted to tundra/
block-field habitats at high elevations (Hoffmann et al.1979,this
study).Both are ecotone species:their homes and shelters are in one
habitat (rocks of various particle size and shape)and their food in
another (various herbaceous tundra types)(Broadbooks 1965).The co-
occurrence of marmots,pikas,and even 9round squirrels in apparently
the same habitat suggests high potential for both competitive and
cooperative interactions.
The arboreal red squirrel occupies a variety of forest habitats,but
prefers mature coniferous forest (Cowan and Guiguet 1956).White spruce
forest is generally considered the optimal habitat in interior Alaska
(Nodler 1973,others).Here,red squirrels feed primarily on the seeds
of spruce,particularly white spruce,but supplement their diet with
fungi,fruits,and even the buds of spruce and aspen (Smith 1967,Nodler
1973).They store large quantities of spruce cones,and mushrooms when
available,in "middens"for winter use (t4urie 1927,Streubel 1968).
Buskirk (pers.comm.)noted that,in fall 1981,red squirrel middens in
his study area appeared composed only of mushrooms and spruce buds.A
massive cone crop failure caused by an area-wide epidemic of white
spruce needle rust (Chrysomyxa ledicola)during 1980 (J.H.McBeath,
Univ.Alaska Agric.Expt.Station,pers.comm.)would explain why
squirrels were storing such low quality food as spruce buds (Smith
1967).What long-term effects this crop failure might have on the upper
Susitna River Basin's red squirrel population is not known,but Smith
(1967)reported a 67%drop in a red squirrel population following the
128
)
)
)
)
)
)
)
)
)
)
)
second year of a two-year cone crop failure in white spruce forest and
suggested that the squirrels had emigrated into surrounding black spruce
stands.
Porcupines occupy a broad range of forest and shrub habitats (Woods
1973).In mountainous regions they prefer heavily wooded forests during
the winter (Hock and Cottini 1966,Harder 1979),but may occasionally be
found above treeline,even during the coldest months (Irving and Krog
1955).We recorded occasional porcupines only in forested areas of the·
upper Susitna River Basin.
In interior Alaska,Wolff (1977)found that snowshoe hare habitat
preference depended on population density:during population lows hares
were restricted to dense black spruce forest and willow-alder thickets;
during highs they used a wider variety of vegetation types,including
recently burned areas with minimal cover.He concluded that a patchy
environment of recently burned sites with inclusions of unburned spruce
was the preferred hare habitat.The chronic scarcity of snowshoe hares
in the upper Susitna River·Basin was probably related to a scarcity of
suitable habitat.Noticeably absent from this area were recent burns
and riparian shrub thickets--early successional habitats that could
provide hares the opportunity to substantially increase and expand their
numbers beyond the safe but unproductive stands of dense spruce and
alder thickets in which we found them.
129
)
)
)
)
)
5 -LITERATURE CITED
Abercrombie,W.R.1899.Birds found in the Copper River Valley.
p.334-336.In:E.F.Glenn and W.R.Abercrombie,Report of
explorations Tn the Territory of Alaska,1898.War Department,
Wash.,D.C.
Argus,G.W.1973.The genus Salix in Alaska and the Yukon.Nat.Mus.
Canada Publ.Bot.No.2.
Bailey,A.M.1926.Winter notes for the Copper River,Alaska.Condor
28:174-175.
Baker;R.H.1951.Mammals taken along the Alaska Highway.Univ.
Kansas Mus.Nat.Hist.Publ.5:87-177.
Baker,R.H.and J.S.Findley.1954.Mammals from southeastern
Alaska.Univ.Kansas Publ.Mus.Nat.Hist.7:473-477.
Banfield,A.W.F.1974.The mammals of Canada.Univ.Toronto Press,
Toronto.
)
~ngs,E.E.1979.The effects of tree crushing on small mammal popu-
lations in south central Alaska.M.S.Thesis,Univ.Nevada,.
Reno.
)
)
)
)
)
Barash,D.P.1974.The social behavior of the hoary marmot (Marmota
caligata).Anim.Behav.22:256-261.
Bee,J.W.and E.R.Hall.1956.Mammals of northern Alaska on the
ay~tic slope.Misc.Pap.Univ.Kansas Mus.Nat.Hist.No.8.
Bente,P.J.1981.Nesting behavior and hunting activity of the
Gyrfalcon,Falco rusticolus,in the Alaska Range,Alaska.M.S.
Thesis,Univ.Alaska,Fairbanks.
Broadbooks,H.E.1965.Ecology and distribution of the pikas of
Washington and Alaska.Amer.Midl.Nat.73:299-335.
Brown,J.H.1975.Geographical ecology of desert rodents.Pages
315-341 in M.Cody and J.Diamond,eds.Ecology and evolution of
communities.Harvard Univ.Press,Cambridge,Mass.
Brown,L.,and D.Amadon.1968.Eagles,hawks,and falcons of the
world.Vol.2.Country Life Books,Hamlyn Publ.Group Ltd.,
Middlesex,Gt.Britain.
130
)
)
)
)
)
)
)
)
)
)
Brown,R.N.1974.Aspects of vocal behavior of the Raven (Corvus
corax)in interior Alaska.M.S.Thesis,Univ.Alaska.
Buckley,J.L.,and W.L.Libby.1957.Research and reports on aerial
interpretation of terrestrial bioenvironments and faunal popula-
tions.Arctic Aeromedical Lab.,Fairbanks,Alaska,Tech.Rept.
57-32.
Cade,T.J.1960.Ecology of the peregrine and gyrfalcon populations
in Alaska.Univ.Calif.Publ.Zool.63:151-290.
Calhoun,J.B.1948.North American census of small mammals.Rodent
Ecology Project.Rel ease No.1.Johns Hopkins University,
Baltimore,Maryland.
Carbyn,L.M.1971.Densities and biomass relationship~of birds nest-
ing in boreal forest habitats.Arctic 24:51-61.
Carl,E.A.1962.Ecology of the arctic ground squirrel,Citellus
parryi.Terrestrial mammals investigation,Ogotoruk Creek -Cape
Thompson and Vicinity.Part B.Final report Univ.Alaska Dept.
Biol.Sci.to U.S.Atomic Energy Commission.
Carl,E.A.1971.Population control in arctic ground squirrels.
Ecology 52:395-413.
Conant,B.,and R.King.1981.Alaska-Yukon breeding pair survey--
1981.U.S.Fish and Wildl.Servo Pacific Waterfowl Flyway
Report 80.
Cottam,G.,and J.T.Curtis.1956.The use of distance measures in
phytosociological sampling.Ecology 37:451-460.
Cowan,I.Met.and C.J.Guiguet.1956.The mammals of British
Columbia.British Columbia Provo Mus.Handbook 11.
Curtis,J.T.,and R.P.McIntosh.1951.An upland forest continuum in
the prairie-forest border region of Wisconsin.Ecology 32:476-496.
Dice,L.R.1921.Notes on the mammals of interior Alaska.J.Mammal.
2:20-28.
Dixon,J.S.1927a.Contribution to the life history of the Alaska
Willow Ptarmigan.Condor 29:213-223.
Dixon,J.S.1927b.The Surf-Bird's secret.Condor 29:3-16.
131
)
Dixon,J.S.1933a.Nesting of the Wandering Tattler.Condor 35:173-
179.
Dixon,J.S.1933b.Red fox attacked by a Golden Eagle.J.Mammal.
14:257.
)Dixon,J.S.1933c.Three magpies rob a Golden Eagle.Condor 35:161.
Di xon,·J.S.1938.Birds and mammals of Mount McKinley National Park,
Alaska.Nat.Parks Fauna Series No.3.
)
)
)
)
)
)
)
)
Dixon,W.J.,and M.B.Brown,eds.1979.Biomedical computer pro-
grams,P-series.Univ.of Calif.Press,Berkeley,Calif.
Gabrielson,I.N.,and F.C.Lincoln.1959.The birds of Alaska.
Stackpole Co.and Wildl.Manage.Inst.
Grant,P.R.1978.Competition between species of small mammals.
p.38-51.In:D.P.Snyder,ed.Populations of small mammals
under natural conditions.Vol.5,Special Publ.Series,
Pymatuning Lab.of Ecology,Univ.Pittsburgh.
Grodzinski,W.1971.Energy flow through populations of small mammals
in the Alaskan taiga forest.Acta Theriol.16:231-275.
Guthrie,R.D.1965.Variability in characters undergoing rapid evolu-
tion,an analysis of Microtus molars.Evolution 19:214-233.
Guthrie,R.D.1967.Fire melanism among mammals.Amer.Midl.Nat.
77:227-230.
Guthrie,R.D.1968.Paleoecology of the late Pleistocene small mammal
community from interior Alaska.Arctic 21:223-244.
Hall,E.R.1980.The mammal s of North America.Vol.I &II.John
Wiley &Sons,New York.
Harder,L.D.1979.Winter feeding by porcupines in montane forests of
southwestern Alberta.Can.Field-Nat.93:405-410.
Hinckley,F.C.1900.Notes on the animal and vegetable life of the
region of the Sushitna and Kuskokwim rivers.p.76-85.·In:
J.E.Spurr,A reconnaissance in southwestern.Alaska in 1898.
U.S.Geological Survey Ann.Rept.20,part VII,1898-1899:31-264.
Hock,R.J.1960.Seasonal variations in physiologic functions of
Arctic ground squirrels and black bears.Bull.Harvard Mus.
Compar.Zool.124:155-171.
132
J
J
J
)
Hock,R.J.,and V.Cottini.1966.Mammals of the Little Susitna
Valley,Alaska.Amer.Midl.Nat.76:325-339.
Hoffmann,R.S.,J.W.Koeppl,and C.F.Nadler.1979.The relation-
ships of the Amphiberingian marmots (Mammalia:Sciuridae).
Occas.Papers,Mus.Nat.Hist.,Univ.Kansas 83:1-56.
Hulten,E.1968.Flora of Alaska and neighboring territories.
Stanford Univ.Press,Stanford,Calif.
International Bird Census Committee.1970.Recommendations for an
international standard for a mapping method in bird census work.
Audubon Field Notes 24:727-736.
Irving,L.,and J.Krog.1955.Body temperature of Arctic and sub-
arctic birds and mammals.J.Appl.Physiol.6:667-680.
Kertell,K.1981.Bird checklist for Denali National Park.Alaska
Nat.Hist.Assoc.in cooperation with the U.S.Nat'l.Park
Service.
Kessel,B.1979.Avian habitat classification for Alaska.Murrelet
60:86-94.
Kessel,B.,and D.D.Gibson.1978.Status and distribution of Alaska
birds.Studies in Avian Biology No.1.
Kessel,B.,S.M.Murphy,and L.J.Vining.1980.Waterbirds and wet-
lands,Chisana-upper Tanana Rivers,Alaska,1979 (with emphasis
on the Scottie-Desper Creek wetlands).Univ.Alaska Museum
unpubl.report to Northwest Alaskan Pipeline Co.
King,J.G.,
1980.
79.
and B.Conant.1980.Alaska-Yukon breeding pair survey--
U.S.Fish and Wildl.Servo Pacific Waterfowl Flyway"Report
)
)
)
)
King,J.G.,and B.Conant.1981.The 1980 census of Trumpeter Swans
on Alaskan nesting habitats.Amer.Birds 35:789-793.
Krebs,C.J.,and I.Wingate.1976.Small mammal communities of the
Kluane Region,Yukon Territory.Can.Field-Nat.90:379-389.
Kurt~n,B.,and E.Anderson.1980.Pleistocene mammals of North
America.Columbia Univ.Press,N.Y.
MacArthur,R.H.,and E.O.Wilson.1967.The theory of island bio-
geography.Princeton Univ.Press,Princeton,N.J.
133
)
)MacDonald,S.O.1980.Habitats of small mammals and birds:evaluat-
ing the effects of agricultural development in the Delta Junction
area,Alaska.Univ.Alaska Museum unpubl.report to Alaska Divi-
sion of Lands,Fairbanks,Alaska.
)
Manville,R.H.,
mammals.
211.
and S.P.Young.1965.Distribution of Alaskan
U.S.Dept.Interior Fish and Wildlife Service Circular
Morris,R.D.1969.
Clethrionomys
50:291-301.
Competitive exclusion between Microtus and
in the aspen parkland of Saskatchewan.J.Mammal.
)
)
)
)
)
Morrison,D.F.1976.Multivariate statistical methods.2nd ed.
McGraw-Hill,New York,N.Y.
Murie,A.1944.Golden Eagle.p.222-229.]n:The wolves of Mount
McKinley.Nat.Parks Fauna Series No.5.
Murie,A.1946.Observations on the birds of Mount McKinley National
Park,Alaska.Condor 48:253-261.
Murie,A.'1956.Nesting records of the Arctic Willow Warbler in ~lount
McKinley National Park,Alaska.Condor 58:292-293.
Murie,A.1962.Mammals of Mount McKinley National Park,.Alaska.Mt.
McKinley Nat.Hist.Assoc.
Murie,A.1963.Birds of Mount McKinley National Park,Alaska.Mt.
McKinley Nat.Hist.Assoc.
Murie,O.J.1923.Nest and eggs of the Wandering Tattler found in
Alaska.Murrelet 4:17.
Murie,O.J.1924.Nesting records of the wandering Tattler and Surf-
bird in Alaska.Auk 41:231-237.
Murie,O.J.1927.The Alaska red squirrel providing for winter.J.
Mammal.8:37-40..',.,
)
Nodler,F.A.
Alaskan
Al aska,
1973.Food habits,vocalizations,and territoriality of
red squirrels (G.Tamiasciurus).M.S.Thesis,Univ.of
Fairbanks.
)
)
Olendorff,R. R.1976.The food habits of North American golden
eagles.Amer.Midl.Nat.95:231-236.
134
)
)
)
)
)
)
)
)
)
)
)
Osgood,W.H.1900.Results of a biological reconnaissance of the
Yukon River region.N.Amer.Fauna No.19:7-45.
Osgood,W.H.1901.Natural history of the Cook Inlet region,Alaska.
N.Amer.Fauna 21:51-87.
Pielou,E.C.1975.Ecological Diversity.John Wiley and Sons,New
York.
Pitelka,F.A.1967.Some characteristics of microtine cycles in the
arctic.p.153-184.In:H.P.Hansen,ed.Arctic biology.
Oregon State Univ.Press,Corvallis.
Pruitt,W.O.,Jr.1968.Synchronous biomass fluctuations of some
northern mammals.Mammalia 32:172-191.
Rausch,R.L.1961.Notes on the collared pika,Ochotona collaris
(Nelson),in Alaska.Murrelet 42:22-24.
Ritchie,R.1980.Results of 1980 aerial surveys of spring waterfowl
concentration areas along the Alaskan Gas Pipeline route,Tetlin
Junction to Pump Station No.3.Alaska Biological Research
unpubl.report to Northwest -Alaskan Pipeline Co.
Ritchie,R.,and J.Hawkings.1981.Summer and fall waterbird investi-
gations along the proposed Northwest Alaskan Gas Pipeline,
Alaska,1980.Alaska Biological Research unpubl.report to
Northwest Alaskan Pipeline Co.
Roseneau,D.G.1972.Summer distribution,numbers,and food habits of
the Gyrfalcon (Falco rusticolus L.)on the Seward Peninsula,
Alaska.M.S.Thesis,Univ.Alaska.
Roseneau,D.G.,C.E.Tull,and R.W.Nelson.1981.Protection
strategies for Peregrine Falcons and other raptors along the
proposed Northwest Alaskan GaS Pipeline route.LGL Alaska
unpubl.report to Northwest Alaskan Pipeline Co.
Sampson,R.J.1978.Surface II graphics sy~tem (revision one).
Kansas geological survey,Lawrence,Kansas.
Schaller,G.B.1954.Some notes on the birds of the Talkeetna Moun-
tains in Alaska.Univ.of Alaska unpubl.manuscript.
Sheldon,C.1909.List of birds observed on the upper Toklat River
near Mt.McKinley,Alaska,1907-1908.Auk 26:66-70.
135
)
)Sheldon,C.1930.The wilderness of Denali:explorations of a hunter-
naturalist in northern Alaska.Charles Scribner's Sons,N.Y.
Smith,M.C.1967.
during spruce
Fairbanks.
Red squirrel (Tamiasciurus hudsonicus)ecology
cone failure in Alaska.M.S.Thesis,Univ.Alaska,
)
)
)
)
Spindler,M.A.1976.Ecological survey of the birds,mammals,and
vegetation of Fairbanks Wildlife Management Area.M.S.Thesis,
Univ.Alaska,Fairbanks.
Spindler,M.A.,and B.Kessel.1980.Avian populations and habitat
use in interior Alaska taiga.Syesis 13:61-104.
Spindler,M.A.,S.M.Murphy,and B.Kessel.1981.Ground censuses of
waterbird populations in the upper Tanana Valley,Alaska.p.133-
148.In:F.L.Miller and A.Gunn,eds.,Symposium on census
and inventory methods for population and habitats.Proc.North-
west Sec.Wildl.Soc.,April 10,1980,Calgary,Alberta.
Strecker,R.L.,F.A.Ryser,W.J.Tietz,and P.R.Morrison.1952.
Notes on mammals from Alaska.J.Mammal.33:476-480.
Streubel,D.P.1968.Food storing and related behavior of red
squirrels (Tamia'sciurus hudsonicus)in interior Alaska.M.S.
Thesis,Un;v.Alaska,fairbanks.
Terry,C.J.1981.Habitat differentiation among three species of
Sorex and Neurotrichus gibbsi in Washington.Amer.Midl.Nat.
106:119-125.
)
Turner,B.N.,M.R.Perrin,and S.L.
ence of voles in spruce forest:
changes in aggression.Can.J.
Iverson.1975.Winter coexist-
the relevance of seasonal
Zool.53:1004-1011.
)
U.S.Corps of Engineers.1977.Final environmental impact statement,
hydroelectric power development,upper Susitna River Basin,
Southcentral rail belt area,Alaska.Office Chief Engineers,
Dept.of Army,Wash.,D.C.
}
Viereck,E.N.1959.
Park,Al aska.
Small mammal populations in Mt.McKinley National
Univ.Colo.unpubl.manuscript,Boulder.
)
)
Viereck,L.A.,and C.T.Dyrness.1980.A preliminary classification
system for vegetation of Alaska.U.S.Forest Service,Pacific
Northwest Forest and Range Experiment Station,Gen.Tech.Report
PNW-106.
136
the 1970-1972-1974
Pipeline.World Conf.
)
)
)
)
)
West,G.C.,and B.B.DeWolfe.1974.Populations and energetics of
taiga birds near Fairbanks,Alaska.Auk 91:757-775.
West,S.D.1979.Habitat responses of microtine rodents to central
Alaskan forest succession.Ph.D.Thesis,Univ.Calif.,Berkeley.
White,C.M.1974.Survey of the Peregrine Falcon and other raptors in
the proposed Susitna River reservoir impoundment areas.U.S.
Fish and Wi·ld1ife Service unpubl.interim report.
White,C.M.,and T.J.Cade.1975.Raptor studies along the proposed
Susitna powerline corridors,oil pipeline and in the Yukon and
Colville river regions of Alaska.U.S.Fish and Wildlife Serv.,
Bur.Land Mgmt.,Nat.Park Service,Arctic Inst.N.Amer.,and
Amer.Mus.Nat.Hist.Unpub1.report.
White,C.M.,T.D.Ray,and L.W.Sow1.1977.
raptor surveys along the Trans-Alaska Oil
Birds of Prey 1:222-229.
Whitney,P.1976.Population ecology of two sympatric species of sub-
arctic microtine rodents.Eco1.Monogr.46:85-104.
)
Whitney,P.H.
species
Thesis,
1973.Population biology and energetics of three
of small mammals in the taiga of interior Alaska.
Univ.Alaska,Fairbanks.
Ph.D.
)
)
)
)
Wilber,C.G.1946.Mammals of the Knik River Valley,Alaska.J.
Mammal.27:213-216.
Williamson,F.S.L.,and L.J.Peyton.1959.Breeding record of the
Double-crested Cormorant in southcentral Alaska.Condor 61:154-155.
Wolff,J.A.1977.Habitat utilization of snowshoe hares (Lepus
americanus)in interior Alaska.Ph.D.Thesis,Univ.Calif.,
Berkel ey.
.Wolff,J.A.,and J.C.Zasada.1975.Red squirrel response to c1ear-
cut .and she1terwood systems in interior Alaska.U.S.Forest
Service Res.Note,PNW-255..
Woods,C.A.1973.Erethizon dorsatum.Amer.Soc.Mammal.,Mammalian
Species 29:1-6.
Youngman,P.M.1975.Mammals of the Yukon Territory.National
Museums of Canada,Pub1.in Zoology No~10.
137