HomeMy WebLinkAboutAPA404,....
.-'!
I
~
I
i
r
I
TK
1425
"88
ItS4
nCh494
SUSIT A HYDROELECTRIC PROJECT
PHASE I FINAL'REPORT
BIG GAME STUDIES
Volume I B'IG GAME SUMMARY REPORT
ALASKA DEPARTMENT OF FISH AND GAME
Submitted to the Alaska Power Authority
March 1982
Susitna File Copy
Acre #t{3 .3_.~;-
.-
..-
-
-
SUSITNA HYDROELECTRIC PROJECT
PHASE I FINAL REPORT·
BIG GAME STUDIES
VOLUME I BIG GAME SUMMARY REPORT
ALASKA DEPARTMENT OF FISH AND GAME
Submi tted to the
Alaska Power Authori ty
March,1982
ff~
l~lS
.~~
-f>stt
¥to.YO~
ARLIS
Alaska Resources
&Information Senri"~
-
'r
:1
r
r
j
-
INTRODUCTION
The Susi tna River Basin is one of the most important wildlife
areas in Alaska.It supports relatively high populations of a
variety of species of special interest to man.close proximity
to human population centers and ease of access by aircraft,high-
way vehicle,off-road vehicle and boat have made the Basin one of
the highest public use areas of the State.For example,Game
Management Units 13,14 and 16 through which the Susi tna River
runs,have been the three highest moose harvest units in Alaska
in recent years.
When the U.S.Corps of Engineers reactivated proposals for hydro-
electric development during the early 1970's,questions were
raised about the impact of these proposals on wildlife and the
use of wildlife.However,with the exception of caribou,little
was known of the importance of the immediate impact area to wild-
life.Limited amounts of money became available for studies of
moose from the Corps of Engineers,U.S.Fish and Wildlife Service
and Alaska Power Authority (APA)between 1974 and 1978.These
studies helped define some of the potential problems,but inade-
quacy and unpredictability of funding prevented any attempts at
comprehensive impact assessment.The Alaska Department of Fish
and Game conducted extensive studies of predator/prey relation-
ships to the north and west of the impact area.These studies
provided a great deal of information useful in understanding
potential effects of hydroelectric development,but were not
specific to the area of greatest impact.
In 1980 the Alaska Power Authority initiated the first compre-
hensive studies to evaluate the feasibility of the proposed
Susi tna Hydroelectric Proj ect.APA contracted with the Alaska
Department of Fish and Game to provide big game·population data
to be used in the feasibi li ty analysi s.Species to be stUdied
were moose (Alces·alces),black bear (U rsus americanus),brown
bear (Ursus arctos),wolf (Canis lupus),wolverine (Gulo gulo),
caribou (Rangifer tarandus)and Dall sheep (Ovis dalli).
Furbearers,small mammals,birds and plants were to be studied by
the Uni versi ty of Alaska and Terrestrial Environmental Specia-
lists,Inc.of Phoenix,New York was responsible for interdiscip-
linary coordinations,actual impact analysis and preparation of
exhibi ts for APA's application for a Federal Energy Regulatory
Commission license to construct the proj ect.
The studies were broken into phases which conformed to the anti-
cipated licensing schedule.Phase I studies,January 1,1980 to
June 30,1982,were intended to provide information needed to
support a FERC license application.If the decision is made to
submit the application,studies will continue into Phase II to
provide additional information during the anticipated 2 to 3 year
period between application and final FERC approval of the
license.
Wildlife studies did not fit well into this schedule.Data col-
lection could not start until early spring 1980 and had to be
terminated during fall 1981 to allow for analysis and report
wri ting.(Data continued to be collected during winter 1981-82
but could not be included in the Phase I report).The design of
the hydroelectric project had not been determined.As little
data was available on wildlife use of the immediate project area,
it was necessary to start with fairly general studies of wildlife
populations to determine how each species used the area and to
identify potential impact mechanisms.This was the thrust of
Phase I Big Game studies.During Phase I I we expect to narrow
the focus of our studies to evaluate specific impact mechanisms,
quantify impacts and evaluate mi tigation measures.
Therefore,the Final Phase I report is not intended as a complete
assessment of the impacts of the Susitna Hydroelectric Project on
big game.
The basic study approach was to delineate "subpopulations"of
each species that use areas likely to be altered by the project,
determine the seasonal ranges and movement patterns of these sub-
populations,determine the degree of dependency of each popu-
2
....
~,
r
I[
r
-
-
lation on areas likely to be impacted by the project and estimate
~~--.---~.-----_.--
the approximate number of animals likely to be impacted.The
defini tion of "subpopulation"varied depending on the species.
It ranged from a pack of wolves to the entire Nelchina caribou
herd.Generally,studies focused initially on animals in or near
areas likely to be impacted,then expanded to the remainder of
the subpopulation.As a result,the boundaries of the study area
varied among species and may expand as the ranges of subpopu-
lations become more evident.During Phase I,studies were con-
fined to assessing the impacts of proposed impoundments and
facilities in the vicinity of the impoundments.The one excep-
tion was moose for which the possible effects of downstream habi-
tat alteration were examined.Phase I studies were not intended
to address impacts on other species downstream or along trans-
mi ssion Corridors.
Specific study objectives for each species varied according to
suspected differences in the nature of their use of proposed
impoundment areas and in the likely mechanisms of impacts.The
specific objectives developed at the beginning of Phase I by
species are:
Moose (upstream)
To identify moose subpopulations using habitats that will be
inundated by proposed impoundments.
To determine the seasonal distribution,movement patterns,
size and trends of those subpopulations.
To determine the timing and degree of dependency of those
subpopulations on habitat to be impacted by the Susi tna
Hydroelectric Project.
Moose (downstream)
To identify moose subpopulations using habitat that will be
al tered by changes in stream flow below Devils Canyon.
3
To determine the seasonal distribution,movement patterns,
size and trends of those subpopulations.
To determine the timing and degree of dependency of those
subpopulations on habitat to be impacted by altered flow
regimes of the Susitna River.
Wolf
To identify wolf packs occupying areas that will be impacted
by the Susi tna Hydroelectric Proj ect.
To delineate the territories of each pack and identify den
si tes,rendezvous sites and maj or feeding areas.
To determine the numbers of wolves and rates of turnover for
each pack.
To determine the food habi ts of each pack.
Wolverine
To determine the distribution and abundance of wolverine in
the vicini ty of proposed impoundments.
To determine movement patterns and home range size of wol-
verines.
Bear (black and brown)
To determine the distribution and abundance of black and
brown/grizzly bears in the vicinity of proposed impoundment
areas.
To determine seasonal ranges,including denning areas,and
movement patterns of bears.
To determine seasonal habitat use of black and brown/grizzly
bears.
4
'"'"
-
-
-
"f"
I
I
~
I
Caribou
To delineate calving areas.
To determine the numbers and sex and
caribou occupying habitats on both
impoundments at different seasons.
age composition of
sides of proposed
To determine migration routes and the timing of major move-
ments in the vicinity of proposed impoundments.
Dall Sheep
To determine the distribution and abundance of Dall sheep
adj acent to proposed impoundments.
The Final Phase I Big Game Report contains data collected between
late winter 1980 and fall 1981.However,data from other studies
conducted by ADF&G are incorporated whenever they appear useful.
The report is organized in the following eight volumes.
Volume I
II
III
IV
V
VI
VII
VIII
Big Game Summary Report
Moose -Downstream
Moose -Upstream
Caribou
Wolf
Black Bear and Brown Bear
Wolverine
Dall Sheep
This volume (Volume I Summary Report)contains excerpts from the
:-other seven volumes.It is intended to provide a brief overview
of our current state of knowledge of how each species uses the
I"""area and to identify the most serious impacts of hydroelectric
development on the upper Susitna River.Individuals desiring
more detailed information should consult Volumes I I through VI I I.
5
Readers should recognize that,because studies are not complete
and our understanding of wildlifejhabitat relationships is imper-
fect,our evaluation of impact mechanisms is often speculative.
We have tried to identify possible problem areas that we feel
warrant attention.Some of the problem areas may be alleviated
by final project design and further study might show some to be
less serious than suggested in this report.Conversely,it is
possible that some impact mechanisms have been overlooked.
Finally it should be recognized that these studies are simply
designed to evaluate the effects of the proposed Susitna Hydro-
electric Project on certain species of wildlife and ultimately to
suggest ways of minimizing adverse effects.Statements in this
report should not be construed to be judgements on the overall
feas·ibi li ty of the proj ect or to imply that the Susi tna Hydro-
electric Proj ect will be any more or less damaging to wildlife
than any other alternative method of meeting Alaska I s energy
needs.
6
-
-
....,
rr
1.1
!'f'"
il
r
.....
METHODS
Techniques used during Phase I are presented in Volumes I I
through VIII and will not be discussed in detail here.The pri-
mary techniques used were radio telemetry and aerial surveys.
Samples of all species except Dall sheep were captured with drug
filled darts fired from a helicopter.Captured animals were
marked with tags and in most cases fitted with a radio-collar.
Information on sex,age,q~productive condition and physiologic
status were collected at the time of capture.Radio-collared
animals were periodically relocated from fixed-wing aircraft.
Over 2,700 radio-relocations of moose,683 of caribou,1,175 of
wolves,·518 of brown bears,724 of black bears and 104 of wolver-
ine were made in the upper basin.In the downstream study area
1,114 relocations of moose were made.When an animal was relo-
cated the activity of·the animal and characteristics of the habi-
tat were recorded and the location marked on a map.These data
were entered into a computer and analyzed in a variety of ways to
determine horne ranges,movement patterns,habitat use,proximity
to propo sed impoundments etc.
Wolf and bear den sites were examined in more detai I from the
ground.Activity of wolves during the denning period·was studied
intensively in an attempt to evaluate effects of disturbance and
formulate guidelines for minimizing adverse effects.
A variety of types of aerial surveys were used to determine
animal distribution,population composition and,in the case of
caribou and moose,population size .
7
"...,,
I
!I
I,i
r
,I
',[
.....
i,
SUMMARY OF FINDINGS
MOOSE-DOWNSTREAM
In its 215 kIn course from Devil Canyon to Cook Inlet,the Susitna
River is an outstanding component of a very productive watershed.
Perhaps the innate value of the lower Susi tna River Valley as
wintering habitat for moose is unsurpassed elsewhere in the
state.
Objectives of this study were to determine the probable nature
and approximate magnitude of impacts of the proposed Susi tna
River hydroelectric project on moose (Alces alces gigas Miller)
in areas along the Susitna River downstream from the prospective
Devi 1 Canyon dam si te .
To ascertain productivity,habitat use,patterns of movement and
to identify populations of moose that are ecologically affiliated
wi th .riparian habitats along the Susi tna River,2 samples of
moose,4 males and 6 females and 5 males and 24 females,respec-
tively,were captured and radio collared in riparian ha1?itats
along the Susitna River between Devil Canyon and the Delta Is-
lands on 17 April 1980 and 10-12 March 1981,respectively and
wer·e radio-relocated through IS October 1981.
Information on productivity and condition was obtained from most
individual moose captured.The bulk of data on habitat use,pat-
terns of movement and identity of populations was synthesized
from information collected at sites of relocation for three males
and three females and four males and 23 females radio-collared in
the 1980 and 1981 samples,respectively.
These data were complimented with information collected on three
aerial censuses for moose,conducted during the early parts of
December,January and February 1981-82,in riparian habitats
along the Susitna River between Devil Canyon and Cook Inlet,to
assess the relative magnitude and regional use of riparian habi-
tats.These census data also provided additional information on
productivi tyjsurvival of moose which winter in riparian habi tats .
8
To relocate radio-collared moose,surveys were conducted at about
biweekly intervals through 16 March 1981 and at about weekly in-
tervals from that time through 15 October 1981.This schedule
provided two,five,seven and five relocation sites for most in-
di vidual moose during the winter (1 January thru 28 February),
calving (14 May thru 17 June),summer (1 July thru 31 August)and
breeding (14 September thru 15 October)periods,respectively.
Relocations with dates not included wi thin those periods were
categorized into spring,summer,autumn and post-breeding tran-
si tory interval periods.
Types of vegetation observed wi thin a 2-4 ha area surrounding
each relocation site were recorded and a rating for percent can-
opy dominance was given to each type which covered 10 percent or
more of the field area.Vegetation types included spruce,birch,
alder,cottonwood,willow,aspen,sedge,grass,sedge x grass,
muskeg,devilsclub,fern and horsetail.
Preliminary findings exhibited grossly different patterns of be-
havior and geographically discrete breeding areas for three
groups of moose within the radio-collared samples and resulted in
asubpopulation classification for individuals with breeding
ranges centered in 3 areas:1)to the north of Talkeetna (north-
ern),2)to the south of Talkeetna and on the eastside of the
Susitna River (eastside)and 3)to the south of Talkeetna and not
in eastside areas (westside).
In most interpretive analyses,sex,seasonal period and sub-
population categories were considered ..
Since magnitude of use of moose winter ranges is partly related
to severity of climatic conditions,information contained in this
report must be interpreted tentatively because of the relatively
mild winters of 1979-80 and 1980-81.
9
-.,
r
I
r
:r"I
All moose radio-collared south of Talkeetna were captured within----~_.---~--- - -.-
the outmost banks of the Susitna River.Because of the relative
scarcity of moose available in riparian habitats to the north of
Talkeetna,some individuals were captured up to 400 m from the
river.
None of the 5 moose captured in riparian habitats in April of
1980 were relocated in those habitats in the winter of 1980-81,
though numerous other moose were present.
Most moose radio-collared south of Talkeetna in 1981 had departed
from Susitna River riparian habitats by mid-April;males appeared
to precede females.Directions of departure were not random;
most moose retreated to the west and several remained in or near
an extensive large island complex throughout the study period.
Differences in general patterns of movements observed between the
1980 and 1981 samples of moose captured south of Talkeetna were
in part attributed to diffe~ences in the response·of local popu-
lations to snow cover and plant phenology.
Moose radio-collared to the north of Talkeetna were relocated on
south-southeast-facing slopes on the north-northwest side of the
SusitnaRiver basin.This behavior was attributed to local popu-
lation phenomena andjorhabi tat selection.
Most females radio-collared north of Talkeetna were commonly
relocated in riparian habitats during the calving period,appar-
ently in response to the availability of highly nutritious and
easily digestible forage plants.After the calving period these
females returned to the south southeast facing slopes above the
river basin where they remained throughout the period of study.
Females radio-collared south of Talkeetna,which departed Susitna
River riparian habitat by mid-April,did not return to those
riparian areas during the calving period,as did radio-collared
females in areas to the north.Instead they were commonly relo-
cated in relatively open,medium-height sprucej muskeg habitats
10
to the west of the Susitna River.A noteworthy concentration of
.--------------
radio-collared females occurred near Trapper Lake during the cal-
ving season.As for females in more northern areas,use of these
moist habitats during the calving period was attributed to the
availability of high quality herbaceous forage.
Moose radio-collared north of Talkeetna were seldom relocated
more than 3 mi from the Susi tna River.Moose in westside areas
were nearly as frequently relocated at distances greater than 3
\
mi from the Susitna River as they were at distances nearer to the
River.One eastside male was seldom relocated nearer than 10 mi
from the Susi tna River i females in that area were more commonly
relocated farther than 5 mi from the Susitna River than at closer
distances.
In comparison to females in other areas,each of the three sea-
sonal ranges for those radio-collared north of Talkeetna averaged
smallest in size and were located nearest to the Susi tna River.
Data indicated that the average moose radio-collared in areas
north of Talkeetna did not have to travel as far from its winter
range to locate habitats required during other seasonal periods.
Though this appears to imply that areas north of Talkeetna are a
more heterogeneous and complete assemblage of habitats,it may
also be interpreted to indicate that adj acent habitats are of
such poor quality that moose cannot physiologically afford to
venture far from nor to travel far to winter on the Susi tna
River,or that in this area the Susitna River is not very attrac-
tive as winter range for moose.
Alder was the dominant vegetative type observed at relocation
sites for females north of Talkeetna.Spruce,a species valuable
to moose for cover,occurred at most sites but was not very
dense.Relocation sites south of Talkeetna were dominated by
birch and spruce.Al though spruce occurred more than bi rch and
rated higher in canopy coverage than at relocation sites to the
north,it still ranked considerably lower than birch in canopy
coverage.
11
-
-
Perhaps it was the prevalence of alder and the relatively poor
representation of birch and spruce that may make areas north of
Talkeetna less desirable for female moose than those areas south
of Talkeetna.
Three aerial censuses conducted between early December and early
February revealed 322,324 and 239 moose,respectively in ripar-
ianhabi tats along the Susi tna River from Devil Canyon to Cook
Inlet in the relatively mild winter of 1981-82.Moose observed
on each census were not evenly distributed.On each census about
90 percent of the moose were observed between Montana Creek and
Cook Inlet.Even wi thin the latter area some locales exhibited
extremely dense concentrations of moose.
About 50 percent of the moose observed in riparian habitats were
calves·and their dams.Twenty nine,26 and 22 percent of the
moose observed on the three respective censuses were calves.If
moose seek Susitna River riparian habitats to avoid deep and per-
sistent snow cover in non-ripa~ian habitats,it ~ould seem that
this behavior would be particularly important for calves whose
legs are considerably shorter than those of adults and would have
more difficulty negotiating deep snow.
Profiles of condition-related blood parameters·from the samples
of moose captured and radio-collared were rated in below average
condition and resembled those from a low productivity population.
However,this implication is questionable because of the rela-
tively high rate of productivity observed for radio-collared in-
dividuals and moose observed on aerial censuses.Eighty-one per-
cent of the 26 females for which data were available in 1981 were
observed with young.Considering the occurrence of twins at
least 93 calves may have been produced by everyone hundred of
the cow moose that wintered on the Susi tna River.
Although predators occurred in the study area,and no instances
of predation were observed.Circumstantial evidence indicated
that most predation which does occur is probably attributable to
black (Ursus americanus)and brown bears (Ursus arctos).Brown
12
and black bears occur throughout the Susitna River Valley.Brown
~-------------------
bears are probably most dense in mountainous areas with black
bears found more commonly in lowland and riparian habitats.The
apparent similarity in habitat requirements between moose and
black bears may place them both in like habitats during the cal-
ving and summer periods.
Wol ves are rare in the study area and have never been observed.
Data indicated that radio-collared moose captured between Devil
Canyon and the Delta Islands,a linear river distance of about
155 kIn,ultimately ranged over an area encompassing about 5000
kIn 2 •
Based on general patterns of movement documented for radio-
collared moose,large geographical units where radio-collared
moose were never relocated and areas along the Susi tna River
where data have yet to be collected,nine hypothetical local pop-
ulations of moose are delineated.
13
-
.....
-
1'IfPm-,
r
r
r
.1
I
MOOSE-UPSTREAM
During April 1980,and March and May 1981,58 adult and 16 calf
moose were captured by darting from helicopter and radio-
collared.Biological specimens and measurements were collected
to evaluate physical condition,age and reproductive status of
each moose.Average age of adult cow moose captured in 1980 was
9.4 years,which was significantly older than moose captured in
1977 and older than other Alaskan moose populations.Sixty-two
percent of the moose were 10 years old or older.At least 73
percent of the cow moose examined were pregnant.This pregnancy
rate was lower than that found in other moose studies but this
may have been due to errors in pregnancy determination.
Blood parameters indicated that calves sampled in 1981 were in
better physical condition than those from 1979 when animals were
suffering from nutri tionalstress during a severe winter .Adult
moose captured in 1979-1980 were in poorer condition than those
sampled in earlierSusitna studies and other Alaskan moose popu-
lations.Thi s suggested that range conditions have deteriorated
in the upper Susi tna Basin since 1977.However,twinning and
natality rates remain high.Earlier studies had indicated that
this moose population was not at range carrying capacity and that
predation was limiting recrui tment.
Data obtained from earlier moose studies in the Susitna Basin
were combined with similar data from this proj ect to evaluate
movements and home range sizes.Between October 1976 and mid-
August 1981,more than 2,700 locations were obtained on 207 moose
of both sexes and all age classes.Moose were subjectively clas-
sified as migratory or nonmigratory.Migratory moose occurred in
areas east of Watana and Kosina Creeks.Most moose located west
of these areas were nonmigratory.Several migratory travel
routes were identified.Most movements followed drainage pat-
terns of creeks and tributaries and,thus,were in a north-south
direction.
14
During this study,moose generally moved to lower elevations
----"..-----
during late spring and early summer.As summer progressed,moose
generally moved to higher elevations.Winter elevations were
significantly higher than summer elevations.Observation of
moose at relatively high elevations during winter was attributed
to mild winters during most of the study period.
Ninety-one percent of radio-collared moose observations were
located on flat or gentle slopes.Flat and southerly exposures,
composed 54 percent of the observations.
Monthly habitat utilization data by radio-collared moose as
determined from aircraft were presented and discussed.Fifty-
nine percent of the basin was covered by conifer and shrubland
habitat types but these two types constituted over 90 percent of
the moose observations.Use of willow habitat types corresponded
wi th observed al ti tudinal movements.Reasons for non-use of
other habitat types were discussed.Problems associated with de-
termin;i.ng habitat use by moose with the methods used were re-
viewed.
From October 1976 through December 1981,33 radio-collared moose
crossed the Susitna River a minimum of 73 occasions.During 1980
and -1981,all documented crossings occurred from May through
November.Track sightings suggested that crossings also occur
during other months .River crossings appeared concentrated in
the following areas:mouth of Fog Creek to area opposite Stephan
Lake,mouth of Deadman Creek upstream for approximately 5 miles,
Watana to Jay Creek,and from Goose Creek to Clearwater Creek.
Data describing the distribution of radio-collared moose during
the rut and parturition were presented.Apparent breeding and
calving areas were identified.
A winter census of the two impoundments was conducted in March
1981.A total of 28 moose were counted in the Devil Canyon im-
15
-
-
..."
r
I
r
r
r
'I
poundment while 42 moose were counted within the Watana impound-
ment.Mild winter conditions probably contributed to the low
count.
Sex and age composition surveys and a random stratified census
were conducted in the study area during November 1980.It was
estimated that 2,046 ±382 moose occupied the areas north and
south of the proposed Watana impoundment.A crude population
estimate of 1,151 moose was made for the project area lying west
of Kosina and Watana Creek.The entire upper Susi tna Basin above
Devils Canyon and excluding Lake Louise Flats and the areas south
of the Maclaren River was estimated to contain 4500 moose in
fall,1980.
Moose parturition from 1977 through 1981 generally occurred from
15 May to 15 June of each year peaking between 25 May to 2 June.
Rates of calf production have been quite high,however,mortality
during the first 6 weeks of life has also been high.Earlier
studies documented the importance of brown bear predation to calf
survival.
Based upon movement studies conducted from 1976 through 1981,13
moose subpopulations were identified which could be impacted by
the construction and operation of the two impoundments.Each
subpopulation was briefly described.Several significant dis-
persals of moose from the impoundment areas were described.
Seasonal and total home range.sizes were determined for 162
radio-collared moose.Total home ranges ranged from 3.8 to 2911
km2 and averaged 224.2 km 2 •Home range sizes of Susi tna moose
were relatively large in relation to those reported elsewhere
from North America.
Average maximum length of moose home ranges was 28.7 km.This
area was used to identify an area of impact around the two
impoundments.Numbers of moose occurring in the impact area were
extrapolated from census and stratification data and from numbers
of radio-collared moose home ranges overlapping the census area
16
boundaries.An estimated 3,040 moose would be moderately
impacted by the proposed project.Of that total an estimated
2,400 moose are expected to be severely impacted.
17
.....-
-
-
~I
r
r
r
i
-
CARIBOU
The Nelchina caribou herd which has occupied a range of about
20,000 mi 2 in southcentral Alaska has been important to hunters
because of its size and proximity to population centers.Overall
objectives of this study were to evaluate potential impacts of
the proposed hydroelectric proj ect on Nelchina caribou and to
suggest possible mitigating measures.Because of the changeable
nature of caribou movement patterns short-term studies of dis-
tribution and movements must be tempered with historical perspec-
ti ve.Fortunately,the Nelchina herd has been studied continu-
ously since about 1948 and records previous to that time have
been reviewed.The primary methodology for this study was the
repetitive relocation of radio-collared caribou.Population
estimates were made with a modified version of the aerial photo-
direct count-extrapolation censu's procedure.
Caribou from the main Nelchina herd were found during winter pri-
marily on the Lake Louise Flat,foothills of the Alphabet Hills
and middle portions of the Gakona and Chistochina River drainages
areas distant from the proposed hydroelectric development.Cari-
bou primarily utilized open spruce forest during this period at
elevations ranging from 2,100 to 4,300 feet (x=2,779).
During spring migration females moved across the Lake Louise Flat
onto the calving grounds in the eastern Talkeetna Mountains on a
broad front from Lone Butte to Kosina Creek.Some caribou util-
ized the Susi tna River in the area of the proposed Watana im-
poundment as a travel route.A small portion of the herd ap-
peared to migrate across the plateau north of the Susitna River
crossing the Susitna between Deadman Creek and Jay Creek enroute
to the calving grounds.Open spruce forest was still the primary
vegetation type utilized,'however,shrublands and tundra-
herbaceous types became increasingly important.Females were
found at elevations ranging from 1,900 to 5,600 feet (x=2886).
Males lagged behind females during spring migration using mostly
spruce forests.Elevations averaged 2,280 feet,ranging from
2,000 to 3,100.
18
During the calving period,~i!~u~~~~_~~~_females from the main
Nelchina herd were found from Kosinia Creek into the Oshetna
River in the eastern Talkeetna Mountains.Tundra-herbaceous ve-
getation accounted for 75%of the sightings and shrublands for
25%.Elevations for females ranged from 2,400 to 5,400 feet
(x=3871).Nelchina bulls were found scattered throughout the
range during calving mostly in transit to summer ranges.Spruce
forests were still the primary vegetation type used by bulls.
Elevations averaged 2,872 feet (range 2,100 -4,400).
Summer range for Nelchina females was the northern and eastern
slopes of the Talkeetna Mountains between 3,300 and 6,000 feet
elevation (x=4,250).Tundra-herbaceous was the dominant vege-
tative type utilized followed by shrublands.Bulls were scat-
tered in "bull pastures"in the high country throughout the
Nelchina range.Shrublands and tundra-herbaceous were the main
vegetative types utilized.Elevations ranged from 2,200 to 4,600
feet (x=3,572).
During autumn considerable dispersal,particularly of females,
occurred as caribou moved out of the Talkeetna Mountains across
the Lake Louise Flat into the Alphabet Hills then back to the
west.Limited use of the Watana impoundment area was documented
during this period.The sexes became mixed particularly late in
September.Use of vegetative types and elevations of relocations
were the most varied of any seasonal period.
During the rut males and females appeared to be well mixed and
the herd moved from the foothills of the Talkeetna Mountains
eastward across the Lake Loui se Flat.Spruce forest was the
principal vegetative type used during thi s period while shrub-
lands received minor use.Caribou ranged in elevation from 2,200
to 3,900 feet (x=2,832).
Historically,Nelchina caribou have used the same calving grounds
however considerable variation in summer and winter range use has
been noted.Migratory routes,although somewhat traditional,
19
have varied depending on the relationship of the calving grounds
to summer and winter ranges.
o On a year around basis habitat use by Nelchina bulls and cows was
il significantly different.Use of shrublands and bare substrate
were similar while bulls occurred more frequently in spruce for-
est and at lower elevations while cows were found more frequently
in tundra-herbaceous vegetation and at higher elevations.
It appeared (based on the year around relocations of radio-col-
lared caribou)that at least three distinct subherds with sep-
arate calving areas exi sted in addition to the main Nelchina
herd.These included the upper Talkeetna River (~400 animals),
Chunilna Hills (L350 animals)and upper Susitna-Nenana (.c:.1000
animals)subherds.Another subherd probably occurs in the upper
Gakona River and others may exist in the Alaska Range and western
Talkeetna Mountains.
In October 1980,the Nelchina herd was estimated to contain
18,713 .caribou and in October 1981,the herd was estimated at
20,730.Herd composition in October 1981 was estimated at 49%
females ~1 year,30%males ~1 year and 21%calves.
Calf survival to 11 months of age (May 1980 to April 1981)was
estimated at 0.43.Average annual natural mortality for caribou
one year old and older was estimated at 0.07 for females and 0.14
for males.Reported hunter harvest of Nelchina caribou averaged
670 animals between 1972 and 1981 .
.....
.....
20
T
r
WOLF
From radio-relocations,ground observations,and previous studies
we were able to describe the histories of individual wolves and
their associated packs.Interactions between pack members and
between separate packs were observed throughout the study.
Wolves in the Watana pack were most frequently observed in shrub
(50%)habitats with ecotones being of particular importance.No
slope or aspect selection was observed.Approximately 1/3 of all
radio-locations of the Watana pack were located in areas to be
inundated by the proposed impoundment.
Of 83 wolf kills observed for 6 packs,57%were moose,33%were
caribou and the remainder were small mammals.Fifty-one percent
of the moose and 7%of the caribou killed by wolves were calves.
Food habits and predation rates data suggested that wolves were
annually preying upon from 11-13%of the moose population and
from 2-10%of the Ne1china caribou herd.These data suggested
that the percentage of caribou in the wolves I diet may be a
function of their availability.As caribou become more abundant,
they make up a greater proportion of the wolves'diet.
The minimum estimated wolf population in the study area ranged
from a"fall high of 80 to a spring low of 40.These wolves were
divided into 13 packs.Pack territory sizes ranged from 346-981
mi 2 and averaged 545 mi 2.
Wolf harvests in GMU 13 from 1971-1981 ranged from a high of 128
in 1977-78 to a low of 45 in 1980-81.The low harvest in 1980-81
21
was attributed to poor weather and relatively low wolf densities.
~---_.------
Shooting was the most common harvest method throughout the per-
iod.
Twenty-three wolf den and rendezvous sites were examined.Most
dens were located on slightly elevated,well-drained sites with a
south or east exposure usually near the center of the territory.
Wolves traditionally return to the sites annually.Average dis-
tance between contiguous natal dens was 28 mi les.
Intensive ground observations of active wolf den sites in May and
June of 1980 and 1981 allowed us to detail summer activity pat-
terns and food habits.These observations revealed that wolves
were present at den sites throughout the day.Helicopters flying
near dens always annoyed wolves;however,they became more toler-
able over ·time.Judging from observed behavior patterns and a
review of the literature,it was recommended that all human
ground activities be restricted within a 1.5 mile radius of
active dens.This is particularly important in spring to avoid
den site abandonment.If human activity must occur near dens,
these acti vi ties should be limited to early morning and late
evening hours.
22
-
-
.....
"""
BLACK BEAR AND BROWN BEAR
Projected impacts of proposed hydroelectric development on upper
Susitna River populations of brown and black bears were investi-
gated in 1980 and 1981.The preliminary investigations for Phase
I of the impact assessment that are reported here were designed
to reveal the kinds of impacts which might result from the pro-
posed project,quantitative assessments of actual impacts were,
in most cases,postponed until Phase II of the assessment studies
scheduled to begin in 1982.
In Phase I a sample of both species was radio-collared and peri-
odically monitored in order to identify the patterns ·of use of
areas that would be impacted by the proposed project.This anal-
ysis was based primarily on a total of 518 brown bear and 724
black bear locations in the study area,collected between April
1980 and October 1981 for black bears and between April 1980 and
1 September 1981 for brown bears.These termination dates re-
present analytical deadlines,data collected subsequently are
being analyzed.
The sample of radio-collared adult brown bears was considered
representative in terms of age structure but biased against
males.In comparison with other North American brown bear popu-
lations,the study area population appeared highly productive and
moderately dense.An estimate of 1 bear/41-62 km2 ,obtained in
1979 in a nearby study area,was considered the best available
approximation of brown bear densi tyin the study area.
Brown bear harvests by hunters have averaged 64/year in 1973-1980
in Game Management Unit 13 (range 44-84),lS/year in the project
study area (9-24).
The mean elevation of 29 brown bear den sites was 4,818 feet
(range=2330-S1S0 feet).No .brown bear den discovered to date
would be inundated by the proposed impoundments but some were in
areas where disturbance during project construction or operation
23
could result in abandonment or avoidance of den sites.
Brown bear home ranges were highly variable between individuals
and years.The mean home range of 11 bears in 1980 was 422 krn 2 ,
487 krn 2 in 1981.Home range sizes varied from 50-2655 krn 2 •
-
Larger home ranges in 1981 relative to 1980 may have resulted
from a relatively poor berry crop in 1981.Brown bears captured
along the Susitna River ranged over a total area of 8,473 krn 2 •~
This represents a minimum estimate of the area in which brown
bears would be affected by the proposed impoundments.
The period of peak use of areas directly impacted by the proposed
impoundments was in spring and early summer .During this period
62%of radio-collared brown bears were located wi thin 1 mile of
the proposed impoundment in 1981,50%in 1980 (excludes females
wi th newborn offspring).In both years 30%of all observations
of these bears were within this,conservatively defined,impound-
ment impact zone.We suspect that brown bears tend to move to
lower elevations near or in the impoundments in early spring be-
cause of the relatively earlier availability of vegetable forage
in these areaSi prey,especially moose calves,may also be more
available in this impoundment impact area.This pattern was not
fo"llowed by females with newborn cubs,these bears tended to
remain at high elevations away from the impoundments.Perhaps
this avoidance of areas where other bears concentrate is adaptive
in minimizing intraspecific predation on their cubs.
This same pattern was verified by statistical analyses of loca-
tions of brown bears within 3 nested regions of the study area:
The actual impoundni.ent,wi thin 1 mile of the impoundment shore-
line,and 1-5 miles from the shoreline.Here observed use in the
actual impoundment area was greater than would have been expected
on the basis of the relative size of the impoundment area.This
difference was especially marked in the spring when observed use
was 4 times greater than expected under the null hypothesis ~f no
selectivity.
24
-
-
-
This same pattern was evident in analyses of the habitats where
relocated brown bears were found.Use of spruce habitats which
occur primarily in the vicinity of the impoundments was signifi-
cantly higher in the spring than during the rest of the year.
Data on availability of different vegetation types based on the
type maps prepared by the Plant Ecology Subtask were not partiti-
oned in a way that would permit meaningful analyses of selec-
tivity of these different vegetation types for the area mapped at
the 1 :63,360 scale.Appropriate partitioning of these data were
available for the actual area that would be flooded by the pro-
posed impoundments,however.Analyses of these data sugge.sted
that brown bears tended to select for mixed conifer-deciduous
forest types in the Watana impoundment area.
Brown bear movements to areas of seasonally reoccurring food
abundance may include movements to Prairie Creek or downstream
along the Susitna to fish for salmon (both have been documented),
or movements to moose or caribou concentration areas such as
calving grounds (movements to caribou concentrations were also
documented).Movements to Prairie Creek by bears from an area of
5,773 km2 were documented in this study,these movements required
crossing the impoundments and the proposed access roads.
Brown bear predation rates were intensively monitored (once/day)
in spring 1981.A kill rate of 1/10.2 days was observed,sub-
stantially lower than has been recorded in more intensive studies
conducted in 1978 in nearby areas.The observed kill rate was
suspected to be biased because of relatively infrequent moni-
toring and relatively poorer visability caused by more dense
vegetation in the study area.
The sample of radio-collared adult black bears was considered
representative in terms of sex ratio and age structure.In com-
parison with other North American black bear populations,black
bears in the study area appeared to be productive although pos-
sibly having an older age of reproductive maturity and higher
rate of cub mortality than an intensively studied population on
25
the Kenai Peninsula.No good density estimate was obtained for
-----------~-----~
the study area although a rough estimate of 1 bear/4.1 km z was
obtained in one relatively open area based on aerial observations
of marked and unmarked bears.
Black bear harvests have averaged 66/year in 1973-1980 in Game
Management Unit 13 (range=48-85),8/year in the proj ect study
area (1-15).
Fourteen black bear den sites used in 1980/81 were located and
measured,an additional 19 dens being used in 1981/82 have been
tentati vely located from the air.All but one den was below
3,000 feet elevation,most were in the immediate vicinity of the
proposed impoundments.Of 13 dens found in the vicinity of the
proposed Watana impoundment,9 will be flooded at an impoundment
elevation of 2,200 feet,the mean elevation of these dens was
2,177 feet (1,800-2,750 feet).In the vicinity of the proposed
Devils Canyon impoundment,1 of 16 known dens would be flooded at
an impoundment elevation of 1450 feet,the mean elevation of
these dens was 2,178 feet (1490-4340 feet).A higher proportion
of black bears in the study area den in natural cavities and re-
use den sites than has been recorded in other Alaskan studies
suggesting relative scarcity and competition for acceptable den
si tes in the study area.
Black bear home ranges were significantly larger in 1981 (mean=
251 km 2 ,range=19-1051)than in 1980 (mean=31 km 2 ,range=3-136).
We suspect the increased movements observed in 1981 reflect,for
the most part,the relatively poor berry crop which forced bears
to move greater distances in search of forage.The total area
encompassed by movements of radio-collared black bears was 4,196
km 2 ;much of this area away from the river was considered unac-
ceptable or poor black bear habi tat.
Acceptable black bear habitat in the study area was largely con-
fined to a narrow finger of forested habitat along the Susi tna
River;these are the areas which will be the most impacted by the
26
-
proposed impoundments.In late summer many black bears moved to
shrubland habitats adjacent to these spruce forests to forage for
ripening berries,generally returning to the forested habitats to
den in September.Such shrubland habitats that are also adjacent
to forested escape habitat are limited in extent and would be
impacted by construction facilities (such as the current site of
Watana Camp),borrow areas D and F,and access roads.
Analysis of the location data wi thin the 3 nested zones of the
study area (impoundment area,1 mile from impoundment shoreline,
and 1-5 miles from the shoreline)revealed exceptionally high
selecti vi ty by black bears.In the area that would be flooded by
the proposed Watana impoundment,black bear use was 2-4 times
higher than expected based on the relative area of this zone,use
was also higher than expected in the zone 1 mile from the
impoundment shoreline.For the Devils Canyon impoundment ob-
served use exceeded expected values in the area within 1 mile of
the impoundment shoreline.
Analyses of selectivity for the different vegetation types mapped
at the 1:63,360 scale by the Plant Ecology Subtask could not be
accomplished as discussed for brown bear.However,as for brown
bear,such analyses were possible in the area that would actually
be flooded by the Watana Impoundment.Here use varied signifi-
cantly from values expected under the hypothesis that black bears
were randomly using all vegetation types.Open birch and closed
birch habitats appeared to be the most favored types.A high
proportion of these 2 vegetative types would be inundated by the,.....,
proposed impoundments.
Three radio-collared black bears moved downstream below the
Devils Canyon damsite in 1981.These movements were suspected to
be motivated by spawning salmon in this region.It is not known
whether these movements occur also in years of normal berry pro-
duction.
27
As discussed for brown bears,relatively low predation rates by
black bear on moose calves were observed.Biases resulting from
relatively infrequent monitoring and poor sightability of kills
are expected to account for the low observed predation rates.
28
-
~I
i"
I
r-
I,
-
WOLVERINE
During Phase I studies,6 wolverine (5 males,1 female)were
radio-collared in an attempt to identify potential impacts of
hydroelectric development on wolverine.A total of 114 point
locations were obtainedi 104 of the locations were of radio-col-
lared wolverine.The annual home range for an adult male (040)
was 627 km 2 (237 mi 2 ).Home range sizes for two males monitored
6 and 8 months were 378 km 2 (146 mi 2 )and 272 km 2 (105 mi 2 ).
respecti vely.Comparing home range sizes for males from the
Susitna River Basin,northwestern Alaska,and northwestern
Montana,suggested that Susitna Basin male wolverine home ranges
were larger than those in Montana but smaller than those in
northwestern Alaska.Differences were probably related to prey
di versi ty and density.
An estimated 65 to 123 wolverine inhabited the study area during
1980 and 1981 providing a density range of 1/76 km 2 (1/29 mi 2 )to
1/143 km 2 (1/55 mi 2 )
Trappers and hunters harvested 27 wolverine from the study area
during Phase I studies.Ninety-three percent (25/27)of the wol-
verine trapped were along the borders of the core study area.
Harvest locations appeared related to accessibili ty.
Wolverines were distributed throughout the impoundment area.
Availability and utilization of different habitat types by radio-
collared wQlverine were compared.There were apparent seasonal
shifts in habitat utilization from tundra dominated habitats
(summer)to forested areas (winter).The shift was probably
influenced by available prey speciesi ground squirrels and cari-
bou in summer and moose and small mammals in winter.Ecotones
were found to be important throughout the study area.
Observations of social and breeding behavior of wolverine were
described.
29
.....
i
DALL SHEEP
Aerial surveys were flown on 3 and 25 March,1981,to assess
winter habitat use by Dall sheep (Ovis daffi).Areas flown were
the Watana Hills count area,and the Mt.Watana-Grebe Mountain
complex.
Ground observation of the Jay Creek mineral lick located at the
2200 ft.elevation revealed heavy utilization by sheep and moose
(Alces alees).Soil samples were taken for chemical analysis.
Frequent observations of the Jay Creek mineral lick were made in
conjunction with other Susitna studies.Sheep were seen at the
Jay Creek site on 34 of 50 occasions (68%)from 6 May to 24 June
1981.
The Watana Hills count area was surveyed on 28 July,1981,to
determine population trend and summer distribution.No sheep
were observed at the Jay Creek site.However,Dall sheep were
observed at another known mineral area in the drainage of the E.
fork of Watana Creek,approximately 7 miles to the north.
The largest number of sheep observed at the Jay Creek mineral
"'""site was 15 which represents 7 percent of the observed summer
population and 17 percent of the observed winter population.
-
F
I
30
r
r
POTENTIAL IMPACTS
Definition of Impact
Impacts of the Susi tna Proj ect on wildlife may range from the
permanent elimination of animals to minor inconvenience to users
of wildlife.Clearly,some impacts are more serious than others.
We focused our attention on those impact mechanisms that have the
potential to cause or significantly contribute to changes in size
or productivi ty of wildlife populations.
Most obvious are changes in the capacity of the habitat to sup-
port animals.However,factors which affect the productivity and
life expectancy of individuals remaining in the population may be
of equal importance.A population in which productivity and sur-
vival rates are reduced may maintain its size under normal condi-
tions,but be less able to sustain stressful climatic conditions,
predation or hunting.
The following are categories of impact mechanisms considered most
important:
1.Loss of habi tat
2.Ai teration of habi tat
3.Loss of a food source
4.Barrier to movements
.S.Increased vulnerabi li ty
hazards.
to predators,hunters or
6.Disturbance when it affects the productivity or
survival of animals.
Since some impact mechanisms are indirect and some big game popu-
lations migrate,impacts may occur far from the impoUndments and
31
construction faci li ties.Generally,impacts become less severe
and affect a smaller proportion of the animals as you proceed
away from the project area.This makes it difficult to delineate
a meaningful zone of impact.A large zone will include a higher
percentage of animals that will not be significantly impacted,
while a narrow zone will miss a higher number of animals that
will be impacted.Therefore it is necessary to be somewhat arbi-
trary in selecting a zone of impact.
One approach to this problem was to assume that animals found
within one home range diameter of project facilities were likely
to be exposed to a variety of impact mechanisms.We focused our
attention on these animals,then expanded or contracted our area
of attention,depending on the nature of the suspected impact
mechanism.
Consequently when we discuss impact zones or groups of animals to
be impacted,we do not intend to imply that every animal in that
area will be lost or seriously affected,nor that no animal out-
side of that area will be lost or seriously affected.These are
areas where we expect changes in population size or productivity
might be great enough to be measured by available techniques or
perceived by users of wildlife.
32
....
....
~,
1'1""
i
'I
"
MOOSE -DOWNSTREAM
Much of the potential for impacts on populations of moose down-
stream from the impoundments will result from the effects of al-
tered and/or controlled flow regimes on riparian vegetative com-
munities.
Effects need not be direct;as in spring we have observed moose
feeding on trees felled by beavers and should altered flow re-
gimes have a negative affect on populations or distribution of
beavers,secondary effects will be transmitted to moose.Like-
wise,activities of beavers falling trees may open the canopy and
encourage new growth of forbs and other understory vegetative
types consumed by moose.Trees killed by beavers also lead to
instabili ty of stream banks and result in erosion which may
secondarily bring about changes in vegetative succession that are
favorable to moose.Dams built by beavers create favorable con-
di tions for lush growth of aquatic plants,an important forage
for moose.
The value of the Susitna River to moose is founded on its innate
instabili ty which results in continual creation and maintenance
of seral vegetative communi ties;any change that would bring
about stability and not interfere with normal successional pro-
cesses would tend to have a negative impact on the types of ri-
parian habi tats that are of value to moose.
Predications of project impacts on moose are in part,dependent
on predications of the effects of water levels on vegetative com-
munities which,in part,depend on predications of water occur-
P!""
I rence and levels which in part,depend on regulation of flow,I
regimes and contours and depths of the river bottom.Due to the
unavailability of those sorts of data,at present,we will
attempt to point out areas,habitats and/or seasonal periods
_which appear to be of particular importance to moose and which
may be affected by the proposed project.
33
i
10
-
i
o
ALASKA
G
o
NoRTH
Figure 1.Spatial relationships for hypothetical subpopulations of moose in the Susitna
River watershed between Devils Canyon and Cook Inlet.Alaska.
Though a relatively low density of moose appear to occur in the
Susitna River valley north of Talkeetna,the island and riparian
habitats appeared to be particularly important to females during
the calving season.Loss of these habitats,in that area,could
seriously affect production,survival and recruitment into that
local population of moose.
If the t±ming of calving for moose in areas north of Talkeetna is
adaptive and indirectly synchronized to occur with plant phen-
ology for nutritional reasons,and the warmer water temperatures
of the Susi tna River resulting from hydroelectric.development
accelerate the growth and development of aquatic and riparian
vegetation,moose would have to alter their.behavior accordingly,
or be confronted with diets of different composition and probably
of lower quality.
Though few moose north of Talkeetna appeared to use riparian
habitats during seasons other than calving,we suspect that
during a severe winter,and knowing the extreme quantity of snow-
fall which can occur in this locality,that those habitats may be
relatively more important to moose in that area than are similar
habitats to moose in areas downstream from Talkeetna.
If the Susitna River is ice-free year-round down to Talkeetna,as
projected,we envision this as having a detrimental impact on the
local population of moose.During cold parts of the winter,the
warm open water may lead to the formation of ice fog and result
in a tremendous buildup of frost or ice on all vegetation in the
river basin.We do not know if moose can metabolically tolerate
the increase in energy required to warm the frost and to process
the increase in dietary water.
The fact that thin ice and ice flows or jams will not occur
during the early spring period prior to calving,probably will
decrease the mortality of female moose as they travel to island
or riparian habi tats or cross the river during this time period.
However,the occurrence of open water during the cold parts of
winter when air temperatures may reach -35 to _45°C,may prevent
35
moose from efficiently utilizing riparian habitats and preclude
-------------
all use of island hahi tats and all crossings of the river.We
question whether moose would enter water or swim under such ex-
treme environmental conditions or if they could survive from the
exposure if they did.
Since many more moose are ecologically affiliated with the Su-
sitna River downstream from Talkeetna than upstream,impacts in
the former area will affect a larger number of moose,and because
of their more extensive patterns of movement,effects will be
realized at much greater di stances from the Susi tna River.Im-
pacts in this area will generally occur directly or indirectly
through the response of vegetative communities to altered and
relatively stable hydrologic flow regimes.Elimination of ex-
treme peaks of water levels will lead to stabilization of those
plant communi ties which will not be periodically inundated and
result in habitats of lesser value to moose as plant succession
progresses.For the same reasons,a decrease in water levels in
other areas will create habitats similar to the type lost.One
ultimate result of this process is the localization or centrali-
zation of riparian habitats to a point more near the main channel
of the river.Since moose are traditional in their use of par-
ticular local habitats,we do not know if they would readily be
aware of and/or make use of newly created habitats in different
areas along the river.
Consequences of changes in flow regimes will be drastically dif-
ferent in the narrow deep channel~d portion of the Susitna River
north of Talkeetna compared to those in the very broad shallow
watered channels,sloughs and marshes which occur between Tal-
keetna and Cook Inlet.Increases or decreases in water may
affect many more times as much land surface area in the Delta
Islands as would similar changes in water levels at Portage
Creek.
Though some moose in the extensive large island complexes utilize
riparian habitats year-round,many more moose use the riparian
hahi tats along the Susi tna River exclusively during the winter.
36
-
~
!
-
Even during the mild winters of 1979-80 and 1980-81 1 substantial---~----"-_.- -
numbers of moose used these riparian habitats.During severe
winters the same habitats probably harbor 2 to 3 times as many
moose.
Not only are more moose using riparian habitats during late win-
ter,but late winter-early spring is also a critical time,a time
when both sexes of moose are most dependent on riparian habitat
for high quality browse.Pregnant females must maintain them-
selves in good nutritive condition to meet the demands required
for fetal growth;a low quality diet would affect not only the
condition of the pregnant females but also the number and quality
of young they produced.Males,on the other hand,are at this
time attempting to recovercondi tion lost in the rigors of the
)
rut.
Since there is no reason to believe that empty niches or surplus
foods are presently available in riparian habitats,any decrease
in distribution or abundance of riparian habitats,caused by al-
tering natural flow regimes of the Susitna River,will likewise
decrease the numbers of moose that can presently be maintained in
good nutritive condition.
Activities associated with construction of impoundments and
transmission line facilities also pose potential impacts on popu-
lations of moose.Past projects in Southcentral Alaska indicate
that construction of vehicular or transmission line corridors
will probably temporarily discourage moose from using those
immediate areas during the active construction phase and subse-
quently will encourage their use of these areas through creation
of habitats that favor growth of preferred moose winter browse.
In winter,moose will gather and feed in these disturbed areas as
long as early successional stages and associated vegetative types
persist.If transmission line corridors are "maintained",these
preferred habi tats would be available indefinitely.
It is important not to create such facilities in areas immedia-
tely near present highway systems or the Alaska Railroad right-
37
of-way,since numerous moose are killed by trains or vehicles in
- - ---------
these areas every year.In severe winters when numerous moose
are attracted to these habitats,trains alone have been reported
to kill about 500 animals annually.
Of course these habitats may act as a substitute to replace,in
quantity,not location,riparian habitats that may have been lost
through altered flow regimes.
It is not known whether the "hum"characteristic of high voltage
transmission lines will discourage moose from using transmission
line corridors.
Another potential impact on moose may secondarily result from the
development of an access network for construction and maintenance
of the impoundments and transmission line structures.Impacts
resulting from increased access into the now remote areas north
of Talkeetna may be relatively greater in magnitude than in areas
south of Talkeetna where a substantial amount of.access and
development is already present.
If access into these areas remains open for the public following
the construction phase,the intensity of human activities,and
moose hunting in the respective areas will increase substan-
tially.A level of management more precise than is presently
necessary will be required for those populations of moose.
38
-,
~MOOSE -UPSTREAM
"
Winter Habitat Loss The most obvious impact of the proposed
project is loss of habitat,primarily through inundation but also
through construction of project facilities such as roads,borrow
pi ts,camps,etc.The normal pattern is for moose to occupy
habitats at lower elevations during winter.Cows with calves use
such areas more heavily than do bulls.The deeper the snow the
heavier the use of lowland areas.Severe winters frequently
cause population declines in moose.Therefore,lowland winter
range is generally considered critical habitat for moose even
though it might not be heavi 1y used every year.Observations
made during the'winter of 1974-75 suggested that this pattern
held true in the vicinity of the proposed impoundments.
We have not observed this pattern during this study.Snow depths
have been less than normal and have in fact been shallower at
higher elevations than below the levels of the proposed impound-
ments.Moose appear to have actually m9vedto higher elevations
and use of the areas to be inundated has been light.
r
.1
'I
I
A key question is what will happen during a more severe winter
when snow depths are greater at higher elevations.Avai 1ab1e
information is inadequate to answer this question.It seems cer-
tain that during severe winters,use of the impoundment areas,
particularly the portion of the 'area that would be flooded by the
Watana Dam,is greater than observed in March 1981.However,
until we are able to observe moose movement under deeper snow
conditions,we will not be able to predict how much greater that
use is.
Limited observations made by plant ecology studies (Subtask 7.12)
personnel suggest that habitat within the Watana i~poundment area
may not support greater use by moose.They suggested that in
November 1980 willow stands along Watana Creek and portions of
39
"""
~
I
(
x
I~
(
,...,...
CD..
eo..--..••.a-
OoK_.o _
0<
0-.
W-I .."c••.aOe.c:..--~c:a.0
.C'IJ
C'IJ_
0 0
W.
-C--~.
..IllIII•:=>0-Ca:
~.
~C-0:••.~
OC'IJ
o ..e •
-0:~~.
-"=Co •o
I -o C-:i:"0---......'"""'1_Z·
o •••.c:e
C-
O cO__0 ~
.0 10
.0 .,01
Oelt"~..n_ e ...
.'i 0
CI.I-"·~..
..:::l •:::lOC;""""=..0u:.c:CO--
.''.
~•oo
E
*
¥
*'*
1.;
\
'\.'1'J ~.
,...
l
(
.J
¥
/
(
"-'":...-...--
/-\
I
(
I
,./J~
the Susitna River within the Watana impoundment area had already
--~._-
been heavily browsed by moose.They continued,"consequently,it
appears that browse supplies in the bottoms of the Susitna River
Canyon and its tributaries may already be depleted before they
would have much value as a browse reserve in late winter or
during severe winters".Although no data were presented on
available browse,browse utilization,browse vigor or pellet
groups this possibility can not be overlooked.More complete
studies of the habi tat are required.
The fact that current annual growth of major browse species has
been consumed by fall does not necessarily mean an area has lost
its value as critical range during a severe winter.Little is
known about the ability of an overbrowsed range to sustain moose
during a severe winter.If deep snows drive moose to the lowland
areas where the current years growth has already been removed,
the remaining forage may be sufficient to prevent a total loss of
the population even though significant mortality from starvation
may occur.Consequently,our knowledge of the movement patterns
and habitat utilization of Susitna moose during a severe winter
and our knowledge of the capacity of habitat to support moose
during a severe winter are inadequate to draw meaningful conclu-
sions.
....
However,in
ling moose
studies,we
1978-79,a severe winter,while capturing short-year-
in the Oshetna and Tyone River areas for mortality
observed a number of starved moose.
Survival of moose was much higher in riparian areas than in up-
land or flat lowland areas.We suspect survival of moose will be
higher during a severe winter along the Susi tna River than in
many other habi tats found in the area.
Spring Habitat Loss -We found that moose use of impoundment
areas was greatest in spring and early summer.This may be a
response to earlier snow melt and vegetation emergence at lower
elevations.This is a critical period for moose,especially fol-
lowing severe winters.Moose tend to have a negative energy
42
-
(
\
\
!
\
f
r '"\
x ~
x
I
\
+
-..
CD
~..
"c-a-::I ..o~..CD=E
...0
...0
~IO..w..e n
~e
-0-..CD -;..
-,,!10:...
1_
>--.::::e-,..:10·..--:cc_o _
-~.....
~e
::I CD
-0.~"c--~::I
QO
e CD..-::I 0".CDC.-
o •o -e-
~
"CD•>
~-_a::---o e-0 _
1-o •
-::I"CD-~~
-.
-~o~
•::I-e".!e..-o _
o e
~~
o
•CD
~Z
CD CD
""c;.--=11.-
\
/
/'
"
'::-~*'*__FU
~-
,/
>
/,
I
**
*\.
t
i
i
~,
•-.o IIO~E:-~~
eD_
~..~--OC::
OeD
I o·
ooC--~:I.0
~CD--o 0.."
c::c::
0--.-.:ID
~~
eD •
~~
01:1:-.-c:::=Ct-
:I :I
~CD
~~c::eD.a.a.
,..:1-:I~,",c::••eD •c:: c::
:1-
'"'oC
-0
~-•eD
E Z
E eD
:l oC.--_c::~0-·...-C::CD eD
,2CDE
;"'0
-'loCO
-CtIO::~w.0'"Q'="-E
...0.0 .....m
...CD
~-:I E lIS
ClOO
~::~
-
balance during winter.Their physiologic condition deteriorates
-.------.-_.-_.
usually reaching a low point around April.This trend is abrup-
tly reversed when melting snow and new plant growth greatly in-
,.-0 crease the quantity and quality of available food.In a nutri-
tionally stressed population,many moose may be near the point
where their survival or,in the case of pregnant cows,their
unborn calf's survival is in question.If availability of emer-
gent vegetation is delayed,either by climatic conditions or loss
of habitat where emergence is e\arly,the population may suffer
significant mortali ty.
Habi tat Alteration -Whi Ie there is some doubt as to the impor-
_~}:-tance of habitat that will be inundated,there is little doubt
that many areas immediatley adjacent to the impoundments are ex-
-.tremely important.There are several mechanisms that could alter
some of these habitats.
For example,changes in precipitation were predicted in portions
of the Yukon Basin following the creation of Rampart Dam Reser-
voir.Also,in more southerly locales it has been demonstrated
that large bodies of water influence the local environmenti in
effect,lengthening the fall season and delaying spring.
Al though the two proposed impoundments are relatively small in
relation to the Rampart Proj ect,small changes in climate might
be more pronounced because of the steepness of the Susitna River
Valley.Climatic changes may result in either more precipitation
in terms of snow fall or a lengthening of spring thaw and a
resulting delay in spring greenup.The climatic effects of the
two impoundments could be highly detrimental to the large number
of .moose which utilize portions of the Basin wi thin 5 miles of
the proj ect shoreline.As no studies have been undertaken to
predict the effects of the impoundments on climate,we can not
estimate the magni tude of their impact.
Some changes in vegetation are likely along the fringes of the
impoundments.These might be beneficial to moose if the new
plant community is comprised of desirable browse species.There
will be a zone above the normal maximum level of the Watana
45
impoundment that would flood only during extremely wet years.
This might be conducive to growth of some species beneficial for
moose such as willow.Also soil moisture conditions might create
new riparian areas.Since no information is available on the
effects of the impoundments on shoreline vegetation,any conclu-
sions on their effect on moose is speculative.
Filling of the impoundments is likely to displace moose into sur-
rounding habitat.Unless the moose population is below carrying
capacity of the remaining habitat,there will be overbrowsing of
this adjacent habitat until the population adjusts.Overbrowsing
could reduce the carrying capacity for some period of time.The
extent and duration of this reduction in carrying capacity de-
pends on many factors which have not been studied.This impact
would be temporary but could last from a few years to several
decades.
Blockage of Migration -Our studies document a number of cros-
sings of the Susitna River by moose.These crossings were most
common during periods of migration.A number of our radio-col-
lared moose displayed home ranges which would be bisected by the
proposed impoundments.Moose attempting to migrate across the
impoundments would encounter either open water or uncertain ice
conditions.While some moose are still likely to cross impound-
ments particularly later in the winter,the option of having sea-
sonal ranges on both sides of an impoundment is likely to be
lost.
Several subpopulations of moose are known to rely on migrations
across the impoundments.Therefore,blockage of migration ap-
pears to be a problem which will limit the ability of individual
moose to adapt to an otherwise stressful situation such as local-
ized overpopulation or severe winters.
Hazards -Mud and ice shelving around the Watana impoundment is
likely to create hazards to moose.There are numerous instances
where moose have been mired in mud or injured or killed by falls
on ice.
46
-',~r:
-
...
Perhaps more important is the role these hazards might play in
-_._.------_.--_._---
increasing vulnerability to predators.Wolves commonly kill
moose at the edges of lakes suggesting that such areas facilitate
hunting by wolves.The presence of ice shelves might further
benefi t the.wolves.Our data indicate that densities of moose
near the shore of the Watana impoundment are likely to be high in
certain areas.The rate of predation by wolves,and possibly
bears,could be significantly higher than in the absence of the
impoundment.
Other hazards are likely to be created by construction of project
facili ties.Moose-vehicle collisions are likely to occur where
roads pass through moose wintering concentrations.Routing of
access roads and control of traffic levels will be major factors
determining the seriousness of this problem.
Vulnerability to Hunting -The vicinity of the proposed impound-
ments is relatively lightly hunted because of limi ted access.
There is some evidence that such areas help sustain harvest
levels in adjacent accessible areas through dispersal.
Roads to the impoundments will greatly increase access by highway
vehicle,ATV,boat and aircraft.There are already indications
that hunting and trapping effort in the area have increased
simply because workers at the Watana became familiar with the
area and tended to return to the area.We can expect a substan-
tial increase of interest in the area by the thousands of workers
that will be brought in during construction and operation of the
project.
Hunting and trapping can be controlled through existing state
regulatory mechani sms.However,the risk of localized or short
term overharvest wi 11 be increased and management of moose is
likely to become less flexible.We can expect more restrictive
regulations over a large portion of the Basin.
47
Numbers of Moose to be Impacted by Susitna Hydroelectric Develop-
ment above Devi 1 Canyon.
Because the mechanisms of impact of the Susitna Project on moose
are likely to be complex and often indirect,it is difficult to
accurately delineate a zone of impact and to estimate the number
of moose that will be impacted.First,it is necessary to define
an impact.Impacts can range from the permanent loss of the
capacity of a habitat to support some number of animals,or even
to support a population,to short term inconvenience to an in-
dividual animal.For the purposes of this discussion we are.con-
cerned with impacts that are likely to affect the size or pro-
ductivity of the population.Impacted individuals would be ef-
fectively removed from the population,would be less capable of
successfully reproducing under stressful conditions such as se-
vere winters,or would have a shorter life expectancy due to en-
vironmental factors such as severe winters,predation or hazards.
We can assume that all moose whose entire home range falls within
areas that will be inundated will be lost.As we move away from
the impoundments we would expect a progressively smaller propor-
tion of moose to experience progressively less severe impacts.
Therefore,based upon the observed movements of moose,the con-
tinuum of impacts ranges from the impoundment areas to approxi-
mately 110 miles (177 km)away from them.We have classified all
impacts into three broad categories.Impact categories include:
(1)severe impacts -moose which reside in the impoundment area
or which spend significant portions of their life in close proxi-
mity to them ( 5 miles)will be subjected to all of the identi-
fied impacts in the previous section at their most severe inten-
sity.Moose which fall into this category will suffer high rates
of mortality,decreased natality and probably disruption of move-
ments and dispersali (2)moderate impacts -moose which are sub-
jected to this level of impact do not reside in the impoundment
area but do spend portions of the year in areas which would in-
directly be influenced by the effects of the project.All of the
mechanisms of impact identified in the previous section would
exist but crowding,VUlnerability to predation,blockage of
48
-
-
-
_.
-
migration and lower dispersal rates appear most important.Moose_._.------- - - - --
in this category would be expected to suffer lower rates of pro-
ductivity and higher rates of mortality than before the project
but the magnitude would be less than those which would be severe-
ly impacted;(3)slight impact -moose in this category would be
affected indirectly by the proj ect to varying but unknown de-
grees.All of the mechanisms of impact may operate on these
moose but the severity will be much less than those in the severe
or moderate category and thus the impacts may not even be detect-
"able.
To estimate the numbers of moose which could be impacted both
severely and moderately by the project we determined the average
maximum length of total home range sizes·for 162 radio-collared
moose for which 4 or more observations had been made (Table 21
and Appendix B.).Based upon this analysis we determined that
the average length of a total home range for all radio-collared
moose of both sex and all age classes was 28.7 km2 (17.8 mi.).
We applied the measurement to the proposed impoundments and plot-
ted this distance from the impoundment.We used the resulting
area to determine moose which would be moderately affected by
construction and operation of the proposed project.Further ref-
erence to this area will refer to the zone of impact (21).We
also delineated a 5 mile zone from the edge of the impoundment,
which roughly correlated to 1/3 of a moose home range,which we
believed all residing moose would be severly impacted by con-
struction and operation of the proj ect.Specific delineations
around.borrow pits and access routes were not made.The 5-mile
zoneds referred to as the severe impact area (S1A).
Boundaries of the 21 and S1A were overlaid onto the boundaries of
the area for which moose population estimates were made in 1980.
The original stratification and census boundary reported in the
first annual report was expanded for this analyses to include an
adjacent area which was also censused by 1980 another study.The
combined population estimate for fall 1980 was 4,500 moose.
49
Individual total home range polygons for 167 radio-collared moose
were superimposed on one map.The numbers of moose within por-
tions of their home range in the area estimated to contain 4,500
moose in fall 1980 were tallied.Of the 167 moose for which home
range polygons existed,19·had home ranges which fell outside the
area of interest.Of the 148 moose contained within the census
and ZI boundaries,100 of them had polygons which completely or
partially overlapped the ZI while 79 completely or partially
overlapped the SIA.The percentage proportions of radio-collared
moose which overlapped the Z1 and S1A were applied to the popu-
lation estimate of 4,500 moose.This resulted in an estimate of
3,040 moose which seasonally or annually occupy the area within
one home range of the impoundment or the Z1 (zone of impact).
These latter moose would be moderately,impacted by the project.
Of that total an estimated 2,402 moose completely overlapped or
had portions of their home range within 5 miles of the impound-
ment (S1A)and these moose would be severely impacted by the pro-
ject.
Several biases exist with the methods utilized to estimate the
number of moose to be severly or moderately impacted by the pro-
posed project.Perhaps,most importantly,the method assumes
that all areas within the census area received equal capture ef-
fort.Although this assumption can not be entirely fulfilled,
the initial ~apture and distribution of radio-collars was gener-
ally based upon the di stribution and density of moose present
during a given capture year.Admittedly capture efforts in
spring 1980 and spring 1981 were focused on areas immediately
adj acent to the impoundments.For that reason and because of
moose movements information,the area above the Denali Highway
was added to the analysis.The addition of the area with its
relatively large numbers of radio-collared moose which did not
overlap the ZI or the S1A helped to reduce or even reverse the
ini tial capture biases.Without the addition (correction),the
estimates for numbers of moose occupying the Z1 and S1A would
have been 3,300 and 2,607,respectively.The analysis also as-
sumes that immigration and emigration of moose were equal.Al-
though too few moose have been captured outside of the area to
50
-
-
-
~I
-.,
"""
measure immigration the preliminary analysis of movement data
-----_.--~--,-
suggests that a significant number of yearling moose may emigrate
from the area.
An additional criticism of the methods used in this section are
that moose which have very small portions of the home range with-
in the impact areas are given equal weight with those which have
most or all of their home range in the area.This argument could
be valid except that moose which become displaced from the reser-
\
voir area will then be competing for home range space with those
moose which have small areas wi thin the impact zone.
Regardless of the biases associated with this method we believe
it provides a minimum estimate of the numbers of upstream moose
which will be severely or moderately impacted by the proj ect.
No attempt was made to enumerate the numbers of moose which would
be slightly impacted.In conclusion,we estimate that 2,400
moose would be severely impacted by the project and an additional
900 would be moderately impacted.
51
CARIBOU
Construction of the proposed Watana dam would create an impound-
ment which would,intersect a major historical migratory route(s)
of the Nelchina caribou herd.During most years between 1950 and
1973 most or all of the female-calf segment of the herd crossed
from the calving grounds in the Talkeetna Mountains to summer in
the greater Deadman-Butte Lakes area.This movement sometimes
occurred in June after calving but more commonly took place in
\
late July.Most crossings of the Susitna in the proposed
impoundment area occurred between Deadman Creek and the big bend
of the Susi tna .
Varying proportions of the herd have wintered north of the pro-
posed impoundment in drainages of the upper Susitna,Nenana and
Chulitna Rivers in many years.Between 1957 and 1964 this was
the maj or wintering area.Spring migration routes during these
~
years would have undoubtedly crossed the impoundment area appar-
ently between Deadman Creek and Jay Creek.
Some use of the proposed impoundment also occurred during the
",-autumn dispersal period as animals moved from the Talkeetna
Mountains north across the Susitna or vice versa.Some crossings
by bulls which'summered at various locations throughout the Nel-
china Range and moved towards the female-calf segment prior to
the rut occurred every year.
Large movements of caribou across the proposed impoundment have
not occurred during the study period,nor have they been recorded
since about 1976.Sixteen of ~2 radio-collared caribou from the
main Nelchina herd were either located in the proposed impound-
ment area or locations of sequential sightings indicated a high
.-probabili ty that they had been in the area a total of 22 times.
Radio-collared caribou were found in the impoundment area during
two periods,spring (about 10 April -31 May)and autumn (1 Aug-
ust -30 September)i fourteen sightings were in spring while
eight were in the fall.During spring 1981 it appeared from both
relocations of radio-collared animals and sightings of tracks and
52
caribou that many animals were using the Susitna River as a tra-
vel route.They apparently traveled the river from,its conflu-
ence at the Tyone and Oshetna Rivers to Kosina Creek and Watana
Lake where they moved west into the Talkeetna Mountain foothills.
Nine crossings of the proposed Watana impoundment by six radio-
collared caribou were documented (six were north to south and
three south to north).Fi ve occurred in spring and four in
autumn.The uppermost portion of the Watana impoundment received
the most use by radio-collared animals in both spring and autumn.
Even though crossings of the proposed Watana impoundment by
Nelchina caribou have been relatively infrequent (when compared
to historical records when virtually the entire herd crossed two
or more times per year)it seems inevitable that they will again
cross in large numbers.The area north and west of the Watana
impoundment was used extensively as summer and winter range in
the past and Skoog (1968)considered some of the area as the most
important habitat for year around use in the Nelchina range.
It appears that major herd crossing of the impoundment area usu-
ally .occurred when population levels were relatively high.
During recent years when maj or crossings have not occurred the
herd has been at low to moderate population levels and has only
used about a third of its historical range (7,000 mi 2 j20,000
mi 2)•It has been suggested that the range use,frequency of
shifts in range and seasonal splitting were positively correlated
with herd size.It appears likely that the probability of major
crossings of the impoundment area and increased use of the north-
western portion of the range wi 11 increase as herd size in-
creases.
The reactions of caribou to the sudden creation of a large im-
poundment intersecting a maj or migratory route cannot be pre-
dicted with confidence.Movements across the impoundment would
largely occur during three periods.Spring migration from the
winter range to the calving grounds would occur from late April
through May.This would be a period of transition from an ice-
53
-.,
-.
.,,-.
,
covered reservoir at maximum drawdown with ice shelving and ice-
-----~------
covered shores to an open reservoir rapidly filling from spring
run off.Post-calving movements from the calving grounds to sum-
mer range north of the Susitna would occur in late June or July
at which time the impoundment would be ice free and nearing maxi-
mum water level.Additional movements throughout August and Sep-
tember would occur but would likely involve smaller,dispersed
groups of animals.At this time the impoundment would be at max-
imum water level and ice free.
A possible reaction to the impoundment by caribou is complete
avoidance and refusal to even attempt crossing.This could re-
duce use of the northwestern corner of the Nelchina range or
change and extend the migration route to avoid the impoundment.
Another possible reaction would be avoidance by some components
of the herd and attempted crossing by other segments.Other
researchers have documented avoidance of the Trans-Alaska Pipe-
line corridor by females and calves 9,uring summer.They also
suggested avoidance by large groups,group fragmentation and/or
decreased group coalescence near the pipeline corridor.Should
animals attempt to cross the impoundment;spring migration would
appear to pose the most serious problems.Pregnant females are
often in the poorest condition of tne annual cycle at this time
and migratory barriers which normally could be easily circum-
vented could become sources of mortali ty.When animals are in
poor physical condition seasonal migrations are easily disrupted.
The potential for injury or death to migrating caribou appears
greater in spring than during other periods.Several instances
of injuries and death resulting from falls on or through ice have
been documented.Ice covered shores,ice sheets and steep ice
shelves formed by winter draw-down of the reservoir could present
formidable obstacles to movement.Ice shelving has been sug-
gested as a mortality factor of reindeer on reservoirs in Scan-
dinavia.Spring breakup would probably occur during the
migration in many years posing additional hazards such as
floating ice floes,overflow and wet ice shelves.
54
'a -.,.
CD
all
o
Q.
o..
a.
~
~-'a
~
II
II
o..o
'a..
CD
~
:=
o
.c..
IIIo
III
C
~o
~
Z
~
~-
=IIIo..o-lIlI-~
CD..
,CD "
.c III~CD..
al III
~..-~C
~
"e
Q)'a
~C..:=
:=0
eta.
~~
-
Crossings during summer and fall when the reservoir would be ice
free appear to pose considerably less hazard.Caribou are excel-
lent swimmers and are known to cross much larger bodies of water
than the proposed impoundment.Young calves might have problems
with this distance if migrations occurred shortly after calving.
Water crossings have been reported as mortality factors but
usually involved rivers rather than more placid bodies of water
such as a reservoir.Open water may pose a barrier,particularly
during post-calving movements and mid-summer migration.Large
lakes are often crossed at traditional sites,often narrow points
or where islands provide interim stopping points.They state
"caribou prefer to avoid open water.If
Relocations of radio-collared caribou demonstrated that at least
during the study period three relatively discrete subherds occur-
red in the western portion of the Nelchina range.Two of these
subherds,the Chunilna Hills and Susitna-Nenana.groups,would
probably become even more isolated from the main Nelchina herd by
construction of the Susitna hydroelectric proj ect although the
extent probably would depend on locations of access corridors.
The importance of periodic infusions of animals from the main
herd for long-term persistence of these smaller groups is un-
known.
Developments which would accompany construction and operation of
the hydroelectric project such as roads,railroads and air fields
and associated human activity might also negatively impact Nel-
china caribou although the extent is virtually impossible to pre-
dict.Roads and railroads and resulting traffic have been sus-
pected in obstructing movements of caribou and reindeer.However
Nelchina caribou continue to cross the Richardson Highway,often
in large numbers and have done so during many years since about
1960.Several studies have recorded responses of caribou to air-
craft disturbance and speculated on deleterious impacts.Cows
and calves were most responsive to di sturbance.Caribou showed
increased sensi tivi ty during the rut and calving.
56
Electrical transmission lines have been reported to disrupt move-
~_.-----
ments of reindeer in Scandinavia because of associated noises
(hum)and because they are foreign objects in otherwise familiar
surroundings.If electrical transmission lines are downstream
from the proposed Watana darn site they should have little impact
on caribou as long as they are routed near the river.Few cari-
bou occur in this area.Several papers have been recently pub-
lished dealing with caribou behavior and reactions to development
and human activi ty.These studies proyide guidelines which may
help design developmental acti vi ties to minimize adverse impacts.
The proximity of the Nelchina calving grounds to the proposed
Watana impoundments is of concern.According to some resear-
chers,the calving ground is the "focal point"of a caribou herd.
The Nelchina herd has shown nearly complete fidelity to its cal-
ving ground since record keeping began in about 1950.The cal-
ving grounds are in one of the most remote and inaccessible re-
gions wi thin the Nelchina range.Development of the Susi tna hy-
droelectric project would change this.Expanded human access and
activi ty would likely occur which have been shown to adversely
impact caribou use of calving areas.Abandonment ~f a portion of
the calving grounds of the central Arctic herd concurrent with
development of the Prudhoe Bay oil fields has already been demon-O
strated.
Dr.Arthur Bergerud presented a somewhat different view and sug-
gested that caribou are quite adaptable and will adjust to human
construction and development.He stated that the impacts of
human development and harassment have been overstated and no good
evidence is available indicating that development has caused
abandonment of ranges.However,he did state that calving areas
may be an exception and should be protected from both development
and disturbance.
The Watana impoundment appears to have the potential to nega-
tively impact Nelchina caribou although the extent cannot be pre-
dicted.The Devil Canyon impoundment would occur in an area
which both presently and historically has received little caribou
57
-
-
"."\
-
.r-
I
use and would probably be of minor significance to the Nelchina
caribou herd."
Perhaps in the long run the major impact of the Susitna hydro-
electric development on the Nelchina caribou herd will a contri-
bution towards gradual,long term cumulative habitat degradation
rather than immediate catastrophic results.The proposed hydro-
electric project is only one (although the major one)of a number
of developments which will probably occur in the Nelchina range.
Considerable mining activity already is taking place in the
southeastern Talkeetna mountains,traditional summer range.A
state oil and gas lease sale is planned for the Lake Louise Flat,
a major wintering area.Considerable land is passing from public
to private Qwnershipthrough the Alaska Native Claims Settlement
Act and through state land disposal programs.While no single
action may have a catastrophic impact it seems likely that long-
term cumulative impacts will result in a lessened ability for
the Nelchina range to support large numbers of caribou.Habitat
destruction,increased access,disturbance,and partial barriers
to movement will all probably contribute to this.
58
WOLF
The most severe impact of the proposed project on wolves would
occur indirectly due to reductions or changes in the density,
distribution,sex-age composition,and/or physical condition of
prey.Reductions in moose or caribou density in the immediate
vicinity of the impoundments would probably cause reductions in
wolf densities for at least six to seven resident wolf packs
which currently occupy the area.Also any disruption of moose
migrations and/or reductions in migratory moose densities may
also reduce wolf densi ties in areas where migratory moose reside.
Immediately following construction of the impoundments we antici-
pate temporary increases in wolf densities next to impoundment
areas due to the increased availability of moose and caribou
which would be displaced from the reservoirs.In turn,this may
amplify the effects of wolf predation on moose and caribou and
ultimately result in lower densities for all species.Increased
competi tion between bear and wolf could be expected which would
probably result in additional mortality to each species.
Aside from the indirect affects resulting from reductions in prey
density,the proposed impoundments would directly eliminate wolf
habitat by inundating den sites,rendezvous sites,travel corri-
dors,and feeding areas.Loss of habitat would force wolf packs
to readjust terri tory boundaries with neighboring packs which
probably would result in an undetermined amount of mortality due
to social strife.Lower wolf densities in the vicinity of the
impoundments may also result in lower densities elsewhere.If
populations reach low enough levels,wolves will no longer be
able to disperse from the impoundment area to territories vacated
by hunting,trapping and natural mortality.
Increases in human activity in the proj ect area will probably
disrupt and in some cases cause wolves to abandon den and feeding
sites.Early den site abandonment could increase pup mortality.
Increased human acti vi ties may result in increased hunting and
59
.
).
.t
'};?::~suspected wolf
...:....;...pack and
concentration area
Figure 7.Distribution of main Nelchlna radio-collared caribou,14 April 1980 through 29 September,1981 (from Pitcher
1981)In relation to known and suspected wolf packs and concentration areas within the Susltna and Nelchlna River
Basins of southcentral Alaska (from this study and Ballard et al.198 U.
.~J _J ).J ,I ~J ,J J
J'
,,1 Iff,
)""'),'~1 ,}
".\
.
)
.J
'~04V~:\.>.:._...
.
(.
(
Fish Lake
Susltna
Susltna-Slnona
Tolsona
Tyone Creek
Watana
~/}suspected wolf
........pack and
concentration area
Figure 8.Migration routes and movement patterns of radio-collared moose In the Susltna and Nelchlna River Basins
(from Ballard and Taylor 1980;Ballard and Gardner 1981,1981a;Ballard et al.1981)In relation to known and suspected
wolf territories (from this study and Ballard et al.1981 a).
trapping activities as the occurrence of different packs become
common knowledge to larger numbers of hunters and trappers and as
access into the project area becomes more developed.
62
-
-
-
.....
BROWN BEAR
Anticipated project impacts on brown bears are similar in type
for both impoundments but are likely to be more severe in degree
for the Watana impoundment than for the Devils Canyon impound-
ment.This is because the upper impoundment is in prime brown
bear habitat whi le the lower impoundment appears to grade into
habitat which is relatively better for black bears and poorer for
brown bears.In order of suspected degree of impact,.the pro-
posed project is likely to influence brown bear populations in
the following ways:
1.
2.
3.
Reduction in the amount of lowland habitats along the river
utilized by many bears early in the spring and by a few
bears throughout the year.These habitats are the first to
be cleared of snow in the spring (especially on south-facing
slopes)and overwintered berries as well as early spring
growth are available in these habitats relatively earlier
than elsewhere~Nutritionally,early spring is likely to be
the most critical period for bears.Much of the area used
in the early spring will be inundated by the impoundments.
Areas more di stant from the impoundment shoreline may be
affected by climatic changes caused by the impoundment
(particularly delay of spring green-up).
Increased human presence during construction and operation
of the dams will result in increased disturbance and hunting
pressure which will lead to corresponding displacements and
reductions of brown bear populations in the study area.
Increased frequency of bears killed in defense of life and
property situations is also an inevitable result of an in-
creased human population;this can be minimized by proper
preventative regulations during construction and operation.
Inhibition or blockage of directional seasonal movements to
areas of reoccurring food abundance.Routes followed in
these movements will be intersected by the impoundments,by
63
')
(\
)
.)
*'J(
!.
//
I
\.
\"\.
\.-------."r1
f
'J
,I)
/1/\(//'\\~.".
ty~I,t~:'IE~i /':{'*\"r'1f)/)1'.''1(l'd /"L~,t';:1.:1'K ''c*'''l;,r .\t;.'"r,1iIei·'''!
j',,tI ,l'1::"''I '~)f l",\'t 'K)I:;'I(*oj()I:.'+.')I(t '~,
•.J ,'_'ilI.:~'I t \'",'i("/.,)f j,1.\.'f)'T ",;;:,"_/..,1:-
.--//.,,///,'1-.'1<t;'\",*\'·,:it·'I~it'*~',,;:R ,
rf
J)r/'f<//'*'~~~~t,~'',f<'j;~~•~;.,t\"~'1'
((
,.;.1 itT .,~~,'K t'1:''.'tV
f ~~'*'fi ,;t I,,t '/-•,'.,'I,'/'fj .:i''*j "',t-";,,,~t *"'"."•~.../_.,..,'~,......,r l ,'",."
"j __,.+........*,',..'~'1i.>I',K,.'--1..:,1''",'~)I:.."
,j j ,,~,:,-.,-:t:'j/'--'I .~.*...1:.'.'.....,.~.·,,,'i<4t '\'~'~,}I\,,tt ,~i:t:,'.t,('***~:\*l''#,f''~t 't -:::'~.,'+./''1.:\
(/;:'~t ...:~.·....,-...:j;iL,:..,~~..-:t..jt."*.'.''."'_*'_"';'w.'.."~!.."'t,~\'*'>.'l·'~J(~".:,,~-.1,.....'1::..{,,..1:)1','"',T,*~''f.t )1("1';,."'-."~'.".~,',*
[(\IC .:f:','I<.b>\'.,.,'~),":t;t,?t1 *'.):.:~,t:~-f;jE *'1-"-';~
)fl
/~"!'~.*'"Ii_;'!J ,(""."'J ....'5,if ,,",'[\\\.-J'.,,I .r'""',.j,'.::+-:.:1':**.....--)*r;f;-_'~~;,f':"';-:l,\...t./'~)),/*'"''lj('".,'--...r:;l'.",,'l,.l) ('__..._.".~i '1-'...,If:.":'K.';'1(.") .'.r&f *'.'i(A-,;,,:.;,"~!{
I '"'*'I"".,I.y
J
'....1'/("",':'"'
/.•J ti'~),*
I (./*.*/*.1.1\
j////)IIi "Ii
'S)Jr ---..,...',--~~/,~)!'-,,--.-"-
l/'()/"'!
'f ')'\J{j ('f .~\IJ',.f·---,--~~~-"'~l
(---~
Figure 9.Brown bear study area (8473 sq.km).513 bro'wn bear locations are Illustrated.(1 cm=7250 meters)
,..J )_,J 'J J ,J ,,,,,,I ,J ,,.~
4.
5.
access routes,by borrow areas,and by construction and
operation facilities and activities.The areas affected
include caribou and moose concentration areas (especially
calving areas),salmon fishing areas (especially Prairie
Creek),and sites where vegetable forage is seasonally
available.
Disturbance,but probably not much direct inundation,of
brown bear den sites.
Indirect impacts through reduction of availability of salmon
in Prairie Creek and downsteam of Devils Canyon.Based on
available evidence,Prairie Creek salmon runs are unlikely
to be significantly affected and there is little documenta-
tion,as yet,that many brown bears in the existing study
area make seasonal movements downstream of Devils Canyon to
fish.Brown bear populations that are resident downstream
of Devils Canyon,however,are likely to be impacted by the
anticipated project-related reduction or elimination of
salmon spawning between Talkeetna and Devils Canyon.
6.Reduction of ungulate prey.This potential is listed last
only because the importance of ungulate prey to bear popu-
lations was not part of the Phase I study plan.Studies
elsewhere,including the upper Susitna River,suggest that
predation on moose calves by brown bear in the spring is
very common.Indirect evidence suggests that brown bear
predation on caribou,especially on caribou calving grounds,
may also be frequent.
65
BLACK BEAR
Upper Impoundment Residents and Transients
Black bears using the upper impoundment area can conveniently be
broken into resident and transient subpopulation.The most af-
fected subpopulation will be residents that have all or most of
their annual home ranges upstream of the Watana Dam site,it is
our suspicion that this group will be essentially eliminated by
the proposed project through a combination of the following fac-
tors (Ii sted in order of suspected degree of impact):
1.Inundation of den sites and scarcity of acceptable post-
construction al ternati ve den si tes.
,~,
2.
3.
4.
Elimination of habitat through inundation.Acceptable
spring,summer,and denningblack bear habitats in this area
appear largely limited to the impoundment area and immediate
vicinity,much of these habi tats wi 11 be flooded.
Increased hunting and disturbance.Black bears in this area
are currently very Vulnerable to hunting by virtue of the
constricted nature of their primary habitat (spruce forests
along the river),this vulnerability will increase as the
impoundment further constricts acceptable upstream spruce
habitats.At present black bears are little hunted in this
area because of its remoteness and difficulty of access;
this pattern will change as project construction and oper-
ation improves access and augments the human population res-
ident in the area.
Reduction of availability (through disturbance,habitat des-
truction,and/or climatic changes)of tableland areas used
for forage in late summer and early fall.The tablelands
between the spruce forests along the Susitna River and the
adjacent mountains north of the river appear seasonally im-
portant for black bears.Access roads,borrow areas and
construction facilities which transect these tablelands are
66
~-----_._--------------------------------------
(;{,
)/~;-//'~,/:~>-'~if /
''!t
\
\
*),
;;..",~I'~~'-'t.,*',1 iJ$;,.-k""-'7'l"',,~,,~[t~,'t<>,',l!..,,",_.;'>,,~,
-..~'"~'\
'""*'I':;,'(*)'~',j,,'"",
'-,.",,,.,,"'"f
"t,,~,-/i ,,,'
'{J I ''''fJ
Figure 10.Black bear study area (4198 sq.km).722 black bear locations are Illustrated.(1 cm=8000 meters)
I ~1 t .J J .~,,'J .J .J ,,I I .;,.,,,
{I
anticipated.
impoundment
impoundment
dent in the
year.
These habitats in the vicinity of the upper
are used both by bears resident in the upper
area and by many transient bears that are resi-
vicinity of the lower impoundment earlier in the
5.Climatic changes.The nature,extent,and direction (deli-
terous or beneficial)of climatic changes resulting from the
impoundment are uncertain.It is considered likely,how-
ever,that establishment of winter snow cover will be
delayed by a warm-body effect of the mass of water behind
the dam.This,in turn,may reduce the potential for
berries (suspected important food in the early spring)to
successfully overwinter because of the absence of a protec-
tive snow cover in the fall and early winter (this appar-
ently happened naturally during the winter of 1980/81 when
snow cover was abnormally slight and delayed).The warm
impoundment waters may also cause some early winter precipi-
tation to fall as rain rather than snow and may increase the
amount of precipitation because of increased local humidity.
Climatic impacts from the impoundment may be more serious in
the spring when breakup may be delayed because of a possible
cold-body influence of the frozen impoundments.This may
retard the phenology of plants important to bears.as early
spring forage at the most vulnerable portion of the bear's
annual life cycle (immediately following den emergence).
Finally,climatic changes resulting from the impoundment
(temperature changes,precipitation changes,etc.)may alter
the distribution or abundance of berries (suspected cri t-
ically important late summer and early spring foods)or
other forage plants.Vaccinium spp.production,for ex-
ample,appears naturally variable from year to year and
appears to correlate with bear behavior;perhaps years of
low Vaccinium production correlate wi th winter conditions or
climatic conditions during pollination (increased spring
precipitation may inhibit pollination).Although the types
of climatic change which may result from the proposed im-
poundments are uncertain,as are the impacts of any such
68
6.
7.
8.
changes on bears,it is noteworthy that black bears in this
area are on the northern limit of their natural distribution
south of the Alaska Range and are,correspondingly,likely
to be in a somewhat precarious balance with their environ-
ment.
Elimination or reduction of salmon runs downstream of the
Devils Canyon impoundment may eliminate an important alter-
native food source for upstream bears.This alternative may
be important only during years when berry crops are sub-
normal.Based on available data the number of Watana
impoundment-area residents that move downstream to fish for
salmon during poor berry years may be small but has been
documented (see discussion and range maps for B348 and
B343).
Increased interspecific competition with brown bear in-
cluding increased predation by brown bears.It is likely
that the constricted·distribution of black bears in the
spruce forests along the river is adaptive to black bears in
limi ting the degree and effectiveness of brown bear pre-
dation,black bears can climb trees and brown bears cannot.
If this is true,decreases in the amount of forested habitat
could result in increased predation by brown bears,especi-
ally in the early spring when the two species are most
sympatric.
Indirect impacts through reduction of ungulates,especially
moose calves,that may be important prey items in early
spring.This potential factor is listed last because of the
lack of adequate data to reveal the level of predation that
exists as well as uncertainties relative to the proj ect's
impact on moose populations.If such predation is important
to black bear populations and if moose populations are mark-
edly affected,this factor may rank first or second in
importance.
69
-
-
-
--
The transient bear population,usually resident in the vicinity
-------
of the lower impoundment but moves to the upper impoundment in
late summer to forage,will be affected in the upper impoundment
area,by the same factors listed above in approximately the fol-
lowing order:
1.Reduction of availability of tableland areas used for forage
in late summer and early spring (see #4 above).
2.Increased hunting and di sturbance (see #3 above).
3.Climatic changes (see #5 above).
4.Reduction of downstream salmon runs (see #6 above).
5.Reduction of escape habitat on late-summer foraging grounds
(see #7 above).
Lower Impoundment
The proposed Devils Canyon impoundment will doubtless have less
severe impacts on local black bear populations than the Watana
impoundment but impacts will be marked regardless.The topo-
,-graphy of the lower impoundment area as well as the wider di s-
tribution of forested habitats downstream,will result in loss of
a relatively lower proportion of acceptable black bear habitat
downstream.In order of suspected degree of influence the anti-
cipated impacts of the lower impoundment are:
1.Elimination of important early spring habitats through
inundation and associated impacts of climate (retardation of
spring phenology)on spring forage.
2.Reduction of the availability (through disturbance and/or
climatic changes)of tableland area used by Devils Canyon-
area black bears are upstream in the vicinity of Tsusena-
Deadman-Watana Creeks.Impacts on these areas were di s-
cussed in points 4 and 5 above for bears resident in the
upper impoundment area.
70
3.Increased hunting and disturbance (discussed in point 3
above).
4.Elimination or reduction of downstream salmon runs (point 6
above).This factor is of relatively greater importance to
the black bears resident near the Devils Canyon impoundment
because of their closer proximity to these runs.In late
summer 1981 three radio-collared bears resident in the
Devils Canyon impoundment area moved downstream,apparently
to fish for salmon.
5.Inundation of den sites.
6.Reduction of ungulate prey.As noted above the importance
of this factor is unknown which is why it is listed last.
Potentially this could be the #1 or #2 impact on this sub-
population of black bears.
Downstream impacts
The above predicted changes in black bear population density in
the vicini ty of the proposed impoundments may affect adj acent
populations as well.The most likely source of this type of im-
pact would be through reduction in the number of bears dispersing
from the reduced population in the.study area to adjacent areas,
mostly to the west.As mentioned above,some documentation of
such dispersals has been obtained in this study.However,the
significance of this to adjacent populations is unknown.On the
short-term,activi ties and disturbance associated wi th project
construction and perhaps proj ect operation as well could force
some individuals.to disperse.Some of the larger movements and
dispersals observed to date could,arguably,be interpreted as
resulting from the increased human activity associated with Phase
I activities conducted during the last 2 years,this is consi-
dered unlikely however.Over the long-term,it would be more
significant if the project area was a source of dispersing indiv-
iduals moving to adj acent areas.
71
~.
-
""'"
,~
~
I
,""
Available data collected by Su-Hydro fisheries biologists indi--------- ------_._-
cate that salmon spawning in mainstem Susitna between Talkeetna
and Devils Canyon will be greatly reduced or eliminated as a
result of the proposed project.If so,this would be likely to
have a major negative impact on black bear populations in this
area that may depend on salmon for food.Reduction of periodic
flooding of downstream riparian habitats which would result from
the project may also reduce the availability of early-succes-
sional stage forage which may be particularly important in the
spring.These possibilities are conj ectual as downstream bear
studies were not conducted in Phase I,they should be a part of
any Phase I I studies.
72
-
-
WOLVERINE
The most obvious potential impact of the Susi tna Hydroelectric
Project on wolverine is loss of over 20,600 hectares due to in-
undation and associated construction of camps,roads,borrow
pi ts,and transmission corridors.Human-wildlife contacts may
also be severe.According to Robert J.Krogseng,Resident
Manager for Terrestrial Environmental Specialists,Inc.,at the
height of construction there wi 11 be 5,000 workers wi thin the
area.The potential for an increase in both harassment and
hunting and trapping pressure due to human activity and easier
access into the area is likely and can be seriously detrimental
to a low density species like wolverine.
The scavenging nature of wolverine could bring them in contact
wi th the camps lending to additional mortality if garbage dis-
posal and the use of firearms are not strictly regulated.If the
population is now being harvested at maximum sustained yield this
could have a serious impact on the population.
Once construction is completed,a permanent core area will be
built to house a minimum of 120 maintenance workers (Robert
Krogseng pers.corom.).The long term effect on wolverine distri-
,-bution will probably be a significant shift away from the perma-
nent facilities.This will probably cause a decrease in wolver-
ine numbers due to an increase in competition for food,mates and
territories.-The loss of habitat as it affects the wolverine I s prey species
will probably cause reductions in wolverine densities.A de-
crease in the food base would probably increase competition be-
tween wolverine,and between wolverine and other scavengers and
predators.These changes could alter home range size and sea-
sonal movements and result in lower wolverine densities.
73
An additional potential long term impact on wolverine is that
once the project is operational,commercial development may occur
on lands adjacent to the impoundments since much of the area may
be in private ownership due to the Alaska Native Claims Settle-
ment Act.
74
-
-
DALL SHEEP
At the time this study was designed it was assumed that the only
significant impact of the Susitna Hydorelectric Project on Dall
sheep would be from di sturbance from construction acti vi ties,
helicopter traffic,etc.Such impacts could be moderated by
avoiding areas used by sheep or scheduling activities at seasons
when sheep use of an area was reduced.However,sightings of
sheep along Jay Creek indicate a possibility of direct loss of
habitat.
The Portage -Tsusena Creek sheep are likely to be impacted only
by di sturbance.Wi th adequate data on seasonal di stribution
serious disturbance probably can be avoided.However,the pro-
posed borrow pit and the corresponding roads to be located on
upper Tsusena Creek could potentially cause a significant shift
in sheep distribution and a loss of critical winter range.The
status of the Mount Watana population is less clear.Limited
data indicate that sheep occupied habitat close to the proposed
Watana impoundment where di sturbance and perhaps even habitat
loss could be problems.This distribution was not confirmed by
the July 1980 or the single winter survey.More survey infor-
mati on is needed.
The Watana Hills sheep population appears to be the most vulner-
able to severe impact from the proposed Watana impoundment.Its
close proximity to the impoundment makes the population extremely
vulne:rable to disturbance from construction and transportation
activities which could alter behavior,affect lambing success and
force abandonment of the Jay Creek mineral lick.
The Watana Hills sheep population appears to be isolated from
other sheep populations.Thus,recovery of this population,if
severly impacted by short term construction activities,could be
slow relative to other sheep populations.
A portion of the Jay·Creek mineral lick will be inundated by the
Watana impoundment.The importance of this lick to the sheep
75
population is not known but our preliminary observations suggest
~-----------
that a significant portion of the sheep population utilize the
area during late May and June.Sheep also use the area during
other months of the year but adequate documentation does not
exist.If sheep utilize the mineral lick similarly to those
recorded elsewhere in Alaska,significant portions of the Watana
Hills sheep population could be influenced,particularly if late
spring snow depths are influenced by the impoundment.Another
lick 7 miles to the north could provide an alternative source of
m~neralization for the sheep utilizing the Jay Creek lick,but
the chemical content of both licks is unknown at this time.Also
the season and type of use at the alternative lick could be a
significant factor dictating whether additional use could or
would be tolerated.Additionally,if only certain sex or age
classes traditionally utilize the licks,different segments of
the sheep population may not be aware of the existence of alter-
native areas.
The scope of the Phase I sheep studies was not adequate to assess
the potential impacts of the project on sheep.Considerable ex-
pansion of study efforts will be required during Phase II.
76