HomeMy WebLinkAboutAPA2321SUSITNA HYDROELECTRIIC PROJECT
1983 ANNUAL RE,PORT
BIG GAME STUDIES
VOLUME n MOOS,E -DOWNSTREAM
Ronald D.Modafferi
ALASKA DEPARTMENT OF FISH AND GAME
S-ubmitted to the Alaska Power Authority
April 1984
DOCUMENT No.2321
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SUSITNA HYDROELECTRIC PROJECT
BIG GAME STUDIES
1983 ANNUAL REPORT
VOLUME I I.MOOSE -DOWNSTREAM
RonaldD.Modafferi
ALASKA DEPARTMENT OF FISH AND GAME
Submi tted to the Alaska Power Authori ty
July 1984
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NO'l"ICB
ANY QUESTIONS OR COMMENTS CONCERNING
THIS REPOR1,i SHOULD BE DIRECTED TO
TBB ALASltA POWER AUTHORITY
SUSXTRA PROJacT O~XCB
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PREFACE
In early 1980,the Alaska Department of Fish and Game contracted
with the Alaska Power Authority to collect information useful in
assessing the impacts of the proposed Susitna Hydroelectric
Project on moose,caribou,wolf,wolverine,black bear,brown
bear and Dall sheep.
The studies were broken into phases which conformed to the
anticipated licensing schedule.Phase I studies,January 1,1980
tiD June 30,1982,were intended to provide information needed to
support a E'ERC license application.This included general
studies of wildlife populations to determine how each species
used the area and identify potential impact mechanisms.Phase I I
studies began in order to provide additional information during
the anticipated 2 to 3 year period between application and final
FERC approval of the license.Belukha whales were added to the
species being studied.In these annual or final reports,we are
niarrowing the focus of our studies to evaluate specific impact
ml=chanisms,quantify impacts and evaluate mi tigation measures.
This is the second annual report of ongoing Phase I I studies.In
SQme .cases I obj ectives of Phase I were continued to provide a
more complete data base.Therefore,this report is not intended
as a complete assessment of .the impacts of the Susi tna Hydro-
electric Project on the ?elected wildlife species.
The information and conclusions contained in these reports are
incomplete and preliminary in nature and subject to change with
further study.Therefore,information contained in these reports
is not to be quoted or used in any publication without the
wri tten permission of the authors.
The reports are organized into the following 9 volumes:
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Volume I.
Volume I I.
Volume I I I.
Volume IV.
Volume V.
Volume VI.
Volume VI I.
Volume VI I I.
Volume IX.
Big Game Summary Report
Moo se -Downstream
Moose -Upstream
Caribou .
Wolf
Black Bear and Brown Bear
Wolverine
Dall Sheep
Belukha Whale
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SUMMARY
Re~cent demand for non-fossil fuel energy has stimulated public
interest and ini tiated the formulation of a proposal to develop
the hydroelectric potential of the Susitna River.The proposal
is founded on construction of two water impoundments,an earth/
rock filled dam at a site between Tsusena and Deadman Creeks and
a concrete arch dam at Devil Canyon,each with electric gener-
at:ing facilities,and together capable of about 1200 Mw of
ca.paci ty.
Feasibility of the proposed project will be determined in part by
evaluating environmental impacts as well as the economic base.
Environmental impacts can be divided into 2 hydrological cate-
gories:1)pre-impoundment,those impacts occurring in areas
upstream from the impoundments and 2)post-impoundment,those
impacts occurring in areas downstream from the impoundments.
Pre-impoundment impacts will primarily involve immediate loss of
habitats through inundation.Post-impoundment impacts will
probably involve gradual and less dramatic changes in riparian
environments through altered flow regimes and altered charac-
teristics of the water itself and through alterations in other
environmental features.Such environmental effects may affect
wildlife directly through hydrologic conditions and/or be medi-
ated indirectly through several intermediate environmental
components.
Irrespective of causative mechanisms,ultimate impacts of direct
or indirect effects of hydroelectric development on migratory
species of wildlife may occur distant,in both time and space,
from their proximate cause.
In its 215 km course from Devil Canyon to Cook Inlet,the Susitna
River is an outstanding component of a very productive watershed.
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Perhaps,the innate value of the Susi tna River floodplain as
wintering habitat for moose is unsurpassed by riparian habitats
elsewhere in the State.
The general objective of this study was to determine the probable
nature and approximate magnitude of impacts of the proposed
Susi tna River hydroelectric proj ect on moose (Afces alees gigas
Miller)in areas along the Susi tna River downstream from the
prospective Devil Canyon dam site to Cook Inlet.To accomplish
this objective one must thoroughly understand how moose utilize
habi tats on the Susi tna River floodplain (i.e.,what is the
ec,0logical value of these habitats to moose?).Only after
ecological values of floodplain characteristics to moose are
assessed,and subsequently I integrated with hypothetical post-
project conditions,can one knowledgeably evaluate impacts of
hydroelectric development on moose.
Primary obj ectives of this study were the following:1)to
identify subpopulations of moose that are ecologically affiliated
with the Susitna River downstream from Devil Canyon;2)to deter-
mine seasonal distribution and movement patterns for each identi-
fied subpopulation;3)to determine timing,location and relative
magni tude of moose use of various riparian habitats along the
lower Susitna River;4)to identify specific mechanisms through
which impacts will be transferred to subpopulations of moosei
fl-5)to determine the probable nature and approximate magnitude of
identified impacts on those particular subpopulations of moose;
6)to delineate a zone in which impacts of the proposed hydro-
electric project may affect subpopulations of moosej and 7)to
dletermine and suggest potential options for mi tigating actions.
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This report is primarily based on data
radio-collared moose collected between
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from relocations
15 October 1982
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6 October 1983,and from supplemental moose censuses and surveys
conducted through March 1984,but also includes pertinent
findings from the Phase I study progress report (Arneson 1981)
and final report (Modafferi 1982)and a Phase II study progress
r,eport (Modafferi 1983).
Since magnitude of use ·of winter range by Susi tna River Valley
subpopulations of moose is partly related to severity of climatic
cl:>ndi tions,findings presented in thi s report must be considered
as preliminary .since sampling occurred and data were accumulated
during the relatively mild to average winters between 1979 and
1984.Though not as severe as winters can be (i.e.1970-71),the
variable nature of weather conditions in the later two winters
e:l{hibi ted the influence snowfall can have on moose behavior and
winter use of the Susitna River floodplain and further substan-
tiated the importance of this concern.The 1982-83 winter was
characterized by large amounts of snowfall through December,
fc:>llowed by mild conditions and.a recession of snowcover by
mid-January.The 1983-84 winter was characterized by an early
snowfall,continued extensive accumulations·of snowcover through
February and an abrupt amelioration of conditions in early March .
In the mild winter of 1981-82,a maximum of 369 moose were
observed in 6 censuses of floodplain habitats.Maxima of 934 and
819 moose were observed in 11 and 7 similar censuses conducted in
winters of 1982-83 and 1983-84,respectively.Though within and
bE:tween year variation in moose use of floodplain habitats were
primarily associated with affects of winter weather conditions on
moose behavior,possible effects of winter mortality in 1982-83
on subsequent population levels in winter of 1983-84 and of other
f'ictors,which historically may affect long term population
lE:vels,should not be overlooked.
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Data on patterns of movement,habitat use,productivity,survival
and identity of moose subpopulations ecologically affiliated with
the Susitna River,presented in this report,were primarily syn-
thesized from 3,184 relocations obtained from samples of 10,29
and 18 moose captured and radio-collared on 17 April 1980,10-12
March 1981 and 24 February to 10 March 1982 ,respectively,in
floodplain habitats along the Susitna River between Devil Canyon
and Cook Inlet and subsequently radio-relocated through 3 October
1983.Five moose initially captured 17 April 1980,were recap-
tured 27 March 1983 and collared wi thnew radio-transmitters.
Radio-collared moose were relocated at intervals of 16 days
through 16 March 1981 and at about 9 day intervals from March
1981 through 3 October 1983.This schedule provided 11, 16,14,
9,and 9 relocation sites for most individuals monitored during
the winter (1 January thru 28 February),calving (10 May thru 17
June),summer (1 July thru 31 August),"hunting season"(1
September thru 30 September)and breeding (14 September thru 15
October)periods,respectively.These data illustrate where
impacts to subpopulations of moose which winter on the Susi tna
River floodplain wi 11 be realized during other seasonal periods.
Most data collected from radio-collared individuals were analyzed
relative to these periods in moose life history.Effects of the
variables sex,subpopulation and year were considered in inter-
pretive analyses.Radio-relocations dated outside of the life
hi.story periods were grouped wi thin spring,summer,autumn and
post-breeding transi tory intervals.
To assess magnitude of seasonal and regional moose use of ripar-
ialn habitats along the Susitna River from to Devil Canyon to Cook
Inlet radio-relocation d.ta were integrated with information
collected on 6,11 and 7 aerial censuses for moose conducted on
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t.he floodplain between 9 December 1981 and 12
between 29 October 1982 and 22 February 1983,
November 1983 and 15 March 1984,respectively.
April 1982 and
and between 17
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During the study period,a maximum of 934 moose were observed on
the lower Susitna River floodplain,but other data,which demon-
strated that moose do not use the floodplain everyday wi thin a
winter and.that some moose do not use the floodplain every year,
suggested that this value may underestimate the true value by a
minimum of 41 percent.
Numerically,moose winter use of the Susitna River floodplain was
greatest south of Talkeetna.Highest moose densities were
recorded for large islanded areas near Cook Inlet.Age compo-
sition of observed moose appeared related to habitat typei calves
were most commonly observed in low relief,relatively open flood-
plain habitats.For the third consecutive year I female moose
north of Talkeetna exhibited an affini ty for riparian habitats
near the time of parturition.Hypothetical explanations for
these observations are provided.
Radio-collared moose north of Talkeetna seldom ranged farther
than 8 kID from riparian habitats;moose south of Talkeetna
commonly ranged farther than 8 kIn from the Susi tna River and
relocations up to 40 kID from floodplain areas were not uncommon
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for the latter area.Though moose north of Talkeetna did not
range far from riparian habitats I some did travel great di s-
tances,parallel to the river,during each annual cycle.
Large variation between individuals and sexes within years,and
wi thin individuals and sexes between years,was.observed in
movements and sizes of ranges for radio-collared moose.Males
g,enerally ranged over greater distances and larger areas than
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females.Though many individual moose were found to range over
similar areas during their third year of study,some individuals
c:ontinued to add different areas to their annual range.
Some data collected from radio-collared individuals suggested
that several moose subpopulations which may choose to winter in
the foothills of the Talkeetna Mountains,only seek winter range
on the Susitna River floodplain when 'confronted with severe
w'inter condi tions in those alpine areas.
To more completely assess the relative importance of Susi tna
River floodplain habitats (vs.adjacent nonfloodplain habitats)
as winter range for moose subpopulations in the Susi tna River
Valley downstream from Devil Canyon,studies on sites where
"natural"vegetation had been altered by acti vi ties of man
("disturbed"sites)were intensified and studies involving winter
moose surveys conducted in forested and riparian habitats adja-
cent to the Susitna River floodplain were initiated.These types
of studies are of importance since mitigation actions may poten-
tially involve selection and procurement of lands (primarily
n,onfloodplain)and alteration (enhancement)of habitats on those
lands for the benefit of moose populations.
Like the Susitna River floodplain,other riparian areas appeared
tlO be the most heavily used nonfloodplain winter range.However,
some nonriparian,heterogenous,relatively open mixed forest
habi tats also appeared to support substantial numbers of win-
tering moose.Dense extensive,homogenous,forest habitats
contained few moose.Because of early spring movements of moose
f:rom floodplain areas in 1984,it was not known if moose had
occupied those habitats all winter.These preliminary obser-
vations require further study before nonfloodplain,forested
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habi tats are altered as a mitigation action for moose habitat
1"enhancement.
Very dense concentrations of moose were observed at "disturbed"
si tes.Data on timing and magnitude of their use by moose is
provided and their roles in interacting with Susitna River
floodplain winter range and in moose winter ecology are evalu-
a"ted.
One nonfloodplain alpine area in the southwestern foothills of
the Talkeetna Mountains,which contained high densities of
wintering moose,was visited to determine what food sources were
attracting moose to the area.It was found that moose wintering
in this alpine area were "cratering"to feed on rhizomes and
immature fronds of ferns.Chemical composition of these non-
browse food items indicated they contained higher concentrations
of essential nutrients and lower concentrations of the less
digestible components than apical shoots of browsed willows which
occurred in the same area.Ferns may be a critical food item for
moose which winter in similar alpine areas.
To understand factors which may limit growth of moose subpopu-
lations associated with the lower Susitna River floodplain,data
on productivity and calf survival were collected from radio-
cC:lllared moose.The latter data when supplemented with infor-
mation gathered during river censuses indicated that the moose
subpopulations studied had very high rates of productivi ty,but
that calves probably sustained early summer predation by black
bears and winter weather conditions affected both productivi ty
and calf survival.
Data available on present and historic moose population levels
were provided for areas along the Susitna River downstream from
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Devil Canyon.Similar da,ta must be considered in assessing the
potential value of the Susitna River floodplain habitats to
-moose,since numbers of moose using those habitats are probably
related to moose population levels and the latter can vary over
time.Likewi se,mitigation plans should not be limited to the
present status or use of habitats but more appropriately,they
should be based on the potential value of those habitats to-moose.
Probable and potential inadequacies of moose samples and sampling
effort in this study are listed and discussed.
A list,summarizing preliminary considerations for reviewing,
sE~lecting,creating and/or maintaining "enhanced"land areas for
the benefi t of moose populations was developed.
An annotated summary of potential impact mechanisms and their
associated effects is provided.General mechanisms considered
were the following:1)altered seasonal river flow patterns and
loss of annual variation in river flow,2)altered water temper-
ature,3)alteration of habitat,4:)increased access,5)human
encroachment,6)increased railway and vehicular traffic,7)loss
of habitat at impoundment,8)saltwater encroachment at Cook
Inlet,9)altered turbidity and 10)altered ecosystem.
It:was recommendated that research studies investigating:
1)moose use of "disturbedll sites;2)moose subpopulations north
of Talkeetna;3)moose use of nonfloodplain habitats;4)ecology
of floodplain areas where high moose densities occurredi
5)annual variation in moose movements and producti vi tYi and
6)effects of "severe"winter weather conditions on moose use of
the Susi tna River floodpl:~,in,be continued.
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ACKNOWLEDGEMENTS
The following persons deserve special thanks for various phases
of this study:
K.Schneider,Alaska Department of Fish -and Game,for providing
numerous helpful suggestions and comments on all aspects of the-research and for his willingness to ease the burden of admini-
strative tasks and meetings which occasionally occurred at
inopportune times.
D.C.McAllister,Alaska Department of Fish and Game,for willing
and able assistance and suggestions and comments in all aspects
of this study.
C.Allen,Charlie Allen Flight Service,and L.Rogers,Kenai Air
Alaska,Inc.,for piloting aircraft on the many long and tedious
radio-relocating surveys.They deserve special recognition for
abili ty,desire and safety.
N.Tankersley,Alaska Department of Fish and Game,for assistance
on radio-relocating surveys,efforts in scheduling and coordina-
ting numerous project activi ties,and in preparation of this
r,eport.
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J.Swiss,John Swiss and family,big game guiding,outfitting and
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air charter service,for his ability and safety in piloting and
navigating aircraft on patterned aerial censuses for moose and
for his enthusiasm in helping to spot moose during those censuses
and his willing attitude to get the job done,as if the project
Wl~re hi sown.
D.Anctil,T.Otto and S.Miller,all Alaska Department of Fish
and Game employees,for assistance in management and analysis of
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-data.D.Anctil also provided excellent,"draft ready"computer
graphics of most figures presented in this report.
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C.Riedner,Alaska Department of Fi sh and Game,for promptly
drafting the figures .
J.Lewis,B.Taylor,and C.
Fish and Game employees for
relocation surveys.
Riedner,all Alaska Department of
occasional assistance on radio-
E.Goodwin,Alaska Department of Fish and Game,for processing
samples of marrow fat from moose and for providing laboratory
supplies whenever they were needed.
G.Couey and R.Lund,Acres American,for logistical support when
capturing moose at the Montana West "disturbed site."
s.Lawler,mostly,and P.Miles,occasionally,Alaska Department
of Fish and Game employees,for tolerating the many corrections,
changes and redrafts and lengthy tables which occurred in the
typing of this report.
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TABLE OF CONTENTS
PREFACE . . . .
SUMMARY . . . .
ACKNOWLEDGEMENTS.....
LIST OF TABLES . . . . .
LIST OF FIGURES
INTRODUCTION . . .
STUDY AREA ...... .
METHODS . . . . . . . .
LIMITATIONS OF SAMPLES AND SAMPLING EFFORT . . . . .
FINDINGS AND DISCUSSION . . . . .. . . .
WINTER FLOODPLAIN CENSUSES . . . . . . .
MOVEMENTS OF RADIO-COLLARED MOOSE
AFFINITIES FOR SUSITNA RIVER FLOODPLAIN HABITATS . .
MOOSE WINTER USE OF SPECIFIC SUSITNA RIVER
FLOODPLAIN AND ISLANDED AREAS.. . ......
SIZE,SHAPE AND SPATIAL ARRANGEMENT OF ANNUAL RANGES
FOR RADIO-COLLARED MOOSE . . . . . . . . . .
ANNUAL VARIATION IN SIZE AND SHAPE OF RANGES
FOR RADIO-COLLARED MOOSE . . . . . . . . .
DISTRIBUTION OF MOOSE IN NONFLOODPLAIN HABITATS
MOOSE USE OF DISTURBED SITES ..
PRODUCTIVITY AND CALF SURVIVAL FOR
RADIO-COLLARED MOOSE . .. . . . . . . . .
ALPINE WINTER RANGE . . .. . . . . . . . .
PRELIMINARY CONSIDERATIONS FOR REVIEWING,SELECTING,
CREATING AND/OR MAINTAINING LAND AREAS FOR THE
BENEFIT OF MOOSE POPULATIONS .
POTENTIAL IMPACT MECHANISMS:And Associated
Effects . . . . ....
RECOMMENDATIONS FOR FUTURE RESEARCH . . .
REFERENCES ...... . .
PERSONAL COMMUNICATION . . . . . . . . . . . . .
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Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
LIST OF TABLES
Inclusive calendar dates of theoretical
ranges based on life history phenomena
for populations of moose along the
Susitna River from Devil Canyon to
Cook Inlet,Alaska.
Sex,age composition and zone of
location for moose observed on the
7 and 9 February aerial censuses of
the Susitna River from Devil Canyon
to Cook Inlet,Alaska,1983.
Sex,age composition and zone of
location for moose observed on the
22 and 23 February aerial censuses of
the Susitna River from Devil Canyon
to Cook Inlet,Alaska,1983.
Sex,age composition and zone of
location for moose observed on the
7 and 8 March aerial censuses of
the Susitna River from Devil Canyon
to Cook Inlet,Alaska,1983.
Sex,age composition and zone of
location for moose observed on the
22 and 23 March aerial censuses of
the Susi tr:\a River from Devil Canyon
to Cook Inlet,Alaska,1983.
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Table 6.
Table 7.
Table 8.
Table 9.
Table 10.
LIST OF TABLES (cont'd)
Sex,age composition and zone of
location for moose observed on the
7,8 and 13 April aerial censuses of
the Susitna River from Devil Canyon
to Cook Inlet,Alaska,1983.
Sex,age composition and zone of
location for moose observed on the
17 and 18 November aerial censuses of
the Susitna River from Devil Canyon
to Cook Inlet,Alaska,1983.
Sex,age composition and zone of
location for moose observed on the
9,14 and 16 December aerial censuses
of theSusitna River from Devil Canyon
to Cook Inlet,Alaska,1983.
·Sex,age composition and zone of
location for moose observed on the
29-30 December 1983 and 5 January
1984 aerial censuses of the Susitna
River from Devil Canyon to Cook
Inlet,Alaska,1983-84.
Sex,age composition and zone of
location for moose observed on the
13,17 and 19 January aerial censuses
of the Susitna River from Devil Canyon
to Cook Inlet,Alaska,1984.
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Table 11.
Table 12.
Table 13.
Table 14.
Table IS.
LI ST OF TABLES
Sex}age composition and zone of
location for moose observed on the
3,8 and 9 February aerial censuses
of the Susitna River from Devil Canyon
to Cook Inlet,Alaska}1984.
Sex,age composition and zone of
location for moose observed on the
21 and 28 February and 1 March aerial
censuses of the Susitna River from
Devil Canyon to Cook Inlet,Alaska,
1984.
Sex,age composition and zone of
location for moose observed on the
15 March aerial census of the Susitna
River from Devil Canyon to Cook Inlet,
Alaska,1984.
Percent of calves observed on each of
24 censuses for moose in floodplain
habitat along 4 zones of the Susitna
River between Devil Canyon and Cook
Inlet,Alaska,1981-84.
Variation in and general affinities
for floodplain habitats of the Susitna
River exhibited by moose radio-collared
and relocated periodically,1980-83.
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Table 16.
Table 17.
Table 18.
Table 19.
Table 20.
LIST OF TABLES
Dates indicating chronology of arrival
and departure from Susitna River
riparian habitat for female and male
moose radio-collared in habitats
downstream from Talkeetna,1980-83.
Timing and frequency of use of Susitna
River riparian habitats by individual
radio-collared female moose,between
Talkeetna and Devil Canyon,Alaska,
1981-1983.
Number,percent calves and densities
for moose observed in floodplains and
islanded areas along the Susitna River
between Montana and Cook Inlet,
Alaska,1981-84.
Data from recent and past moose
composition surveys conducted in areas
adjacent to the Susitna River down-
stream from Devil Canyon,Alaska.
Data on strata classification,sample
unit size,densities of moose and
population estimates from a stratified
random census conducted along the
Susitna River,Alaska,24-29 February
1984.
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Table 21.
Table 22.
Table 23.
Table 24.
Table 25.
LIST OF TABLES
Composition,numbers,and density
for moose observed at various locations
removed from the Susitna River
floodplain,Alaska,1984.
Numbers of moose observed on sites
adjacent to the Susitna River,Alaska,
where climax vegetation has been
altered by activities of man,1981-84.
Calf production for female moose radio-
collared along the Susitna River
between Devil Canyon and Cook Inlet and
relocated during 1981-83.
Calf survival and calf:cow ratios for
female moose radio-collared along the
Susitna River between Cook Inlet and
Devil Canyon,Alaska,and relocated
from 1981-84.
Chemical components for samples of
fern (Dryopteris dilatata)and willow
(Salix sp.)moose browse collected at
700-800m elevation in the southwestern
foothills of the Talkeetna Mountains,
Alaska,3 January 1984.
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94
96
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Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
LIST OF FIGURES
Map of the study area.
Location of floodplain and islanded
areas along the Susitna River,Alaska,
where densities and calf composition
were determined for wintering moose,
1981-83.
Location of sites adjacent to the
Susitna River,Alaska,where climax
vegetation has been altered by man
and numbers of moose were counted
periodically during the winter,1981-84.
Geographic locations for moose surveys
conducted in areas removed from the
Susitna River floodplain,Alaska.
Geographic areas along the Susitna
River,Alaska downstream from Devil
Canyon,where numbers and sex and age
composition of moose have been
assessed by aerial survey techniques.
Radio-relocations for moose captured
and radio-collared between Devil Canyon
and Cook Inlet,Alaska,and monitored
from 17 April 1980 through
3 October 1983.
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9
10
11
12
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Figure 7.
Figure 8.
Figure 9.
LIST OF FIGURES
Radio-relocations for 40 female moose
captured and radio-collared along the
Susitna River between Devil Canyon and
Cook Inlet,Alaska,1980-83.
Radio-relocations for 15 male moose
captured and radio-collared .along the
Susitna River between Devil Canyon and
Cook Inlet,Alaska,1980-83.
Locations where 40 female moose captured
and radio-collared along the Susitna
River between Devil Canyon and Cook
Inlet,Alaska,were radio-relocated
during the calving period,1980-83.
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Figure 10.Locations where 39 female moose captured
and radio-collared along the Susitna
River between Devil Canyon and Cook
Inlet,Alaska,were radio-relocated
during the summer period,1980-83.
Figure 11.Locations where 12 male moose captured
and radio-collared along the Susitna
River between Devil Canyon and Cook
Inlet,Alaska,were radio-relocated
during the summer period,1980-83.
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LIST OF FIGURES
Figure 12.Locations where 38 female moose captured
and radio-collared along the Susitna
River between Devil Canyon and Cook
Inlet,Alaska,were radio-relocated
during the month of September,1980-83.
Figure 13.Locations where 11 male moose captured
and radio-collared along the Susitna
River between Devil Canyon and Cook
Inlet,Alaska,were radio-relocated
during the month of September,1980-83.
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Figure 14.Locations where 38 female moose captured
and radio-collared along the Susitna River
between Devil Canyon and Cook Inlet,Alaska,
were radio-relocated during the rut period,
1980-83.51
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Figure 15.Locations where 11 male moose captured
and radio-collared along the Susitna
River between Devil Canyon and Cook
Inlet,Alaska,were radio-relocated
during the rut period,1980-83.
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I~LIST OF FIGURES
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Figure 16.Locations where 7 male moose and 40
female moose captured and radio-collared
along the Susitna River between Devil
Canyon and Cook Inlet,Alaska,were
radio-relocated during the winter
period,1980-83.
Figure 17.Shape and spatial relationships for ranges
of 11 female and 3 male moose captured
and radio-collared along the Susitna
River,Alaska and relocated during 1980-83.
53
68
Figure 18.Shape and spatial relationships for ranges
of 7 female moose captured and radio-
collared along the Susitna River,Alaska
and relocated during 1980-83.69
Figure 19.Shape and spatial relationships for ranges
of 7 female and 2 male moose captured
and radio-collared along the Susitna
River,Alaska and relocated during 1980-83.70
Figure 20.Annual ranges for 4 female moose captured
and radio-collared along the Susitna
River,Alaska,which exhibited relatively
little "between year"variation in their
movement patterns.Polygons encompass
radio-relocation points for consecutive
annual periods commencing from date of
capture to the 1980-81,1981-82,1982-83,
and 1983-84 annual periods.
xxi
73 .
....
"...
LIST OF FIGURES
Figure 21.Annual ranges for 3 female and 2 male
moose,captured and radio-collared
along the Susitna River,Alaska,
which exhibited noteworthy "between
year"variation in their movement
patterns.Polygons encompass radio-
relocation points for consecutive
annual periods commencing from date
of capture to the 1980-81,1981-82,
1982-83 and 1982-84 annual periods.
Figure 22.Locations of areas where moose
population size was estimated
and densities of moose were
determined from the stratifi-
cation fight of a random
stratified census conducted
along the Susitna River,Alaska,
26-29 February,1984.
xxii
Page
74
81
INTRODUCTION
More than 30 years ago,the search for an economical source of
power to serve Alaska IS railbel t region stimulated interest in
construction of a hydroelectric facility on the upper Susi tna
River.Feasibility assessments then,by the U.S.Bureau of
Reclamation,and subsequently,by the U.S.Army Corps of
Engineers indicated that the proposed project was economically
feasible and that environmental impacts would not be of suf-
ficient magni tude to affect its authorization.
More recently,in response to an anticipated demand for a non-
fossil fuel source of energy,previous ideas and plans were
rejuvenated in 1976 as attention was again focused on a Susitna
River hydroelectric project.At that time,the Alaska State
Legislature created the Alaska Power Authority to administer
detailed studies to reevaluate the feasibility of developing the
hydroelectric potential of the upper Susi tna River.Environ-
mental studies were of particular importance since technical
field research studies designed to assess environmental impacts
of such a project were never adequately addressed in the past and
in recent times,regulations and public sentiment for environ-
mental conservation have become increasingly more conservative.
Environmental impacts of the proposed hydroelectric project can
be divided into 2 general hydrological categories:those up-
stream (pre-impoundment)and those downstream (post-impoundment)
from the impoundments.Initial environmental impact assessments
emphasized concern in the pre-impoundment area;environmental
assessments in the post-impoundment area were "token"in nature.
Perhaps,conceptually,acute effects involving loss of habitats
through inundation were considered to be more significant n;J;lan
"indirect,long-term chronic type effects that would occur in
habitats downstream as a result of altered characteristics of the
water and hydrologic flow regimes.
1
-
....
....
The Susitna River flows about 215 km downstream from Devil Canyon
before entering Cook Inlet.In a narrow sense,the surrounding
Susitna River Valley watershed encompasses approximately 800,000
km 2 of extremely productive habitat for many species of wildlife.
Perhaps,its innate value as wintering habitat for moose (Alees
alees gigas Miller)is unsurpassed elsewhere in the State.
Though proposed impoundments will be located in the upper reaches
of the Susitna River,environmental impacts resulting from
altered hydrologic flow regimes will occur throughout the 215 km
downstream section of river;indirect effects will also be
realized in a corridor of terrestrial habitats adjacent to the
river.An assessment of the types and magnitude of influence of
the Susi tna River hydraulics on environments at perpendicular
distances from the river is as important to determine as those
impacts that occur immediately along the river.For migratory
species of wildlife,ultimate effects of proximate impacts may be
geographically distant and not obvious,but should not be over-
looked nor regarded lightly.
Prior to statehood,the Susi tna Valley was ranked as the most
productive moose habitat in the territory (Chatelain 1951).
During this same time period,some wintering areas were said to
sustain moose at concentrations greater than 22/km 2 (Spencer and
Chatelain 1953).More recent evidence indicates that concen-
trations and densities of moose in the Susitna Valley are
greatest when deep snows in surrounding areas and at higher
elevations persist into late winter and bury browse species
(Rausch 1959).Such dense aggregations are the probable result
of moose from numerous subpopulations,some as remote as 30-40 km
(LeResche 1974)to more than 110 km away (Van Ballenberghe 1977),
gathering to seek refuge and forage in lowland habitats.It
appears that many moose,from an extensive area and numerous
sUbpopulations,utilize winter range in the Susi tna River Valley .
2
....
The desi rabi li ty of thi s area for moose in the early 1950's was
greatly enhanced by early successional stages of vegetation
resulting from wildfires,mild winters,and abandonment of land
cleared for homesteads,highway and rai lroad construction and
rights-of-way.
By the 1970's,browse on previously cleared land had been lost
through succession,strict fire suppression efforts had essen-
tially eliminated fire subclimax vegetation,and moose popula-
tions began to decline in response to the loss of important
winter range browse species.In subsequent years,several severe
winters compounded the population decrease.A low proportion of
males in the breeding population may also have been another
contributory factor (Bi shop and Rausch 1974).Presently,many
habitats in the Susitna River Valley have reverted to the
pre-1930 pristine state and populations of moose have responded
accordingly.This does not mean that the area is any less
important to moose than in the early 1950's,but that fewer moose
may be using it.
In the past,wildfire and extensive land clearing were the most
dominant disruptive factors involved in creation and maintenance
of young second-growth browse species for moose.Other pheno-
mena,such as beaver activity,periodic flooding,ice scouring,
riparian erosion,and alluvial or loess translocation of soil,
which acted on a smaller and less dramatic scale,were primarily
restricted to riparian habitats along the Susitna River,and were
considered to be relatively insignificant.
However,recent policies and efficiency in suppression of wild-
fire and disposal of only small parcels of land for private
"homesites"in3tead of larger parcels for "homesteads"have,for
all practical purposes eliminated the influence of fire and land
clearing on habitat alteration.For these same reasons,disrup-
ti ve factors once viewed as of little significance have become
3
-
paramount in the creation and maintenance of habitats and browse
species for moose wintering in the Susi tna River valley.
In the near future,habitats in the Susitna River basin may again
experience a broad ecological perturbation,if the hydrologic
regime and other characteristics of the Susitna River are altered
to accommodate hydroelectric development.Though alterations in
the flow regime and other characteristics of the Susi tna River
(temperature,turbidity,ice formation and scouring,substrate
erosion and deposition,ice fog,icing of vegetation,etc.)could
impact moose in a number of waysi one of the most profound would
be through changes in vegetative communi ties which occur along
the river course to the extent that critical habitats or winter
browse species were no longer available to various subpopulations
of moose.
The present research study was designed to assess the potential
impacts of the proposed Susi tna River hydroelectric proj ect on
subpopulations of moose which are ecologically affiliated with
that portion of the Susi tna River between the proposed Devil
Canyon impoundment and Cook Inlet and to suggest possible actions
for mi tigating those impacts.
Primary objectives of this study are the following:1)to ident-
ify subpopulations of moose that are ecologically affiliated with
the Susitna River downstream from Devil Canyoni 2)to determine
seasonal distribution and movement patterns for each identified
subpopulationi 3)to determine timing,location and relative
magni tude of moose use of various riparian habitats along the
lower Susitna Riveri 4)to identify specific mechanisms through
which impacts will be transferred to subpopulations of moose;
5)to determine the probable nature and approximate magnitude of
identified impacts on those particular subpopulations of moose;
6)to delineate a zone in which impacts of the proposed hydro-
electric proj ect may affect subpopulations of moosei and 7)to
determine and suggest potential options for mi tigating actions.
4
The following report is an interim update to the Phase 'I Final
and the First Annual Phase II reports (Modafferi 1982 and 1983,
~respectively)and was initially intended to largely address
:
studies continuing from 20 October 1982 through 3 October 1983.
However,due to unusual variability in 1983-84 winter weather
condi tions and to recent resurgence in interest,concern and
questions pertaining to the planning of a contingency habitat
enhancement program for moose as a mitigation option,that
reporting period was protracted to include data gathered through
the 1983-84 winter.In consideration of the above factors,the
,extended reporting period facilitated a more meaningful overall
assessment of observed moose behavior.
Addi tional data contained in this report are:moose surveys
conducted through 5 April 1984 at "disturbed sites,"moose
surveys conducted through 15 March 1984 in areas removed from the
Susitna River floodplain,periodic moose surveys conducted
through 15 March 1984 in the Susi tna River floodplain,and
general observations from a 23 December 1983 field trip to the
western foothills of the Talkeetna Mountains near Little Willow
Creek.
In this report,the terminology "disturbed sites"is used loosely
in reference to any parcel of ground where human activities have
altered climax vegetati:on and resulted in establishment of seral
stages of vegetation which moose utilize as winter browse.
~
,
Though this report is based primarily on information obtained
_since completion of the Phase I Final Report and the First Annual
Phase II report;where appropriate,all available data sets were
integrated to provide a more meaningful and current descri~tion
and assessment of particular findings.
I~
,5
,.....
i
-
....
....
....
More detailed overall accounts of the Introduction,Study Area
and Methods pertinent to this study are available in the Phase I
Final Report (Modafferi 1982)and the First Annual Phase II
(Modafferi 1983)reports.However,portions of those reports
particularly salient to data herein,are reiterated.
STUDY AREA
The Susitna River flows about 215 kIn downstream from the proposed
Devil Canyon dam site before emptying into Cook Inlet.In its
course to the sea,it descends about 300 m in elevation,it
accepts glacial and non-glacial contributions from numerous
tributary streams,its character changes greatly and it is a
dominant force influencing characteristics of adj acent terres-
trial habitats along the way (Fig.1).The map in Fig.1,
excluding labels for features,is used as a geographical base for
most other figures in this report.A more detailed description
of the general ecological features in the Susi tna River valley
are avai lable in Modafferi (1982).
Boundaries delineating the research study area for assessing
impacts of Susitna hydroelectric development will be determined
by the extent of actual movements documented for moose which were
known to utilize habitats along the Susitna River.Until further
research proves otherwise,it will be assumed that moose which
use Susitna River floodplain habitat in any manner,in any
seasonal period for any length of time may be impacted by hydro-
electric development.Ultimately,the spatial area or zone where
impacts may be realized by subpopulations of moose will encompass
all movements of all moose which were at one time known to use
Susi tna River floodplain habi tats.
Data on several more specific aspects of
collected from smaller geographical areas
general,overall study area.
6
moose ecology were
located wi thin the
-
o 'I::'=o"-=:::::iiIO_=:::i
~o'""
F
£
A BIg lelend
•.ell lelend
C Mount SueUne
o Little Mount Sualtna
E Lower aeluga Lake
F .eluga Mountain
G
H
COOK INLET
Flgur.1.Map .howlng location of the .tudy ar.a In Ala.ka with na",••
lI.t.d fot rlv.r ••lak ••and oth.r promln.nt land.cap.f.ature ••
7
~
ji
.-
-
.....
-
Data for comparing densities and age composition of moose
wintering in different are~s and habitats were collected from 2
predominantly small islanded,low relief,floodplain areas and 4
higher relief,large islanded habitats located on the Susi tna
River floodplain south of Talkeetna (Fig.2).
Data for determining moose use of habitats where "natural"plant
succession had been altered by man,were collected from 13 sites
located adjacent to the Susitna River floodplain south of
Talkeetna (Fig.3).
Data for assessing moose use of areas /other than the Susi tna
River floodplain but within the overall area of study,as winter
range were gathered from 3 predominantly riparian habitats and 8
predominantly nonriparian habitats located west of the Susi tna
River floodplain and south of Talkeetna (Fig.4).
Data for assessing recent and historic moose population levels in
the hypothetical impact zone,were obtained from Alaska Depart-
ment of Fish and Game files on moose composition counts and from
a stratified random census conducted in game management subunits
located along the Susi tna River corridor south of Devil Canyon
(Fig.5).
METHODS
To identify subpopulations of moose that are ecologically affil-
iated with Susitna River floodplain habitats downstream from
Devil Canyon,to assess the ecological importance of these
habitats to individual subpopulations of moose,and to determine
timing,location,duration,magnitude,type and seasonal and
annual use patterns for those floodplain habitats wi thin and
between individual moose subpopulations,it was necessary to
periodically locate and observe individually identi fi able moose .
8
oo
Figure 2.Location of floodplain and lalanded areas along the
Sueltna River.Alaska.where denaltles and calf composition
were determined for wintering moo ae.1981-83.
(A =Caswell floodplain.B =Kaahwltna floodplaIn.C =Delta leland.
D =Bell Island.E =Alexander Island.F =Beaver laland)
9
-...,
~
I
Figure 3.Location of sites adjacent to the Susitna River,Alaska,where climax
vegetation has been altered by man and numbers of moose were counted periodically
during the winter,1981-84.(A =Talkeetna West,B =Montana West,C =Montana East,
0=Montana North.E =Montana Middle,F =Montana South,G =Goose Creek,H =Chandalar
East and West,I =Kashwltna Bluff,J =Kasowitna Lake,K =Kashwitna East and L =Willow Creek)
10
.\,
oo
\
J
(E
I~i
-
Figure 4.Geographic locations for moose surveys conducted In areas.
removed from the Susltna River floodplain.Alaska.(A.Oeshka River.
B =Moose Creek.C ~Trapper Creek.0 ::.Whltsol Lake,E =Swede.
F =Lockwood Lake,G =Kahiltna/Moose Creek.H =Nell Lake,
I =Kashwltna Knobs,J =Trapper Lake and K =Parker Lake)
11
H
o
(;
Figure 5.Geographical areas (A -J)along the SusUna River,Alaska.
downstream from DevH Canyon,where numbera and sex and age composition
ot moose have been a.sessed by aerial survey techniques.(See Table 19
tor aur:,ey data.)
12
.....
.....
-
-
-
-
-
To provide individually identifiable animals that could be
periodically located,samples of moose were captured and tagged
with visual and radio transmitting collars.Each collar featured
a di screte number and radio frequency.
Moose were collared during the winter on the ice and snow covered
Susitna River floodplain between Sheep Creek and Sherman in 1980
(Arneson 1981),between the Delta Islands and Portage Creek in
1981 (Modafferi 1982)and between the Delta Islands and Cook
Inlet in 1982 (Modafferi 1983).Due to the relative unavail-
ability of moose on the floodplain north of Talkeetna,some indi-
viduals were captured up to 400 m on either side of the river
proper.
Five moose (No.22,23, 26,27 and 91)originally captured and
radio-collared in April 1980 were relocated,recaptured,and
retagged with new radio-transmitting collars on 27 March 1983.
Original radio transmitters on these moose were expected to
expire wi thin several months.
Relocation flights with Cessna 172,180 or 185 aircraft-equipped
with a yagi antenna on each wing were conducted at intervals of
about 2-3 weeks in 1980 and about every 1-2 weeks thereafter.
Inclement weather occasionally altered this schedule.
Locations (audio-visual or audio)of radio-collared moose were
noted on 1:63,360 scale USGS topographic maps and later trans-
ferred to mylar overlays for computer digi tization.Data on
elevation,vegetation,snow cover and other moose at the reloca-
tion sites were also recorded.For more complete details of data
management,see Miller and Anctil (1981).
Three subsamples of moose were used to provide information on
movements,population identity,habitat use,physical condition
r
I and productivity;a subsample of 10 moose captured between Sheep
i
13
Creek and Sherman on 17 Apri 1 1980 I a subs ample of 29 moose
captured between the Delta I slands and Portage Creek on 10-12
March 1981 and a subsample of 18 moose captured between the Delta
I sl ands and Cook Inlet on 24 February I 3 and 10 March 1982.
To relate these findings to moose ecology and to illustrate the
relative magnitude of use and timing of use of Susitna River
floodplain habitats by moose,a descriptive technique based on
life history phenomena and their inclusive calendar dates,was
employed.A description of the life history base and inclusive
calendar dates for those periods are presented in Table 1.
Calendar dates for the range use periods did not encompass the
entire year.Between dates for ranges,intervals were delineated
to accommodate movement or transition from one range or period to
another.To prevent transitory movements from affecting calcu-
lation of range location,a very narrow spread of inclusive dates
was selected to describe locations for respective life history
activity periods.Perhaps determination of areal extent of these
ranges would suffer at the expense of determining their location,
but the latter data and their spatial relationship to the Susitna
River were considered to be of greater importance and relevance
in this study.Data provided from this methodology may be inter-
preted to illustrate how and where>impacts of Susi tna River
hydroelectric development will most likely be realized in-relation to both moose population ecology and subpopulation
geography (i.e.,habitat or moose lost in hydroelectric develop-
ment may impact hunters in a particular area,affect results of
fall moose composition surveys in another area and affect spring
_and winter calf composition surveys in yet other geographical
areas,etc.)
Moose were known use the Susi tna River floodplain year-round;
however,a previous study indicated that the magnitude (time and
.~
I numbers)of use was significantly greater during the winter and
14
-
Table 1.Inclusive calendar dates of theoretical ranges based on life history phenomena for
populations of moose along the Susitna River from Devil Canyon to Cook Inlet,Alaska.
Range or transitory interval
Winter range
Spring transitory interval
Relevance to life history
Males recondition from breeding.
Pregnant females nurture fetus and
prepare for parturition.
First winter for calves.
Calendar dates
1 January
thru
28 February
~Calving range Females bear young.10 May
thru
17 June
0'
Summer transitory interval ------------
-Summer range Growtb of new born young.Females 1 July
recondition from parturition and thru
lactation.Males begin antler 31 August
growth.
Autumn transitory interval ------------
Breeding range Males establish breeding units.14 September
Sexes breed.
Location of breeding perhaps tbru
critical for denoting subpop-
~ulation units.31 October
Post breeding transitory interval -------_._---
~
15
-,
r-,
r-
I
i
i,
particularly so during winters characterized by deep snows which
persist late into early spring (Rausch 1958).In consideration
of this a priori knowledge,a series of periodic aerial moose
censuses were conducted wi thin the floodplain of the Susi tna
River from Cook Inlet to Devil Canyon,to assess the magnitude of
ri ver use,to delineate the timing of use and to determine the
location and spatial distribution of use.
No periodic river census was conducted in the winter of 1980-81,
because when I became familiar with this project in early 1981
radio-collared moose had already begun to leave the Susitna River
floodplain and censuses then would have been futile.Within the
winters of 1981-82,1982-83 and 1983-84,6,11,and 7 aerial
moose censuses,respectively,were conducted on the Susitna River
floodplain.In winter of 1981-82,censuses were conducted on
9 and 10 December;28 December and 4 January;2 and 6 February;
1 and 2 March;23 and 24 March;and 12 April.During the winter
of 1982-83,censuses were conducted on 29 October and 6 November;
10 and 18 November;I,2,and 6 December;20,21 and 22 December;
5 and 6 January;20 and 24 January;7 and 9 February;22 and 23
February;7 and 8 March;22 and 23 March and 7,8,and 13 April.
In winter of 1983-84,censuses were conducted on 17 and 18
November;9,14,and 16 December;29 and 30 December;and
5 January;3,8,and 9 February;21 and 28 February and 1 Marchi
and 15 March.
Aerial river censuses were conducted with a PA-18 aircraft flown
at low elevation in a parallel transect pattern from floodplain
bank to opposite floodplain bank,up the Susitna River from Cook
Inlet to Devil Canyon.Though limitations of aerial surveys of
moose were known (LeResche and Rausch 1974),the object of each
aerial river census was to count all moose within the banks of
the Susi tna River floodplain and any of its interconnecting
sloughs.
16
~
I
River censuses were conducted over a time period to encompass the
build up,peak and decline in moose use of winter range in
Susi tna River floodplain habitats.Censuses were conducted at
frequent intervals to assess population dynamics in moose use of
these floodplain habitats and to correlate those data with
factors which may be responsible for observed dynamics.During
aerial river censuses the following categories of moose were
distinguished:large antlered males,small antlered males,lone
non-antlered animals,females with one calf,females with 2
calves,and lone calves.
Location of each moose observed was recorded on USGS 1:63,360
scale topographic maps.Weather and numbers of moose counted
affected duration of individual censuses.Inclement weather and
inadequate snowcover for counting moose frequently interrrupted
continui ty wi thin and between censuses.Characteristics of the
Susi tna River and adj acent floodplain habitats change greatly
between Devil Canyon and Cook Inlet.To reflect these obvious
ecological changes,data from each river census was presented for
each of 4 physiographic zones.Detai led descriptions for phy-
siographic zones appear in Modafferi (1982,p.5-15).
To facilitate calculation of relative densities of moose which
were observed wintering in habitats within each of the 4 riparian
zones on each census of Susitna River floodplain within or
between years,one may utilize surface area calculations that I
determined for each zone,by making visual estimates of land
areas as they appeared on 1:63,360 scale USGS topographic maps.
These visual estimates revealed that riparian zones I,I I,I I I
and IV each contained 28 and 31;23 and 21;65 and 104;and 65
and 29 km 1 ,respectively,of aquatic and terrestrial habitats,
respectively.
After conducting numerous aerial river censuses over a period of
several years,it became apparent that moose were not distributed
17
f""!"evenly throughout the course of the Susi tna River.To examine
this contention,densities and age composition of moose observed
on periodic river censuses were calculated and compared between 2
low relief,predominantly floodplain areas (Caswell and Kashwit-
na)and 4 higher relief predominantly large islanded areas
(Delta,Bell,Alexander and Beaver).These areas were selected
because they represented different types of riparian habitat and
numbers of moose observed on surveys appeared to differ greatly
between them.Study of geography,physiography and habitat types
wi thin each area could provide baseline data for appraising
relati ve values of different habitats to moose and for secon-
darily assessing the role of river flow hydraulics in creating
and maintaining those habi tats.
Since mitigation actions may potentially involve selection and
procurement of lands and alteration of habitats on those lands
for the benefit of moose populations,studies were initiated in
areas downstream from·Devil Canyon and off the Susi tna River
floodplain,to obtain information on moose winter use of 1)sites
where "natural"vegetation had been altered by man ("disturbed
sites"),and 2)sites where "natural"vegetation occurred in
non-Susi tna River floodplain habi tat.
Preliminary studies on moose use of "disturbed sites"were
initiated in 1981 and continued through winter of 1982-83
(Modafferi 1983).In 1983-84,periodic aerial censuses for moose
were conducted on the 6 original sites studied in 1981-83 and on
7 additional sites.Eight,14 and 17 moose censuses were
conducted on "disturbed sites"during the 1981-82,1982-83 and
1983-84 winters,respectively.
To census moose on "disturbed sites,"aerial surveys were con-
ducted by flying low-level transects over the area in a PA-18.A
100 m band around the disturbed area was also surveyed to include
moose which may be using the site but were "bedding down"in
18
denser vegetative cover along the perimeter of the site.Moose
observed were categorized into sex and a:te classes utilized in
river censuses.
To obtain more definitive baseline data on moose use of "dis-
turbed sites,"3 male and 4 female moose were captured and tagged
wi th radio-transmitting collars on 31 January and 1 February,
1984 at the Montana West "disturbed site,"located opposite
Montana on the west side of the Susitna River (Fig.3).This
sample of moose will be relocated periodically along with other
samples of radio-collared moose.
Immobilization and field procedures for capture,tagging and
radio-relocating were described in Modafferi (1982 and 1983).
To assess moose use of nondisturbed ("natural"),nonfloodplain
habi tats,aerial censuses were conducted in March 1984 on 11
si tes removed from the Susi tna River floodplain.In general,
sites surveyed contained either riparian successional or "climax"
type,forested habitats.Information from these studies will be
-used to evaluate the absolute value of such areas and habitats to
moose as winter range,will assist in appraising the relative
winter range value of Susitna River floodplain habitats,and will
provide data on moose winter use of "climax"type habitats.
Since the latter type habitats are likely to be selected for
enhancement,it is important that their overall value to moose be
well understood before they are altered in favor of other more
iF"seral,vegetative associations.
surv~~s in nonfloodplain areas were conducted in a manner
simi~ar to river censuses (Modafferi 1983)and procedures
!
rese~led those recommended by Gasaway (1981)for counting moose
in sample uni ts of standard statified random moose surveys.
I'"""
!,
19
--
....
-
Information obtained from these aspects of downstream moose
studies were intergrated w~th other baseline data on moose
ecology to formulate a Ii sting of facts and procedures to be
considered in selection of lands and alteration of habitats for
the benefit of moose.Thi s Ii sting is preliminary and may be
updated as new data become available.
Censuses in nonfloodplain areas were planned to be conducted when
seasonal moose use of Susi tna River floodplain habitats was
greatest and annual winter conditions were rated as "severe."By
early February,winter conditions in 1984 appeared destined to
satisfy both stipulations and censuses in nonfloodplain areas
were initiated.Harsh winter conditions continued through early
March,but subsequently,ameliorated tremendously,as record warm
and dry weather conditions occurred in mid-March.The afore-
mentioned,unanticipated change in pattern of weather conditions
must be considered when evaluating results of these censuses.
To relate present moose population levels to historic levels,
data from recent Alaska Department of Fish and Game moose
composi tion surveys were compared to record high,hi storical
counts available from Alaska Department of Fish and Game moose
composition survey data files.These data may be used to place
present moose population levels and associated moose use of
Susitna River floodplain habitats into perspective,historically.
Count areas considered were those utilized by the Alaska Depart-
ment of Fish and Game to reflect composition and status of moose
subpopulations in areas which parallel the Susi tna River down-
stream from Devil Canyon,Game Management Subunits 13E,14B and
16A.
Data from previous moose composition surveys indicated that
particularly dense winter concentrations of moose occurred in
alpine areas between Little Wi llow Creek and the Peters Creek
20
-
.....
--
fork of Wi llow Creek ("Wi llow Mountain").Observa tions inci-
dental to routine radio relocating surveys,confirmed these
reports and indicated that most moose were actively "cratering"
for food.On 3 January 1984,the area was visited to determine
what foods ini tiated the "cratering"behavior and to collect
samples of those foods for chemical analyses.Chemical analyses
were conducted at the University of Alaska,Agricultural Experi-
ment Station,Palmer,Alaska.
Data obtained from radio-collared female moose during routine
aerial relocation surveys and from aerial river censuses were
used to document calf production and survival for moose popula-
tions which winter on the Susitna River floodplain.These data
were also used to assess and rate factors which may be limiting
growth of those moose populations.
LIMITATIONS OF SAMPLES AND SAMPLING EFFORT
Samples are only representative of the population from which they
were drawn.Since moose subpopulation use of the Susi tna River
floodplain is greatly influenced by winter conditions,photo
period (seasonal time)and location,samples of radio-collared
moose are winter,season and location specific subpopulation
samples.As a result,radio-collared samples of moose probably
do not contain representatives from all moose sUbpopulations
which winter on the Susitna River floodplain.For a more
detailed discussion see Modafferi (1982,1983).
The sample of moose radio-collared north of Talkeetna,where
impacts from hydroelectric development are expected to be
greatest,was small and data were collected from only two males.
For these reasons,I believe data presently availabte to identify
and assess habitat use for moose subpopulations which use this
portion of the Susitna River floodplain are inadequate.
21
i"',
-
....
-
FINDINGS AND DI SCUSSION
WINTER FLOODPLAIN CENSUSES
Interaction between hydraulics of the Susitna River and adjacent
terrestrial ecosystems have,over time,resulted in a heteroge-
neous assemblage of early successional plant communi ties which
along with local climatic conditions appear to provide attractive
winter range for moose (Collins 1983).
Moose use Susitna River floodplain habitats throughout the year,
but greatest use occurs in winter,when snow and foraging con-
di tions become unfavorable in adj acent habitats (Rausch 1958).
Though timing,duration and magnitude of moose use is strongly
influenced by occurrence and extent of snowfall in the Susi tna
River valley,I believe that activities and movements associated
wi th rutting and calving would override any extreme effects of
weather on the timing of moose movements.With these con-
straints,the winter period,would be bounded by late October,in
the fall,and by late Apri I,in the spring.
Periodic censuses of floodplain habitats wi thin a given winter
and over several winters provide information on:1)when moose
seek these habitats;2)which habitats or areas are most attrac-
tive to moose;3)numbers of moose which utilize floodplain
habitats in a particular winter;4)numbers of moose which flood-
plain habitats may potentially support;5)sex and age-class
specific use of riparian habitats,and 6)when moose depart from
these habitats.Surveys conducted prior to an influx or after
departure of wintering subpopulations may additionally provide
indirect information on numbers of moose which are "resident"to
floodplain habi tats throughc.".It the year .
Information obtained from 24 censuses for moose in floodplain
habitats along the Susitna River downstream from Devil Canyon to
22
-
.....
-
,-
-
Cook Inlet (Modafferi 1982 and Tables 2-13)substantiate beliefs
of Rausch (1958)and others (Chatelain 1951 and LeResche 1974)
about affects of weather on behavior of the !!rai lbel t popula-
tions!!of moose and their use of winter range along the Susitna
River.Six of the censuses were conducted from 9 December
through 12 April during the relatively mild winter of 1981-82,11
censuses were conducted from 29 October through 9 February during
the relatively inclement winter of 1982-83,and 7 censuses were
conducted from 17 November through 15 March during the highly
variable seasonal and area weather conditions in winter of
1983-84.
Maximum numbers of moose observed (minimum numbers of moose using
the area)annually on the Susi tna River floodplain varied from
369 in Census No.4,to 934 in Census No.10 to 819 in Census
No.23,respectively,for the winters of 1981-82,1982-83 and
1983-84 (Table 14).These peaks in total numbers of moose
occurred in early March,mid-December and late February for the 3
respective winter periods.Though these particular censuses
yielded maximum numbers for all censuses within a year,greater
hypothetical values are obtained,if one calculates an aggregate
annual total by summing the maximum numbers of moose observed for
each zone wi thin each year.Considering these annual maxima
values wi thin zones,their aggregate annual sum,and the fact
that moose interchange between zones was probably minimal,then a
minimum of (36 +25 +236 +123)420,(84 +94 +460 +412)
1,050,and (88 +107 +325 +403)923 different moose utilized
the Susi tna River floodplain during the respective winters of
1981-82,1982-83 and 1983-84.These data may also be interpreted
to indicate maxima values for moose use (moose days)which
occurred on the floodplain in each of these winters.
The winter of 1981-82 was mild and resulted in a subtle increase
and low,early March peak in moose use (369 moose)of floodplain
areas.
23
Table 2.Sex,age composition and zone of location for moose observed on the 7 and 9
February aerial censuses of the Susitna River from Devil Canyon to Cook Inlet,
Alaska,1983.
Census No.13
2
~
I
-
,.,..
i
River l Males 2 Females 3 Lone Total
zone Ad 1m 1470 Ill/I W72 calves Ads Calves Moose
I 0 0 8 6 2 0 16 10 26
II 0 0 25 8 1 0 34 10 44
III 0 1 107 63 4 5 175 76 251
IV 0 0 118 42 1 1 161 45 206
Total 0 1 258 119 8 6 386 141 527
1 I =Devil Canyon to Talkeetna,II =Talkeetna to Montana Creek,III =Montana Creek
to Yentna River and IV =Yentna River to Cook Inlet.
1m =small antlered males,mostly yearlings,probably some two-year old males;
Ad =males with large antlers.
May be underestimates (see footnote 3).
3 W/O =females without young,W/1 females with one young;"/2 females with 2 young.
The W/O category may also include males which have shed their antlers;this
becomes prevalent by mid-December.
24
,..
Table 3.Sex,age composition and zone of location for moose observed on the 22 and 23
February aerial censuses of the Susitna River from Devil Canyon to Cook Inlet,
Alaska,1983.
Riverlzone
-
I
II
III
IV
Total
1
Census No.14
Males 2 Females 3 Lone
Ad Im W/O i'lll i'l12 calves Ads
0 0 17 5 0 0 22
0 0 28 16 1 2 45
0 0 146 58 2 1 206
0 0 133 38 1 0 172
0 0 324 117 4 3
445
I =Devil Canyon to Talkeetna,II =Talkeetna to Montana Creek,III
Creek to Yentna River and IV =Yentna River to Cook Inlet.
Total
calves Moose
5 27
20 65
63 269
40 212
128 573
=Montana
2
',';,
1m =small antlered males,mostly yearlings,probably some two-year old males;
Ad =males with large antlers.
May be underestimates (see footnote 3).
3 W/O =females without young,WIl females with one young;W/2 females with 2
young.The wlO category may also include males which have shed their
antlers;this becomes prevalent by mid-December.
25
Table 4.Sex,age composition and zone of location for moose observed on the 7 and 8 March
aerial censuses of the Susitna River from Devil Canyon to Cook Inlet,Alaska,
1983.
Census No.15-
River l "'..ales 2 Females 3 Lone Total
zone Ad 1m W/O WIl A/2 calves Ads calves Moose
I 0 0 24 4 0 0 28 4 32
II 0 0 38 10 1 1 49 13 62
III 0 0 161 46 2 1 209 51 260
IV 0 0 124 31 1 1 156 34 190
""I"Total 0 0 347 91 4 3 442 102 544
l,
1 I ::Devil Canyon to Talkeetna,II ::Talkeetna to Montana Creek,III ::Montana Creek
~to Yentna River and IV =Yentna River to Cook Inlet.
2 1m ::small antlered males,mostly yearlings,probably some tvo-year old males;
Ad ::males vith large antlers.
May be underestimates (see footnote 3).
3 H/O =females without young,Wil females with one young;W/2 females with 2 young.
The H/O category may also include males which have shed their antlers;this
becomes prevalent by mid-December.
-
26
-
Table 5.Sex,age composition and zone of location for moose observed on the 22 and 23 March
aerial censuses of the Susitna River from Devil Canyon to Cook Inlet,Alaska,
1983.
Census No.16
River l Males 2 Females 3 Lone Total
zone Ad 1m 01/0 w/1 0172 calves Ads Calves Moose
I 0 0 13 2 0 0 15 2 17
II 0 0 26 13 1 0 40 15 55
I'""'"III 0 0 158 56 2 1 216 61 277
IV 4
Total 0 0 197 71 3 1 271 78 349
1 I =Devil Canyon to Talkeetna,II =Talkeetna to Montana Creek,III =Montana Creek
to Yentna River and IV =Yentna River to Cook Inlet.
2
--
1m =small antlered males,mostly yearlings,probably some two-year old males;
Ad =males with large antlers.
May be underestimates (see footnote 3).
3 W/O =females without young,Wil females with one young;W/2 females with 2 young.
The WID category may also include males which have shed their antlers;this
becomes prevalent by mid-December.
4 Snow cover in this zone insufficient for counting moose.
27
Table 6.Sex,age composition and zone of location for moose observed on the 7,8 and 13
April aerial censuses of the Susitna River from Devil Canyon to Cook Inlet,
Alaska,1983.-
Census No.17
River l Males 2 Females 3 Lone Total
zone Ad 1m WId Wll k'J2 calves Ads calves Moose-I 0 0 2 1 0 0 3 1 4
II 0 0 21 4 0 1 25 5 30
III 0 0 82 22 1 1 105 25 130
IV 4 0 0 80 16 0 0 96 16 112
Total 0 0 185 43 1 2 229 47 276-
1 I =Devil Canyon to Talkeetna,II =Talkeetna to Montana Creek,III =Montana Creek
"'""to Yentna River and IV =Yentna River to Cook Inlet.,
.-,
-
-
-
-
2
3
4
1m =small antlered males,mostly yearlings,probably some two-year old males;
Ad =males with large antlers.
May be underestimates (see footnote 3)•
WID =females without young,Wll females with one young;W/2 females with 2 young.The
WIO category may also include males which have shed their antlers;this becomes
prevalent by mid-December.
Due to insufficient snow cover,on 7 and 8 April,census in this zone could not be
conducted until 13 April.
28
,...
-
Table 7.Sex,age composition and zone of location for moose observed on the 17 and 18
November aerial census of the Susitna River from Devil Canyon to Cook Inlet,
Alaska,1983.
Census No.18
River l Males 2 Females 3 Lone Total
zone Ad 1m W/O W71 W/2 calves Ads calves Moose
I 1 0 5 6 1 0 13 8 21
II 0 0 3 2 2 2 7 8 15
III 7 6 27 26 1 1 67 29 96
rv 4
Total 8 6 35 34 4 3 87 45 132
-
..-
1
2
3
4
I =Devil Canyon to Talkeetna,II =Talkeetna to Montana Creek,III =Montana Creek,
III =Montana Creek to Yentna River and IV =Yentna River to Cook Inlet.
1m =small antlered males,mostly yearlings,probably some two-year old males;
Ad =males with large antlers.
May be underestimates (see footnote 3).
w/a =females without young,W/1 females with one young;W/2 females with 2 young.The
w/a category may also include males which have shed their ant~ers;this becomes
prevalent by mid-December..
Snow conditions in Zone IV not suitable for counting moose •
29
Table 8.Sex,age composition and zone of location for moose observed on the 9,14~d
16 December aerial censuses of the Susitna River from Devil Canyon to Cook Inlet,
Alaska,1983.
~
Census No.19
.....2 3RiverlMalesFemales Lone Total
zone Ad 1m 1'110 1'01 1'172 calves Ads Calves Moose
I 0 0 5 10 3 0 18 16 34
II 1 0 7 1 1 1 10 4 14
1II4 7 1 33 27 2 2 70 33 103
IV 8 2 43 28 6 0 87 40 127
Total 16 3 88 66 12 3 185 93 278
1 I =Devil Canyon to Talkeetna,II =Talkeetna to Montana Creek,III =Montana Creek
to Yentna River and IV =Yentna River to Cook Inlet.
-
2
3
4
1m =small antlered males,mostly yearlings,probably some two-year old males;
Ad =males with large antlers.
May be underestimates (see footnote 3).
W/O =females without young,Hil females with one young;W!2 females with 2 young.
The W/O category may also include males which have shed their antlers;this
becomes prevalent by mid-December.
Frost and snow on vegetation during survey of Zone III and IV made observing moose
somewhat difficult;counts may be relatively lower than in other zones.
30
Table 9.Sex,age composition and zone of location for moose observed on the 29-30
December 1983 and 5 January 1984 aerial censuses of the Susitna River from
Devil Canyon to Cook Inlet,Alaska,1983-84.
Census No.20
River lzone
I 4
Males 2
Ad tm
Females 3
w/e wI!Wll
Lone
calves Ads
Total
Cal ves MOose
II
III
IV
Total
o
9
7
16
o
1
3
4
17
53
52
122
9
33
29
61
2
5
3
10
o
o
o
o
28
101
94
223
13
43
35
91
41
144
129
314
1 I =Devil Canyon to Talkeetna,II =Talkeetna to Montana Creek,III =Montana Creek,
III =Montana Creek to Yentna River and IV =Yentna River to Cook Inlet.
2
-
-
,~
In!=small antlered males,mostly yearlings,probably some two-year old males;
Ad =males with large antlers.
May be underestimates (see footnote 3).
3 w/O =females without young,WIl females with one young;W/2 females with 2 young.The
W/O category may also include males which have shed their antlers;this becomes
prevalent by mid-December.
4 Weather conditions in Zone I not sUitable for conducting survey.
31
Table 10.Sex,age composition and zone of location for ooose observed on the 13,17 and 19
January aerial censuses of the Susitna River from Devil Canyon to Cook Inlet,
Alaska,1984.
Census No.21
["1'River l Males 2 Females 3 Lone Total
zone Ad 1m wlo IVI W/2 calves Ads Calves Moose
I 0 0 9 6 2 a 17 10 27
II 5 1 14 8 2 1 30 13 43-III 6 1 78 37 3 1 115 44 159
IV 10 3 122 67 7 0 209 81 290
Total 21 5 223 118 14 2 381 148 529
'"""
1 I =Devil Canyon to Talkeetna,II =Talkeetna to Montana Creek,III =Montana Creek
to Yentna River and IV =Yentna River to Cook Inlet.
r-2 1m =small antlered males,mostly yearlings,probably some two-year old males;
Ad =males with large antlers.
May be underestimates (see footnote 3).
-
--
IIIJ3Dl
3 WIO =females without young,Hil females with ODe young;H/2 females with 2 young.
The HIO category may also include males which have shed their antlers;this
becomes prevalent by mid-December.
32
Table 11.Sex,age composition and zone of location for moose observed on the 3,8 and 9
February aerial censuses of the Susltna River from Devil Canyon to Cook Inlet,
Alaska,1984.
Census No.22
Riverl Males 2 Females 3 Lone Total
zone Ad 1m Wid wll W72 calves Ads calves Moose
I 1 1 46 20 0 a 68 20 88
II a 0 52 26 1 0 79 28 107
III 0 1 ISO 46 4 1 231 55 286
IV4 1 6 160 59 6 1 232 72 304
Total 2 8 438 151 11 2 610 175 785
1 I =Devil Canyon to Talkeetna,II =Talkeetna to Montana Creek,III =Montana Creek
to Yentna River and IV =Yentna River to Cook Inlet.
,~2 1m =small antlered males,mostly yearlings,probably some two-year old males;
Ad =males with large antlers.
May be underestimates (see footnote 3).
3 w/a =females without young,H/I females with one young;W/2 females With 2 young.
The M/O category may also include males which have shed their antlers;this
becOllles prevalent by mid-December.
4 Frost and snow on vegetation during survey of Zone III made observing moose difficult;
count may be relatively lower than in other zones •
.-
33
2
-
.,....
....
-
-
-
Table 12.Sex,age composition and zone of location for moose observed on the 21 and 28
February and 1 March aerial censuses of the Susitna River from Devil Canyon
to Cook Inlet,Alaska,1984.
Census No.23
River l Males 2 Females 3 Lone Total
zone Ad fm WIO WIl R/2 calves Ads Calves Moose
I 0 0 35 3 0 0 38 3 41
II 0 0 40 5 0 0 45 5 50
III 0 0 214 52 2 1 268 57 325
IV 0 1 232 70 10 0 313 90 403
Total 0 1 521 130 12 1 664 155 819
1 I =Devil Canyon to Talkeetna,II =Talkeetna to Montana Creek,III =Montana Creek
to Yentna River and IV =Yentna River to Cook Inlet.
1m =small antlered males,mostly yearlings,.probably some two-year old males;
Ad =males with large antlers.
May be underestimates (see footnote 3).
3 WIO =females without young,Wll females with one young;W/2 females with 2 young.
The W/O category may also include males which have shed their antlers;this
becomes prevalent by mid-December •
34
.-
Table 13.Sex,age composition and zone of location for moose observed on the 15 March
aerial census of the Susitna River from Devil Canyon to Cook Inlet,
Alaska,1984.
Census No.24
r-2 3RiverlMalesFemales Lone Total
zone Ad 1m WIO WIl W/2 calves Ads Calves MOose
1 4 0 0 9 0 2 0 11 4 15
II
III
IV
Total 0 0 9 0 2 0 11 4 15-.
,
1 I =Devil Canyon to Talkeetna,II =Talkeetna to Montana Creek,III =Montana Creek
to Yentna River and IV =Yentna River to Cook Inlet.
~2 1m =small antlered males,mostly yearlings,probably some two-year old males;
Ad =males with large antlers.
May be underestimates (see footnote 3).
,~
-
,~
3
4
WID =females without young,WII females with one young;W/2 females with 2 young.
The w/e category may also include males which have shed their antlers;this
becomes prevalent by mid-December.
Snow cover in Zones I -III not suitable for counting moose.
35
J .~J I ~l 1 j i j j J
Table 14.Percent of calves (numbers of moose)observed on each of 24 censuses for moose in floodplain habitat along
4 zones of the Susitna River between Devil Canyon and Cook Inlet,Alaska 1981-84.
~
Winter No.River Zone 1
period census Date I II III IV Census total
1981-82 1 9 and 10 Dec 22 (36)31 (16)31 (147)28 (123)29 (322)
2 28 Dec 81,4 Jan 22 (l8)26 (19)26 (l91)28 (96)26 (324)
3 2 and 6 Feb 0 (8)20 (5)25 (134)21 (92)23 (239)
4 1 and 2 Mar 0 (7)24 (17)16 (236)20 (107)17 (369)
5 23 and 24 Mar 20 (25)36 (25)20 1166)20 (41)22 (257)
6 12 Apr 14 (7)17 (18)32 (57)
_2
27 (82)
1982-83 7 29 Oct and 6 Nov 22 (14)25 (4)32 (60)29 (89)29 (171)
8 10 and 18 Nov 18 (57)36 (28)25 (232)26 (159)25 (476)
9 1,2 and 6 Dec 17 (76)24 (46)31 (292)18 (412)23 (826)
10 20-22 Dec 20 (76)34 (86)28 (460)21 (312)25 (934)
11 5 and 6 Jan 21 (84)28 (94)29 (345)-27 (523)
12 20 and 24 Jan 34 (56)19 (62)29 (329)-29 (447)
13 7 and 9 Feb 38 (26)23 (44)30 (251)22 (206)27 (527)
14 22 and 23 Feb 19 (27)31 (65)23 (269)19 (212)22 (573)
W 15 7 and 8 Mar 13 (32)21 (62)20 (260)18 (190)19 (544)
0\16 22 and 23 Mar 12 (17)27 (55)22 (277)-22 (349)
17 7,8 and 13 Apr 25 (4)17 (30)19 (130)14 (112)17 (276)
1983-84 18 17 and 18 Nov 38 (21)53 (15)43 (96).51 (132)
19 9,14 and 16 Dec 47 (34)29 (14)32 (103)31 (127)33 (278)
20 29 and 30 Dec and 5 Jan -31 (41)30 (144)27 (129)29 (314)
21 13,17 and 19 Jan 37 (27)30 (43)28 (159)28 (290)28 (529)
22 3,8 and 9 Feb 23 (88)26 (107)19 (286)24 (304)22 (785)
23 21 and 28 Feb and 1 Mar 7 (411 10 (SO)17 (325)22 (403)19 (819)
24 15 Mar 27 (ls)---27 (15)
1 I =Devil Canyon to Talkeetna,II =Talkeetna to Montana Creek,III =Montana Creek to Yentna River and
IV =Yentna River to Cook 'Inlet.
2 -=Zone not censused because of insufficient snow cover or inclement flying weather.
......
I
-
-
-
'1Qll!!llo'l!
-,
In 1982,following an early snowfall in October,relatively few
moose (171 moose)were observed on the floodplain.Extensive
snowfall later in that winter precipitated a rapid,early (mid-
December)and high peak in moose use (934 moose)of floodplain
habitats.However,in response to a relative scarity of snowfall
after December and melting of the exi sting snowcover,moose
numbers decreased sharply,but remained at a relatively high
level (550 moose)through March,as the snow cover persisted,
until subsequently decreasing to a lower level by mid-April (276
moose).
Winter in 1983-84,was characterized by average early winter
weather conditions.Mild weather conditions prevailed through
December and moose use of the Susitna River floodplain was
correspondingly low (about 300 moose).Heavy snowfall during
January and frequent snowfall and increasing accumulations of
snow through February,apparently triggered a gradual movement of
moose toward the Susitna River riparian habitats and ultimately
resulted in a large concentration of moose (819)on the river's
floodplain by late February/early March (Census No.23).How-
ever,one of the warmest and driest months of March on record
followed.Because of the rapid decrease in snow cover inadequate
survey conditions occurred and aerial moose censuses were not
done.Consequently,information on moose use of the floodplain
in late March-early April 1983-84 is not available.
Data gathered from river censuses demonstrate that moose use of
Susi tna River floodplain habitats is closely related to winter
weather conditions,particularly snowfall and resultant depth of
the snowcover.Wi thin years,mild weather conditions may pre-
clude movements of large numbers of moose (1981-82),early snows
may initiate early moose movements (1982 83)and late snows may
delay moose movements to floodplain areas (1983-84).Moose
movements to floodplain areas may be rapid (1982-83)or gradual
(1983-84).High levels of moose use may be sustained for long
37
....
P"'"
I
....
-
-
periods of time (1982-83)or may be relatively short-lived
(1983-84).Abrupt decreases in moose numbers associated wi th
ameliorating weather conditions,occurred in all winters.Even
in mild winters,moose from some subpopulations apparently still
move to floodplain habi tats (1981-82).
Data gathered from Census No.7,indicates that approximately 171
moose may be closely associated wi th Susi tna River floodplain
habitats throughout the year.If this is true,then the flood-
plain moose population may double during a mild winter (369 moose
in 1981-82)and even increase by 5 times during a more severe
winter (934 in 1982-83).Apparently,the numbers of moose which
move to floodplain habitats is related to severity of the winterj
as winter severity increases more moose seek forage in floodplain
habitats.If winter in 1982-83 had ended harsh like the 1983-84
winter,there probably would have been many more moose on the
floodplain then were present in either winter separately.
It was very interesting that large numbers of moose which moved
to floodplain habitats in winter 1982-83 (Census No.10)did not
remain in those areas through the winter (at least through early
March)but departed by at least early February.Several of the
possible explanations for this occurrence are:1)that habitats
from which they came are much more desirable and 2)the
floodplain could not support them and other transient moose for
the remainder.of the winter.It is still unknown whether these
highly mobile moose were a part of a subpopulation already
present on the river or a part that carne from greater distances
or different areas or were from a completely different moose sub-
population.It is also not known whether moose which immigrated
early in winter 1982-83 are the same groups of individuals which.
moved to floodpl~in areas late in 1983-84 (i.e.,Does timing of
snowfall affect likelihood of specific subpopulations to move to
floodplain habitats?).If different subpopulations are involved,
then,numbers of different moose which use floodplain habitats
38
r-
!
-
....
-
-
would be significantly greatly than simply considering the
maximum numbers of moose within years (1982-83 and 1983-84)but
would also involve adding some early winter moose of 1982-83 to
the late winter moose of 1983-84.
Numbers of moose utilizing floodplain habitats in 1983-84 may
have been depressed by winter mortality sustained by moose
populations in the previous winter.Percent calves observed in
floodplain habitats in 1983-84 on Census No.23 (Table 14)
indicates that calf moose sustained a higher rate of mortality in
the 1983-84 winter than in previous winters.
Percent of calf moose observed on the Susi tna River floodplain
decreased dramatically in 1982-83.The decrease in percent calf
moose observed on floodplain censuses became apparent by late
February and early March (Census No.14 and 15),when 22 and 19
percent of the moose observed were calves.The percent calves
observed on the previous 7 censuses conducted by early February
in 1982-83 averaged 26 percent.Decreases in percent calves in
1982-83 did not become apparent until several months after peak
moose numbers were attained (Census No.10 VB.14).
Similar comparisons for the winter of 1983-84 indicated that
decreases in numbers of calves became apparent a month prior to
appearances of maximum numbers of moose (Census No.22 vs.
Census No.23).
MOVEMENTS OF RADIO-COLLARED MOOSE
To knowledgeably assess impacts of hydroelectric development of
the Susi tna River on moose ,one must;1)delineate subpopu-
lations of moose which are ecologically affiliated with habitats
potentially subject to alteration;2)determine in what way I
when and how many moose from those subpopulations utilize flood-
plain habitats;3)determine how and where potential impacts to
those moose subpopulations will ultimately be realized;and
39
,....
4)propose various mitigation plans and determine the overall
posi ti ve effects of those plans on the moose resource.These
sorts of data can only be provided by studying movements of
individual moose within those subpopulations and determining the
ecological significance of those movements.
Data presented in Fig.6 illustrate the spatial distribution of
all radio relocations (3184)for all moose captured and radio-
collared along the Susi tna River between Devil Canyon and Cook
Inlet.Generally,these data may be interpreted to indicate the
minimum area or zone within which impacts incurred by moose that
utilize Susitna River riparian habitats,may be realized.These
data show that impacts to moose on the Susitna River floodplain
between Devil Canyon and Cook Inlet may ultimately become obvious
in areas as far west as Beluga Lake,Little Peters Hi 11 s,the
Chuli tna River,as far north as Hurricane;or as far east as
Chunilna Creek,Sheep River,the headwaters of Sheep Creek,
Pittman and Big Lake;an area covering approximately 10,380 krn 2 •
The impact zone broadens widely in areas south of Talkeetna
(Fig.6)and it is apparent that impacts to moose,from Susitna
River hydroelectric development are likely to be realized in
areas quite distant from the river's floodplain.
Likewi se,posi tive effects of mitigation efforts undertaken in
riparian habitats may be realized throughout this same area or
may be directed at locations distant from the floodplain and
still benefit moose subpopulations which utilize floodplain
habitats.
Figures 7 and 8 illustrate points of relocation for female and
male radi,o-collared moose,respectively.These data indicate
that the extent and spatial relationships of impacts will,in
part,depend on the sex of affected moose.Though samples for
males were considerably smaller than for females,particularly
north of Talkeetna,the males,as individuals,appeared to range
more widely.
40
...4:.+""+.........""..
...
+
+..++~
+
+
+...
t
·.-.
-~..~..:-.......,-
Flgur.8.Polygon encompassing 3184 relocation points for 10 moose
radio-collared 17 April,1980.29 moose radlo"'collar.d 10-12"March,1981
and 17 moos.radIo-collared 28 February -10 March,1982 along the Susltna
River between Devil Canyon and Cook Inlet.Alaska and monitored through
3 October,1983.(Inclusive area =103S0 km 2 )41
Figure 7.Radio-relocations (2462)for 40 female moose captured and radio-collared
along the Susltna River between Devil Canyon and Cook Inlet,Alaska,1980-83.
-
,..,.
i
I""'"
I
I.
+
++
+
\+
...+
+.+1lf+
+
42
.....
__or
+
+
+
+
o
(;
+
-
-,
-
-
Figure 8.Radio-relocations (722)for 15 male moose captured and radio-collared
along the Susitna River between Devil Canyon and Cook Inlet,Alaska,1980-83.
43
"""".........._........--,-------------------------------_._---------------
.....
-
--
..-
I
In areas south of Talkeetna,individual males tended to range
annually over larger areas than individual females (lYlodafferi
1983)but bounds of overall impact zones between "populations"of
sexes may be quite similar.
Changes in environmental conditions along the Susitna River as a
resul t of hydroelectric development may affect producti vi ty of
some subpopulations of moose directly by elimination of females
through changes in carrying capacity or indirectly,by affecting
productivity of subpopulations through alteration of female
nutri tive condition.In either case,effects may be realized
locally or distant from floodplain habitat.Likewise,mitigation
measures which improve the calving environment or winter range in
riparian habitats may increase productivity of moose subpopula-
tions in those particular areas and result in higher population
levels.However,enhancement of environments for moose in
riparian areas which do result in greater subpopulation produc-
tivity,may subsequently place additional stress on environments
used by those moose subpopulations during other seasonal periods.
Figure 9 illustrates where female moose captured and radio-
collared in winter on the Susitna River floodplain were relocated
during the calving period (10 May-I?June).These data illus-
trate that most female moose south of Talkeetna leave the flood-
plain to calve,but that female moose north of Talkeetna return
to,and those females in large islanded areas south of Talkeetna
may remain in,floodplain areas for calving.
For a period of time after calving,females with calves remain
relatively sedentary,but by July moose have generally started to
move to summer range areas where they will remain until rutting
activities start.Relocations for radio-collared female and male
moose,respectively during the summer period (1 July-31 Augustj
appear in Figs.10 and 11.These data show that by the summer
period,female moose north of Talkeetna have again departed from
floodplain areas and only females in larger islanded areas south
of Talkeetna remain on the Susi tna River floodplain.
44
:;f/
.....",,:'
-
-
......
-
•11
1I •.,•.-•1I ,.6-
..:
-11 11
I-II
It-1I
~....
Figure 9.locations (506)where 40 female moose captured and radio-collared
along the Susltna River between Devil Canyon and Cook Inlet,Alaska were
radio-relocated during the calving period (10 May-17 June),1980-83.
45
.....It is probably during the summer period,when many people are
traveling,picnicking,camping,fis~ing,boating and recreating
in the outdoors,that nonconsumptive values of moose are
greatest.Impacts of the proposed Susitna hydroelectric project
on moose,may be expected to influence summer distribution and
abundance of moose in areas similar to those illustrated in Figs.
10 and 11,and affect nonconsumptive use of the moose resource in
those areas.
Consumptive use of the moose resource by hunters occurs primarily
during the month of September.Figures 12 and 13 illustrate
where female and male radio-collared moose,respectively,were
relocated during that time period.Those sorts of data indicate
where hunters may realize impacts of Susitna hydroelectric
development on moose.These data demonstrate that moose which
winter on the Susitna River floodplain may provide opportunities
for consumptive use throughout an extensive area,including areas
far from the Susitna River floodplain.
Data presented in Figs.14 and 15,respectively,illustrate
locations where female and male moose,which were captured in
winter on the Susitna River floodplain,were subsequently relo-
cated during the rutting period (14 September to 31 October).
Few moose of either sex spent the rut period in or near their
winter range on the Susi tna River.Most rutted to the west of
the floodplain and some individuals occurred in areas up to 40 km
from the Susitna River.Impacts of hydroelectric development to
moose which winter on the Susitna River may likely affect rutting
acti vi ties in subpopulations throughout this large area.
Data gathered from moose captured and·radio-collared along the
Susi tna River iii).late winter and relocated during subsequent
winter periods (1 January-28 February)indicated that not all
individual moose had returned to floodplains habitats during the
later winter period (Fig.16).Other data collected indicated
46
-
Figure 10.Locatlona (393)where 39 female moose captured and
radio-collared along the Sualtne River between Devil Canyon and
Cook In'~t.Alaska.were radlo-relo4;ated during the summer period
(1 July -31 Augu8t).1980-83.
47
....
..
oo
•
Figure 11.locations (129)where 12 male moose captured and radio-collared
along the Susitna River between Devil Canyon and Cook Inlet,Alaska were
radio-relocated during the summer period (1 July-31 August),1980-83.
48
-
Figure 12.Locations (242)where 38 female moose captured and radio-collared
along the Susltna River between Devil Canyon and Cook Inlet.Alaska were
radio-relocated during the month .of September ("hunting season"),1980-83.
49
r
j-'",i
/
Figure 13.Locations (72)where 11 male moose captured and radio-collared
along the Susitna River between Devil Canyon and Cook Inlet,Alaska were
radio-relocated during the month of September (·hunting season")"1980-83.
50
--_.,:p--"~-----"""-",,,,,---_._-------------------------------------
Figure 14.Locations (286)where 38 female moose captured and radio-collared
along the Susitna River between DevU Canyon and Cook Inlet,Alaska were
radlo-relC'cated during the rut period (14 September-31 October),1980-83.
51
-
---..
Figure 15.Locations (86)where 11 male moose captured and radio-collared
along the Susitna River between Devil Canyon and Cook Inlet,Alaska were
radio-relocated during the rut period (14 September-31 October),1980-83.
52
!'i"'"
"
"""
!
I
i
6-
,.//
,'...>f
-I
:.\
r:,/
...••
r-
I
Figure 16.Locations (348)where 7 male and 40 female moose captured and
radio-collared along the Susitna River between Devil Canyon and Cook Inlet.
Alaska were radio-relocated during the winter period (1 January-28 February).
1980-83.
53
individual and annual variation in the timing that moose arrived
on the Susitna River floodplain winter ran~.Though most moose
arrived on the winter range by January I some arrived later and
some individuals even wintered in entirely different and distant
areas in subsequent years.These data support the contention
that winter river censuses may underestimate the numbers of
different moose which seek winter range in Susitna River flood-
plain habitats.Information collected from behavior of radio-
collared moose may be used in conjunction wi th data from river
censuses to adjust for underestimates in the numbers of different
moose which may be dependent on floodplain habitats for winter
range.Since timing and location of sampling (capturing moose)
as well as winter conditions are critical to obtaining represen-
tatives from all moose subpopulations,only very intensive
radio-collaring and careful review of collected data will
identify numbers of moose and all moose subpopulations which are
ecologically affiliated with the Susitna River floodplain in
winter.
AFFINITIES FOR FLOODPLAIN HABITATS
Before one can knowledgeably assess impacts of the proposed
Susi tna hydroelectric proj ect on subpopulations of moose down-
stream from Devil Canyon,it must be known how and when those
respective subpopulations of moose utilize Susitna River flood-
plain habitats.To knowledgeably predict potential impacts,one
must also be cognizant of the annual and between year variation
which may be expected in those patterns of use,so long-term
behavioral.patterns for those subpopulations may be adequately
"bounded."
Data on timing and frequency of use of riparian habitats and on
variation inaffinities for those habitats obtained from radio-
collared moose are presented in Tables 15 and 16,.respectively.
54
1 1 1 J 1 1 i j
Table 15.Variation in and general affinities for floodplain habitats of the Susitna River exhibited by moose
radio-collared and relocated periodically,1980-83.
Percent of relocations at dIstances Imil
No.from floodplain (F)
Area 1 Sex 2 Treatment3 Moose 4 ReiocaUons 5 F 0-1 1~3 3-5 5-10 10-15 15-20 20+
Upstream F Min 1 79 11 29 48 8 4 0 0 0
Max 1 79 16 61 23 0 0 0 0 0
Total 8 597 10 41 43 5 1 0 0 0
M Min 1 73 1 47 34 3 15 0 0 0
Max 1 61 2 30 51 18 0 0 0 0
Total 2 134 2 39 42 10 8 0 0 0
Downstream
F Min 1 43 26 0 0 2 7 9 14 42
Max 1 81 90 9 1 0 0 0 0 0
Total 29 1,823 25 11 14 9 24 12 3 3
M Min 1 98.1 2 7 2 2 20 30 36
Max 1 80 8 25 50 18 0 0 0 0
U1 Total 8 520 6 16 20 7 21 10 12 8
U1
-
1 Upstream =north of Talkeetna,Downstream =south of Talkeetna.
2 F •female,M =male.
3 Max =data for individual moose which exhibited maximum affinity for floodplain habitats,Min =similar but for
minimum affinity,Total =mean affinity calculated for respective population.
4 Moose =numbers of different individuals which provided data:same individuals provided data for more than
three years.
5 Relocations =number of relocations:sampling intensity relatively similar throughout year.
Table 16.Dates indicating chronology of arrival and departure from Susitna
River riparian habitat for female and male moose radio-col1ared in
habitats downstream ·from Talkeetna,1980·83.
Date females Males
1980
Riparian a Non-riparian Riparian Non-riparian
Apr.3 b 0 3 0
May ND c ND ND ND
Jun.0 3 0 3
~Jul.0 3 0 3
Au.g.0 3 0 3
Sep.0 3 0 3
Oct.0 3 0 2
Nov.0 3 0 2
Dec.0 3 0 3
1981
Jan.0 3 0 2
Feb.d ND NO NO ND
I""'"Mar.15 3 4 2
Apr.7 11 1 5
May 2 16 0 6
Jun.4 14 0 6
Jul.5 13 1 5-Aug.3 15 0 6
Sep.4 14 1 4
Oct.3 14 1 4
Nov.2 15 0 5
Dec.8 9 1 4
JIIIIIiQl
1982
Jan.e 9 8 0 5
Feb.f 18 6 7 4
Mar.17 10 5 6-Apr.12 15 5 6
May 5 22 3 7
Jun.5 22 3 6
Jul.3 24 1 7
Au.g.4 23 1 7-Sep.3 23 1 5
Oct.3 23 0 6
Nov.10 15 1 5
Dec.15 10 2 4
~1983,Jan.17 8 3 3
Feb.19 6 3 3
Mar.15 10 3 2
Apr.15 10 2 3
May 8 17 2 3
JuD.5 19 1 4
Jul.ND ND ND NO
Aug.6 17 1 4
Sep.6 17 0 4
a Riparian =individuals relocated at least once during respective Ume period
within outmost ba.nlts of the SusitDa River;Non-riparian =individual not
relocated during respective time period within outlllost banks of the SusitDa
River.
b 3 females and 3 males radio-collared in riparian habitats.
c ND =no data collected during time period.
r d 16 females and 4 _les radio-collared in riparian habitats.
I e 7 females and 6 .ales radio-collared in riparian habitats.
f 3 females radio-collared in riparian habitats.,,-
!
1"""
l
56
-
-
-
Data gathered from individual moose north of Talkeetna indicated
that for 3 consecutive years their greatest affinity for use of
riparian habitats occurred during May and June,but even that
affinity appeared reduced in 1983 (Table 15).Since radio-
collared female moose throughout the study area calved between
mid-May and mid-June,riparian habitats may likely be important
to this moose subpopulation for production and/or survival of
newly-born young.Particular factors involved in this associ-
ation have not yet been identified but might be related to
presence of early growing nutritious foods (LeResche and Davi s
1973)and/or relative absence of predators (Stringham 1974 and
Edwards 1983).
Wolves are not common along the Susi tna River downstream from
Devil Canyon;but brown and black bears occur commonly in the
area and are known to utilize mid-elevations on south facing
slopes during this seasonal period (Sterling Miller,per.comm.),
and could be responsible for female moose moving from ridges and
mid-slopes to lower elevations along the floodplain,as was
hypothesized by Edwards (1983)for female moose in association
with wolves at Isle Royale.High rates of predation by brown and
black bears on neonatal moose calves have been documented for a
moose population in an area several miles upstream from Devil
Canyon (Ballard et ale 1982a).Coyotes are abundant throughout
the entire study area and may also be involved in prompting
female moose to move to floodplain areas near parturi tion.
Edwards believed that diet diversity was inversely related to
diet quality (i.e.increased diversity in dietary constituents
decreased overall diet quality).Howeyer,it may be that under-
story vegetation in riparian habitats provides a variety of
nonbrowse plant species which eLch at any given time occur at
different stages of phenological development,but when considered
over time they could,in combination,provide a continuous supply
57
"...,
.....
-
of young,tender,highly digestible and nutritious phenological
stages of vegetation.Collins (pers.comm.)has observed in late
May and early June that ferns on some floodplains islands north
of Talkeetna were heavily browsed by moose.He also believed
that ferns (particularly at the fiddlehead stage)were an
excellent source of nitrogen (see pg.109,this report,for
chemical composition of fern rhizomes collected alpine areas in
January).
The apparent "unattractiveness"of floodplain habitats (from
January through April in 1981-82)to the moose subpopulation
north of Talkeetna may have in part been related to the rela-
ti vely mi ld weather conditions that winter,since in the much
earlier and harsher winter of 1982-83,moose from that same
subpopulation appeared to utilize riparian habitats from November
through February.
Data presented in Table 17 indicate that radio-collared moose,in
winter 1981-82,started to move to floodplain habitats in Decem-
ber,were most frequently relocated in those habitats in February
and March,and proceeded to depart from the floodplain areas
during Apri 1.
However,in winter of 1982-83,heavy,early snowfall apparently
stimulated moose to move to floodplain habitats in November,and
as in the previous winter,moose numbers built up to a peak in
February.But apparently,the persistence of snowcover and
wintery conditions late into the spring of 1983 caused more moose
to remain in floodplain areas through April and into May.
In spite of the relatively harsh winter conditions in 1982-83,1
male and t female moose which were previously captured on the
Susitna River floodplain,were not known to return to those areas
that winter.These data,along with the former,indicate that
many more moose may utilize riparian habitats than are present at
58
1 ~---~--l 1 J I )
Table 17.Timing and frequency of use of Susitna River riparian habitats by individual radio collared fe.ale moose,between Talkeetna
and Devil Canyon,Alaska 1981-1983.
1981 1982 1983
IncUvidual It'ir.Hiy Jut.Sip.NOv.Jan.Har.Hay Jut.sep.NOv.Jan.Mir.Hay July~p.
and a and and and and and and and and and and and and and and and
Apr.Jun.Aug.Oct.Dec.Feb.Apr.Jun.Aug.Oct.Dec.Feb.Apr.Jun.Aug.OCt.
29 1/7 b t/7 0/7 1/7 0/5 0/5 0/5 3/6 0/3 0/2 1/2 Oft Olt 0/9 1/2 0/3
42 0/6 0/7 0/7 0/7 0/5 0/5 0/5 1/6 0/3 0/2 1/2 3/4 ott 0/9 0/2 0/3
63 0/6 2/7 0/7 0/7 0/5 0/5 0/5 0/6 0/3 0/3 0/2 1/t O/f 1/9 0/2 0/3
68 0/6 5/7 0/7 0/7 0/5 0/5 0/5 3/6 0/3 0/1 0/2 ott O/t 4/9 0/2 0/3
69 0/6 0/7 0/7 0/7 0/5 0/5 0/5 0/6 0/3 0/1 0/2 O/t 0/4 0/9 0/2 0/3
73 0/6 3/7 0/7 0/7 0/5 0/5 0/5 1/6 l/3 c 0/2 0/2 O/t l/ff 2/9 0/2 0/3
7f 0/6 1/7 0/7 1/7 1/5 0/5 0/5 2/5 d
eo 0/6 3/4 e
81 0/5 3/7 0/7 0/7 0/5 0/5 0/5 1/6 0/2 0/2 1/2 2/t O/f 0/9 0/2 0/3
In
1.0
No.indi-
viduals
relocated
in riparian 1/9 7/9 0/8 2/8 1/8 0/8 0/8 6/8 1/7 0/7 3/1 3/1 1/7 3/7 1/7 0/7
habitat/
Total
individuals
a Number of radio relocations in riparian habitat/total number of observations during
respective time period.
b Riparian habitat observation on 28 April.
e Riparian habitat observation on 8 July.
d Individual observed dead in Susitna River south of Talkeetna on 16 July.
e Individual captured south of Talkeetna but moved north of Talkeetna and was found
silted and dead on bank of Susitna River;died approxiaately 6 July.
f Riparian habitat observation on 20 April.
-
,.....
I
any onetime or during any one year.For instance,data from
radio-collared moose indicated that in February 1983,for every
22 moose,19 females and 3 males,observed in floodplain areas,
there were probably another 9 moose,6 females and 3 males,that
also use those habitats.Similarly,moose censuses in riparian
habitats at that time may have to be expanded by a factor of 41%
(9/22)to approximate the actual numbers of moose which use those
habitats.
Most moose apparently utilize the Susitna River floodplain south
of Talkeetna only as a winter range,but in all years some
individuals remained in riparian areas and apparently utilized
those habitats throughout the entire year.This behavior was
most typical of individuals which were found to range in and near
the large islanded areas of the Susi tna River (i.e.,the Delta
Islands and the Big/Bell Island complexes).Available data
indicated that roughly 18%(4 of 22,4 of 27,and 5 of 23 radio-
collared moose relocated in 1981,1982 and 1983,respectively,
Table 17)of the moose subpopulation which utilized floodplain
habi tats as winter range were found to be "resident"to those
areas throughout the year.During more severe winter conditions,
one would probably expect that the floodplain habitats are shared
amongst a higher proportion of "nonresident"moose.
Though the greatest potential impacts to the moose sUbpopulation
upstream from Talkeetna may occur in May and June and to the
downstream moose subpopulations from December through April and
into May in severe winters,there is a portion of moose in the
latter popUlation which utilize riparian habitats throughout the
year and will be vulnerable to impacts incurred during any
seasonal period.
Additional data exhibiting variation in affinities for riparian
habi tats and in behavioral patterns for both individuals arid
subpopulations of moose are presented in Table 16.This summary
60
-
-
-
of.data for over 3 years of study demonstrate considerable
differences in movement patterns between upstream and downstream
moose subpopulations.Those moose subpopulations downstream from
Talkeetna spent a considerable amount of time at distances
greater than 3 miles from the Susitna River floodplain,whereas
their counterparts north of Talkeetna were seldom relocated
farther than 3 miles from the floodplain.Males in both subpopu-
lations,usually ranged relatively farther than females from the
riparian habitats,and males in downstream areas exhibited less
affini ty for floodplain habitats than those in upstream areas.
These data also indicate notable differences in behavioral
patterns between individual moose within a subpopulation (i.e.,
comparing minimum and maximum values for affinities).
In summary,these data illustrate that impacts to subpopulations
of moose which utilize Susitna River riparian habitats primarily
as winter range,may be realized in areas quite remote from the
banks of the river and the source of the impact.Impacts most
remote from the Susitna River will probably occur in moose
subpopulations south of Talkeetna and in male moose of both
subpopulations.
MOOSE WINTER USE OF SPECIFIC SUSITNA RIVER FLOODPLAIN AND
I SLANDED AREAS
Alterations in Susitna River flow hydraulics will affect differ-
ent habitat types differently,and those effects will secondarily
vary depending on the location of that habitat on the river's
overall floodplain.Changes in flow hydraulics may also have
posi tive effects with respect to moose by duplicating specific
desirable hydraulics at other locations on the floodplain and
thereby creating preferred hrbi tats.However,it must be re-
membered,that factors other than vegetative associations,as
mentioned above,also interact to influence the precise quality
of habitats for moose.Moose use of the Susitna River floodplain
61
-
,....
I
-
-
is not random.Moose most likely preferi select and utilize
specific habitat types and the quality of those habitat types may
secondarily be influenced by factors such as location on the
floodplain,local snow conditions,occurrence of predators and
suitability of adjacent,nonfloodplain habitats during other
seasonal periods.
One hypothetical method of assessing impacts of Susi tna River
hydroelectric development on moose,is to delineate and charac-
terize which habitats are most heavily used (important)by moose,
and to secondarily determine if those habitat characterics will
be altered by proposed changes in river flow hydraulics.To
examine this particular method of assessing moose-habitat
relationships,age composition and densities of moose were
determined for 6 specific sites delineated on the Susitna River
floodplain (Table 18).
Data presented in Table 18 exhibit variation in densities and age
composi tion of moose observed at different areas of the flood-
plain.In all years,greatest moose densities were observed on
Bell Island.Moose densities on Alexander Island were also
considerably greater than those in the other 4 areas,but were
still less than those on Bell Island.In all 3 years,lowest
densi ties of moose were observed on the Delta Islands.Moose
densities observed on Bell Island ranged from 4 to 7 times higher
than densities observed on the Delta Islands.
Differences in observed densities or apparent attractiveness of
these areas to moose may,in part,be attributed to both habitat
type and location on the floodplain.Vegetation on the Delta
Islands appears largely to be the typical "climax"type riparian
habitat mature forest characteristic of the Susitna River flood-
plain.Aside from occasional deep water sloughs,habitat on the
Delta Islands is monotonous.Bell and Alexander Island contain
similar climax riparian habitat but,in contrast,those islands
62
'--]-1 --I 1 1 I 1 J -]-1 ')1 )
Table 18.Number,pe~ent calves and densities for moose observed in floodplain and islanded areas along the Susitna
River between Montana and Cook Inlet,Alaska,1981-83.
sample areal Moose observed2
Location Size (ml )No.Percent calves Calculated densit 3
'Siiitace Terrestrial BJat-82 1982-83 1983-84 1981-82 1982-83 1§83-84 1981-82 1982-83 19~3-84
Kashwitna floodplain 14.5 5.5 27 39 12 23 27 25 1.9 2.7 0.8
Beaver Island 9.0 9.0 22 27 32 19 20 20 2.4 3.0 3.6
Alexander Island 10.5 10.5 29 80 54 27 24 18 2.8 7.6 5.1
Bell Island 13.0 13.0 41 120 101 18 18 24 3.2 9.2 6.6
Caswell floodplain 15.5 10.5 42 60 34 31 31 19 2.7 3.9 2.2
Delta Islands 21.0 18.0 16 27 21 18 21 18 0.8 1.3 1.0
0'\
W
1 Locations of sample areas are illustrated in Fig.•Total surface area and size of its terrestrial component area estimated
from 1/63360 scale USGS topographic maps.
2 Data for moose observations are derived from 6 and 11 independent censuses conducted in the winters of 1981-82 and 1982-83,
respectively.Numbers of moose represent the greatest number observed on a single census of each area.Calf percentages
were calculated after accumulating totals for calves and individuals observed on all censuses within each entire winter.
3 Densities were calculated by dividing maximum number of moose observed at each location by its surface area size (km 2 ).
....
.....
-
....
are profusely interspersed with other plant communi ties (i.e.,
short and tall shrub,sedge meadow and immature mixed forests).
Along with more subtle differences in vegetative composition,
interspersion of habitat types appears to be slightly greater on
Bell than on Alexander Island and may in part explain observed
differences in moose densi ties between those two areas.
Moose densities observed on Beaver Island were intermediate
between those observed on the Delta Islands and those observed on
Bell and Alexander Islands.Habitat types on Beaver I sland did
not appear grossly different from those on the latter islands but
proportional relationships and interspersion between those
habi tat types may have differed (i.e forests on Beaver Island
were more extensive and infrequently interspersed with more seral
habi tat types).Moose densities on Beaver Island may have been
lower because most transient moose originate mainly from the west
and they encounter satisfactory winter range on other islands
first,and do not proceed farther east;so immigrating moose
merely fail to "reach"Beaver Isiand and its winter range remains
"undi scovered"by those moose subpopulations .
The Caswell and Kashwitna floodplain areas are composed of
numerous small islands of low relief which are dissected by a
network of rivulets and shallow sloughs.Habitats in these areas
are primarily short and tall shrub communities along with
occasional stands of immature deciduous forest.
Though it was not known why these earlier successional plant
communi ties appeared to attract fewer moose than some of the
large islanded areas to the south,several potential reasons
contributing to this discrepancy may be differences in:vege-
tative associations,density of forest cover,amnunt of snow
cover,availability of alternate adjacent winter ranges and/or
less dense moose subpopulations in adj acent areas.
64
.-
.....
Proulx (1983)found that forest cover was an important component
of moose winter habitats in southern Quebec.Perhaps,"moose
preferred areas which contained forest cover.
Though the Caswell and Kashwitna floodplain areas contained
relatively low moose densities,both areas appeared to be used by
a higher percentage of calf moose than other areas studied.In 2
of the 3 years studied,nearly twice the percentage of calves
were observed on the Caswell floodplain area (31%)as on Bell
Island (18%).Potential explanations for this occurrence are the
following:cows with calves select low relief,open "floodplain"
types of habitat,moose subpopulations which winter in this are
more productive,more male moose occurred in the other areas and
"diluted"the calf ratio or mortality factors (predation,nutri-
tion and etc.)on calves are not similar between those moose
subpopulations or wi thin those habitats.Thompson and Vukelich
(1981)found that cows with calves avoided areas where large
concentrations of moose occurred but they also found that their
use of cutover areas (relatively open,early successional habi-
tats,similar to floodplain areas)was restricted.
These data suggest that age composition and density of moose on
winter range were closely related to the occurrence and inter-
spersion of a variety of habi tat types.
In winter,gusty north winds commonly occur on the Susitna River
floodplain south of the Yentna River.These winds blow fallen
snow off the floodplain and frequently leave large portions of
the area snowfree.Strong,gusty winds seldom occur near the
Delta Islands and their effects on snowcover are greatly reduced
because of the dense,extensive mature forests.Lack of persis-
tent,deep snowcover,whic~may hinder moose movements and
blanket ground forage vegetation,may contribute to Bell and
Alexander Islands being more attractive to moose than the Delta
Islands.Alternate winter range may be more readily available in
65
-
areas adj acent to the Delta I slands than in areas adj acent to
Bell and Alexander Islands and may enable greater proportions of
local moose subpopulation to remain off the floodplain in winter
or similar proportions of moose from both subpopulations may seek
floodplain areas,but there may be a larger overall transient
component with the moose subpopulation in areas adjacent to Bell
and Alexander Islands than there is near the Delta Islands.
These baseline data provide some information and pose many
questions regarding habitat use by moose.Perhaps future studies
may be designed to critically evaluate specific differences
between those habi tat types and areas and to determine what
affected their attractiveness to moose.These data also indicate
that female moose with calves may select different types of
habi tats for winter range than single female moose.
By determining more specifically what vegetative types occurred
in those areas and by assessing the role of flow hydraulics in
creation and maintenance of those habitat types,one could
perhaps predict the effects of hypothetical flow regimes on
floodplain habitat types that appear most important for moose
winter range.
SIZE}SHAPE AND SPATIAL ARRANGEMENT OF ANNUAL RANGES FOR RADIO-
COLLARED MOOSE
Information on size,shape and spatial arrangement of ranges for
male and female moose is useful in assessing how individuals and
subpopulations utilize resources and habitats avai lable on and
off the Susi tna River floodplain,in considering and selecting
areas for habitat enhancement and in anticipating how moose might
respon.d to enhanced habitats.Since previous data collected
indicate that most moose are very patterned and consi stent in
their use of ·winter range along the Susitna River and appear to
explore and/or exploit few areas that are not in their normal
66
,~
-
range,they will be slow to realize the presence of new winter
range,which may be created as a mitigation measure,unless it
were wi thin their normal range.Likewise,with information on
sizes and spatial arrangement of moose ranges,the areal influ-
ence of habitat alterations may be predicted.An assessment of
annual variation in range size for individual moose may be used
to predict annual variation in use of Susi tna River riparian
habi tats and to provide information on the utility of studying
movements of individuals over several consecutive years.Such
data also document adjustments moose make to their range in
response to annual variation in climatic conditions or other
environmental factors.It is commonly thought that the value of
the Susitna River floodplain to moose increases with severity of
winter conditions,and it is apparent,that these sorts of data
must be collected during a relatively "severe ll winter,to fully
appreciate the importance of the Susi tna River floodplain to
moose and to learn how moose use the floodplain under those
conditions.
Data presented in Figs.17,18 and 19 illustrate relative size,
shape and spatial relationships for annual range areas utilized
by a subsample of radio-collared moose monitored from 1.5 to 3.5
years.These data exhibit a wide spectrum in types of patterns
of moose use of the Susi tna River floodplain:from individuals
with annual ranges which center on floodplain habitats (No.37,
90 and 95)i to individuals with annual ranges that "traverse ll
floodplain habitats (No.23,87 and 100);and to individuals with
annual ranges which merely abut floodplain habitats (No.27,40
and 99).Apparently,the Susitna River floodplain provides
winter range for several subpopulations of moose which utilize
spatially distinct ranges in different areas during other sea-
sonal periods.The fact that moose from many different geo-
graphical areas (different subpopulations)utilize a common
winter range indicates that winter range areas are limited and
67
44
o
(;
-
.-,
.....
-
.-
r Flgur.17.Shape (convex polygons)and .patla'relationships for
range.0'11 femal.and 3 male (#27.44 and 89)moo.e captured
and radio-collared al,ong the SUlltna River,Alaska and relocated
during 1980-83.
68
.....
I
....
-
r
:-.\/
Figure 18.Shape (convex polygons)and spatial ,elatlonshlps for
rangee of 7 female moose captured and radio-collared along the
Sueltna River.Alaaka and ,elocated during 1980-83.
69
"""
.....
....
-
Figure 19.Shape (convex
rang ••of 7 femal.and 2
radio-collared along the
during 1980-83.
polygons)and spatial relationships for
male .(#91 and 95)moose captured and
Sualtna River,Alaska and relocated
70
.....
-
-
do not commonly occur throughout the Susi tna River Valley and
suggestst that the Susitna River floodplain functions as an
important winter range for moose from thi s large area.
These data also show that except for large islanded areas south
of Talkeetna,the Susi tna River floodplain fails to provide a
complete,annual range for moose (i.e"most moose seek calving,
summer and rutting ranges in other areas).
These data,along with those presented in Fig.6,illustrate that
very few radio-collared moose ranged east of the Susi tna River
and none ranged between the Kashwi tna River and Wi llow Creek.
Hypothetical reasons for the apparent failure of radio-collared
moose to use these areas,are the following:1)moose from those
areas utilize winter range within that respective area;2)moose
from those areas move toward the Susi tna River floodplain in
winter,but find sui table range in "disturbed"sites along the
Parks Highway,east of the floodplain;and 3)moose from those
areas failed to be sampled because they move to the Susitna River
floodplain only during "severe"winters or only very late in the
winter period.In either case,for those reasons,individuals
from subpopulations with the third types of behavioral pattern
were not captured in the radio-collared samples.
Though females generally had smaller ranges than males,some
(No.41)utilized areas as large as males (No.27).Some males
(No.95)were even known to range over areas smaller than those
uti lized by most females (No.90).
Directional patterns for orientation of ranges appeared inconsis-
tent,though the basic direction was east-west (No.56,99 and
100).North and south "slants l1 were also apparent (No.40,59,
47 and 95).
71
-
-
-
....,
These data,along with those previously collected (Modafferi,
1982),illustrate that moose north of Talkeetna generally ranged
over smaller areas than moose south of Talkeetna.I doubt if
overall range conditions are significantly "better"in the
northern area to permit smaller ranges,but I suspect greater
snow depths in the latter areas,have discouraged (through evolu-
tionary processes)moose from traveling far to winter range and
moose subpopulations have accommodated the lower quality range by
existing at lower area wide densities.
ANNUAL VARIATION IN SIZE AND SHAPE OF RANGES FOR RADIO-COLLARED
MOOSE
Annual variation in behavior and movement patterns for individual
moose affects the size and shape of their annual range.In part,
annual variation may be attributed to the effects of local
weather and reproductive status of individual moose.Other
factors,yet to be identified,surely also influence the con-
figuration of moose annual ranges.
Since it is known that moose use of Susi tna River floodplain
habitats is greatly influenced by winter weather conditions,it
is imperative that annual variations in moose behavior and move-
ment patterns be delineated,to accurately assess and place
"bounds"on moose use of those habitats.Data presented in
Figs.20 and 21,illustrate the extremes in variation that
individual radio-collared moose exhibited in annual range use
patterns.
Some individual moose exhibited relatively consistent annual
(between year)patterns of range use (Fig.20).Range use
patterns exemplified by each these individua.~moose,probably
represent general patterns of range use common to large numbers
of moose within 4 behaviorally different subpopulations.Though
these individuals utilized a similar and common winter range on
72
~,
-
...
-
./
.{
/
r-r~~..........
.'
Figure 20.Annual rangea (convex polygona)for 4 female mooae,
captured and radio-collared along the SusUna River,Alaaka,wltlch
exhibited relatively little -between year·variation In their movement
patterns.Polygons encompaS8 radio-relocation poInts for conaecutlve
annual periods commencing from date of capture to the 1980-81 (------)
1881-82 (),1982-83 ()and 1983-84 ()annual
periods.
73
.....
-,
r
.~
.~>
~;-
/./
o
I::;
\
"Figure 21.Annual range.(c.onvex polygon.)for 3 female and 2
male (#27 and 95)moose.captured and radlo-cofl.red .'ong the
Su.Una River,Alaska,which exhibited noteworthy 'between year-
variation In their movement pattern..Polygons encompass
radio-relocation points for consecutive annual periods commencing
from date of capture to the 1980-81 (-----),1981-82 (),
1982-83 ( )and 1983-8"()annual periods.
74
--
......
.-
-
the Susitna River floodplain,and selected and utilized habitats
in very different nonfioodplain areas during other seasonal
periods,each utilized very similar annual ranges over 2,3 or 4
consecutive years.Annual environmental variations may have
affected the timing of movements of these individuals but those
factors had little effect on the extent and direction of these
movements.It might be said that a single year of study would
have provided adequate information on annual range configuration
for these individuals.
To the contrary,Fig.21,depicts annual ranges for individual
radio-collared moose which exhibited substantial annual (between
year)variation in range use patterns.Behavioral patterns
between these individuals also differed sUbstantially,and
suggest that these patterns may represent general behavioral
patterns characteristic of different subpopulations of moose.In
spi te of these variations,these moose utilized a common type
winter range on the Susitna River floodplain.Since these
individuals exhibited significantly different annual patterns in
range use during the 2,3 or 4 years studied,it may be said that
one year of study of these behavioral types of moose would have
provided inadequate information on movements of patterns of range
use.To adequately assess extent and locations of potential
impacts of Susitna River hydroelectric development on moose with
the latter type behavioral patterns,no less than 4 years of
study would be required.
These data indicate that individual moose (No.27,42 and 63)
which make exceptional and extraordinary movements may actually
interact with several different moose subpopulations,and these
apparently inconsistent behavioral patterns in annual range use
may expose them to more different habitats,areas and subpopula-
tions in a lifetime.Such behavioral patterns would enable this
type of individual moose to locate other (or alternate)desirable
habi tats in new areas or "di scover"recently available habitats,
75
....
-
-
-,
created naturally by wildfires or by human activi ties.This
behavioral type of moose could potentially learn about enhanced
habi tats,created as a result of mitigation actions I that were
apparently not formerly wi thin thei r "apparent"or "usual"range.
DISTRIBUTION OF MOOSE IN NON-FLOODPLAIN HABITATS
Before one can knowledgeably predict ultimate impacts of Susitna
River hydroelectric development on moose,one must understand how
moose utilize the potential impact area (i.e.the ecological
value of the area to moose must be determined).Because greatest
moose use of the Susi tna River floodplain occurs during the
winter,initial downstream moose studies were primarily directed
at assessing the ecological value of the floodplain as winter
range for moose.These downstream moose studies indicated that
several behaviorally distinct subgroups of moose form the popu-
lation of moose which utilizes the Susi tna River floodplain as
winter range.These studies have provided information on how
those moose populations utilize the Susitna River floodplain and
have indicated the existence of other moose subpopulations in the
Susi tna River valley,which do not necessarily winter on the
floodplain but may calve or summer in Susi tna River riparian
habitats.Though hydroelectric development may proximately
affect specific portions of particular moose subpopulations,
ul timate ecological consequences of those impacts can only be
assessed after interrelationships between all moose populations
in the Susi tna River valley are understood.
Mitigation actions associated with hydroelectric development may
be directed at providing winter habitats for moose.Such proce-
dures may not always require alteration of existing habitats.
Many contemporary habitats on and adjacent to the Susitna River
appear to be preferred moose winter range and are presently
heavily utilized by large numbers of moose.Presently,altera-
~tion of these habitats is not necessary,they need only be
protected and maintained.
76
-
.....
.....
-
,.....
The greatest return from enhancement procedures may be possible
in areas which presently receive minimal use by moose but have
the potential to provide desirable winter range.Since many
areas on the Susitna River floodplain presently provide adequate
winter range for moose,nonfloodplain areas should receive
consideration for enhancement.However,even amongst nonflood-
plain areas,it is necessary to understand how moose are dis-
tributed in those areas during other seasonal periods,as well
as during the winter.It would be unwise management to transform
a subpopulations preferred calving or rutting habitats into
winter range.Since it is not known how moose subpopulations
which do not winter on the Susitna River floodplain (not sampled
in this study)utilize nonfloodplain habitats as winter range,
care must be taken not to unknowingly transform habitats utilized
by one moose subpopulation to winter range habitats for another
subpopulation.
Mi tigation actions designed to benefit moose populations may
occur through regulation of flow regimes.Since various instream
flow regimes can have different effects on different habitats,
quanti ty and timing of water discharge may be regulated at the
damsite to alter or maintain particular floodplain habitats.
However,since different habitat types will be affected dif-
ferently and those effects will vary with respect to specific
location along the river or on the floodplain,different flow
regimes may ultimately affect different moose subpopulations
differently .Since benefits of particular flow regimes may be
mutually exclusive between moose subpopulations,it is desirable
to understand the interrelationships between all moose subpopu-
lations before recommending any particular flow regime.
Preliminary investigat.ons in downstream areas were directed at
assessing winter distribution of moose in nonfloodplain areas and
data were derived from a variety of sources and methods.These
data which were gathered from early winter moose sex and age
77
_composition surveys (Table 19,Fig.5),a late winter stratified
random moose census (Table 20,Fig.22),and late winter moose
surveys in nonfloodplain areas (Table 21,Fig.4),provide
baseline information on fall to winter distribution of moose in
areas removed from the Susi tna River floodplain.
,....
Data presented in Table 19 are derived from standard sex and age
composition surveys conducted periodically by the Alaska Depart-
ment of Fish and Game.Though these surveys are not specifically
designed to determine moose distribution and abundance,they do
still roughly reflect those values.Results of these surveys,as
evidenced in previous winter moose river censuses,are probably
subject to significant variation due to seasonal and.annual
weather patterns and should be treated cautiously.In view of
potential shortcomings,these data suggest that more southerly
areas adjacent to the Susitna River (Areas J,F,G and Hi
Fig.5),support higher densities of moose than the more northern
areas (A,B, C,D and Ei Fig.5).Since little movement out of
Areas A,Band C was detected in the sample of moose radio
collared in that area,it seems reasonable to believe that,
excluding observer sightabili ty corrections,these values may
approximate year-round moose densities for those respective
areas.Values from all these areas indicate that moose densities
are well below 1 per sq mi.Though similar supporting data from
radio-collared moose are lacking for Area D,I suspect that
characteristics of its moose subpopulations resemble those of the
former areas and that observed densities are near to actual moose
densi ties.Al though relatively low moose densities were also
detected in Area E,I suspect moose populations in that area are
more SUbject to large seasonal movements (winter emigration)and
more moose may actually inhabit the area during other seasonal
periods.
78
.-
Table 19.Data from recent and past moose composition surveys conducted in areas
adjacent to the Susitna River downstream from Devil Canyon.Alaska.
1'Area Most recent survey 3Priorsurvey
DateNameSize(m1 2 )2No.moose Date No.Moose
A 90 73 Nov 1983 NA
~
B 80 61 Nov 1983 NA
C 90 56 Nov 1983 NA
D 350 182 Nov 1983 NA
E 430 202 Dec 1983 NA
F 215 335 Dec 1983 471 Jan 1984
~G 250 397 Dec 1983 780 Nov 1968
H 320 894 Dec 1983 1,017 Nov 1970
I 550 160 Nov 1982 573 Nov 1981
J 990 2,1284 Feb 1984 NA
1 Location of survey area illustrated in Fig.5.Size represents a rough
approximation visually calculated from 1:250.000 scale USGS topographic maps.
2 Data obtained from Alaska Department of Fish and Game files.These surveys are
primarily conducted to assess sex and age composition of moose populations;they
are not conducted as strict population censuses and winter weather conditions
can affect numbers of moose observed in all areas.
3 Historical hi~h count where data were available.NA =no other data available.
4 Estimate obtained from a stratified random moose census;t 12.7%at a 90%
confidence interval.
l-
I
i 79
]~l 1 1 ~~~~1 J j J 1 J
Table 20.Data on strata classification.sample unit size.densities/of moose and population estimates from a
stratified random census conducted along the Susitna River.Alaska 24-29 February 1984.
Density observed within
No.units sampled (Total
and between units sampled
(moose per sq.mi)
Strata total
(percent)
1Densitystrata(;lassification _size 8.6 t()19.6Jlq.miL_Low High Mean Area(m1 2 )1No.Moose
1 Location of study area distribution of moose density as estimated from stratification survey are
<XIo
Low
Medium
High
Superhigh
Combined:unadjusted estimate
adjusted estimate
9 (40)
6 (6)
14 (14)
7 (7)
36 (67)
0.0
0.5
1.6
3.5
0.7
1.2
4.3
14.2
0.3
0.8
2.8
6.1
615 (62)
79 (8)
198 (20)
98 (10)
990
203 (15)
64 (5)
550 (39)
580 (42)
1.397 3
2.218
illustrated
in Fig.22.
2 No.moose estimated for all sample units within strata.
3 Total moose estimated.Adjustments to this estimate for two types of observer sightability correction
factors (Gasaway et al.1980)inflates estimates to 2.218 moose.between 1.858 and 2.399 moose estimated
at a 90%confidence interval (112.7%of estimate).
-
-I
-
-
MOOSE DENSiTIES
UIII!110W
I@;~:;~mediumohigh
S sup.r hiGh
Figure 22.Locations of areas where moose population size ()was estimated
and densltfes of moose were determined from the stratification flight of a random
stratified census conducted along the Susltna RIver,Alaska,26-29 February,1984.
81
Table 21.Composition,nu~rs,and density for moose observed at various
locations removed from the Susitna River floodplain,Alaska,1984.
2 Flight3 Density
Size No.observed time (moose!
Location 1 (S9 mi)Date Moose Calves Carcasses (min)s9 mi)
Deshka River 60 5 March 37 3 13 NA 0.6
Moose Creek 30 5 March 58 9 0 NA 1.9
Trapper Creek 12 5 March 1 0 0 NA 0.1
Whi tso!Lake 5 15 March 12 0 42 NA 2.4
Swede 4 8 March 7 0 0 28 3.1
Lockwood Lake 3 8 March 7 1 0 28 2.3
Kahil tna I
Moose Creek 3.5 8 March 11 0 0 28 3.1
Neil Lake 5.5 8 March 4 0 0 33 0.7
~
Kashwitna Knobs 3 8 March 5 0 0 11 1.7
Trapper Lake 2.5 8 March 0 0 0 15 0....
5 4ParkerLake88March 0 1 56 0.6
1 Refer to Fig.4 for geographical location of survey areas.
.....2 Size for areas estimated from 1:63,360 scale USGS topographic maps.For river
and creek areas sizes represent rough approximations of stream course
distances.Surveys were confined to floodplain habitat paralleling water
courses.Densities represent moose per mile of stream.
3 NA·flight time for stream surveys not applicable.since flight paths varied
greatly.
4 All moose in Parker Lake survey area were observed along eastern boundary near
riparian habitat.
82
....
I
.....
In contrast,in the western foothills of the Talkeetna Mountains
(Areas F and G and particularly Hi Fig.5),observed moose
densi ties ranged from 1.5 to over 2.75 per sq mi.Though few
moose from these subpopulations were represented in the radio-
collared samples,it is believed that in "severe"winters a
higher percentage of moose from these subpopulations move to the
Susi tna River ripari an habi tats.
Reasons for observed differences in moose densities between areas
north and south of Talkeetna may be related to winter weather
condi tions,habitat attributes and level of predation.Areas
north of Talkeetna along the Susitna River generally have greater
amounts of snowfall than more southern areas.Heavy snowfall and
extreme snow depths probably inhibit moose movements to,from and
wi thin this area in winter and decrease its desirability to
moose.The Susitna River valley north of Talkeetna is narrow,
steep sided and dominated by extensive stands of alder,the river
banks are abrupt,the floodplain is brief and low relief islands
of early successional vegetation are relatively scarce.These
features are considerably less attractive to moose than the flat,
wide braided river,extensive low relief floodplain,heavi ly
islanded habitats characteristic of the Susi tna River south of
Talkeetna.In contrast to riparian areas south of Talkeetna,
where coyotes and black bears are probably the most common
potential predators,areas north of Talkeetna contain substantial
populations of brown and black bears (Miller and McAllister 1982)
and occasionally wolves (Ballard et al.1982a)which probably act
to suppress moose population levels.Extensive predation by
wolves on adult moose and by bears on moose calves which has been
documented for a nearby area (Ballard et al.1982b)and data
collected by Modafferi (1982)suggesting that during parturition
female moose move to islands in the Susi tna River to avoid
harassment by predators,lend support to the contention that
predation may affect population level.
83
.-
,.,...
-
.....
-
If this were the case,and if this moose subpopulation was under
a different wildlife management scheme (i.e.,one that may
decrease numbers of wolves and bears in the area),one would
expect a corresponding increase in numbers of moose in that
subpopulation.Perhaps,then,calculations of mitigation
compensation for potential loss of moose to this subpopulation
should consider the numbers of moose the area would support if it
were intensively managed for them (i.e.,if predator populations
were maintained at lower levels).
Reasons for the relatively low counts of moose in Area I (extreme
southeastern foothills of the Talkeetna Mountains,Fig.5),are
presently little understood.Some moose radio-collared on the
Susitna River floodplain moved into this area for a short period
during mid-winter and perhaps composition counts slightly later
in the winter would have revealed densities similar to the more
northern areas in the Talkeetna Mountains (F,G,and H).
Relatively easy access to Area I may lead to more intense hunting
pressure and a higher hunter kill and result in lower moose popu-
lation levels.Additionally,a high annual "accidental"kill of
moose in the winter (sometimes over 200)on the Parks Highway
between Willow Creek and the Talkeetna River (Game Management
Subunit 14B)by vehicles and on the Alaska Railroad right-of-way
by trains may also contribute to depressing this moose
subpopulation.
Other data included in Table 19,are results from previous moose
composi tion surveys which illustrate variance that may be ex-
pected in these survey data.However,the higher counts may also
indicate that these areas are capable of supporting significantly
more moose under different conditions or at other times.If
similar data were available for Areas A,B,C and D,we may see
that historically these areas supported significantly more moose
then were counted in 1983 and that,likewise,under some circum-
stances many more moose may be dependent on the Susi tna River
floodplain winter range than were observed in winters of 1981-84.
84
-
This rational must be considered when planning mitigation actions
to compensate for possible loss of moose or their habitat I to
fully appreciate the potential numbers of moose which may be
involved.
Data in Table 20,exhibit the extreme importance of the Susitna
Ri ver floodplain to moose subpopulations in Area J.Though
Area J as a whole contained an estimated average of over 2 moose
per sq mi in late winter,a high proportion of those moose
occurred in riparian areas (Deshka River,Moose Creek,Yentna
River,etc.)during the survey and probably more than half of the
latter moose occurred and wintered on the Susitna River
floodplain (Fig.22).
Data in Fig.22,indicate that large portions of Area J contain
relatively low densities of wintering moose.Data from radio-
collared moose (this report and Modafferi 1982 and 1983)indicate
that many of'the'moose thatinhabi t the interior of this area
during other seasonal periods move to the Susi tna River flood-
plain for winter range.Together,these data indicate that the
interior of Area J would be a logical location to enhance avail-
able winter range for local moose subpopulations which usually
winter on the Susi tna River floodplain.
Data provided in Table 21 appear to contradict some data
presented in Table 20.These apparent inconsistencies may in
part be explained by the fact that survey data in the former
table were obtained in March,during which time some moose had
already proceeded to depart from riparian wintering areas to
early spring non-riparian ranges.It may also be that amongst
the expansive interior of Area J,,small areas contain sui table
wiIf,ter range for moose (Whi tsol Lake,Swede,Lockwood Lake and
the KahiltnajMoose Creek areaSi Table 21),and support locally
high moose densities.These data also'suggest that because very
low winter densities were observed at the Neil Lake,Trapper Lake
and Parker Lake areas,they may be potential candidate areas for
85
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.....
-
-
habitat enhancement;providing these areas do not provide a
preferred range during another seasonal period.Parts of the
Parker Lake area were consistently used by a radio-collared
female moose (No.45)during all other seasonal periods,but it
is not known if many other moose,similarly,used thi s same
habi tat during those seasonal periods.
MOOSE USE OF DISTURBED SITES
Surveys conducted on disturbed sites will provide:1)infor-
mation on moose use of these apparently important areas which
supplement the Susi tna River floodplain moose winter range and;
2)information which will be useful in assessing,proposing and
implementing mitigation actions for moose habitat enhancement
programs.Knowledge of moose use of di sturbed sites is par-
ticularly important since maj or mitigation strategies,to com-
pensate for impacts of the proposed Susi tna River hydroelectric
development on subpopulations of moose,will be through main-
tenance,replacement and/or creation of new habitats to augment
those presently used by moose for winter range.
Human activities have altered natural habitats at numerous sites
~
near the Susitna River floodplain and have resulted in the
reestablishment of seral type vegetative communities.Vegetative
associations which occur at these sites during a time period
r after the initial disturbance are composed of desirable moose
browse plant species and attract large numbers of moose in
.....winter.
Since these sites provide a substantial alternate,but temporary,
food source for moose which normally winter on the Susitna River
floodplain,one must determine how moose utilize them and how
they interact with the floodplain sites,to adequately assess
their role in winter ecology of dependent moose subpopulations.
86
-
-
.....
Early successional vegetative stages in floodplain habitats are
temporarily and spatially maintained over the long term by
natural phenomena (floodplain subclimax),but disturbed sites are
temporary occurrences and may only be maintained by the whims or
posi tive actions of man.
Therefore,it is probable that at some time in the future,moose
subpopulations along the Susitna River will most likely have to
rely solely on the Susi tna River floodplain for winter range.
To assess moose use of these areas,periodic censuses,
leling the timing of river censuses,were conducted on
turbed sites in the winters of 1981-82 and 1982-83 on
disturbed sites in winter 1983-84.
paral-
6 dis-
and 13
.-
-
-!
Most sites surveyed were immediately adj acent to the Susi tna
River floodplain,but some sites were located up to 5 km east of
the Susi tna River.Because of the relative proximity of these
sites to floodplain habitats,they may possibly compete with or
compliment the latter winter range presently available to,and
used,by moose subpopulations which usually winter on the Susitna
River floodplain.
Though these sites were near to floodplain habitats,numbers of
moose counted on them,were not included in talleys for river
censuses.However,it seems likely that moose using many of
these si tes are not subgroups,discrete from those which use
adjacent floodplain habitats.In reality,there is probably a
flux of individual moose between both habi tat types.
Data presented in Table 22 (and Fig.3)demonstrate intensive use
of some di sturbed sites and variabi Ii ty in intensity and in
seasonal and annual timing of use between different sites.
87
Table 2'2.Numbers of moose observed on sites adjacent to the Susitna River,Alaska,
where climax vegetation has been altered by activities of man,1981-84.
r Location l
Winter Date MW MN'MM TW KL MS ~1E GC We KB ew CE KE
~1981-82 2 Dec 41
10 Dec 8 0 23 4 17
14 Dec 23
28 Dec 25 11 7
,..,...6 Feb 9 4 4
1 Mar 24 1 2 1 1 6
24 Mar 6 0 4 1 6 0
12 Apr 4 0 0 0 1 1
~1982-83 29 Oct 13 0 0
6 Nov 22 0 2 4 3
10 Nov 14
18 Nov 68 0 12 8 3
I"""2 Dec 68 1 43 16 23
6 Dec 56 3 47 21
20 Dec 8 21
21 Dec 36 40 25 19
22 Dec 41 41 10
Jidi!t1tIr.5 Jan 28 6 41 9 22
20 Jan 21 0 59 36 5
24 Jan 48 0 63 14 29 13
7 Feb 14 11
1"'""9 Feb 57 0 7 27
22 Feb 8 2
23 Feb 30 2 16 6
7 Mar 7
8 Mar 43 3 22 8 2.....20 Mar 7
22 Mar 17 43 17
23 Mar 21 45 10 16
30 Mar 8 1-8 Apr 2 6 1 1
1983-84 17 Nov 6 0 4 4 11 0 1 0 0 3
18 Nov 0 0 0
25 Nov 22
""'"29 Nov 45 0 5 3 0 3 0 3 2 0 0
9 Dec 32 0 5 9 14 2 10 0 7 2 0 3 5
16 Dec 47 0 7 11 7 2 6 0 5 0 0 3
24 Dec 72 0 5 18 3 0 7 0 2 2 2 0 1
30 Dec 49 0 0 1 0 0
3 Jan 23 5 11
5 Jan 73 0 12 14 8 0 12 6 1 2 4 3 2
13 Jan 29 1 18 14 4 5 0 2 2 4 2 2 0
17 Jan 4 21 13 3 4 4 6 1 6 6 5 1
'"""19 Jan 31 2 31 10 2 2 4 8 4 6 6 2 1
27 Jan 49 4 25 5 16 6 7 22 8 15 7 4 2
8 Feb 48 5 38 8 6 12 3 12 1 40 23 6 2
20 Feb 49 6 26 21 8 25 3 21 1 27 22 9 1
28 Feb 42 7 59 26 14 12 6 4 0 31 18 0 2
5 Mar 19 0 43 10 16 5 0 4 2 33 34 2 0
8 Mar 17 1 37 3 9 6 1 4 2 28 34 2 0
15 Mar 3 0 38 3 8 6 0 1 5 16 16 0 0
29 Mar 4 0 27 1 21 3 0 0 5 6 3 0 0
i MW =Montana west,Mri =MOntana north,RIii =MOntana middie
TW =Talkeetna west,Kl =Kashwitna Lake,Ms =Montana south,
ME =Montana east,Ge =Goose Creek,We =Willow Creek,
1..•..KB =Kashwitna bluff,Cw =Chandalar west,Ce =Chandalar east and
]1 KE =Kashwi tna east.Locations Me,Ge,We,Kb,Cw,Ce and Ke were only
,surveyed during 1983-84.
f"'"
I
88
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In part,apparent vari ation between intensity of use between
si tes may be attributable to differences in size of indi vidual
si tes,but it is probably also related to factors as plant
species cornposi tion,age of plants,proximity to other simi lar
si tes,and location of site with respect to floodplain habitats
and to general movement patterns of moose subpopulations.
The Montana west site was the most heavily used site;it is also
the largest site and apparently is located in the pathway of a
major moose subpopulation movement from west,to east of the
Susitna River.A west to east movement of moose was documented
for most radio-collared moose and also appears to be evidenced by
the fact that moose numbers always increased at the Montana west
site before at other sites east of the Susitna River.Decreases
in moose numbers at Montana west,in mid-to late January,also
appeared to correspond with increases in moose numbers at the
Montana middle site located on the adj acent east bank of the
Susi tna River.
Low moose use of disturbed sites in winter 1981-82 may be attri-
buted to the relatively mild weather conditions in that winter,
compared to weather conditions in winters of 1982-83 and 1983-84.
Differences in timing of use between the 1982-83 and 1983-84
winters may be attributed to differences in timing of seasonal
snowfall;large quantities of snowfall occurred early in 1982-83,
but in 1983-84 significant quantities of snowfall did not accum-
ulate until much later in winter.Heavy moose use of Montana
west occurred during late December in winter 1983-84,compared to
late November-early December in the 1981-82 and 1982-83 winters
and moose appeared to remain "s taged ll longer at that site as they
did not "flow over"to the Montana middle site in significant
I,umbers until late January or even late February 1984,several
months later than in previous winters.
89
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The apparent large buildup of moose at the Kashwi tna bluff,
Chandalar west,Montana south and Goose Creek sites late in
winter 1983-84 may have been in response to the gradual,but
significant overall,late winter accumulations of snowcover,or
were the result of typical moose migratory movements.
The Montana north site was probably very recently disturbed as
grasses and forbs appear to dominate the ground cover and shrub
type vegetation was relatively scarce.This site also lacked
tall shrub or tree cover which moose may prefer to bed in when
not feeding.These factors,along with small size,may account
for low use of this site by moose.
Moose were seldom observed evenly distributed throughout a par-
ticular site.They appeared to prefer to be in close associ-
ations with other moose.It was not uncommon to observe most
individuals browsing in one portion of a site on one survey and
on a subsequent survey see most individuals still concentrated
but in different portion of the site.It is possible that the
behavior to congregate is a defense mechanism to combat secretive
approaches and attacks by wolves or simply exhibits a seasonal
social tendency in moose.This intraspecific tolerance behavior
also enables moose to occur and browse in very dense aggregations
during the winter period.
It was not uncommon to observe many moose bedded down in the
relatively open portions of a site.It may be that moose prefer
to bed down in tall vegetative cover,but it was not uncommon to
observe many moose bedded down in relatively open portions of a
si te.I suspect that,energetically,there is a posi ti ve heat
gain for moose which bed in areas exposed to the sun over those
moose which bed in forested surroundings,protected from wind and
concealed from predators,but without any direct exposure to the
sun.Though open habitats leave moose visually exposed to
wolves,the lack of dense vegetative cover may also preclude
secreti ve approaches by wolves.
90
,....
It is not known why moose use of the Kashwi tna Lake si te was
relatively low in 1983-84 compared to use in the previous
winters.Perhaps vegetation at the site is overbrowsed and moose
are no longer attracted there or activity of hunters during the
late winter (January-February)open moose season caused moose to-leave the site.
-The Talkeetna west site appeared to be used less relative to
other sites surveyed.This may be attributable to vegetative
species composition,but this site also contained more "slash"
and downed trees than any of the other sites.Moose may prefer
to utilize sites that are not cluttered with downed trees and
other debris which may hinder their movements or those of their
calves.
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The Willow Creek site was used by relatively few moose,but this
is probably attributable to the substantial amount of coniferous
regrowth it contained amongst potential decidous browse species.
Whether the coniferous regrowth was attributable to site charac-
teristics or techniques used to clear the site is presently
unknown.
To adequately assess the long term importance of the Susi tna
River floodplain in winter ecology of moose downstream from Devil
Canyon,the interaction between floodplain habitats and disturbed
si tes must be understood.Presently,disturbed sites probably
provide winter range for as many moose as floodplain areas.If
disturbed sites are not maintained in the early successional
vegetative stages which provide preferred moose browse,then more
moose will be forced to seek winter range in the "floodplain sub-
climax,"riparian habitats along the Susitna River and the
relative value of the latter habitats will >e greatly increased .
Additionally,knowledge obtained from the study of disturbed
sites,may be utilized to assess,propose or implement mitigation
actions involving enhancement of moose winter habi tat.
91
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PRODUCTIVITY AND CALF SURVIVAL FOR RADIO-COLLARED MOOSE..
Moose subpopulations are limited by factors which affect produc-
tion and survival of potential recruits to the population.To
assess and understand ultimate impacts of hydroelectric develop-
ment on moose subpopulations and to prepare appropriate mitiga-
tion plans,it is necessary to know which factors limit growth of
those subpopulations prior to hydroelectric development and if
the hierachy of those factors will be altered following that
development.
Observed or hypothetical positive or negative impacts on produc-
tion or survival of potential recruits are only academic,unless
they are realized at the subpopulation level.An increase in
calf prodl,lction in an area where calves will likely die or be
killed by predators should not be considered as a replacement or
enhancement measure to that respective moose subpopulation.
Implementing a predator management scheme to benefit moose
subpopulations in an area where moose are limited by food
resources,likewise should not be considered as a positive
management measure for that moose subpopulation.Conversely,if
moose subpopulations are limited by predators,loss of moose
winter range to hydroelectric development may have no net con-
temporary effects on that moose subpopulation but it will
ul timately affect future moose management options should pre-
dators be managed in a different manner.
If mitigation actions are to enhance particular moose subpopu-
lations,then it is necessary to know which factor(s)may be
limiting moose subpopulation growth before an appropriate miti-
gation plan can be selected.It may be futile to employ a winter
range enhancement prc~ram,which primarily affects moose nutri-
tive condition,to increase the size of a moose subpopulation
that in reality is limited by predation.'Conversely,in the
former situation,it would be nonsense to implement a predator
92
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-,
management scheme to benefit a moose subpopulation that is
limited by availability of high quality winter range.Obviously,
impacts of hydroelectric development on moose subpopulations and
meaningful mitigation enhancement programs can only be assessed
and designed,respectively,after factors which limit moose
subpopulations are understood.
Studies designed to assess production and fate of moose calves
and mortality of adult moose provide information on subpopulation
status and factor(s)which may be limiting subpopulation growth.
Data from these studies,can be used to assess impacts of hydro-
electric development and to formulate meaningful mitigation
programs.
Data provided in Table 23 indicate that between 88 (1983)and 98
(1982)percent of the radio-collared female moose produced calves
annually.These data further indicated that 17,61 and 72
percent of the productive females in 1981-83,respectively,
produced twins.Forage conditions for downstream Susitna River
moose subpopulations must be rated above average,since twinning
rates of 70 percent were also found for productive female moose
on "prime"Kenai Peninsula moose range (Franzmann and Schwartz
1984,in prep.).Actual and relative twinning rates for the
radio-collared sample were probably higher,since they were
determined with fixed-winged aircraft and searches were less
intense in nature than the helicopter survey procedures conducted
on the Kenai Peninsula.
Search efforts for calf moose in 1981 were not as intense as in
~subsequent years and may in part,account for the relatively low
twinning rate observed for that year.
The relatively high rate of
females in 1982,may in part,
1981-82.Theoretically,mild
productivity for radio-collared
be associated with the winter of
winter weather conditions would
93
-1 1 J --.J J 1 ----)1 1 J 1
Table 23.Calf production for female moose radio-collared along the Susitna River between Devil Canyon and Cook Inlet and relocated
during 1981-83.
No.females No.calves per 100 Percent of females with Percent productive
Yearl
1981
1982
N
27
34
with twins with singles
4 20
20 13
females productive females
104 117
156 161
no calves singles
11 74
3 38
twins
15
59
females with twins
17
61
\0
.c::..1983 32 18 7 134 172 22 22 56 72
1 Data obtained primarily from observations at 7,6 and 9 relocations of radio-collared moose during May and June in 1981,1982 and
1983,respectively.
-
,...,.
i
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I
promote good foraging conditions and enable pregnant females to
approach parturition in good nutri ti ve condi tion and produce
large numbers of high quality calves.Similarly,the inclement
weather conditions in winter of 1982-83,may have affected
nutri tive condition of pregnant females and resulted in the
relatively high number of nonproductive females observed during
calving in 1983.
Data in Table 24 partition calf mortality into various seasonal
periods.These data exhibit annual,as well as seasonal,dif-
ferences in the patterns of calf mortality.Comparatively good
calf survival occurred up to and through the mi ld winter of
1981-82 when less than 25 percent mortality occurred before early
December and less than 30 percent of those calves subsequently
disappeared by early April.Calf losses prior to December may
actually have been higher,since as previously mentioned,search
efforts were less intense that spring.These data suggest that
over 50 percent of initial productivity was subsequently incor-
porated into the moose population.
Similar data for subsequent years of study (1982-84,Table 24)
indicate that a higher percentage of calf mortality occurred
before the early winter period.This higher rate of early winter
mortali ty most probably was related to the heavy,late October
and early November snowfalls which occurred in those winters,
respectively.
Calf mortality between early and mid-winter was similar in
1981-82 and 1983-84.However,during the winter of 1982~83,when
the greatest numbers of moose were counted in floodplain areas,
calf mortality was more than twice that which occurred in the
former two winters.Though snow condi tHns did not worsen nor
ameliorate,these relatively high rates of calf mortality were
apparently carried over into the early spring in 1982-83.The
parallel and similarly high calf mortality rates exhibited during
95
Table 24.Calf survival lIDd c:alf:coy ratios for felllille IIIOOse radio-c:ollared along the Susitna River
between Cook Inlet and Devil Canyon,Alaska,and relocated from 1981-84.
..-Year 1981-82 1982-83 1983-84
No.females 24 34 31
No.females vi til calves 22 33 25
No.calves produced 25 53 43
No.(percent)calves surviving to:
Early 1I'1Ilter 2 Dec.19 (76)13 Dec.33 (62)25 Nov.21 (49)
Mid-wiDter 29 JaJI.14 (56)"Feb.18 (34)2 Feb.17 (40)
Early spr1Ilg 5 Apr.13 (52)1 Apr.12 (23)14 Mar.11 (26)
No.calves per 100 fellll.les:
at birth 104 156 139
by early spr1Ilq 54 3S 3S
-
96
,....
this period in 1983-84 were associated with continued snowfall,
an increasing snowpack and the persistence of winter conditions
into early spring.Since the latter data were only accumulated
through 14 March (compared to 5 and 1 April in prior years)/ I
suspect that mortality rates calculated for a more comparable
time period would actually have been much higher/in spite of the
fact that winter conditions drastically ameliorated in early
March.During the mi ld winter of 1981-82/very low mortality
rates were detected for this same late winter period.
Together,data collected during these three winter periods
indicate the profound influence that winter weather conditions
can have on productivi ty and calf survival in moose subpopu-
lations that seek winter range on the Susitna River floodplain.
Though summer range quality may influence the early winter
nutri tive condition of moose and affect their ability to cope
with subsequent inclement winter weather,the following dis-
cussion will only consider the ecological relationship of Susitna
Ri ver floodplain winter range to producti vi ty and survival of
moose.Winter range quality,winter weather conditions and
perhaps moose population levels interact annually,and/in part,
result in the "winter conditions,"which affect nutritive con-
dition of moose.Latent effects from previous winter conditions
may affect condition and calf production of pregnant females.
Inclement winter conditions may affect nutri tive condition of
pregnant females and result in lower quality (smaller physical
size,lower nutritive condition,etc.),of in utero calves.The
neonates,produced by dams exposed to inclement winter condi-
tions,may experience higher rates of mortality,shortly after
parturi tion,or much later,during the subsequent winter,than
neonates produced from dams which were exposed to less severe
winter conditions.Relatively early inclement winter conditions
(perhaps as in 1982-83)may affect calf survival in several
manners:1 )calves may be forced to travel great di stances to
97
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the Susi tna River floodplain winter range before they are phy-
'"sically or nutri tionally ready;2)an early influx of moose to
the winter range dictates that the range must support a given
number of moose over a relatively longer period of time;3)an
early influx of moose also implies the winter range must support
a greater number of moose over a given period of time;4)rela-
tively large concentrations of moose on winter range for longer
periods of time may increase rates of predation on them;5)large
moose concentrations may affect ability of the range to rejuve-
nate for subsequent years;6}increased mortality from drowning
or exposure may result if moose move to floodplain winter range
early before river ice becomes sUfficiently hard,and 7}in-
creased mortality will result from collisions with trains and
vehicles if moose move early to a winter range near railroad and
highway rights-of-way.Effects of the aforementioned mortali ty
factors will be reduced if occurrence of inclement winter con-
di tions is delayed.
Winter conditions need not be "severe"(e.g.1982-83)to cause
significant calf mortality.If relatively mild winter conditions
_persist on into early spring (e.g.1983-84),total calf mortality
may approach that of an early winter.
Calf mortality which occurred before the early winter period,may
be attributed to predation (1981-82)or a latent effect from
winter conditions the previous year.Predation in areas south of
Talkeetna is most likely from black bears,but brown bears and
coyotes,and less likely wolves occur there and are also poten-
tial predators.In areas north of Talkeetna,brown bears and
_wolves are more common,black bears are similarly abundant and
coyotes less common than in areas south of Talkeetna and the
relative rates of their respective contribution to predation
probably vary accordingly.
98
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r
Since adult productivity and survival of calf moose ultimately
affect subpopulation status,proximate factors which affect those
variables must be identified and studied before impacts of hydro-
electric development can be assessed.Furthermore,it should be
known whether those affects are ultimately additive or compensa-
tory to other sources of mortality sustained by those moose
subpopulations.
ALPINE WINTER RANGE AND FORAGE
Since mitigation actions to benefit moose need not be limited to
areas or subpopulations which may be directly impacted by Susitna
River hydroelectric development,knowledge about moose winter
ranges in areas remote from the floodplain and about moose
subpopulations which utilize them will increase the land base
from which mi·tigation lands may be knowledgeably selected.
In contrast to moose subpopulations which winter at low eleva-
tions (sea level,Bell Island to 250m,Devil Canyon)in flood-
plain habitats along the Susitna River,some moose subpopulations
winter at higher elevations (up to 750m)near timberline along
the western slopes of the Talkeetna Mountains.Though moose are
commonly observed in these alpine areas from Devil Canyon south
to the southwestern corner of the Talkeetna Mountains,particu-
larly high concentrations have been reported in the area above
timberline between the Peters Creek fork of Willow Creek and
Little Willow Creek,"Willow Mountain"(see Fig.1 and 5,Area H
and Table 25).
Infrequent observations and meager data suggest that moose appear
to gather in these areas above timberline during October,perhaps
for the rut,and remain densely concent ..-ated in some areas until
late January (the aforementioned area),in other areas until late
February (north Fork of the Kashwitna River)and in other areas
until late April (Sheep Creek and South Fork of Montana Creek)
before moving to lower elevations in late winter or early spring.
99
J 1 j J ]'-"]~J J 1 1 J I i J 1 I 1
Tllble 25.CheJllical component.s for slIDIples of fem (Dryopteris dllatllta)lind w1110w (~sp.)lIoose browse collected at 700 -80~e levlltion
in the southwestern foothills of the Ta1keetnll Mountains,AllISkll,3 January 1983.
C hem i c:a 1 c:0 • p 0 n e n t s 1
Sub'Crude Cellu-Residual
Ite.Part slImple fat NOr AD'Lignin lose Ash N P K Ca M9 Na Cu*2n·Mo·Fe·
Fern:
Rhhome 1 ••5 23 19 10 8 0 1.3 0.12 0.7 0.0 0.3 0.1 0.1 44 173 129
2 5.9 27 22 9 13 0.1 1.2 0.14 0.7 0.:.1 0.3 0.1 3.0 73 745 62
.....
0 3 5.9 33 29 15 14 0.3 1.2 0.13 0.6 0.2 0.3 0.1 5.0 77 570 133
0
Helin 5.4 28 23 11 12 0.1 1.2 0.13 0.7 0.1 .0.3 0.1 2.7 65 496 108
Rhbome lind
fiddlehellds 1 5.1 26 19 9 10 0 1.6 0.25 1.3 0.2 0.3 0.1 4.0 61 183 98
Nil low:
ApiclIl shoots 1 4.1 45 39 14 25 0.2 1.2 0.18 0.4 0.6 0.1 0.1 7.0 92 137 91
2 3.6 51 40 14 26 0.1 1.2 0.21 0.3 0.6 0.1 0.1 8.0 88 110 48
Melin 3.9 48 40 14 26 0.2 1.2 0.20 0.4 0.6 0.1 0.1 7.5 90 124 70
1 NO'=neutral detergent fiber,AD,a acid detergent fiber.
VlIlues expressed in percent of dry mlltter at 105 DC,VII lues with IIsterlsk (*)expressed in ppm.
..-
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Data collected from a radio-collared female relocated period-
ically for 4 years (No.22 in Modafferi,1983)suggest that this
individual ranges above timberline in the Sheep Creek/South Fork
Montana Creek area until early spring (late April),then moves
about 30 miles southeast to calve near Lockwood Lake,by mid-June
she moves about 15 miles north to near Trapper Lake where she
remains until the end of July when she again returns to the
Lockwood Lake area,where she remains until the last week of
September when she departs for the Sheep Creek area.By 1
October she is back on the alpine winter range near Sheep Creek.
The evidence for this individual appears quite conclusive,and
contrary to most all other radio-collared moose,that she appears
to move into the Talkeetna Mountains for winter range (and
perhaps the rut).Numbers of moose or subpopulations which share
this or similar behavioral patterns are not presently known.
Moose which winter in these alpine areas have commonly been
observed pawing away snow ("cratering ll )to obtain nonbrowse
foods.At the Sheep Creek site,where moose No.22 was captured
and collared with a new transmi tter,a sample of vegetation
extracted,from a recent crater revealed fern rhizomes with young
fronds (fiddleheads)and a grass (probably Calamgrostis sp.).At
that time,it was not known which,if ei ther,the moose were
seeking .
A 3 January 1984 excursion to Willow Mountain revealed that fern
rhizomes commonly occurred at the bottom of the craters.Most
rhizomes were scraped into a concave form shaped like the
incisors from a moose lower jaw.Some of the less disturbed
rhizomes contained young fronds (fiddleheads).The moose were
apparently feeding on fern rhizomes and may have primarily been
seeking the fiddlehead portion.
101
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Samples of fern (Dryopteris dilatata)rhizomes,immature fronds
(fiddleheads)and apical shoots from nearby wi llows (Salix sp.)
which had been browsed by moose were collected for chemical
analyses.Data on composition of these food sources indicated
that several major,desirable chemical components,crude fat,N
(N x 6.25 =crude protein),P and K,occurred in higher concen-
trations in the fern items than in the willow apical shoot
samples (fat 38%higher,N 33%higher in fiddleheads,P 25%
higher in fiddleheads and K 225%higher in fiddleheads).The
chemical analyses also revealed that several less desirable,
fibrous components,lignin and plant cell wall constituents
(NDF),were less concentrated in the fern items,than in the
willow shoot samples (29%less lignin,56%less NDF).Together,
these data imply that diets composed of fern items would be of
higher quality due to higher concentrations of essential nutri-
ents and lower concentrations of the fibrous relatively undiges-
tible components.
Whether moose subpopulations move to these alpine areas primarily.
to rut and subsequently and secondarily,linger near timberline
to feed on nonbrowse food sources,which probably remain avail-
able through the winter because wind action prevents large
accumulations of snow,or whether the reverse is true and moose
primarily move to these areas for the latter reasons,is pres-
ently unknown.Moose on the Kenai Peninsula,Alaska,where
annual snowfall is light,feed on other nonbrowse foods and
associated high moose densities in that area were,in part,
attributed to that activity (LeResche and Davis,1973).
It would seem that if movements of a moose subpopulation from
alpine areas to the Susi tna River floodplain were precluded,
because of the availability of nonbrowse foods,moose from that
subpopulation would be in better nutritive condition and produce
more higher quality calves than moose from subpopulations which
had to make that journey.If this reasoning is correct,such
102
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moose subpopulations would potentially be much more productive
than those which had to travel great distances to winter on t*e
Susi tna River floodplain.If circumstances on Willow Mountain
are unique in the Susi tna River Valley/perhaps protection of
these fern rich habitats should be considered along with other
mitigation plans.
PRELIMINARY CONSIDERATIONS FOR REVIEWING,SELECTING,CREATING AND
MAINTAINING LAND AREAS FOR THE BENEFIT OF MOOSE POPULATIONS.
Some lands are already highly productive or desirable for moose
and may only need to be protected from alterations and/or devel-
opments in the future to benefit moose subpopulations.Al ter-
ation or rehabilitation of these lands is presently not neces-
sary_However,in order to sustain high levels of productivity
on these lands,moose populations must be managed and maintained
at levels commensurate with carrying capacity of the range.
These lands need not be winter range habitats but may be calving
or rutting areas or simply travel corridors between summer and
winter ranges.These areas may be natural and undi sturbed or
they may be altered habitats that in the past were cleared and
now are at the seral vegetative stages desired by moose.Pres-
ently /several of the latter type areas have been located and
data documenting moose use (timing and numbers)of them are
available (see MOOSE USE OF DISTURBED SITES pg.86).It is
possible that areas,which already support substantial wintering
populations of moose,may be procured from their present land-
holder and maintained (maybe further improved)in that enhanced
condi tion indefini tely.
Other lands along the Susitna River may presently be unproductive
for moose or be declining in producti~rity but have the potential
to be rehabilitated,manipulated and/or enhanced to increase
their productivity for moose.However,under these circumstances
it should be reemphasized that if mitigation actions are to
103
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enhance particular moose subpopulations,then it is necessary to
know which factor(s)may be limiting moose subpopulation growth
before an appropriate mi tigation plan be selected.It may be
futile to employ a winter range enhancement program,which
primarily affects moose nutritive condition,to increase the size
of a moose subpopulation that in reality is limited by predation.
Conversely,in the former situation,it would be nonsense to
implement a predator management scheme to benefit a moose sub-
population that is limited by availability of high quality winter
range.Obviously,impacts of hydroelectric development on moose
subpopulations and meaningful mitigation enhancement programs can
only be assessed and designed,respectively,after factors which
limi t moose subpopulations are understood.
Rehabili tation of lands for moose typically involves removing
climax type vegetation to encourage growth of higher quality
early successional vegetative types than were previously avail-
able on that given area or range.
It is critical that age and species composition of succeeding
vegetati ve types be those which are preferred by moose.I have
observed sites where it appears climax vegetation had been
altered by human activities,but the resulting regrowth was
predominantly sprucej a highly undesirable winter browse species
for moose.One of these sites immediately abutted another where
regrowth was composed of preferred browse species.Apparently,
subtle environmental factors may be present and result in con-
trasting regrowth patterns.Obviously,selection of sites to be
enhanced must be conducted in a knowledgeable manner.
Rehabilitated lands may be of little value to moose until pre-
ferred successicrtal vegetative types dominate the site.The time
lag between alteration and appearance of preferred browse may be
3 or 5 years (Spencer and Chatelain 1953 and Preston 1983,
104
respecti vely)but can vary wi th habi tat type I si te character-
istics and techniques employed.
Interspersion of habitat types may be important to a successful
rehabi Ii tation program.Extensive cleared areas I 1 acking adj a-
cent cover (spruce forests or densely vegetated berms)may be
less than ideal for moose winter range.Ideal winter range
probably is composed of a mix of cover types and browse species.
Moose may be slow to utilize a newly rehabilitated habitat that
is spatially removed from their more usual patterns of movement
or winter ranges.Newly rehabi li tated areas may have to be
colonized by a "new generation"of moose.However,colonization
and plant succession may proceed at the same rate so that the
area may be at its peak carrying capacity of moose when preferred
browse is also at its peak of development and availability.It
may be undesirable or difficult to develop a newly enhanced
winter range if substantial numbers of moose immediately start to
use the area before preferred vegetative types are firmly estab-
lished.
Enhanced habitats that are in close proximity to a usual and
heavily used winter range or are located between usual summer and
winter ranges may receive more immediate use by moose than
enhanced habitats which are more removed from exi sting moose
subpopulations.Enhanced areas located between existing seasonal
moose ranges,may temporarily hold moose as they pass through the
area in route to their usual wintering area,and in effect
receive immediate use and decrease use of their usual winter
range.
Since enhanced habitats are designed to attract and hold large
numbers of moose,consideration must be given to location of
these rehabilitated areas with respect to highway vehicle and
railroad rights-of-way.If enhanced habitats are located near
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such rights-of-way or moose must move across them when traveling
from one range to another,many moose will be killed annually and
tremendous public safety problems will result.Similarly,
location of enhanced areas near present or potential residential
housing subdivisions or field agricultural businesses may cause
large concentrations of moose which may impact residential
landscape plants,cultured agricultural shrubs and endanger
residential occupants.
If carrying capacity of winter range is increased,the resulting
increase in moose subpopulations may have detrimental impacts on
other potential limiting components in their ecosystem;i.e.,
spring,summer and fall foraging areas.
Each winter range type rehabilitated area should be managed on a
rotational basis,so that a given proportion of the area contains
the composition and age class of plants preferred by moose.Per-
haps each area could be divided into four parts,one of which is
rehabilitated every other summer.This method of land management
will foster a rather stable carrying capacity and prevent boom/
bust forage conditions.
When selecting areas for enhancement,maximum annual snow depths
which occur every 10-20 years should be considered.Snow depths
less than 40 cm did not hinder moose movements on the Kenai
Peninsula (Franzmann et al.1984).
Plans for long term maintenance of enhanced areas must accompany
proposals for creation of them.If areas are not maintained,
elevated moose populations would be forced to utilize other
remaining winter range and would lead to overutilization of
forage avai lable on those ranges.
If areas are to be enhanced
to them must be reasonally
equipment will be required for
and maintained in that state,
convenient,particularly if
rehabilitation.
106
access
heavy
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Enhanced areas need not be large.Data presently available
indicate that 40 to 70 moose may browse in about 2 km 2 of early
successional habi tat from November through March (Table 22).
Location of enhanced sites should not be limited to areas immedi-
ately adj acent to Susi tna River.Lands near alpine areas along
Montana,Sheep,Kashwitna and Willow Creek as well as areas 5 to
15 miles west of the Susitna River should also be considered for
enhancement.
Preliminary data from moose censuses along the Susi tna River
floodplain indicate that cow moose with calves may not be evenly
distributed throughout that winter range.Possibly,location of
enhancement sites may benefit particular sex and age classes of
moose.
Numbers of moose using enhanced areas must be managed and regu-
lated to prevent overutilization of food resources.Regular open
hunting season (1-30 September)may not be an adequate management
measure and seasonally later,additional open hunting periods
when moose are on the winter range (enhanced areas)may be
necessary to control population growth.The latter technique
would appear to be the most direct,specific and precise method
of controlling moose population size and preventing overbrowsing
and starvation on the winter range and would also provide the
maximum sustainable yield of browse and moose.If open hunting
seasons were the primary population controlling measure,it would
be necessary that enhanced areas were readily accessible to
hunters.
Since enhanced areas must be maintained over a long term period
(indefinitely?),careful considerat'oh should be given to poten-
tial and planned future land uses on adjacent land and the more
distant lands upon which the respective moose subpopulations
subsist during other seasonal periods.It would be shortsighted
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to enhance winter habitat in an area,if it were known that a
major highway was to be constructed between the enhanced winter
range and summer range of that particular moose subpopulation.
Perhaps,most of all _we must be knowledgeable about moose,
enhanced habitats,and how moose use them before going out and
al tering climax vegetation.Baseline,general studies could be
conducted where happenstance,It enhanced"areas presently exi st,
to assess characteristics of the areas,how moose use them and to
predict how new ones may be created to best serve local moose
populations.Additionally,before altering habitats for the
benefit of moose,we must assess the ultimate impacts of those
changes on its prior wildlife inhabitants.
Lastly,follow-up studies should be conducted on several select
areas after enhancement takes place,to determine how moose are
utilizing the areas and if their use is different than was
anticipated.
POTENTIAL IMPACT MECHANISMS:And Associated Effects
Altered Seasonal River Flow Patterns and Loss of Annual Variation
in River Flow:soil erosion and deposition,inundation,
drought,ice jams,ice scouring,fertilizing effects of
inorganic and/or organic nutrient loads,water for ice
surface area,terrestrial floodplain surface area,floods,
effects on beavers,bears or other sUbpopulations of moose,
composition,distribution and/or abundance of plant species
or plant communi ties.
Altered Water Temperature:ice fog/fog (may result in physical,
physiol0gical,visual,isolation and insulation problems for
moose),frosting of vegetation,plant phenology,cornpo-
si tion,distribution and/or abundance of plant $pecies or
communi ties,ice scouring,ice j arns,open water in winter.
108
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Alteration of Habitat:development associated with pre
pro j ect'"influx of humans,transmission corridors,
and vehicle rights-of-way,project facilities,
predators and conspecific competitors.
and post
railway
attracts
Increased Access:transmi ssion corridors,rai lway and vehic Ie
rights-of-way,winter boating.
hunters,visitors,recreationists.r
Human Encroachment:construction and maintenance employees,
-
Increased Railway and Vehicular Traffic:disturbance,inter-
ference wi th movement,direct mortali ty.
Impoundment:inundation displaces predators and conspecific com-
peti tors which move to downstream areas.
Altered Turbidity:composition,distribution and/or abundance of
aquatic plant species.
Salt Water Encroachment at Cook Inlet:composition,distribution
and/or abundance of aquatic and riparian plant species.
Altered Ecosystem:secondary and tertiary effects from
on plant and other wildlife species as salmon,
bears,wolves and other subpopulations of moose.
RECOMMENDATIONS FOR FUTURE RESEARCH
impacts
beaver,
.-Until specifics and limits of seasonal and annual variation in
post-project flow regimes and water levels of the Susitna River
are known and secondary responses of plant communities are pro-
jected,it is not possible to assess their subsequent impacts on
moose subpopulations which are ecologically affiliated with the
Susitna River floodplain.Before such data are available,I
109
recommend continuation
of the ecology of moose
face with environments
present state.
of a general,~road based research study
subpopulations which are known to inter-
influenced by the Susi tna River in its
-,
General studies of individual moose and of subpopulation behavior
will continually provide an updated data base useful for knowl-
edgeably assessing impacts or predicting responses of moose to
any type of hydroelectric development on the Susitna River.
These studies will also provide the data base necessary to plan
and make recommendations for various mitigation actions designed
to benefi t moose subpopulations.
As limits of expected changes and variation in flow hydraulics
and in plant communities are further refined,research on down-
stream moose may likewise be re-directed to investigate particu-
lar impacts in finer detail.At the present time,it seems
inappropriate to become too specific in addressing particular
potential impacts on moose while disregarding other more general
baseline studies.
To date,it seems that the extent and magnitude of expected
hydraulic changes and their influence on vegetative communities
between Talkeetna and Cook Inlet remain uncertain.Until these
potential changes are more clearly outlined,general information
on behavior of these moose subpopulations should definitely not
be discontinued.If at a later date,it is learned that impacts
in this reach of the river will be negligible on moose,the data
collected on behavior of these more southern moose 5ubpopulations
may,at worse,form a basis for assessing and recommending
various mitigation actions in this area.For these reasons,
relocation of radio-collared moose,downstream from Ta.'.keetna,
should continue through the winter of 1984-85.
110
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Periodic winter censuses for moose in floodplain habitats along
the Susitna River should be continued through the winter of 1984-
85.These censuses document variation within and between winters
in the distribution and intensity of moose use for all stretches
and floodplain habitat types along the Susitna River downstream
from Devil Canyon.This information also provides the ,basis for
classifying winter severity.Perhaps,in the future,only key
portions (high use areas)of the floodplain need be surveyed to
document annual variation and identify winter severity and
surveys of the entire floodplain need be conducted only if winter
conditions are gauged as severe.Information on annual variation
in size and shape of moose ranges should continue to be col-
lected.
Data obtained from relocation of radio-collared moose and winter
moose censuses over a number of years provide information to
assess within and between variations in movements and moose use
of Susitna River floodplain habitats.Ideally,this type of data
should also be collected in a relatively severe winter.
Because of the imperative need to obtain a sample of moose in
floodplain habitats during a severe winter,equipment and
finances should be set aside for sampling activities (river
censuses,carcass counts,additional radio-collaring and moni-
toring)during a severe winter.Perhaps a severe winter may be
characterized as one in which about 1300+moose are observed in
floodplain habi tats along the Susi tna River.
Since protection and enhancement of plant communi ties to favor
moose may be a prime mitigation option for project related loss
of moose or their habitat,surveys to assess moose use of sites
where vegetative communi ties hav'"already been altered by man,
should be continued.To more fully learn about ecology of those
si tes and their interface with moose ecology,I strongly rec--ommend that the sample of moose radio-collared at the Talkeetna
III
West site continue to be relocated and perhaps an additional
sample of moose be radio-collared at a site on the east side of
the Susitna River (at either the Montana middle,Kashwitna Lake
or Kashwi tna bluffs di sturbed si te).
Because large alterations in flow regimes and floodplain habitats
are expected between Talkeetna and Devil Canyon and information
presently available for this stretch of the Susitna River flood-
plain is limited and heavily skewed toward females,an additional
sample of moose should be radio-collared in that area to increase
our general knowledge about those particular moose subpopula-
-tions.Island habitats in this reach of the floodplain appear
important to female moose during calving and decreased post
proj ect spring river flows may alter many of these habitats.
Since behavior patterns for male moose differ greatly from those
of females and presently little information is available on males
in that area,efforts should be made to radio-collar additional
males in that subpopulation.
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Arneson,P.1981.Moose-downstream.AK.Dept.Fish and Game.
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Ballard,W.B.,c.L.Gardner and S.D.Miller.1982a.Nelchina
yearling moose mortality study.AK.Dept.Fish and Game.
Fed.Aid Wild.Rest.Proj.Final Rept.,W-21-1 and W-21-2,
Job 1.27R.Juneau.37pp.
J.H.Westlund and J.R.Dau.1982b.
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Bishop,R.H.,and R.A.
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Rausch.1974.Moose population fluc-
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Chatelain,E.F.1951.Winter range problems of moose in the
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Franzmann,A.W./C.C.Schwartz
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In Prep.
Condi tion assessment of
expressed as twinning
Gasaway,W.C.,S.D.DuBois and S.J.Harbo.1981.Moose
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Fed.Aid Wild.Rest.Proj.Final Rept.W-17-9 through-W-17-11,W-21-1 and W-21-2.Juneau.66pp.
LeResche,R.E.1974.Moose migrations in North America.
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and,J.L.Davis.1973.Importance of nonbrowse
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and R.A.Rausch.1974.Accuracy and precision of
aeri al moose censusing.J.Wi ldl.Manage.38:175-182 .
Miller,S.and D.Anctil.1981.Biometrics and data processing.
AK.Dept.of Fish and Game.Susitna Hydroelectric Proj.
Ann.Prog.Rept.Big Game Studies.Part I.16pp.
Miller,S.D.and D.C.McAllister.1982.Black Bear and Brown
Bear.AK.Dept.Fish and Game.Susitna Hydroelectric Proj .
Phase I Final Rept.Big Game Studies.Vol.VI.233 pp.
Modafferi,R.D.-1982.Moose-Downstream.AK.Dept.Fish and
Game.Susi tna Hydroelectric.Proj.Phase I Final Rept.Big
Game Studies.Vol.II.114pp .
1983.Moose-Downstream.AK.Dept.Fish and Game.
Susitna Hydroelectric Proj.Phase II Ann.Prog.Rept.Big
Game Studies.Vol.I I.114pp.
Preston,D.J.1983.Moose habitat in areas of ongoing and
_proposed agricultural developments and moose populations in
areas of ongoing and proposed agricultural developments.
AK.Dept.Fish and Game.Fed.Aid Wildl.Rest.Proj.
Final Rept.W-21-2 and W-22-1,Job 1.34R and 1.35R.
Juneau.1 7pp.-i
Proulx,G.1983.Characteristics of moose (Alces alces)winter
yards on different exposures and slopes in southern Quebec.
Can.J.Zool.61:112-118.
Rausch,R.A.1958.The problem of railroad-moose conflicts in
the Susitna Valley.AK.Dept.Fish and Game.Fed.Aid
Wi Idl.Rest.Proj.Final Rept.Juneau.12 (1):1-116.
114
1959.Some aspects
rai lbel t moose populations,
Alaska,Fairbanks.Slpp.
of population dynamics of the
Alaska.M.S.Thesis.Univ.
'"'"'
Spencer,D.L.and E.
management of the
N.Am.Wi ldl.Conf.
F.Chatelain.1953.
moose of southcentral
8:539-552.
Progress
Alaska.
in the
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stringham,S.F.1974.Mother-infant relations in moose.
r Naturaliste can.101:559-593.
Thompson,I.D.and M.F.Vukelich.1981.Use of logged
habitats in winter by moose cows with calves in northeastern
Ontario.Can.J.Zool.59:2103-2114.
Van Ballenberghe,
southcentral
13:103-109.
V.1977.
Alaska.
""'I"
Migratory behavior of moose in
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PERSONAL COMMUNICATION
Collins,William.Agric.Exper.State.,Univ.of AK,Biologist,
April 1984.
Miller,Sterling,AK Dept.Fish and Game,Game Biologist,May
1984.
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