Mule deer population organization, behavior and dynamics in a northern Rocky Mountain environment

325 Pages·1991·21.1 MB·English

by  Pac, David F.(David Frank),1952-

S Pacr David Frank
599o7357 MuLe deer
F2mdpo population
199l organizationr
behavior and
dynamics in a
northern &ocky
MULE DEER POPUI-ATION ORGANIZATION,
BEHAVIOR AND DYNAMICS IN A
NORTHERN ROCKY MOUNTAIN
ENVIRONMENT
David F. Pac
RichardJ . Mackie
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Henry E. Jorgensen
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FINAL REPORT
I RESEARCHP ROJECT
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STATE: Montana
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PROJECTN O: w-r20-R-7-18 TITLE: StatewideW ildlife Research
I PROGRAMN O: I TITLE: StatewideB ig GameR esearch
STUDYN O: BG-I.2 TITLE: StatewideM ule Deer Ecology
Snrdies
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JOBN O: 1 TITLE: Populatione cologya ndh abitat
relationshipos f mule deeri n the
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I BridgerM ountains,M ontana
Mule deerp opulation
organizationb, ehaviora nd
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dynamicsin a northernR ocky
Mountaine nvironment
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PeriodC overed:July 1, 1975- June3 0, 1987
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Preparedb y: DavidF . Pac Approvedb y: DonaldA . Childress
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RichardJ . Mackie JohnP . Weigand
HenryE . Jorgensen
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Date: October3 1, l99l
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ACKNOWLEDGEMENTS
Although compiled and written by the three of us; this report representsa
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compendium of our studies ilnd the work of many others who completed graduate
researcht heseso r participatedi n studiesi n the Bridger Mountains. Thesei nclude Bruce
T. Wilkins, who conductedth e first studieso f muled eeri n the BridgerM ountainsd uring
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1955-1956( Wilkins 1957), and subsequentlye stablisheda nd measuredt ransectsa nd
exclosureso n winter ranged uring 1957-1959.L ater, thesiss tudiesw ere completedb y
William F. Schwarzkoph(1 973),R ichardA . Bucsis( 1974),K ennethL . Hamlin (1974),
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Mary A. Morton (1976), David F. Pac (1976), William F. Steerey( 1979), Heidi B.
Youmans( 1979), Hanrey E. Nyberg (1980), and Alfred I. Rosgaard,J r. (1981).
I KennethL . Hamlin and John G. Mundingerp articipatedin studiesd uring 1975,S hawn
T. Stewarti n 1976,a nd Craig J. Knowlesi n 1977. Specialt hanl$ are extendedt o Ken
Hamlin, Terry Lonner, Gary Dusek,J ohnM undinger,R ich DeSimone,A lan Wood, Phil
I SchladweilerK, en Greer, ShawnR iley, Fred King, Harry Whitney, Mike Ross,a nd the
late Dan Palmiscianof or their technical assistancee, ncouragementa, nd friendship.
Numerous other Montana State University studentsa nd personnel of the Montana
I Departmento f Fish, Wildlife and Parks provided assistancein trapping, mortality
surveys, and vegetationm easurementtsh roughoutt he study. Ray Mule', William
Hoskins,a nd SteveM artin assistedin datac ompilationa nd statisticala nalyses.
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Other Fish, Wildlife and Parks personnelc ontributed significantly through
directiona nd generals upport,e speciallyR esearchB ureauC hiefs EugeneO . Allen and
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John P. Weigand. Arnold J. Foss, RegionalW ildlife Manager, Bozeman,p rovided
assistancaen d unendings upportf or populations urveysa nd other efforts from inception
of the studyt hroughh is untimelyd eathi n March 1988.
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The assistancea nd skills of SuperC ub pilots Roger and David Stradleya nd the
late JamesD . Stradley,G allatin Flying Service,B elgradea nd helicopterp ilots Murray
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and Mark Duffy, CentralH elicopters,B ozeman,a nd Larry Schweitzer,L arry's Flying
Service,D enton,a lso contributedg reatly to the studya nd resultsa chieved.
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This studyc ould not haveb eenc onductedw ithout the cooperationa nd supporto f
manyl andownerse, speciallyL loyd andS andyM aher, Elsie Armstrong,H oraceM organ,
I Dick Morgan,D ick Scott,I *e Eblen, GeorgeE blen,F rank NormanJ r., Buck Anderson,
Davel rish, Hank, Georgea ndM ary Irffingwell, CharlieP apke,Irster Warwood,D ave
Warwood,O . F. PeckinpaughC, huck Callatine," Bud" Miles, "Frosty" Rall, James
I Taylor, Tom LaProwse,K en Goering,H elen Walker, Jack Dunne, Orville fohns, Pehr
Anderson,M ike Lee, and Park Swandal.
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We thank Martha A. Lonner and MarshaLentz of Media Works, Bozeman,f or
their efforts in producing high qudity figure graphics and Diana Haker for the cover
drawing. MargaretM orelli, Erin Hooten,T ami Fuller, and Kay Coquyt demonstrated I
unending patience in typing and proofreading the final manuscript and the many
revisions. Finally, we would like to especiallyt hank our wives, Helga, Barb, and
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Dorothy, and our families for their sacrificesd uring this long endeavor.
The study was conductedw ith funding provided by Federal Aid in Wildlife
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RestorationM, ontanaD epartmenot f Fish, Wildlife andP arksP rojectsW -98-R, W-100-
R, and W-120-R. Additional supportw as providedb y the Departmento f Biology and
the MontanaA gricultural ExperimentS tation,M ontanaS tateU niversity.
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TABLE OF CONTENTS
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CHAPTER 1 - INTRODUCTION I
CHAPTER 2 - APPROACH AND METHODS 3
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Deer Distributiona nd Home Range 4
EnvironmentalD escription and Deer Habitat Use 5
PopulationC haracteristicas nd Dynamics 8
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CHAPTER 3 - THE BRIDGER MOUNTAIN STUDY AREA t2
Location and Topography L2
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Geology 15
Climatea nd Weather 16
I Vegetation 19
land Use and Other Animals 22
I CHAPTER 4 - SPATIAL ORGANIZATION 24
PHU.l - NorthwestS lope 27
PHU2-SouthwestSlope 29
t PHU 7 - BlacktailM ountain 3L
PHU 3 - Livingston 32
PHU4-BrackettCreek 33
I PHU5-BartleRidge 34
PHU6 - South1 6M ile 35
PopulationS ubunitsw ithin PHUs 36
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BehavioralF oundationsfo r Population-HabitaUt nits 40
Home RangeF idelity 40
Distribution and Use of Spaceb y RelatedD eer 42
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GeneticC ompositiono f Population-HabitaUt nits 48
Summary 49
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CHAPTER 5 - DEER DISTRIBUTION AND HABITAT USE IN
RELATION TO ENVIRONMENTAL FACTORS 50
t Topographya nd Climate 50
Winter 50
Spring,S ummer,a nd Autumn 55
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SeasonaEl levationalR elationships 55
Winter 55
Summer 62
Influenceo f Barrier Ridges &
Deer Distribution and HabitatUse in Relation to Vegetation 73
GeneralP atterns 73
SeasonaDl eer Distribution and Habitat Use in Relation to
VegetationC haracteristicisn PHUs 1 and 4 74
Winter 74
Spring 81
Summer 82
Autumn 89
Food Habits and Forage Relationships 90
SeasonalTrends :... 90
Summary 94
CHAPTER 6 - DEER MOVEMENTS AND BEHAVIORAL
RESPONSET O THE ENVIRONMENT 97
Individual MovementP atterns 97
SeasonaUls eo f AccessorAy reas 101
WinterA ccessorAy reas 103
Springa ndA utumnA ccessorAy reas 106
Early SummeAr ccessorAy reas 115 I
LateS ummeAr ccessorAy reas t2l
SpatialR elationshipsBetweenM ales and Females r23
MonthlyM obility t24 I
Variationi n Mobility BetweenS exes 128
SeasonaHl ome RangeS izea nd Mobility 131
Distancea nd Timing of MovementsB etweenS easonaRl anges 137 I
Emigration 140
Summary r43
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CHAPTER 7 - SOCIAL STRUCTURE 145
MaternalD oe Groups t46
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Mature Buck Groups 150
Mixed Groups 153
YearlingM ale Groups 153 t
Monthly and SeasonaCl hangesin Group Size 156
Habitat FactorsI nfluencingG roup Size and Distribution 156
Summary r63 I
CHAPTER 8 - REPRODUCTIONA ND MORTALITY 165
ReproductionF, awn Mortality, and Recruitment r65 t
Conceptiona nd Birthdates 165
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Pregnancy,Ovulation,a nd Fetal Rates 165
Litter Size 168
I Fawn Mortality 169
Fawn Recruitment 178
Fawn Sex Ratios 185
I Fawn Mortality in Relationt o Adult Density 189
Adult Mortality 191
Annual andSeasonaMl ortality Rates 192
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Adult Mortality/RecruitmenRt elationships 198
Age-SpecificS urvival Rates r99
Adult females r99
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Adult males 202
Adult Mortality-Winter SeverityR elationships 203
Adult Mortality-DensityR elationships 205
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Females 205
Males 207
I Summary 208
CHAPTER 9 - POPULATION COMPOSITION,S IZE, AND
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Sex and Age Composition 2t0
Adult Age Structure 214
I PopulationS izea nd Trend 223
PHU 1 224
PHU 4 227
I Total Deer Numbersa nd 230
PopulationG rowth Rate 234
Summary 237
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CHAPTER 10 - POPULATION-HABITAT RELATIONSHIPS 239
Definition of Populationa nd Habitat 239
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The Population-HabitaUt nit (PHU) Concept 240
Developmenot f PHUs 242
Deer Behaviora nd Habitat Use Among EstablishedP HUs 245
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Influenceo f Behavior 245
Influenceo f StableH abitat Characteristics 246
I Influenceo f VariableH abitat Characteristics 252
CHAPTER 11 - POPULATIOND YNAMICS 258
I HabitatF actorsA ffecting PopulationS izea nd Composition 2s8
Reproductiona nd JuvenileM ortality in Mountain Environments 261
Adult Mortality in MountainE nvironments 266
I Adult Females 267
Adult Males 269
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PopulationR egulation 271
CHAPTER 12 - MANAGEMENT RECOMMENDATIONS 274
PopulationM anagement 274
Habitat Management 276
APPENDIX A - ENVIRONMENTAL CHARACTERISTICS OF
MULE DEER POPULATION-HABITAT UMTS IN THE
BRIDGER MOI]NTAINS, MONTANA 281
Topography 28r
Climate and Weather 283
Temperature 283
Precipitation 286
Snow Depthsa nd Coverage 286
Wind 289
GeneralV egetationaCl haracteristicos f PHUs 291
SpecificV egetationC haracteristicisn PHUs I and 4 292
APPENDIX B 295
AppendixT able Bl. Estimatedn umbero f mule deer bucks, does
and fawns harvesteda nnually in eacho f three west slope
population/habitaut nits by yar, 1975-1986. 295
AppendixT able 82. Estimatedn umbero f mule deer bucks, does,
and fawns harvesteda nnuallyi n eacho f four easts lope
population/habitaut nits by year, 1975-1986. 296
APPENDIX C 297
AppendixT ableC l. Mark-recaptur(eL incolni ndexesp) opulation
estimatefso r muled eero n theA rmstrongs egmenotf PHU 1
during April, 1973-1987. 297
Appendix Table C2. Mark-recapture( Lincoln indexes)p opulation
estimatesa nd countinge fficienciesf or helicopters urveyso f
mule deer on winter rangesa long the west slopeo f the Bridger
Mountains,l ate winter 1979-1987 298
AppendixT able C3. Mark-recapture( Lincoln indexes)p opulation
estimatesa nd countinge fficienciesf or helicopters urveyso f
mule deer on winter rangesa long the east slope of the Bridger
Mountains,l ate winter 1979-1987 300
Literature Cited 302
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I CHAPTER 1
INTRODUCTION
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Mule denr( Odocoileush emionreso)c cupya broad spectrumo f habitatst hroughout
their range. Althoughb iologistsh avel ong recognizedth at life history and demography
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of deer vary among populations along this spectrum, documentationw as generally
lacking. Recentlyc ompleteds tudieso f mule and white-tailedd eer (O. virginiarus) in
severanl orthernp lainsh abitatsin Montana( Hamlina ndM ackie 1989,W ood et al. 1989,
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Dusek et al. 1989) have provided new knowledgec oncerningd eer-habiat relationships
and the role of environmentala nd behavioralf actors on population ecology.
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Our study focusedo n mule deer in Rocky Mountain habitat which may constitute
the strongholdo f the speciesth roughouti ts range. This effort was initiated in 1975b y
I the MontanaF ish and GameD epartmenta s part of a long-termi nvestigationt hat included
the three studiesd iscusseda bove( Mackie et al. 1976). Becauseo f the large size and
complexityo f our mountainouss tudy area, we were particularly interestedin studying
I variation in habitatu sea ndp opulationc haracteristicsa mongd ifferent local environments.
Perhaps,a s suggestedb y Geist (1981),h abitats election,f ood habits,r eproduction,a nd
populationd ynamicsa re all closely linked to behaviorala daptionst o individual habiats.
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Objectivesw ere to: 1) inter-relatee nvironmentacl haracteristicws ith patternso f
mule deerh abitatu sea nd populationp arameters,2)r elateo ur resultst o studiesi n other
I major habitatsa nd the prevailing conceptso f population ecology, 3) develop new
methodsf or improving deer managemenitn Northern Rocky Mountain habitat.
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The effort was initiated at a time when deer managersa nd scientists were
perplexedb y the failure of existing ecological conceptst o explain widespreadd eclines
in mule deerp opulationsin Montanaa nde lsewherein westernN orth America. Because
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of this, the studyw asc onducteds pecificallyf or deerm anagemenat,n d our dataa nalyses
and this report are directed substantiallyt o that end. Managementp ractice and theory
are not mutuallye xclusive,h owever,a nd studiesa nd data relative to one may address
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questionsim portantt o the other.
I Few biologists would deny that seriousg aps exist in current knowledge of
populatione cology. There is, for example,l ack of agreemento n such fundamental
issuesa s definition of the term population. Yet, knowledgeo f how individuals of a
I specieso ccupyingn aturale nvironmentsa re organizeda nd integratedin to populationsis
basic to understandingth eir ecology.
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