AgricultureUidSJtWolfPopulationintheCntrasFNotrtnCEexptrraentupriorN - PDF document

1 AgricultureU:i::dSJ:t_):,.WolfPopulation
AgricultureU:i::dSJ:t_):,.WolfPopulationintheCnt.ra/sFNo_tr__tnCEexptrra/entupriorNationalResearchPaperNC,270NForest,1967-198'_'/L.DavidMechal.._._..........•...:.-...:-=.-:.._.........._._--ml¢..._-o.....-...__._..........:......-•_....................--..-::.-:._-____.'-m.!-.-.::-.--..................;....--:.-..-.--,--......".-_1i::............::._.-........:....:-..:-.'--::2::-::,..--,-_.i"i;-:_;;--::;::;;:::-_...._"........"............._.._--.-...-.--.--._....•_._o-......_..-....,...................................-.........__.....----............._.;-:_2z-.:,"?._::_•.......".-.--:"--.............._..---..-._"@I,_._.._',......L.....".....-."-::'----".._----"-",°..........--.i.•..-1i.__..__._.._,_'.-..:-'----'-_....-..._!i'I•-.-...;__......:..._..:•.. Mech,L.David.WolfpopulationinthecentralSuperiorNationalForest,1967-1985.Res.Pap.NC-270.St.Paul,MN:U.S.DepartmentofAgriculture,ForestService,NorthCentralForestExperimentStation;1986.6p.Aerialradio-trackingandobservationshowedtotalnumberofwolvesperyearin2,060-kin2areavariedfrom35to87_nwinterandfrom30to78inspringandgenerallydeclinedbecauseofadecreasingdeerherd.Sincewinter1977-1978,thepopulationhasremainedrela-tivelystablebecauseanincreasingproportionofithasswitchedtopreyingonmoose.Thenumberofwolvespreyingondeerhascontin-uedtodecline.KEYWORDS:Deer,moose,territoriality,homerange,radio-•tracking,telemetry,predator,prey,Minnesota.NorthCentralForestExperimentStationForestService--U.S.DepartmentofAgriculture1992FolwellAvenueStPaul,Minnesota55108ManuscriptapprovedforpublicationFebruary6,1986'1986 WOLFPOPULATIONINTHECENTRALSUPERIORNATIONAl.FOREST,1967-1985°..-L.DavidMech,WildlifeResearchBiologist,.Patuxent'WildlifeResearchCenter,U.S.FishandWildlifeService..Largecarnivoresarelong-lived.Wolves(Canislu-withthefollowingspeciespresent:jackpine(Pinuspus),f0rexample,canlivesome16yearsincaptivitybanksianaLamb.),whitepine(P.strobusL.),red(Young1944)andatleast13yearsinthewild(Mechpine(P.resinosa),blackspruce(Piceamariana1981).Thusacompleteunderstandingoftheirecol-(Mill.)B.S.P.),whitespruce(P.glauca(Moench)ogyandpopula

2 tiondynamicsrequireslong-termin-Voss),ba
tiondynamicsrequireslong-termin-Voss),balsamfir(Abiesbalsamea(L.)Mill.),whitevestigations.Thelongeststudyofwolfnumbershascedar(Thujaoccid,ntalisL.),andtamarack(Lar/xbeenconductedinIsleRoyaleNationalPark,Lake/ar/cina(DuRoi)K.Koch).However,asaresultofSuperior,wherewolveshavebeencensusedannu-extensivecuttingandfiresmuchoftheconifercoverallysince1959(Mech1966,Jordanetal.1967,isinterspersedwithlargestandsofwhitebirch(Be-Peterson1977,Petersonetal.1984).Thatstudyhastu/apapyriferaMarsh.)andaspen(Populustremu-yieldedseveralnewinsightsintowolfandpreyrela-/o/desMichx.).Detaileddescriptionsoftheforesttionships(Allen1979,Petersonetal.1984).How-vegetationwerepresentedbyOhm_nnandReamever,IsleRoyaleisa544-km2islandwiththewolves(1969).livingonamoose(Alcesalces)economy.ThusitisInthenortheasternhalfofthisstudyarea,aswellusefultostudywolf.numbersinalarger,mainlandecosystemwithamorecomplexpreybase.asintheregionimm_ediatelynorthandeastofit,the_In1966suchaninvestigationwasbeguninthecentralSuperiorNationalForestofnortheasterno.tn/Minnesota.Thisareahadtheaddedadvantageof/backgrounddatafromotherstudies(Olson1938,..........._-............Stenlund1955).Earlierresultsofthepresentstudyihavebeenreported(Mech1973,1977),butthe_lO...presentdocumentsummarizesthedatafrom1967....."s...'•./through1985.my•_...__STUDY//""''---/,/.......Thepresentstudyareaencompassessome2,060kin_2immediatelyeastofElyintheeast-centralSu-...jperiorNationalForest(48°N,92°W).AlthoughIsomewhatsmallerthantheareasreportedonear-"....:eKe:!lier,thisStudyareaencompassesthecoreofthat,_l_regioninwhichIhavebeenabletomonitorthewolfpopulation.duringtheentire19-yearperiod(fig.1).Thearearepresentsapproximately3percentoftheFigure1.--Wolfcensusarea(2060km2inthecentraltotalwolfrangeinMinnesota.SuperiorNationalForestofnortheasternMinne-Thetopographyvariesfromlargestretchesofsota.Outlined,numberedareasrepresentmini-swampstorockyridges,withaltitudesrangingfrommumwolfpackterritoryboundariesforwinter325to700metersabovesealevel.Wintertempera-1984-1985asfollow:1,EnsignL.Pack;2,Pagamitureslowerthan-35°Carenotunusual,andsnowPackNo.2;3

3 ,WoodL.Pack;4,BirchL.Pack;5,depths(usual
,WoodL.Pack;4,BirchL.Pack;5,depths(usuallyfromaboutmid-NovemberthroughLittleGabbroPack;6,JackpinePeekNo.4;7,Saw-aboutmid-April)generallyrangefrom50to75cmbillPack;8,QuadgaL.PackNo.2;"9.ManiwakiL.onthe!evel.SummertemperaturesrarelyexceedPackNo.2;10,MalbergL.Pack(approximateterri-+35°C.Coniferspredominateintheforestoverstory,torybecausepackwasnotradioedin1984-85). r|overwinteringpopulationofwhite-taileddeer(Odo-andlateryear'sdataforradioedpacksoccupyingcoileusvirginianus)weredepletedabout1975byathoseterritories.Datafrombefore1968werebasedcombinationofaseriesofseverewinters,maturingsolelyonobservationsofnonradioedpacksduringvegetation,andhighwolfnumbers(MechandKarnsintensiveaerialobservationofthearea.1977).MooseinhahittheentirestudyareabutoccurInthisestimateofwolfpopulationtrend,thehum-atahigherdensityinthenortheasternhalf(Peeketal.1976).Inspring,some32percentofthedeerberoflonewolveswasconsideredinconsequentialinhabitingthesouthwesternhalfofthestudyareabecausetheirproportionofthepopulationwaslow.migrateintothenortheasternhalfOrbeyondandDuringtheearlierpartofthepresentstudy,10nereturninfall(HoskinsonandMech1976,Nelsonwolveswereestimatedat7-14percentofthepopula-tion(Mech1973),andlonerscomprised16percentofandMech1981,1986).Beaver(Castorcanadensis)282wolvescapturedinandaroundthepresentstudyareavailablethroughoutthestudyarea,butgener-area(Mechunpublished).allyonlyfromaboutAprilthroughNovemberbe-causeoficeduringtherestoftheyear.AlthoughallSomedatapertainingtoindividualpackyearsinthreepreyspeciesareconsumed,bywolvesinthethepresentarticlemaydifferfromdatapresentedre.on(Frenze]1974),Sinceabout1975theprimarypreviously(Mech1973,1977)becauseofreinterpre-preyofwolvesinhabitingthenortheasternhalfhastationofthedatabasedonadditionalexperienceeenmoose,whereasthoseinthesouthwesternhalfwiththesepacks.Furthermorethewolfpopulationhaveconsumedprimarilydeer(Mech,unpublished),trendmayalsovaryslightlyfrompreviouspublica-•tionsbecauseofthedifferenceinthepreciseYear-aroundhuntingandtrappingofwolveswasboundariesofthestudyareasconsidered.Neverthe-legaluntilOctober1970whentheywerefu

4 llypro-te_onfederallandWithintheSuperior
llypro-te_onfederallandWithintheSuperiorNationalless,tlzeearlierresultsremainbasicallythesameinForestbytheU.S.ForestService.InAugust1974,thepresentstudy.wolveswereprotectedbytheEndangeredSpeciesActof1973.In1978,thewolfinMinnesotawasRESULTSreclassifiedfromendangeredtothreatenedbutre-mainslegallyprotectedexceptwhentakenbyU.S.Some250wolvesrepresentingupto13packsinFish.&WildlifeServiceagentsreactingtodepreda-thisstudyareawereradio-taggedandstudiedfromtionsonlivestockoutsidethepresentstudyarea.1968through1985(table1).ThenumberofradioedHowever,inpartsofthestudyareaadjacenttotownspacksinthestudyareaeachwinterandspring(fig.1),moderateillegaltakingcontinues,primarilyrangedfrom1to8.Eachradioedwolfwaslocatedaninfallandwinter(Mech1977,andunpublished),averageofapproximately38timesperyear,andtheyandtheirpackmemberswereobservedanaver-METHODSageofapproximately18timesperyear.Packsizesvariedfrom2to15duringwinterandfrom2to11•Theprimarytechniqueusedinthisinvestigationduringspring.Somepacksdisappearedasdeter-minedbytheindividualhistoriesofradioedmem-hasbeenlive-trappingwolves,outfittingeachwithabetsofthosepacks(Mec]iunpublished).Sometimesradi0-collar,_aeriallyradio-trackingthematleasttheirplacesweretakenbynewcolonizingpacks•OnceperweekfromAprilthroughNovemberandat••leasttwiceperweekfromDecemberthroughMarch,whichmayormaynothavesettledinpreciselythesameterritories.Apackoccupyingageneralareaandaeriallyobservingandcountingthemasoftenasinhabitedearlierbyaradioedpackwasusuallypossible,primarilyfromDecemberthroughAprillistedunderthesamename(table1)eventhough(Mech1974):ThemaximumnumberofwolvesseenineachpackduringDecemberthroughFebruaryiscontinuityviaoverlappingradiotenureswasnotal-consideredthewinterpacksize,andthemaximumwaysdocumented.seenineachpackinMarchandAprilrepresentstheGenerallythewolfpopulationincreasedeachyearspringpacksize(Mech1973).upto86percentfromspringtowinterasaresultofPackterritoriesbasedon.radiolocationswerede-reproduction,althoughduringtwosummerswolflineatedforeachradioedpackinthestudyareaeachnumbersactuallydecreased(table2).Fromwinteryear,Theexistenceofnonra

5 dioedpacksintheStudytospringthepopulatio
dioedpacksintheStudytospringthepopulationdecreasedasmuchasareainanyyearwereinferredfromvoidsinthe40percentperwinterasaresultofmortality(Mechmapsoftheterritorialmosaic.Incidentalobserva-1977)anddispersal(Mechinpress).tionsofnonradioedpacksinthesevoidswereusedtoThetotalnumberofwolvesinthecensusareainrepresentsizesofthesenonradioedpacks.Ifsuchwintervaried.from35to87andinspring,from30todatawereunavailableinagivenyear,pack-sizees-78overthe19-yearperiod,andgenerallydeclined_imatesweremadesubjectivelybasedonprevious(fig.2).However,about1978wolvesbeganrecoloniz-2 Table2.--WolfpopulationchangesinthecentralSuperiorNationalForest,basedOndatafromtable1PorcentchangeInwolfnumbersm•PercentchangeintotalnumbersinstudyareadeereconomyInstudyareaWintertoSpringtoWinterto_d_toWintwtoMmrtoIkNriqtoYearspringnextwinterwintwspnngspdngmS_rl__ln_winter1967-1968--+4---+4-1969--+11---+11--1970.--+6---+6-1971'-7+5-3--7+5-3-1972-27+17-2-23-27+17-2-231973..-40+55-15-30-40+55-15-301974-35+5-7O0-35+5-7O01975-14+47-32-10-14+47-32-10.1976,-14-6+27+26-14-6+27+281977-27+52-20-3!-27+45-20-311978.-26"+24+11+12-29+15+7+31979-24+54-8-5-26+62-19-151980-19+9.+17+26-19+8+21+311981-15+15-11-7-15+3-13-81982-6+14-2+7-8+15-12-61983"-26-5+6-16-32-12+6-211984-14+80-30-19-13+50-39-231985-20-+54+43-27-+30+10qnsuflidentdataavailablebeforeSislimebecausepackswerenotradioed.ingthenortheasternpartofthestudyareainwhichThefateoftheothermxmembersoftheoriginaloverwinteringdeeranddeer.killingwolveswereMs]bergL.Packisunknown,exceptthatpupswerethenabsent(MechandKarns,1977).Thenewlycolo-producedinthenorthendoftheterritory,sothenizingMalbergL.Packincreasedto12membersbypackprobablypersisted.1983,preyedexclusivelyonmooseduringwinter,Meanwhilebywinter1984-1985,apackoffiveandoccupiedsome20percentofthestudyarea.includingpups,wascolonizingthesouthwestern20Inspring1984,fourmembersoftheMalbergL.percentofthe1983-1984MalbergL.PackterritoryPack,includingradioed2-year-oldwolf6417,appar-andexpandingsouthwestward(QuadgaLakePack).entlysplitfromtheremainderofthepackandcolo-Inaddition,theEnsignL.Pack,radioedinspringnizedthesoutheast

6 ernhalfofthepreviouswinter's1984,numbere
ernhalfofthepreviouswinter's1984,numberedsevenanimalsbywinter1984-1985,territory,expandedsoutheastward,andincreasedtoandpreyedprimarilyonmoose.Thelasttimeapack;seven;thispackwasrenamed'_IaniwakiL.Pack"inthatareahadbeenradio-tagged(winter1979-becauseitoccupiedtheterritoryoftheformerMani-1980)theyhadmigratedoutoftheirterritoryduringwakiL.Packwhichhaddiedoutthepreviousyear.winterandpreyedondeerseveralmileswestward.Theresultofthewolfpopulation'spartialswitch_.-toamooseeconomyfrom1978through1985wasto"allowthetotal.populationofthestudyareatore-"_mainrelativelystableduringthatperiod(fig.2).Meanwhile,thenumberOfdeer-killingwolvesinthestudyareacontinuedtodecline,althoughboththist:sosubpopulationandtheentirepopulationofthestudy_areaincreasedfrom1984to1985(fig.2).m\..,VDISCUSSIONANDCONCLUSIONo,,........•Thewolfpopulationdeclineinthisstudyareare-Figure2.--WolfpopulationtrendinthecentralSu-suitedfromadecreaseinthewowsmainprey,theperiorNationalForestduringwinter.Solidlinein-white-taileddeer(MechandKarns1977).Thedeerdicatestotalpopulationinthe2,060-km_studydeclineendedabout1977,andsincethenthepopula-area.About1976-1977,partofthepopulationbe-tionhasremainedlowalthoughrelativelystableganpreyingprimarilyonmooseduringwinter.The(NelsonandMech1986).Neverthelessthewolfpopdottedlinerepresentsthetrendinnumberofwolvesulationonadeereconomycontinuedtodeclineforcontinuingtopreyondeer.severalmoreyears(fig.2).Thisfactseemstoindi-4 catethatatlowdeernumberswolvesareunabletoprovals,permits,andmiscellaneoussupportanden-killenoughdeertoenablethewolvestomaintaincouragement.G.DelGiudice,L.Rogers,andtheirnumbers.FurtherevidenceisfoundintheT.Fullerofferedhelpfulsuggestionstoimprovetheswi'tchingofpartofthewolfpopulationtoamoosemanuscript.economywhichallowedthewolfpopulationtostabi-lizeinthestudyareaatadensityofabout2.3per100km2forseveralyears(fig.2).LITERATURECITEDItisunknownwhetherthewolvescolonizingtheAllen,D.L.WolvesofMinong.Boston:Houghtondeer-freeareain1978dispersedfrompacksonadeerMifflinCo.;1979.499p.economyandthenlearnedtoexploitmoose,orwhethertheycamefromamoose-killingpopulationFr

7 enzel,L.D.Occurrenceofmooseinfoodofwolve
enzel,L.D.Occurrenceofmooseinfoodofwolvesasrevealedbyscatanalyses:areviewofNorthtothenorth.WolvescandispersedistancesofatAmericanstudies.NaturalisteCan.101"467-479;least866km(Fritts1983),butitapparentlytook1974.severalyearsforwolvestofillthevoidinthenorth-easternpartofthestudyarea(Mechunpublished)Fritts,S.H.RecorddispersalbyawolffromMinne-sota.J.Mammal.64:166-167;1983.eventhoughdisperserswereavailablefromdeer-killingwolvestothewestandsouth(Mechinpress).Hoskinson,R.L.;Mech,L.D.White-taileddeermi-•grationanditsroleinwolfpredation.J.Wildl.Thesecondalternativeseemsmorelikely.AlthoughwolvesthatpreyprimarilyondeercanlearntokillManage.40:429-441;1976.moose(Mechunpublished),therewasnoindicationJordan,P.A.;Shelton,P.C.;Allen,D.L.Numbers,turnover,andsocialstructureoftheIsleRoyalethatthisprocesstookplaceinthenortheasternpartwolfpopulation.Am.Zool.7:233-252;1967.ofthestudyarea.Mech,L.D.ThewolvesofIsleRoyale.Faunaser.7.ThewolfpopulationtrendinthisstudyareadoesWashington,DC"U.S.NationalParkService,notnecessarilyapplytosurroundingregionsorto1966.210p.theremaining97percentofMinnesotawolfrange.Mech,L.D.WolfnumbersintheSuperiorNationalBecausethedeerdeclineitselfwaslocalizedtotheForestofMinnesota.Res.Pap.NC-97.St.Paul,immediatevicinityofthestudyarea(MechandMN:U.S.DepartmentofAgriculture,ForestSer-Karns1977),wolvesthroughoutmostoftherestofvice,NorthCentralForestExperimentStation;theirMinnesotarangealmostcertainlywerenot1973.10p.similarlyaffected.Mech,L.D.Currenttechniquesinthestudyofelu-sivewildernesscarnivores.Int.Conf.GameBiol.SwitchingofpartofthewolfpopulationtoamooseProc.11:315-322;1974.economyminimizedtheeffectsofadrasticdeerde-Mech,L.D.Natality,mortality,andpopulationclineonwolfnumbers.Althoughextremefluctua-trendofwolvesinnortheasternMinnesota.J.tionsinbothwolvesandpreycanoccurinwolf-Mammal.58:559-574;1977.moosesystems(PetersonetaI.1984),thepresenceofMech,L.D.Adecadeofdatafromasinglewolf.thewhite-taileddeerasanalternatepreyinthisEndangeredSpeciesTech.Bull.6:4;1981.studyareashouldhelpstabilizewolfnumbers.Mech,L.D.Age,season,andsocialaspectsofwolfdispersalfromaMin

8 nesotapack.In:Chepko-Sade,B.D.;Halpin,Z.
nesotapack.In:Chepko-Sade,B.D.;Halpin,Z.,eds.Proceedings,Sympo-ACKNOWLEDGMENTSsiumonpatternsofdispersalamongmammalsandtheireffectsonthegeneticstructureofpopu-ThisstudywassupportedbytheUSDIFish&lations;inpress.WildlifeServi'ce,theUSDANorthCentralForestMech,L.D.;Karns,P.D.RoleofthewolfinadeerExperimentStation,theMardagFoundation,WorlddeclineintheSuperiorNationalForest.Res.Pap.WildlifeFundandtheNewYorkZoologicalSociety.NC-148.St.Paul,MN:U.S.DepartmentofAgri-Numeroustechnicians,volunteers,andstudentsas-culture,ForestService,NorthCentralForestEx-sistedwithlive-trapping,radio-tagging,radio-track-perimentStation;1977.23p.ingandobservingthewolves,,andmanybushpilotsNelson,M.E.;Mech,L.D.Deersocialorganizationprovidedskillf_flying.ThefollowingindividualsandwolfpredationinnortheasternMinnesota.bearspecialmention:M.E.Nelson,J.Renneberg,Wildl.Monogr.77;1981.53p.S.T.Knick,J.Burch,P.Magie,D.Mahl,Nelson,M.E.;Mech,L.D.DeerpopulationintheJ.Ortmann,Jr.,S.Gheen,J.Grummet,D.Glaser,centralSuperiorNationalForest,1967-1985.Res.G.Riley,R.Himes,D.Monson,F.H.Harrington.Pap.NC-271.St.Paul,MN:U.S.DepartmentofTheUSDASuperiorNationalForestandtheMinne-Agriculture,ForestService,NorthCentralForestsotaDepartmentofNaturalResourcesgrantedap-ExperimentStation;1986.7p.°5 Ohmann,L.F.;Ream,R.R.VegetationstudiesintheBWCA-abriefreportonplantcommunities.Naturalist20:20-29;1969.Olson,S.F.Astudyinpredatoryrelationshipwithparticularreferencetothewolf.Sci.Monthly46:323-336;1938.Peek,J.M.;Urich,D.L.;Mackie,R.J.Moosehabitatselectionandrelationshiptoforestmanagementinnorth-easternMinnesota.Wildl.Monogr.48:65p.;1.976.Peterson,R.O.WolfecologyandpreyrelationshipsonIsleRoyale.Sci.Monogr.Ser.II.U.S.NationalParkService;1977.210p.Peterson,R.O.;Page,R.E.;Dodge,K.M.Wolves,moose,andtheallometryofpopulationcycles.Sci-ence224:!350-1352;1984.Steniund,M-H.1955.Afieldstudyofthetimberwolf(Canislupus)ontheSuperiorNationalForest,Minnesota.Tech.Bull.4.St.Paul,MN:MinnesotaDepartmentofConservation,1955.55p.Young,S.P.ThewolvesofNorthAmerica,PartI.Washingtzn,DC:Am.Wildl.Inst.;1944.385p.f966- 6NORTHCENTRALEHPERIIIIENTSTATIO