GeorgeP. Keister, Jr.,r Oregon Department of Flshand W d fe 2995Hughes Lane, Baker Cty. Oregon97814 and WalterA. Van Dyke,Oregon Depart.nent of F sh andWidlife, 38T4 C ark B vd. Ontarlo,Oregon 97914
A PredictivePopulation Model for Gougarsin Oregon
Abstract
Cougar nunbers in Orcgon declinedberween 1928 and 1961.prinrdrily due lo exccssjveharvest ffom the bc'untysystem. Cougafs werc classified as a game mammal in I967 and spo harvestbegan on a limiled basis in I 970. B ecause detemining population size ofcougars by direct count mcthodsis impractical,indircct nrethodsto evalualestatus are needed. \\'e analyzedharrcst ]cvels. lianage conrplaints.and data obuincd from harvestedcougars 1o evaluate their statusin Orcgon. Biological data oblained lrom oregon and other stateswere used1() dcvelop a densitydependen! nrodel of the cougarpopulation ofOregon. As indicaledby thc model. nLrmbersi ncreased fioln an cslimatedlow of 2 1.1in 196I to 2,830i n I 992, which coincidcdwith other indicators including incrcascdlivesrock damrge. human safety complaints.and sport hanest. The nodel indicaled higher moltality r.rteslbr hunled poputarjonsand lo*,er proportionsofj venile cougarsin populatjonsat caffyirg capacit]'.For the modeledpopuladon in 1993. sportharrest ratesof5.4q. alowed a 5% annualgrowlh. A sporthanest of 107. of thc populationand a total mortality rale of 35% was neededto srabilizethat populatjon.The model predictedthat if spofi harlest ceascd.cougar nunbers would incrcaseuntil carrying capacily is reachedin thc year 2009.We believe the model is a useful lool lo summariTeexisting data.erplorc cffectr of hyporhcsizcdrn anagemenr plans. and adaptivelyaid in managcmcn!deci sion s. The nodel can be adaptedto olher statesifappro priate populadon parameterscan be determlned lntroduction reports, and past harvest history have been the primarl lactor.u'eLl lo recommendhunting.er- (Puma concolor) were con- Historically,cougars sons.Legal challengesto cougarhunting in 1988 predator in the western sidered an undesirable prompted the Oregon Department of Fish and a threatto livestock, United States.Perceived as Wildlife (ODFW) to look for additional ways to implementedprograms stateand federal agencies assessthe statusof cougarpopulations. rhdtre.ulred in r.ubstantialreduction in cougar numbersand elimination of cougarsfrom much Becauseof their low densities,secretive na u of their historic range (Dixon 1978).ln Oregon, ture.and largehome rrnge.. ildlife managers problem a bountysystem fbr cougarsexisted until 1961. and researchershave struggledwith the populations.We Statisticalanalyses in the early 1970s,based on of accwately measuringcougar populrtione.timate: lium hlrvesledcougars. in- are unableto measurc,on an lLnnualbasis, most precisely dicatedthat the statewidepopulation in 1961was of the parametersnecessarJ to know what populations extremely low and without protection, cougars is happeningwith local cougar at all poor is because would likely have been extirpatedfuom Oregon times. Our monitoring capability by the early 1970s(Wanen W. Aney. 1973.un- methodsare simply not availableto measureoougar possible publishedletter on file at OregonDepartment of populationswith the precision for other (e.g. mule Fish and Wildlife, Portland). species Douglas-fir trees,bald eagles, deer, pronghom) and money is rarely available were afforded game mammd status Cougars to use the methods that are available.The best and no season by the 1967 Oregon Legislature population estimatescome from intensive field 1970. Limited hunting be- was authorizeduntil work (Lindzey1987). Track counts have been used were pri- gan in 1970 when 25 tags authorized, in severalareas (Ashman et al. 1983,Neal et al. livestock damageconcems ma ly in responseto 1987).However this method only providesan index Sincethen, in a smallarea of northeasternOregon. to population,depends on a good tracking sub- complaints, cougar sighting livestock damage stratesuch as snow or dust, and hasbeen costly. Most commonly, radio telemetry has been em- rAutbor to whom conespondenceshould be addressed.E- ployed in mark-recaptureand complete capture mail : glwkeisr@)oregonVOS.net studies.Several years are necessary to determine
NorthwestScience. Vol. 76, No. l, 2002 15
O2002byrhe\oflh*e{S.1.rtfi.A$ociatior Allrighcre\erred a population estimate.Both methods are costly dationhas occurred since 1980. Reproductive sta- and tjme consumingbecausc of the logistics in- tus. stomachcontents, age, and sex of harvested volved in captu.ingo high prcportionof thepopu- cougarswere determinedat the ODFW Wildlif'e lation in a large areaof mgged habitat. In addi- Laboratoryin Corvallis. tion. resultsof suchstudies may representonly a small portion of the state.Wc employed statisti Analysisof Harvestand Cornpla nt Data cal analysisand populationmodeling to assess We used regressionanalysis to examine hulter statusofcougar populationsthroughout the state. haryestrLnd success and to determineif therewere We relied on data accumulatedover many years signiticant trends through time. Severaldepen and resultsof studiesin Oregon and other states. dentvariables (bountied cougaLrs, sport harvested Whereasit appearsthere are numerouspieces of cougars.hunter success)were individuallyre- unrelatedinformation relative to cougars.through gressedagainsttime. The analysiswas broken into population modeling we can combinc this infor- two periods:l) 1928-61during the cougar bounry mation in a way that approachesreality and bet- years.and 2) 1970-92when cougarswere hunted ter explainscougar population performance. Our as a big game mammal with an annual limit on objectivesfbr this paperwere to: l)analyzehis- the number of tagsissued per hunt unit. In addi- torical data to help determine status of cougar "other tion, losses"(e.g. depredation, accidents), populationsin Oregon and 2) developa biologi 1980-1992,and damage complaints, l91O-1992, cally intuitive nodel that relies on data that are were used as dependentvariables in simple rc- readily available and which can be createdand gressionsagainst time. Relationshipsbetween usedby managers. dependentand independentvariables were con- sideredsignificant atP ( 0.05.Dunage complaints StudyArea most commonly included complaintsto ODFW Habitatsin Oregonarc diverse.Temperate conif- ftom depredationon livestock and sightings of erousforests dominate the CoastRange and west- cougars on pnvate property where there were ern slope of the Cascades.Several interior val- concernsfor human safety. leys of westernOregon are usedfor agriculture. suchas grass seed production. fruit andvegetable B ologicalParameters llrming.dairl larming.rnd lirestockuperation.. Mary biologicalparzrmeters affecting cougupopu- Most (1377.)of the hummpopulation('3,000.000) Iationsmustbe consideredin modeldevelopment. residein thewestem interior valleys (Levine 1995). Factorsthat affect productivity were age at first Eastofthe CascadeMountains, habitats are drier breeding,birth interval, litter size,sex ratio, and and include coniferousfbrests on the east slope longevity.Factors affecting age-specificmo al- ofthe CascadeRange and in the Blue Mountains; ity includednatural and human causedmorlality shrub steppedominates the southeasternthird of (e.9.sport or depredationharvest, auto collision). the state. Intensive agriculture occurs at lower Severalstudies of cougarsin the westem states elevationsin the Columbia and SnakeRiver ba- andCanadahave reported rcsults relative to these SlnS. tactors (Table 1). We used plausible values for Cougars are distdbutcd statewideexcept for theseparameters based on data collectedmostly areas where agricultural practices and human in Oregonor representativeof cougarpopulations developmenthave alteredhabitat suitability for throughouttheir range. cougars and thet prey. For the most paft, cou- Seidenstickeret al. (1973)believed young te- garsare closely associatedwith deerand elk dis- malesusually breed only afterestablishing ahome tributions in the state.In the 1990s,reports to range.Data collectedin Oregonsupport that hy ODFW of cougarsin urban and suburbanareas pothesis(Trainer and Colly, 1989).Based on these becameincreasingly common. data and rcsults found elsewhere(Table l), we assumedthat all females> 3 yr old and 6970of Methods thosebetween 2 and 3 yr of age breed.Thereaf- A mandatorycheck-in of all cougfs taken dur- ter.females normdly breedsoon after loss of k ittens ing hunting seasonsin Oregon was institutedin or dispersalof their litter (Lindsey 1987)causing 1970,while check-inof cougarskilled on depre- the binh intenal to vary (Table 1). We assumed
16 Keister and Van Dyke TABLE 1. Factorsailecling cougurpopulations and the range ol valuesrepo(ed by various authon.
Producti!it! lac|or Sourcc
Age at first breeding 16-29mo Eaton and Velander 1977 27 3l mo Young and Coldnan 19.46 29mo Rabb 1959 22-)1.r'o Ashmanet al. 1981, Loganet al 1986 20 mL) Lindre) 1987
Bift irlenal 2,1mo Johnsonand Couch 195,1 2.1mo Robinetteet al. l96l 1220 mo Homocker 1970 Ashmanet a]. 1983 l8-21mo Lindze]'1987 12-17mo Lindzel et al. I994 Andcrsonct al. 1992
Lirler sire 2.O Johnsonand Couch 1954 2.5 Hornocker1971 2.5 Eabn and Velander1917 2.6 Anderson1983 2.8 Ashmanet al. 1983 2.1 Logan er al. 1986 2.1 Hemkeret al. 1982 2.1 Lindzeyei al. 199.1 2.8 Toweill er al. 198,1 2.1 To'\'eill et al. 1988 2.4 Trainer et al. 1993
Se\ LJIio (m.nc.lemJleJ 100:100(populadon) Johnsonand Couch 195,1 100:100(population) Tanncr 1975 l15:100(ki!!ens) Ashnan ct al. 1983 l25rl00(haNe\t) AndeNon1983 100:l00lcaplure) Logan et al. 1986 120:100(harvesr) Torveill et a]. 198,1 150:100(harvcs!) Traincr ct al. 1993
Longevit)- 18vr Anderson 1983 1518 !r Young and Coldman 19,f6 l0 yr Johnsonand Couch 1954 1v' Loeanet al. 1986 l2 l7 vr Trainer ct al. I993
Age Speciiic \{orlalit} Racs Adults 107. Johnsonand Couch 195:l Kittens-26'/. Tannefl9l5 Adults 127. Tanner 1975 OveIall 327. Robinerreel al. 1977 Kitlcns 28q. Ashman c! al. 1983 Overall 307 Ashmanet al. 1983 Ovcrall 26 287. L-indzcve! al. 1988 Overall-12f. Andersonet al. 1992 an averagebirthinterval of l9 mo, which is equiva- Documentedlitter sizes are somewhat consis- lcnt ltl a 63% (12 mo/19mo) annualpregnancy tent amongexisting studies(Table l). Littcr size rate. can be indicated by counting cor?ora lutea in
CougarModel 11 harvestedlemales each year However,we do not rates of illegal kill have been difficult to docu- know how long corporalutea may Iast1br cou- ment.Anderson et al.(1992) reported that two of gilrsrnd cory)orrlutea counts tend to o\cr-c.li- 49 radio-markedcougars in an unhuntedpopula mate litter size. We, therefore,used a value of tion jn Coloradowere illegally killed from 1981 2..1kittens/litter in our modelbecause it wasbased through1988. Neal et al. ( 1987)reported I 17.to on fetusesprcscnt in pregnantcougars rather than 167oof 19 markedcougars were lost illegally in corporalutea (Tniner et al. 1993).It wasthe most Nonhern Caljfornia over a two year period. tn recent and complete measurementof litter size Washington,eight of 26 markedcougars were il- for cougarsin Oregon and was similar to values legally killed fiorn 197,1through 1986 (Dave repoftedelsewhere. Brittell, 1987, WashingtonDepanment of Fish Scx ratiosat bifth arecommonly equal whereas andWildlife, personalcommunication). Average sexratios in the harvestare often skewedtoward annual illegal mortality in an ongoing study in llales (Tablc1) duc to eitherhigher vulnerability southwesternOregon was 6.24lr:lbr 65 radio col- of malesor selectionfor malesby hunters.In the laredcougars from 1993through 1998(DeWaine interest of simplicity, we assumedequal sex ra- H. Jackson,1999. Oregon Department ofFish and uos. Wildlife, personalcommunication). In northeastem A widc rangcof longevityvalues has been re- Oregon,one of 27 collaredcougars was illegally (Mark ported (Table L). In Oregon, 22 ot 1,089 (2Va) killedbetween 1989 and 1994 G. Henjum, cougarsaged from 1987 through 1992 wcrc be- 1995, Oregon Departmentof Fish and Wildlife, tween 12 and 17 yr of age(Trainer et al. 1993), personalcommunication). For our model,a value therefbre we used a maximum age of 17 yr for of 3.57cof the adult populationwas chosento this model. representillegal kill for the entire state. "other Age specific,natural mortality ratesare difli- Legallyharvested cougans were added to cult to assessaccurately. Specific moftality mtes losses"and estimatedillegal kill to obtain total arc not availablefor each age (Table 1.).but are human-relatedloss. Based on agesof 1,089cou- necessarylbr modcling.Several authors agree that gars killcd in Oregonbetween 1987 and 1993 kittens, dispersingsubadults, and vcry old cou- (Traineret al. 1993),human-related loss was ap- garsexperience higher mortality thanprime-aged portionedto the 0 to I yr age class at 5.6clo;and adults (Tanncr 1975. Russell 1978,Anderson to the 1 to2yrageclassat 11.47o.However. for' 1983).For ourmodel. the fbllowing natural mor- adults(age 3 to 17yr). we assumedlosses in each talil)'ratcs were assumed: 57. fbr kittens(
CougarModel l9 We conductedsensitivity analysis to determine limjted sport haryest began in l970 (Figurc 2), which factors were nost important in affecting annualharvest increased significantly through l992 population performance.We varied proportion from l0 in 1970to a high of 187in 1992.Hunt- pregnant,litter size, natural mofiality rates,and ing successaveraged 41% duringthe period and "other rates of losses" and illegal kill by 10%, did not declinesignigicantly. Since 1970. dam- then noted the resulting changein cougarpopu- agecomplaints increased signiticantly (Figure 3), lation after 1 yr and 20 yr. as did "other losses"(Figure 4).
Results Popuation model DataAna ys s The modeling proccssallowed the logical com bination of seeminglyunrelated infonnation into Number ofcougars takenannually undcr the bounty an understandableform that helpedexplain cou systen peakedat 337 in 1930 and thereafterde- gar populationtrcnds and statusin Oregon.The clinedto a low of26 in l96l.Analysisofharvest modei indicatedover-exploitation of the popula- databet$'een 1928 and 1961showcd a signifi- tion during the period ofthe bounty system.with cantdecline in cougarsbountied (Figure 1).Since thepopulation reaching alow in 1961andrebound- 350 ing underlimited harvestregulations to a high of 300 2.830in 1992(Figure 5). The modcl was usedto predictpopulation per B zoo formanceunder four scenarios(Table 2). For 1993 E i5o conditions in Oregon, hunted and below carry- ing capacity,5.4% ofthe modeledpopulatlon was 100 3 legally harvested.The lotal monality rate,kitten 50 monality rate,and mortality ratesfor dispelsing 0 juveniles ( l-2 yr-old and2 3 yr-old) wercgreater 25 35 45 55 65 lhanfor an unhuntedpopulrtion belou carrl ing Year(+l9oo) capacity (Table 2). For an unhuntedpopulation Figure L Simple linear regression of number of cougars below carrying capacity.mortality rateswere re- bountied\s. tine in Oregon0:=0 59),1928-1961. duced to natural mortality rates for l-2 yr old.
E Harvest-r- Success 200 70 180 60 160 rao 50 !a Q) {art :F I ''" o - tvv o 9nn o ;'60 20 o40 10 20 0 70 72 74 76 78 80 82 84 86 88 90 92 Year Figure2.Nunrbcr ot har\cstcd cougars andhunter success (7, h Oregon.1970-1992 (No hunter survcy in 198,1and1985).
20 Keister and Van Dykc 180 and adults between3 and 9 yr (Tablc 2). How- 160 ever,the mortality rate tirr kittenswas higher ( 19%). E 14a r,"" becausein addition to the 57. direct ratural mor E .^. tality built into the model,kittens also died when adultfcnalcs dicd of naturalcauses. The mod- eled popul tion .tabili,/edal canling caprcitr througha combinationof decreasedproductivity and increasedmorrality (Table2).
65 70 75 80 35 90 95 Yea. TABLE 2. Char.rcteristicsof a hypotheticalcousar popula- Figurc l. Pol)nomial rcgrcssion of cougar danagc com lion in Oregor deGmined by a snnulationmodel. plaints in Oregon vs. time (r = 0.19), 1970-1992. P0pulalionStatus Ilclow canling At can_virg capnqlJ capQ!1!I Hunrcd Unhuntcd llunlcd Unhunred
Nlolalily Rates(%l 'Iotal 30 21 2r) 26 ci =3a Kittens 3l 21 20 1","r 2l 20 29 3: )1 20 l1 l2 a.r 39]r 16 13 l0 l3vr 2/ 20 3L 32 11-17yr 35 36 Birh Inten'al (mo) l9 t9 )6 l0 5 78 80 A2 84 a6 33 90 92 94 Age Structure (7 ofpopulation) Y€ar KitGns 26 21 23 2i .1. Figure Simplelinear regression ofkno\!n cougarnroltrli- lllr l9 l8 I7 l5 (r = ties fioD other thrn legal harvesl in Ofegon 317rr 55 55 oL) 6l 0.73),1980-1992.
--s- PoDulation--€- Harvest
4,000
3,500
g 3,000 IE 3 2,500 o b 2,000 -6 1 500 j r,ooo
500
0
Fieure 5. Cougarpopulation. as dererm ined from simulation modeling.and han'estin Oregon. I 928 I 992. Cougar\ wcre bountied until I 961.The season\\'as clo\ed until 1970when limited huntins besan.
CougarModcl 21 Age distribution of the modeled population larly on the west sideofthe Cascadesand in cen dependedprimarily on the statusrelative to car- tral Oregon,that increasehas mostly been con- rying capacity rather than on whether it was hunted fined to thoselower elevationareas. (Table 2). Propo ion of 0-2 yr-old animalswas For model development,we input basic bio- greatestfor populations below predicted carry- logical datarelative to productivity and age spe- ing capacity(457ajuveniles: 55% adults). At car- cific motality obtainedfrom numeroussources, q'ing capacity,age strllctureof a huntedpopula- mostly Oregon.We then comparedpopulation tion (,107rjuveniles: 607r adults)was similar to performance (total population mofiality and popu- an unhuntedpopulation (387. juveniles: 62% lationage ratios), as calculated by the model,to adults). resultstrom severaldiff-erent sources. Sensitivityanalysis sho$,ed that l0% changes Comparisonof studiesof wild cougar popu- in litter sizeand proportion pregnantcould change lationswith model simulationsis complicatedfor thepredicted population afier 20 yr by 159Vcnd severalreasons. Researchers are often unableto 143%.A,lOEa change in naturalmortality rate monitor all membersof a particular population had a 117c/ceffect on populationperformance. and small samplesizes are common. Kitten mor- "other In contrast,l07r changesin losses"and tality is olten underestimatedbecause kittens are illegal kill had only 16% and 22% effectson usuallynot found until severalmonths afterbirth. population. Populationstatus (below or at carrying capacity) is often not known or statedin study results.In Discussion addition,researchers have sometimes not defined agesfor kittens,juveniles, and subadultsand have Our analysisof harvestdata agrcedwith Warren sometimesused these terms to representdiffer- W. Aney ( 1973,unpublished letter on file at Or- ent ugedanimul. in differentrtudies. c-ronDepartnent of Fish andWildlilt, Portland). Tn.pite oldilficulties in preciscl5mea\uring who usedlinear rcgression of numberof cougars wild cougarpopulations and comparing with modcl bountiedversus time (19l3 196l) to conclude simulations,results ofseveral studies allow some that if the state'scougar population had contin- compari.onsoI popuJationperlormance in term. ued to decline at the same rate. it would have of mortality rates and age composition.We cal- reachedzero by 1973. Cessationof the bounty culated mortality rates from data presentedby systemin 1961and limited hunting.which be- Hornocker (1970) for a cougar population in a gan in 1970,resulted in significant ncreasesrn cental Idaho wildemess during 196,169. That spofiharvest, with stablehunter success, and in- "other populationreceived light huntingpressure dur- creasesin damagecomplaints and losses". .lud). "other int lhe hutua\ hunleJtor buunty prior to Significantincrcascs in harvest, losses", the late 1950s.Therefore, this Idaho population and damagecomplaints indicate cougarpopula- iikely representedan unhuntedpopulation bclow tions i[ Oregol have grown and addssupport to carryingcapacity. Overull mort ity was 17./,r,with the validityof themodcl. 217o fbrjuveniles and 147,for adults.From data "othcr Increasesin damagecomplaints and collectedin the samearea by Seidenstickeret al. losses"may be somewhatinfluencedby increases ( 1973),$,e calculateda meanof 277ojuveniles in thc state'shuman population. The state'spopu in the populationbetween 196,1 and 1972.These Iationincreased lron -2.092.000to 3,082,000 resultsare similar to mofiality ratesand agecom- (,17%)f'rom I 970 to 199,1(Levine 1995). But in position determinedby our model for a hypothetical the I I eastemcounties that constituteabout half unhuntedpopulation below carrying capacity in the landarea, the humaur population increased only Oregon.Overall mortality was247c with l9clolbr 26E (-116,000),1910-1994. In addition.land kittens,207r, for I 2 yr old, and 8% for adults(3- ownership patterns are such that most human 9 yr-old). The popuJationcomprised 27ola kittens habitation is in morc developed,lowland areas and l87c 1 2 yr-old (Table 2). However,Andcr- andnot in historiccougar habitat. In Oregon,55'lo sonct al. (1992)calculated a lower overallmor- of the land is publicly owned(Levine 1995),most tality rate ( 127.) for a population in Colorado which oi u hichi. locatedat highereler ations: prir ate was unhuntedduring the study,but had beenhunted lands are primarily located at lower elevations. beforethe study.For cougarscaptured during that While humanpopulations have increased, pafiicu- stud)'.46%were kittens and 2l% were 1 2 yr.
22 Keister and Van Dyke Our modelgenerally agreed with lindingsfrom There areparameters that vary fiom year to year .cr errlhuntedpopulations and monalitl rates $ere with weather.such as suryival, productivity. sus- greaterthan lbr unhuntedpopulations. For a hunted ceptibility to human harvest (varies with snow population below carrying capacity, the model conditions),or disease.Whereas we canmeasure predictedmortality rates of 30% total and 3l7o harvest from year to year, we htve no way to for kittens. and an age ratio of 26% kittens and measurcthe other variableson an annualbasis. jq',. | 2)r-oidr lrhlc 2r.The.eproponionqsug- The rest of the variableswere determinedover gestan age ratio ofapproximately 387. (26.0q. + severalyears fiom measurementofdead cougars 9.5%)fbrjuveniles 9 000 8 000 7,000 E 6,000 ,q 5.ooo = b 4.000 z J.uvu 2,000 1,000 0 Figure 6. Modeled cougar populadon ol Oreson with sport hanes! hcld ar 160 cougarvlr after 1992. CougarModel 23 $'hat u'ould happenif spoft harvest$'ere discon- the model will need adjustn]ent.Intensive field tinuedatier 1993but otherhunan-caused losses researchacross the statecould provide indepen continued'l The model predicted the population dent population estimatesthat could be used to would initially increaseat a l370 annualrate. The re-calibratingthc statewidernodel and would al- rateofincrease would declineby year2000. when low developmentof more localized models for densitvdcpendency became a factor,and the popu- smallerareas ofthe state.Sensitivity analysis in- lation would stabilizc in the year 2009 at about dicated that of those factors examined.produc- threetimes the 1993level. lf this hypothesized tivily (i.e. proportionpregnant and litter size)and populationincrease is corect. we shouldsee f!r- mofialily rateshad the greatesteffect on popula- ther increasesin hunran-cougarinteractions that lion pedbrmanceover time: thcrefbre,emphasis ccluldinclude increased damage complaints. more should be focuscd on determining those rates. cougar\Lilled a\ a re\ullol depredrtion.more Producliril). monalitlrate.. lnd lrgeratio. mea sightings.more instancesofcougiLrs in urbanand suredin the field could be comparedto popula- suburbanarcas, ;lnd possibly attackson huntans. tion pefbmance prcdictedby the model.As habitat Anothcrpeninent question was: What harvest conditions and prey populationschange, canl' was necessaryto stabilize the population at the ing capacitiesfor cougarsmay change,afl'ccting 1993level'l To answerthat question,harvest rates thc maximumdensity function in the model. were adjustedafter 1993until the rnodeledpopu- Webclievethis modelhas application tbr other lalionstabilized near the 1993estimatc of 2,960. \l:rtc\lh.rl milnrge couElrrs. Rcfr,rJuctire rrte.. We found that an annualsport harvest rate of28l age specific moftality rates.rates of illegal kill cougars(107. ofthe population)and a totalmor- ijurddepredation loss. estimates of maximum den- talityratc of 35%would be necessary to stabilize sity. and someknowledge ofthc populationlevel the population.Population pedoflnance could bc andtrend arc neededto modelthose cougar popu- testedin the future if methodsallou'ed a signifi- lations. cantincrease in spofihaNest iD Orcgon. Harvest ratescould be increasedto thele!el ncccssaryto Acknowledgements stabilizeor reduccthc popuJationas indicated by We thankR. E. Anglin, M. Conner,S. R. Denncy. the model.We would expecta levelingordecrcase N. Hartmann.M. G. Henjum.D. H. Jackson,T. in damagecomplaints. depredation kills, sightings, W. Keegan.F. Lindzey,E. C. Meslow.H. and other human-cougitrinteractiols Quigle1,, S. J. Riley,C. E. Traincr,C. A. Wheaton.and G. As knowledgcincreases about those param- Witmer for rcviewingprevious drafts of this manu- etersthatconffol the nodcl orasconditions change. script. LiteratureCited Conlribution\to BreedingBiology. Behavi(n. and Husbandry.Clami!orc ResearchIn\tirure. Uni!crsir\, Anderso..A. E. 1983.A criticrl revie$ ol literaturcon pul1lir of \l'ashington,Seattle. $'ashington. ll tlis ctrld)k, ). Coloftdo Di!isit)n of wildlife Sl]e- Hen*ef. T. P. F. G. LindTc). B. B. Ackeman. and r\. J. But cial Rcpoi 5,1.FoI( Collins, Colomdo. ton. 1981.Surlnal of cougarcubs in a non hunted Andcrson.A. E.. D. C. Bo\\den.and D. M. Kattnci 1992. popuhrior. Pages237 312 /n S. D. Miller and D D. The pun on UncolnpahgrePlatcau. Clolorrdo. Colo- E\efett (editort. Proccedirgsofthe IniernalionalClrl rado I)i!ision ol Ulldlife TechnicalPublicatio.,l0. S,vmposium. Kin gs! ille, Tex.rs. Fon Clollins.Cobrado. Homockcr. NL G. I 970. An anall sis of mountain lion preda Ashnrn D., G. C. Christcnscn.NI. C. Hes\. C. K. T\ukamoto. tlon upon mulc dccr and elk in dre Idaho Primi(ire and ivl. S. Wichershrm. 1981.The nrountainlion in ,A.rca.Wildlile Vonograph ll. \e\,ada. Nelada l)cpafim.nl ol Wildlife. Reno. Ne- Homocker, N,l.G. 197l. Suggcstionslbr the managcnrcnro1' nounlain lions as troph! spccics ir lhe intermouD Diron. K. R. 1978.lvlounlain lion. Pages711 727 n J. A. tain region.Pages 399 -1021,Proceedings ofthc Fi[,,- Chapmanand C. A. Fcldhamer(editort. Wild Nianr First Annual Conlerenceof \re\rerD Associali|)n of inals oi Norlh Americ.r: Biolog],. Nlanagemerr!.and StatcCamc and Fish Corlnlrissions.Aspcn. Colorado. Economics.John Hopkins Unilersitt Prcs\.Ballinore. I). IL Jackson.D.Immell, M. C. Boula!.D. Jones.R. Kilbane. I{rryland. V Ored\on. L. lloberlson- D. Nlcalisrer.and J. On Eaton. R. L.. and K. A. \tlander. 1977.Reproductjon in thc 1999. Ecolog] of mounlainlions ir soudnr,estOregon. puma: biolog). bcha\ ior. ard ontogeny.Pages,l5 70 Progress Rcporl. P R. Proiecr W 90 R 5. Oregon 1" R. L. 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Repmduction and vocal behavior 1ncap- Young. S. P, and E. A. Coldmrn. 19'16.The Pu a. Nl,,-sreri- tive pumas.Joumal ol Mannulog1 40:616 617. ousAmcicanClt. Amefica. Wildlile Instirure.\\hsh Robinct|e.\\i L. J S. Gash$'iler.and f). W: \lorris. 1961. irgton,D. C. \oies on cougu produdivlt) and lit! history.Joumr 01\IamDalog! .12:20,1217. Reteivedl3 March 2001 Actepted.for publicqtion 3 August 2001 CougarModel 25