https://cpw.cvlcollections.org/files/original/67d739b0c956f3f49d16fdffbb410ea1.pdf 14f686d2153fcc82363ecced8ab5b101 PDF Text Text The research in this publication was partially or fully funded by Colorado Parks and Wildlife. Dan Prenzlow, Director, Colorado Parks and Wildlife • Parks and Wildlife Commission: Marvin McDaniel, Chair • Carrie Besnette Hauser, Vice-Chair Marie Haskett, Secretary • Taishya Adams • Betsy Blecha • Charles Garcia • Dallas May • Duke Phillips, IV • Luke B. Schafer • James Jay Tutchton • Eden Vardy �22 (Anderson_lindzey).qxp 6/24/2005 12:39 PM Page 179 COUGAR POPULATION TREND FROM SEX-AGE COMPOSITION 179 Experimental evaluation of population trend and harvest composition in a Wyoming cougar population Charles R. Anderson, Jr. and Frederick G. Lindzey Abstract Cougar (Puma concolor) management has been hindered by inability to identify population trends. We documented changes in sex and age of harvested cougars during an experimentally induced reduction in population size and subsequent recovery to better understand the relationship between sex–age composition and population trend in exploited populations. The cougar population in the Snowy Range, southeast Wyoming, was reduced by increased harvest (treatment phase) from 58 independent cougars (>1 year old) (90% CI = 36–81) in the autumn of 1998 to 20 by the spring of 2000 (mean exploitation rate = 43%) and then increased to 46 by spring 2003 following 3 years of reduced harvests (mean exploitation rate=18%). Pretreatment harvest composition was 63% subadults (1.0–2.5 years old), 23% adult males, and 14% adult females (2 seasons; n = 22). A reduction in subadult harvest, an initial increase followed by a reduction in adult male harvest, and a steady increase in adult female harvest characterized harvest composition trends during the treatment phase. Harvest composition was similar at high and low densities when harvest was light, but proportion of harvested subadult males increased at low density as they replaced adult males removed during the treatment period (high harvest). While sex ratio of harvested cougars alone appears of limited value in identifying population change, when combined with age class the 2 appear to provide an index to population change. Composition of the harvest can be applied to adaptively manage cougar populations where adequate sex and age data are collected from harvested animals. Key words adaptive management, cougar, exploitation, population trend, Puma concolor, sex–age composition Several authors have noted the need for reliable techniques to adequately monitor cougar population changes (e.g., Shaw 1981, Lindzey 1991, Anderson et al. 1992, Riley 1998). While populations have been monitored with long-term, intensive capture efforts over relatively small areas (Ashman et al. 1983, Anderson et al. 1992, Ross and Jalkotzy 1992, Lindzey et al 1994, Logan and Sweanor 2001), reliable and affordable techniques to monitor population trends for large-scale management programs remain elusive. Cougar management traditionally has employed harvest levels to achieve specific population objectives with little understanding of the quantitative effect that differing harvest levels have on cougar population demographics. Sex and age classes of cougars exhibit different and relatively predictable movement patterns (Barnhurst 1986). These differences, in turn, presumably expose each group to differing risks of being harvested. This concept has been applied to managing black bear (Ursus americanus) populations in many western states Address for Charles R. Anderson, Jr.: Zoology and Physiology Department, University of Wyoming, Box 3166, University Station, Laramie, WY 82071, USA; present address: Wyoming Game and Fish Department, 260 Buena Vista, Lander, WY 82520, USA; email: charles.anderson@wgf.state.wy.us. Address for Frederick G. Lindzey: United States Geological Survey, Wyoming Cooperative Fish and Wildlife Research Unit, Box 3166, University Station, Laramie, WY 82071, USA. Wildlife Society Bulletin 2005, 33(1):179–188 Peer refereed �22 (Anderson_lindzey).qxp 180 6/24/2005 12:39 PM Page 180 Wildlife Society Bulletin 2005, 33(1):179–188 (Garshelis 1990). Barnhurst (1986) investigated the vulnerability of cougars to sport hunting as a step toward understanding how to interpret harvest data. He proposed that vulnerability to harvest would be related to the frequency at which differing sex- and age-class cougars cross roads because cougars are generally hunted using trailing hounds, typically from roads or trails. The vulnerability index he developed from road-crossing frequencies suggested that transient males were most vulnerable, followed by resident males, transient females, resident females both without young and with young >6 months old, and finally resident females with young <6 months old. Conceptually, the likelihood of a specific sex or age class of cougar being harvested would reflect its relative abundance in the population multiplied by its relative vulnerability. The least-vulnerable individuals should become prominent in the harvest only after the population had been reduced in size by removal of more vulnerable cougars. Our objective was to test the hypothesis that sex and age composition of the harvest would vary predictably with population size in a cougar population primarily hunted using hounds. Study areas Experimental population The Snowy Range, located in southeast Wyoming about 30 km west of Laramie, was a 2,760-km2 timbered region including a 2,170-km2 portion of the Medicine Bow National Forest surrounded by private, Bureau of Land Management, and state-owned lands. This terminal mountain range was surrounded by sagebrush (Artemisia tridentata) grasslands except on the southern end, where it was connected to contiguous habitat by a 14-km-wide segment of the Medicine Bow Mountains. Cougars occupied about 1,700 km2 of this area during winter. Wyoming State Highway 230 on the west, United States Interstate 80 on the north, the Laramie River and Sand Creek drainages on the east, and Colorado highways 125 and 127 on the south bounded the Snowy Range. The area was topographically diverse, ranging in elevation from about 2,100 m in the valleys to 3,652 m at Medicine Bow Peak. Vegetation communities were dominated by sagebrush grasslands in the peripheral valleys; lodgepole pine (Pinus contorta) stands with interspersed quaking aspen (Populus tremuloides), Rocky Mountain juniper (Juniperus scopulorum), and limber pine (Pinus flexilis) at mid-elevations; and Engelmann spruce (Picea engelmannii)–subalpine fir (Abies lasiocarpa) forests with occasional limber pine at higher elevations (Alexander et al. 1986). Understory dominants in the mid- and highelevation communities included huckleberry (Vaccinium scoparium), buffalo berry (Shepherdia canadensis), serviceberry (Amelanchier alnifolia), snowberry (Symphoricarpos spp.), and common juniper (J. communis). Riparian areas were composed primarily of willow (Salix spp.) with interspersed narrowleaf cottonwood (P. angustifolia) at low elevations. Abundant roads provided good access to most cougar habitat in the Snowy Range. Annual harvest was relatively constant during the 5 years before our study, ranging from 9–12 cougars. Comparison population The northern portion of the Laramie Range included an isolated mountain range near the cities of Casper and Wheatland in southeast Wyoming and encompassed 2,960 km2 of timbered habitat. Elevation ranged from 1,620 m in the eastern valleys to 3,132 m at Laramie Peak. Ponderosa pine (P. ponderosa) stands dominated low to mid elevations, with lodgepole pine common at mid to high elevations. Low-elevation, nonforested regions and interspersed meadows were vegetated by grasses, forbs, and shrubs. Riparian areas consisted primarily of willow with occasional aspen pockets. Other forest species occurring at low levels included limber pine, subalpine fir, Douglas-fir (Pseudotsuga menziesii), and Engelmann spruce. Annual harvest in Laramie Peak averaged 11 cougars during the 5-year period before harvest treatment, ranging from 7–16 cougars per year. The Wyoming Game and Fish Department changed its management objective from sustained harvest of a stable to increasing population to reducing the population through increased harvest in 1996 and increased harvest quotas from 10 to 34 for the next 7 seasons. Regional Wyoming Game and Fish Department personnel believed the Laramie Peak cougar population was at a relatively high density prior to 1996 based on increased cougar sightings, depredation incidents, and hunter interviews. Methods We trailed cougars using hounds and immobilized them upon capture with a mixture of 5 mg/kg �22 (Anderson_lindzey).qxp 6/24/2005 12:39 PM Page 181 Cougar population trend from sex-age composition • Anderson and Lindzey Telazol (Aveco Co., Inc., Cherry Hill, N.J.) and 1 mg/kg xylazine hydrochloride delivered in a hypodermic dart fired from a CO2 pistol; we reversed the effects of xylazine hydrochloride using yohimbine hydrochloride (0.15 mg/kg). We tagged independent cougars (>1 year old and solitary) with standard VHF radiocollars (Model 9D, warranty battery life = 3 years) and dependent young with 22-g ear-tag transmitters (Model 7PN, warranty battery life = 295 days; Advanced Telemetry Systems, Inc., Isanti, Minn.); we equipped transmitters with mortality-sensing options. We also attached a uniquely numbered ear tag to all captured cougars. We recorded sex, age, weight, and morphometric measurements at capture. We estimated age (juvenile <1 year, subadult 1–2.5 years, adult >3 years) from tooth wear, canine ridge eruption, spotting progression, and evidence of previous lactation for females (Shaw 1979, Ashman et al. 1983, Lindzey et al. 1989, Laundre et al. 2000) or known birth date for cougars born to radiocollared females based on female denning behavior. We located radiotagged cougars weekly from fixed-wing aircraft between December 1997 and May 2001 and once per month from June 2001–April 2003. We used radiotelemetry to identify female denning behavior (consecutive locations at the same location), timing of family breakup, and emigration of subadults. We assumed emigration when an individual dispersed from its mother, had not yet exhibited territorial behavior, and we were no longer able to detect its radio signal. We estimated age of juveniles of unknown birth date by applying the growth-curve models developed in the Northern Great Basin (Laundre and Hernandez 2002) after adjusting them for differences detected when comparing model estimates to size of known-age juveniles in the Snowy Range (C. R. Anderson, unpublished data). Experimental design We manipulated size of the Snowy Range cougar population using regulated hunter harvest to reduce and then allow recovery of the population; all cougars harvested during the study except 2 were taken using hounds. The cougar-hunting season was open from 1 September–31 March, but most cougar harvest did not occur until midNovember, when snow conditions were adequate for tracking cougars using trained hounds; >90% of cougars harvested in Wyoming were taken using hounds (Wyoming Game and Fish Department 181 2003). Annual harvest levels were regulated by a quota system in which the season was closed if the quota was met before 31 March. Young (<1 year old) cougars and females with young at side were legally protected from harvest. We concurrently monitored sex and age composition of the population and the harvest and annually tested predictions of harvest composition based on abundance of sexand age-class cougars in the population and their relative harvest vulnerability (Barnhurst 1986). We predicted that harvest composition would be predominantly subadults (possibly more females) during the pretreatment year (high density, low harvest), shift to adult males during the first year of treatment (from high to moderate density, high harvest), shift from adult males to adult females during the second treatment year (from moderate to low density, high harvest), and return to subadults during the post-treatment period (increasing population, low harvest) where the subadult segment would initially consist primarily of males and eventually consist primarily of females as the population approached pretreatment levels. We examined annual changes in harvest composition of adult males, adult females, and subadults using the Fisher’s exact test; we applied 1-tailed tests to compare the first 4 seasons where changes were predicted and 2-tailed tests to examine the recovery period when composition was not expected to change greatly. We also examined the relationship between proportion of adults in the female harvest and estimated harvest rate using simple linear regression analysis, expecting adult female harvest composition to increase with harvest level. We then compared harvest composition documented in the Snowy Range to that observed in Laramie Peak. Although we did not monitor density in this area, it represented a geographic population (i.e., occupied cougar habitat surrounded by inhospitable, unoccupied landscapes) similar to the Snowy Range, contained a similar amount of cougar habitat, had adequate hunter access to facilitate population reduction, and the population was exposed to harvest levels similar to those we applied in the Snowy Range before and during the treatment period. We assumed that harvest composition from this area would show similar trends to those documented in the Snowy Range if harvest composition changed predictably with population size in harvested populations. We tested for differences in annual harvest composition between populations using the Fisher’s exact test (2-tailed). We �22 (Anderson_lindzey).qxp 182 6/24/2005 12:39 PM Page 182 Wildlife Society Bulletin 2005, 33(1):179–188 also determined ages from counts of cementum annuli of harvested adult females in both populations to determine whether age of adult females declined as the population declined following high harvest levels. Age-class estimates We assigned harvested and captured cougars to age class based on tooth wear, presence or absence of a canine ridge, evidence of spots or foreleg bars, evidence of previous lactation if female (Anderson and Lindzey 2000), and counts of bands in the cementum of premolars removed from harvested cougars. We first gave priority to evidence of previous lactation in females (subadult: nipples white and ~4–6 mm wide; adult: nipples dark or mottled and ~8–10 mm wide), followed by annuli age (subadult=1–2 yr), canine ridge eruption (absent= subadult), and finally foreleg bars (dark = subadult or young adult) and spots (present = subadult or young adult). To evaluate reliability of our aging techniques, we compared ages estimated from counts of cementum bands to ages estimated with the other criteria for those cougars that were captured and later harvested. Population estimates During the first winter (Dec 1997–Apr 1998), we conducted intensive capture efforts in 2 regions of the Snowy Range to obtain an initial density estimate and to create a marked sample for subsequent mark–recapture efforts. We captured cougars in a 439-km2 area in the southeast region and a 382-km2 area in the west-central region of the Snowy Range; 90% of cougar harvests in the Snowy Range came from these primarily public land areas (Wyoming Game and Fish Department mountain lion harvest data base, Lander, Wyo.). We estimated density for the 2 areas by summing number of cougars marked and tracks of known, unmarked cougars. We included unmarked cougars only if track characteristics (identified as male or female via planter pad width and stride length; Fjelline and Mansfield 1988) and number and size of young accompanying a female suggested a unique individual and when tracks were located outside traditional use areas of radiocollared cougars identified from previous telemetry locations. The initial density estimates from the 2 areas were then applied to the remainder of cougar habitat in the Snowy Range to estimate population size for the study area. Cougar habitat was delineated using elevations and topography used by radiocollared cougars February–April, 1998. We applied the Lincoln-Peterson estimator (Pollock et al. 1990) to calculate annual, pre-hunting-season (autumn) population estimates of independent cougars. Post-hunting-season (spring) population estimates were pre-season estimates minus harvest removals and estimated natural mortality from our marked sample. We attempted to meet assumptions of the technique by modifying our sampling design and using information from radiotagged cougars. We addressed geographic closure by recapturing during late autumn and winter months when emigration and immigration were least likely (Ross and Jalkotzy 1992). We addressed the demographic closure assumption by adjusting for deaths based on records from radiocollared cougars and by considering young cougars in our marked sample independent at the mean age family groups became loosely associated (prior to dispersal), and thus available for recapture (e.g., harvest), by the beginning of the recapture period (15 Nov, average date of sufficient snow for hunting). Because cougar captures relied heavily on adequate snow conditions for tracking that varied temporally and spatially, maintaining equal capture effort throughout the study area was not possible and reduced our ability to assure equal capture probabilities across cougars. To minimize potential biases from capture heterogeneity and provide sufficient time to sample the entire study area, we treated the entire winter sampling period (15 Nov–31 Mar) as a single capture effort and counted each individual detected only once in the recapture sample regardless of the number of times they were actually detected. Because captured cougars remained ear-tagged throughout the study but transmitter failures occasionally occurred, we assumed individuals that had established territories prior to transmitter failure and that had been monitored until the previous summer were still in the population and available during the following winter recapture period; on 10 of 12 occasions where transmitters failed, marked residents were subsequently recaptured or harvested. The capture sample was independent, radiotagged cougars in the population at the beginning of the recapture sampling period (15 Nov) during both treatment and recovery periods. The recapture sample was cougars harvested by hunters during the hunting seasons of the treatment periods, but, because harvests were intentionally reduced during the recovery period (winters of 2000–2001, �22 (Anderson_lindzey).qxp 6/24/2005 12:39 PM Page 183 Cougar population trend from sex-age composition • Anderson and Lindzey 2001–2002, and 2002–2003), we augmented the recapture sample by hunting the study area after hunters had finished. During our hunting we tagged and released unmarked cougars, recorded marked cougars recaptured, and recorded presence of individual, unmarked cougars (defined earlier) we were unable to capture. We included cougars marked in the population prior to 15 November each year in our initial capture sample and those captured from 15 November–31 March in our recapture sample. We recorded capture effort as number of hunter days for successful hunters (no data for unsuccessful hunters) and number of days spent tracking and capturing cougars by study personnel. Post-season population estimates were preseason estimates minus harvest and mortality from other causes estimated from our marked sample during the recapture period. We estimated 90% confidence intervals around pre-season population estimates following Pollock et al. (1990). We estimated autumn sex and age composition of the population by adding unmarked cougars harvested during that year’s hunting season to our sample of marked cougars. Results 183 became independent at an average age of 14 months (range = 11–17 months, n = 7); 2 litters became independent following the death of their mother at 14 and 17 months old (1 natural, 1 harvest). Association among family members became progressively looser over the month before independence. Thus, to account for recruitment in our recapture sample, we included marked dependent young as subadults if they were 13 months of age by 15 November each season. Emigration occurred between April and September for 8 of 9 emigrants monitored; 1 subadult male emigrated during January. Population estimates We tagged 18 cougars in the study area and identified 6 others from tracks after 60 days of trapping and tracking in the southeast and 45 days in the west-central section of the Snowy Range during winter 1997–1998. We estimated independent cougar density at 3.42/100 km2 in the southeast (15 cougars/439 km2 × 100) and 2.35/100 km2 in the west-central region (9 cougars/383 km2 × 100). Cougar habitat in the Snowy Range during this period, estimated from characteristics of habitat used by marked cougars February–April 1998, was 1,720 km2. We estimated 50 independent cougars in the Snowy Range in spring 1998 (45–55 depending on the density estimate applied). A harvest quota of 25 was then set for the next 2 hunting seasons (treatment; 1998–1999 and 1999–2000) to elicit the desired (about 50%) reduction in the Snowy Range cougar population. Harvests were 25 and 17 cougars for the 2 treatment seasons, resulting in an estimated population of 20 independent cougars by spring 2000 (Table 1). Harvest quotas were then reduced to 6–8 cougars per season to facilitate population recov- We tagged 16 independent and 13 dependent male and 17 independent and 15 dependent female cougars between December 1997 and February 2002. Twenty-one marked, independent cougars were harvested during the treatment and recovery phases of the project, and 9 marked cougars (5 adult males, 4 adult females) were alive at the end of the study. Cougar ages estimated using cementum annuli counts were in agreement with other aging criteria in 14 of 18 comparisons and within 1 year for 3 others (Anderson 2003). We noted that ages of dependent young of known birth date in Table 1. Pre (autumn) and post-harvest (spring) cougar population estimatesa from the Snowy Range, Wyoming, USA, autumn 1998–spring 2003. Note population decline following 2 the Snowy Range were years of high harvest and population increase following 3 years of light harvest. consistently underestimated (x– =1.47 mo, SD=1.26, No. % natural n2 m2 n̂pre (90% CI) n̂post n1 n=13) using the Northern Season harvested mortality Great Basin growth-curve 1998/99 15 25 6 58 (36–81) 25 11 30 19 17 8 39 (28–50) 17 9 20 models (Laundre and 1999/00 15 21 9 34 (26–42) 8 0 26 Hernandez 2002) and 2000/01 2001/02 15 25 10 37 (29–44) 6 0 31 therefore added the mean 2002/03 11 39 7 59 (42–76) 8 9 46 difference to estimate a n̂ pre = [(n1 + 1)(n2 + 1) / (m2 + 1)] – 1, where n1 = number marked and released in first ages for litters of sample, n2 = number captured in second sample, and m2 = number captured in second samunknown birth date. ple that were marked from first sample. n̂post = (n̂pre – harvest) – [(% natural mortality) (n̂pre Dependent cougars – harvest)]. �22 (Anderson_lindzey).qxp 184 6/24/2005 12:39 PM Page 184 Wildlife Society Bulletin 2005, 33(1):179–188 ery. The population increased to an estimated 46 independent cougars by spring 2003 (Table 1). The number of hunter-days totaled 47 and 79 during the 2-year treatment period and 27, 50, and 21 days during the 3-year recovery period; high hunter effort during the second treatment year and the second recovery year were due to excessive time spent hunting by an individual hunter each year (30 and 36 days, respectively). We spent 60, 54, and 68 days tracking and marking cougars to augment the recapture sample during the recovery phase. Cougar harvest composition in response to manipulation Cougar harvest (n = 22) composition during the pretreatment period was composed primarily of subadults (36% F, 27% M) followed by adult males (23%) and finally adult females (14%; Figure 1). As harvest levels increased and the population declined in size, there was an initial increase (40%) followed by a decrease (24%) in proportion of adult males in the harvest and a consistent increase in the proportion of adult females (14 to 24 to 41%). Subadult harvest declined from the pretreatment period (from 63 to 36%) but was consistent during the treatment period (35%) and was primarily composed of females (28 and 29%). Subadult cougars again dominated the harvest after harvest quotas were reduced, but subadult male composition was relatively higher than during pretreatment and treatment periods until the third year of recovery when the population returned to pretreatment levels. Annual harvest composition among adult males, adult females, and subadults differed significantly (P < 0.034) from the pretreatment period through the first year post-treatment and was similar (P>0.664) during the 3-year recovery phase. We compared harvest records from Laramie Peak, the comparison population, to harvest records from the Snowy Range including the first 3 years of harvest (harvest levels below quota) in Laramie Peak and 2 years of harvest treatment and the first year post-treatment in the Snowy Range. During the 3-year period, harvest declined and pri- Figure 1. Sex–age composition of cougar harvest (pie charts) from the Snowy Range, Wyoming, relative to population change through increased (1998–2000) and reduced (2000–2003) harvest levels (order of sex–age classes in bar graphs follow pie charts). Harvest composition and rate prior to 1999 represent harvest years 1996–1997 and 1997–1998 combined (first column). The population estimate for spring 1998 was determined from mountain lion density detected from capture and tracking efforts during winter 1997–1998; subsequent population estimates were derived using mark–recapture methods. Error bars represent 90% confidence intervals. Number of cougars known to be in the population each spring were 22, 12, 15, 18, 20, and 34, respectively. �22 (Anderson_lindzey).qxp 6/24/2005 12:39 PM Page 185 Cougar population trend from sex-age composition • Anderson and Lindzey marily consisted of adult males initially, followed by adult females, and finally subadults in both populations (Figure 2); annual harvest composition was similar between populations (P > 0.217). Mean annuli age of adult females declined following the first treatment year from 6–8 years old to 3–4 years old the second year in both populations. Unlike the Snowy Range, unrestricted harvests continued in Laramie Peak for the next 4 years, resulting in annual oscillations in harvest level and harvests of primarily subadults (Figure 2); adult females averaged 4.3 years of age during this period. Characteristics of female cougar harvest We noted that proportion of adults in the female harvest increased with harvest rate, ranging from 20% with a 21% harvest rate to 58% with a harvest rate of about 44% (Figure 1), but this relationship was not statistically significant (r2 =0.40, F1,6 =3.32, P = 0.13). Sixteen adult and 19 subadult females were harvested (total harvest = 64) in the Snowy Range during the 2-year treatment and 3-year posttreatment periods. Of 8 marked adult females har- 185 vested, 4 were without young, 3 had young at the time, and we suspect the last female may have had young when harvested because we had seen kitten tracks with her 2 months earlier. All harvested females with young were taken during the treatment period (>40% harvest rate). Discussion The Snowy Range cougar population recovered in numbers after 2 years of intensive harvest (~43% of independent cougars) followed by 3 years of light harvest (~18% of independent cougars). Recovery of the population was facilitated by immigration of males and recruitment of females from within the population as found in other recovering cougar populations (Lindzey et al. 1992, Logan and Sweanor 2001). Composition of the harvest from pretreatment through the 2 years of heavy harvest supported our predictions based on predicted relative vulnerability of the various sex and age classes. The most vulnerable classes were harvested until their reduced abundance in the population Figure 2. Comparison of total harvests (bar graphs) and harvest composition (sex–age class; pie charts) from Laramie Peak and the Snowy Range in southeast Wyoming. Cougar harvest quotas were not met, except in the Snowy Range during years 1 and 3. Note similarities in harvest levels and composition between populations exposed to similar harvest treatments. �22 (Anderson_lindzey).qxp 186 6/24/2005 12:39 PM Page 186 Wildlife Society Bulletin 2005, 33(1):179–188 exposed the next most vulnerable class, terminating in a harvest dominated by adult females (Figure 1). The increase in adult females in the harvests coincided with a decrease in size of this hunted population, suggesting that proportion of adult females in harvests may be a useful indicator of trends in other hunted cougar populations. The similarity of composition trends in the Snowy Range and Laramie Peak populations during the initial years of intensive harvest suggests that the intensive harvest in the Laramie Peak population had achieved its goal of reducing population size in this area. Decline in average age of harvested females in both populations further suggested that harvests had similar effects on the 2 populations. While factors other than composition of hunted cougar populations (e.g., weather patterns, changes in legal access) can influence harvest level, none should result in adult females dominating the harvest if they are not proportionately the most abundant sex or age class present in the population. Experienced cougar hunters often can differentiate males and females from track size, presence of scrapes, or body characteristics if the cougar is seen, but selective hunters tend to harvest males. Further, our experience suggests that hunters tend to be most selective when competition for available cougars is low. When demand exceeds harvest quotas, competition among hunters appears to result in less-selective hunting, and harvest should reflect the relative abundance or vulnerability of sex and age classes. Snow conditions also can affect hunting success (>90% of cougars harvested in Wyoming are hunted using hounds and most require snow cover), but this should influence harvest rate, not the relative vulnerability of the sex and age classes. Access, influenced by weather events or land-ownership patterns, can create ephemeral or more permanent refuges within cougar management areas. In these situations harvests may be maintained by adjacent, unavailable adult females providing young females for the harvest (e.g., Figure 2). We identified areas of suitable cougar habitat in the Laramie Peak area that received no cougar harvest and apparently were functioning as refuges. The similar abundance of subadult females in the pretreatment Snowy Range harvest and post-treatment harvests from Laramie Peak illustrates the contribution of refuges to maintaining harvests and underscores the need to monitor harvest composition over a number of years before drawing inferences about trend in the pop- ulation from harvest composition. Subadult females in the pretreatment Snowy Range harvest reflected their relative abundance and vulnerability to harvest, while their dominance in later harvests from Laramie Peak apparently reflected their abundance in the portion of the area accessible to hunters. Examination of composition of earlier harvests should help identify whether the harvest reflects a lightly hunted population or one that has been reduced with harvests being supported by young produced by adjacent, unavailable adult females. Prior harvests in the Laramie Peak area were composed of progressively more adult females, suggesting the population had been reduced in size. Management implications Cougar managers typically have used harvest level and occasionally sub-quotas typically aimed at protecting females to achieve population objectives, although both imply knowledge of population size. While observations suggest that cougar populations can sustain harvest rates of up to 20–30% (Ashman et al. 1983, Ross and Jalkotzy 1992), the effect of harvests on populations will differ depending on sex and age of cougars removed. Harvest of males, the cohort most easily replaced by immigration, and subadult females, which can be quickly replaced by female young produced in the population, will have less impact on the population than harvest of adult females, which are more difficult to replace. Adult females that die are most often replaced by the population’s female progeny and less often by immigrating subadults because most female progeny are philopatric (Lindzey et al. 1989, Duggin Wroe’s dog, Luna, corners male cougar number 610. Photo by Hall Sawyer. �22 (Anderson_lindzey).qxp 6/24/2005 12:39 PM Page 187 Cougar population trend from sex-age composition • Anderson and Lindzey Anderson et al. 1992, Logan and Sweanor 2001). Monitoring levels of adult females in cougar harvests to index the effect the harvest is having on the population is intuitive. Sensitivity analyses by Martorello and Beausoleil (2003) suggest that cougar populations are most sensitive to survival of this sex and age class. Adult females provide the resiliency in a population that allows it to respond to loss of members. This approach will work well in an adaptive management framework, where harvest composition goals are set to achieve specific population objectives. Hunting programs can simply be modified until harvest composition indicates that desired population and recreation objectives are being met. The proportion of adult females in the Snowy Range harvest when the more vulnerable sex and age classes had been removed and the population was beginning to decline was about 25%, while the population appeared to sustain a harvest composed of 10–15% adult females (Figure 1). The 25% estimate came from a single experiment and should be used with caution in other programs because cougar populations more isolated than the Snowy Range or that contain more refuge areas may respond differently to similar harvest rates of adult females. Also, because harvest from a single management area in a single year may be too small to support inferences, and harvest level may vary because of weather events, combining years or adjacent management areas for analyses may be appropriate. Acknowledgments. The Wyoming Game and Fish Department, Wyoming Animal Damage Management Board, and the Pope and Young Club funded this project. We thank D.Wroe,T. Barkhurst, S. Keller, and J. Talbott for cougar captures. Field assistance from J. Sherwood, H. Cruickshank, L. Johnson, H. Sawyer, T. Chapman, R. Grogan, S. Rothmeyer, J. Koloski, and M. Hooker was appreciated. Thanks to D. France of France Flying Service, Rawlins, WY for aerial telemetry. Wyoming Game and Fish Department personnel from the Laramie Region and the Trophy Game Section were helpful throughout the project. This project would not have been possible without cooperation of the landowners surrounding the Snowy Range. Suggestions by C. L. Hayes and G. P. Keister improved the manuscript. Capture protocols were reviewed and approved by the University of Wyoming Animal Care and Use Committee (form No. A-3216-01). 187 Literature cited ALEXANDER, R. R., G. R. HOFFMAN, AND J. M. WIRSING. 1986. Forest vegetation of the Medicine Bow National Forest in southeastern Wyoming: a habitat type classification. United States Department of Agriculture Forest Service Research Paper RM-271, Rocky Mountain Range Experiment Station, Fort Collins, Colorado, USA. ANDERSON,A. E., D. C. BOWDEN, AND D. M. KATTNER. 1992. The puma on the Uncompahgre Plateau, Colorado. Colorado Division of Wildlife Technical Publication No. 40, Fort Collins, USA. ANDERSON, C. R., JR. 2003. Cougar ecology, management, and population genetics in Wyoming. Dissertation, University of Wyoming, Laramie, USA. ANDERSON, C. R., JR., AND F. G. LINDZEY. 2000. A photographic guide to estimating cougar age classes. Wyoming Cooperative Fish and Wildlife Research Unit, Laramie, USA. ASHMAN, D. L., G. C. CHRISTENSEN, M. L. HESS, G. K.TSUKAMOTO, AND M. S.WICKERSHAM. 1983. The mountain lion in Nevada. Nevada Department of Wildlife, Federal Aid in Wildlife Restoration Project W-48–15, Final Report. BARNHURST, D. 1986. Vulnerability of cougars to hunting. Thesis, Utah State University, Logan, USA. FJELLINE, D. P., AND T. M. MANSFIELD. 1988. Method to standardize the procedure for measuring mountain lion tracks. Pages 49–51 in R. H. Smith, editor. Proceedings of the Third Mountain Lion Workshop. Arizona Game and Fish Department, Phoenix, USA. GARSHELIS, D. L. 1990. Monitoring effects of harvest on black bear populations in North America: a review and evaluation of techniques. Proceedings of the Eastern Workshop of Black Bear Research and Management 10: 120–144. LAUNDRE, J.W., AND L. HERNANDEZ. 2002. Growth curve models and age estimation of young cougars in the Northern Great Basin. Journal of Wildlife Management 66: 849–859. LAUNDRE, J.W., L. HERNANDEZ, D. STREUBEL, K. ALTENDORF, AND C. L. GONZALEZ. 2000. Aging mountain lions using gum-line recession. Wildlife Society Bulletin 28: 963–966. LINDZEY, F. G. 1991. Needs for mountain lion research and special management studies. Pages 86–94 in C. E. Braun, editor. Mountain lion–human interactions symposium. Colorado Division of Wildlife, 24–26 April 1991, Denver, USA. LINDZEY, F. G., B. B.ACKERMAN, D. BARNHURST,T. BECKER,T. P. HEMKER, S. P. LAING, C. MECHAM,W. D.VAN SICKLE. 1989. Boulder-Escalante cougar project, Final Report. Utah Division of Wildlife Research, Salt Lake City, USA. LINDZEY, F. G., W. D. VAN SICKLE, B. B. ACKERMAN, D. BARNHURST, T. P. HEMKER, S. P. LAING. 1994. Cougar population dynamics in southern Utah. Journal of Wildlife Management 58:619–624. LINDZEY, F. G.,W. D.VAN SICKLE, S. P. LAING, AND C. S. MECHAM. 1992. Cougar population response to manipulation in southern Utah. Wildlife Society Bulletin 20: 224–227. LOGAN, K.A., AND L. L. SWEANOR. 2001. Desert puma: evolutionary ecology and conservation of an enduring carnivore. Island Press,Washington, D.C., USA. MARTORELLO, D. A., AND R. A. BEAUSOLEIL. 2003. Characteristics of cougar harvest with and without the use of dogs. Pages 129–135 in S. A. Becker, D. D. Bjornlie, F. G. Lindzey, and D. S. Moody, editors. Proceedings of the Seventh Mountain Lion Workshop, May 15–17, 2003. Wyoming Game and Fish Department, Lander, USA. POLLOCK, K. H., J. D. NICHOLS, C. BROWNIE, AND J. E. HINES. 1990. Statistical inference for capture–recapture experiments. �22 (Anderson_lindzey).qxp 188 6/24/2005 12:39 PM Page 188 Wildlife Society Bulletin 2005, 33(1):179–188 Wildlife Monograph No. 107. RILEY, S. J. 1998. Integration of environmental, biological, and human dimensions for management of mountain lions. Dissertation, Cornell University, Ithaca, New York, USA. ROSS, P. I., AND M. G. JALKOTZY. 1992. Characteristics of a hunted population of cougars in southwestern Alberta. Journal of Wildlife Management 56: 417–426. SHAW, H. G. 1979. Mountain lion field guide. Arizona Game and Fish Department Special Report No. 9, Phoenix, USA. SHAW, H. G. 1981. Comparison of mountain lion predation on cattle on two study areas in Arizona. Pages 306–316 in L. Nelson and J. M. Peek editors. Proceedings of the Wildlife Livestock Relationships Symposium. University of Idaho Forest,Wildlife, and Range Experiment Station, Moscow, USA. WYOMING GAME AND FISH DEPARTMENT. 2003. Annual mountain lion mortality summary harvest year 2002. Trophy Game Section, Lander,Wyoming, USA. Fred Lindzey (above) is the assistant unit leader for the Wyoming Cooperative Fish and Wildlife Research Unit, and an associate professor in the Department of Zoology and Physiology at the University of Wyoming. He received his B.S. from Texas A&M, his M.S. from Utah State University, and his Ph.D. from Oregon State University. Fred’s current research interests focus primarily on big game and predator ecology. Chuck Anderson (above) is a wildlife biologist with the Wyoming Game and Fish Department. Chuck received his B.S in wildlife biology from Colorado State University and his M.S. and Ph.D. in zoology and physiology from the University of Wyoming. His research interests have focused on largemammal ecology and management with emphasis on sampling populations, population dynamics, and genetics. Chuck has been a member of The Wildlife Society since 1989. Associate editor: Crête � Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Journal Articles Description An account of the resource CPW peer-reviewed journal publications Text A resource consisting primarily of words for reading. Examples include books, letters, dissertations, poems, newspapers, articles, archives of mailing lists. Note that facsimiles or images of texts are still of the genre Text. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Experimental evaluation of population trend and harvest composition in a Wyoming cougar population Rights Information about rights held in and over the resource <a href="http://rightsstatements.org/vocab/InC-NC/1.0/" target="_blank" rel="noreferrer noopener">In Copyright - Non-Commercial Use Permitted</a> Date Created Date of creation of the resource. 2010-12-13 Subject The topic of the resource Adaptive management Cougar Exploitation Population trend <em>Puma concolor</em> Sex–age composition Description An account of the resource <span>Cougar (</span><i>Puma concolor</i><span>) management has been hindered by inability to identify population trends. We documented changes in sex and age of harvested cougars during an experimentally induced reduction in population size and subsequent recovery to better understand the relationship between sex-age composition and population trend in exploited populations. The cougar population in the Snowy Range, southeast Wyoming, was reduced by increased harvest (treatment phase) from 58 independent cougars (&gt;1 year old) (90% C***l = 36–81) in the autumn of 1998 to 20 by the spring of 2000 (mean exploitation rate = 43%) and then increased to 46 by spring 2003 following 3 years of reduced harvests (mean exploitation rate = 18%). Pretreatment harvest composition was 63% subadults (1.0–2.5 years old), 23% adult males, and 14% adult females (2 seasons; </span><i>n</i><span> = 22). A reduction in subadult harvest, an initial increase followed by a reduction in adult male harvest, and a steady increase in adult female harvest characterized harvest composition trends during the treatment phase. Harvest composition was similar at high and low densities when harvest was light, but proportion of harvested subadult males increased at low density as they replaced adult males removed during the treatment period (high harvest). While sex ratio of harvested cougars alone appears of limited value in identifying population change, when combined with age class the 2 appear to provide an index to population change. Composition of the harvest can be applied to adaptively manage cougar populations where adequate sex and age data are collected from harvested animals.</span> Creator An entity primarily responsible for making the resource Anderson Jr, Charles R. Lindzey, Frederick G. Language A language of the resource English Is Part Of A related resource in which the described resource is physically or logically included. Wildlife Society Bulletin Format The file format, physical medium, or dimensions of the resource application/pdf Extent The size or duration of the resource. 10 pages Bibliographic Citation A bibliographic reference for the resource. Recommended practice is to include sufficient bibliographic detail to identify the resource as unambiguously as possible. Anderson, C. R. Jr, and F. G. Lindzey. 2005. Experimental evaluation of population trend and harvest composition in a Wyoming cougar population. Wildlife Society Bulletin 33:179-188. <a href="https://doi.org/10.2193/0091-7648(2005)33%5B179:EEOPTA%5D2.0.CO;2" target="_blank" rel="noreferrer noopener">https://doi.org/10.2193/0091-7648(2005)33[179:EEOPTA]2.0.CO;2</a> Type The nature or genre of the resource Article