Characteristics of a Hunted Mountain Lion Population in Wyoming

Abstract

Population characteristics were estimated from June 1981 to July 1983 for a hunted mountain lion (Felis concolor) population occupying a 741-km2 study area in the Big Horn Mountains, Wyoming. Based on the capture-recapture of 46 lions and radio-telemetry, snow-tracking, and harvest data, winter population densities were estimated at 29 km2/lion (1981-82) and 22 km2/lion (1982-83). Sex ratios of 28 kittens and 22 adults did not differ (P > 0.05) from equality. Kittens, born primarily in autumn, comprised about 50% of the population each winter, and 11 postnatal litters averaged 2.7 kittens. Some juveniles dispersed at about 12-15 months of age; 5 were recovered 9-274 km from their natal areas. Two resident females bred at 13and 19-month intervals. The age structure of both sexes was young, the oldest adult being about 7 years old. Observed mortality the 1st year was 27% of the total population and 0% the 2nd year; immigration apparently compensated for mortalities. Home areas of 4 resident females averaged 67 km2 and overlapped almost completely. Those of the 2 resident males overlapped slightly and averaged 320 km2. Male home areas overlapped several female home areas. J. WILDL. MANAGE. 50(4):648-654 Characteristics of unhunted mountain lion populations have been reported in California (Sitton and Weaver 1977; Hopkins et al., in press) and Utah (Hemker et al. 1984). A lightly hunted lion population was described in Idaho (Hornocker 1969, 1970; Seidensticker et al. 1973), and relatively heavily hunted populations were described in Arizona (Shaw 1977), Colorado (Currier et al. 1977), and Nevada (Ashman et al. 1983). This paper reports characteristics of a hunted lion population in the Big Horn Mountains, Wyoming, from June 1981 to July 1983. Impetus for this study was provided by the lack of detailed biological data on lions in Wyoming; information previously was limited to general status reports. Day and Nelson (1929, cited in Nowak 1976) reported that the species was very scarce, and Young (1946) said it was confined mainly to the western mountains. Long (1965:705) believed the lion was nearly extirpated by the early 1960's. Roop (1971) indicated that lions were scarce and restricted to relatively inaccessible areas. Berg et al. (1983) conducted a mail survey in Wyoming and concluded the state's lion population was stable or had increased during the last 10 years, particularly in the Big Horn Mountains. Long-term resident ranchers and trappers in our study area corroborated this apparent, recent increase in mountain lions. This study was funded by the Wyo. Coop. Fish. and Wildl. Res. Unit and the Wyo. Game and Fish Dep. The Sheridan Work Unit of the U.S. Fish and Wildl. Serv. provided radio-telemetry equipment. Assistance also was provided by the Univ. Wyoming, the U.S. Bur. Land Manage., and the U.S. For. Serv. M. E. Bush, J. Hyde, and J. Childs assisted in a variety of important ways. We also are grateful to C. M. Gillin and H. L. Osborn, our technicians, and to the private landowners who cooperated with us during this study. S. H. Anderson, W. G. Hepworth, E. T. Thorne, T. J. Killough, and R. L. Phillips provided valuable support. We thank M. L. David for typing the manuscript.