We monitored size and composition of a southern Utah cougar (Felis con
color) population during 1979-87 to document the dynamics of this unhu
nted population and to test the hypothesis that cougars would regulate
their density at a level below that set by prey abundance alone (Seid
ensticker et al. 1973). We captured cougars when detected during ongoi
ng searches for sign in the study area. Resident adult cougar density
remained relatively constant (0.37/100 km2) for the first 7 years but
increased slightly in the last 2 years. Mule deer (Odocoileus hemionus
), the cougar's primary prey, increased over the 9 years, but magnitud
e of this increase was unknown. Results supported the hypothesis that
cougar density is set by environmental features other than prey abunda
nce alone. Adult resident females bred as young as 17 months and produ
ced litters that averaged 2.4 kittens at an interval of 24.3 months.