Ecology of mule deer on the Pinon Canyon Maneuver Site, Colorado

Mule deer (Odocoileus hemionus) population dynamics, movements, and habitat use were studied on the Pinon Canyon Maneuver Site in southeastern Colorado during January 1983-December 1984. Thirty-eight adults and 28 fawns were radio collared, and 35 adults were color collared or ear tagged. Population estimates were 365 and 370 deer for 1983 and 1984, respectively. The sex ratio (yearling and adult) was 60 males: 100 females. Adult female pregnancy rate was 95%; the mean litter size for females over 1.5 years was 1.7 fawns. Annual fawn survival was 29% in 1983 and 22% in 1984. Coyote (Canis Iatram) predation was responsible for 76% of fawn mortality. Adult survival was 88% in 1983 and 87% in 1984; coyote predation accounted for 67%, and hunting for 33% of the annual adult mortality. The calculated annual rate of increase (λ) was 1.01, indicating a stable population. Seasonal home range size differed (p < 0.05) between males and females only in the fall. Females preferred pinyon-juniper woodland in all seasons, and shrub grassland in winter, summer and fall; proportional use of woodland/open grassland and shrub/open grassland edge was greater than proportional availability. Males preferred pinyon-juniper woodland and avoided open grassland in all seasons. Fawns preferred shrub grassland and shrub/open grassland edge; they avoided cholla/open grassland edge. Fawns selected bed sites with greater (P < 0.05) concealment cover at all 0.5 m intervals up to 2 m in height, and greater ground cover of trees, shrubs, and grasses (P < 0.01) than random sites.