Winter ecology and food habits of black bears in Big Bend National Park (Texas, Ursus americanus).

摘要

Black bear (Ursus americanus) reproduction is once again occurring in the Big Bend region of Texas, following extirpation in the mid part of the 1900's. I monitored 10 radio-collared black bears for 15 den-years in Big Bend National Park during 1998–2000. All pregnant females ( n = 5) denned and 1 female with yearlings denned. Females with yearlings (n = 3) remained active during the 1999–2000 winter. Males (n = 4) and solitary females (n = 2) also denned. I located 10 dens of which 4 were cave dens, 3 ground dens, and 3 located in rock piles. The mean (±SE) volume of den sites was 2.2 ± 1.3 m3. Mean elevation (m) for den sites was 1,905 ± 271. The mean date of den entrance for pregnant females ( n = 5) was 24 December ± 21 days and den emergence was 21 April ± 11 days, producing a mean denning period of 118 ± 19 days. Date of den entry (P = 0.058) and duration of denning (P = 0.044) varied among sex and age classes, but date of den emergence did not differ (P = 0.522). Black bears consumed 19 different food items. Plant material composed 98%, 82%, 87%, and 88% of the diet during winter, spring, summer, and fall seasons, respectively.