From 1988 to 1991 we observed the denning activity of 27 radio-collared black bears (Ursus americanus) at 57 dens on the Tanana River Flats, near Fairbanks, Alaska. This is the northernmost population of black bears studied using radio telemetry, and nears the northern extreme of their range. We compared differences in den chronology, morphology, and habitat use, among sex, age, and reproductive classes. All bears pooled across all years gave a mean den entry date of 1 October, a mean emergence date of 21 April, and a mean den period of 205 days. Females denned earlier (30 Sep vs. 4 Oct), emerged later (23 Apr vs. 15 Apr), and had longer den periods (208 days vs. 195 days) than males. No significant differences were observed in denning chronology between adults and subadults, or among female reproductive classes. Differences in den characteristics between sex, age, and female reproductive classes were generally insignificant, except that males had larger dens than females, and females denning with young had the largest dens among the female reproductive classes. Most dens were excavated (83%, n = 41), and all contained nesting material. Reuse was low (18%, n = 34) and 10 dens (29%) were flooded to varying levels. Bears significantly favored willow/alder and black spruce habitat types for den sites, avoiding marshland and heath meadow habitat types.
- Volume 9
- Issue
- Pages 513-522
- Publication Date 1 January 1994
- DOI 10.2307/3872739
- File Size 411.36 KB
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