Denning Behavior of Black Bears in Boreal Forest of Alberta

Publisher Website
Google Scholar
Abstract
Denning chronology and behavior of black bears (U. americanus) were investigated in east-central Alberta. Instrumented bears (28) were monitored from fall through spring in 1975-1976 and 1976-1977. Adult males exhibited significantly longer movements to den sites than other cohorts. Bear dens usually were located on the periphery of summer ranges or beyond. Bears selected mixed stands of mature aspen (Populus spp.) and spruce (Picea spp.), or mature spruce stands for den sites. Muskeg was avoided. All but 2 dens were excavated beneath ground level or under rootmasses of fallen trees. All chambers were lined with grasses and litter from the immediate proximity of the den. Observed periods of den construction ranged from 5-10 days. Bears entered their dens during a 4 wk period starting Oct. 7, 1975 and during a 5 wk period starting Oct. 1, 1976. Delayed denning in 1975 was attributed to the abundance of blueberries (Vaccinium spp.) that persisted into fall. Denning dates varied among bear cohorts; adult females and subadults denned first and adult males last. The average overwinter weight loss of 11 bears without offspring was 16%. The energy demands of nursing offspring (1 bear) or den abandonment (4 bears) each accounted for an additional 9% overwinter weight loss. Time of emergence from dens spanned the 1st 2 wk of April in both years. Adult males emerged first and females with cubs last. Females with offspring (i.e., females with cubs or yearlings) remained in the vicinity of dens for an average of 17 days (9-23 days) after emergence, whereas bears without offspring (i.e., adult males, subadults and barren females) did so for an average of 7 days (2-13 days).

This publication has 2 references indexed in Scilit: