Habitat and spatial relationships of 47 radio-collared black bears (Ursus americanus) were studied in 1975 and 1976 on 218 km2 of boreal mixedwood forest in east-central Alberta. Mean sizes of areas occupied by bears were larger (P < 0.05) in 1976 when food was scarce than in 1975 when food was abundant; 102 km2 and 39 km2 in 1976 compared to 65 km2 and 19 km2 in 1975 for males and females, respectively. Bears engaged in 2 types of excursionary movements away from areas in which they were usually located. Short-range excursions occurred throughout the non-denning period, typically did not exceed 10 km in distance and 4 days in duration, and resulted in an expansion of areas occupied by bears when natural foods were scarce. Long-range excursions occurred during late summer and fall each year, averaged 23 km in distance and 47 days in duration, and were apparently a response to annual changes in the distribution of preferred foods. Home ranges of females, exclusive of short-range excursions, were generally stable in size and location each year regardless of food abundance. Scat analyses indicated the most important food-bearing plants were vetchling (Lathyrus sp.), wild sarsaparilla (Aralia nudicaulis), bearberry (Arctostaphylos uva-ursi), blueberry (Vaccinium myrtilloides) and hazelnut (Corylus cornuta). Aspen (Populus tremuloides) stands were the most abundant and important food-producing cover type because it contained foods eaten by bears during all seasons, whereas muskeg was the poorest food-producing cover type. Adult females selected aspen (P < 0.05) and avoided muskeg (P < 0.05) when natural foods were scarce; use of cover types reflected availability when natural foods were abundant. No differences were evident in the use of cover types by females with cubs and those without cubs. Adult males selected aspen (P < 0.05) and avoided muskeg (P < 0.05) each year regardless of food availability, and avoided jack pine (Pinus banksiana, P < 0.05) when blueberries were scarce there.
- Volume 6
- Issue
- Pages 81-92
- Publication Date 1 January 1986
- DOI 10.2307/3872809
- File Size 563.36 KB
- Download