Habitat
The American black bear requires a mosaic of vegetation associations rather than one plant community, so habitat diversity is important. Generally inhabits forested habitats from sea level to alpine areas. Prefer semi- open areas with fruit-bearing shrubs and herbs, lush grasses, and succulent forbs. Extensive open areas are avoided (ADF&G 1973, Lariviere 2001). In general, meadows are preferred for foraging on grasses and forbs during spring. Riparian habitat, avalanche chutes, and early-successional habitat created by logging or fire are preferred for foraging during summer, and mature forest containing hard mast is preferred during fall. For denning and cover, mature or old-growth forest containing coarse woody debris, snags, and adequate cover are typically preferred (ULEV 2007). In the Yukon-Tanana uplands of interior Alaska, preferred spring forage areas with riverbottoms containing brush ≥2.5 feet (0.8 m) tall and paper birch (Betula papyrifera), quaking aspen (Populus tremuloides), and black cottonwood (P. balsamifera ssp. Trichocarpa). Riverbottoms contained new green leaves and abundant horsetail (Equisetum spp.), which composed 86% of their spring diet. During summer, American black bears preferred foraging for bog blueberries (Vaccinium uliginosum) in “old” burns (age not given) dominated by willow (Salix spp.), alder (Alnus spp.), and dwarf birch (B. nana; Hatler 1972). On the Kenai Peninsula, American black bears denned in 2 major vegetation types: “regrowth” boreal upland forest (67% of dens, “regrowth” not defined ) and “mature” boreal upland forest (31% of dens, “mature” not defined). At high elevations of the Kenai Peninsula and the Susitna River Basin, caves and excavated dens under large boulders and rockpiles were used most often because few trees attained large diameters. In virgin coastal rain forest at low elevations of the Kenai Peninsula, large-diameter western hemlock, white spruce (Picea glauca), and black spruce were preferred for denning. At low elevations in the Susitna River Basin, American black bears preferred denning in alder draws with spruce or paper birch. In Prince William Sound, excavated dens at low elevations were more prone to flooding at low altitudes and were not used as often as tree dens or rock caves (Schwartz et al. 1987). In southeastern Alaska, American black bears preferred den sites located in windstorm-protected forest (58%) over windstorm-prone forest (6%). In windstorm-protected forest, large, hollow trees (>35 inches (88 cm)) were least prone to wind damage. Density of large trees was twice that of the windstorm-prone forest and the forest was in later successional stages (DeGayner et al. 2005).
References
ADF&G. 1973. Alaska’s wildlife and habitat. Anchorage, Alaska. 144 pp. + maps.
DeGayner, E. J., M. G. Kramer, J. G. Doerr, and M. J. Robertsen. 2005. Windstorm disturbance effects on forest structure and black bear dens in southeast Alaska. Ecological Applications. 15(4): 1306-1316.
Hatler, D. F. 1972. Food habits of black bears in interior Alaska. The Canadian Field-Naturalist. 86(1): 17- 31.
Lariviere, S. 2001. Ursus americanus. Mammalian Species 647: 1-11.
Schwartz, C. C., S. D. Miller, and A. W. Franzmann. 1987. Denning ecology of three black bear populations in Alaska. In: P. Zager, ed. Bears-their biology and management: Proceedings, 7th international conference on bear research and management; 1986 February-March; Williamsburg, VA; Plitvice Lakes, Yugoslavia. [Place of publication unknown]: International Association of Bear Research and Management: 281-291.
Ulev, E. 2007. Ursus americanus. In: Fire Effects Information System, [Online]. USDA, USFS, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [2011, July 22].
