Some aspects in the ecology of the black bear (Ursus Americanus) in interior Alaska

Abstract

Research during 1964 and 1965 revealed that black bears in interior Alaska are active only 5 to 5.5 months each year. Emerging from winter dens in early May, the animals spend most of the first 3 months in river bottom and other lowland situations where green vegetation, especially Equisetum spp., composes the bulk of their diet. From the last half of July until mid-September bears are observed most commonly in alpine areas where fruits, especially Vaccinium uliginosum, are the important food. Animal food, constituting less than 15 percent (volume) of the animal's diet, is apparently taken whenever it is obtainable. Most animal food occurrences involve insects. Litter size averaged 1.73 for 30 litters observed during the 2 years studied. Litters larger than two do not seem to be common in interior Alaska. Intestinal parasites were found in 12 of 16 bears. Two heavy infestations of ascarids, 249 worms in one bear and 53 in another, were observed. Serious predation by interior Alaskan black bears upon the nests of some waterfowl has been recorded; predation upon most other wildlife species appears to be negligible. Evidence gathered during this study suggests that the rash of black bear problems experienced by interior Alaskans in 1963 was due largely to the widespread lack of blueberries during that year.