BLACK BEAR HOME-RANGE SIZES IN WASHINGTON: CLIMATIC, VEGETATIVE, AND SOCIAL INFLUENCES

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Abstract
We evaluated size of home ranges for male and female black bears (Ursus americanus) at 3 study sites in Washington to determine whether home-range sizes differed between sexes, study sites, and objectives of forest management. Vegetative conditions differed among study sites as a result of differences in mean annual precipitation (52, 200, and 380 cm/ year) and forest management practices. We analyzed ranked proportions of forest-cover types within error polygons for telemetry locations as measures of use, interspersion, and juxtaposition of cover types and compared these with ranks of cover types available within composite home ranges for all bears in each study site and with those available within adaptive-kernel home ranges for individual bears. Fixed-kernel estimates of home ranges for males were 3.8 times larger than those for females. Home-range size for females differed (P = 0.04) between study sites but home-range size for males did not (P = 0.79). In the study site with intensively managed and relatively undisturbed forestlands, home ranges for females were of similar size. Males and females occupied cover types different from that available within study sites and within individual home ranges. Differences among study sites for home-range sizes for females may be correlated to differences in available forage plants and cover, which may be explained by differences in annual precipitation. Behavioral differences for males and females, too, may explain differential use of forest-cover types. Hence, differences in home-range sizes between males and females and among regions may result, in part, from climatic and vegetative conditions, as well as from social status.

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