Activity Patterns of Radio-Collared Black Bears in Idaho

Activity patterns of 13 radio-collared black bears (Ursus americanus) in west-central Idaho were studied between June 1973 and December 1974. Bears did not react in a significant way to the disturbances of an investigator. Females were more active than males during the early spring and late fall. Bears were primarily diurnal and crepuscular; however, they were less active and more nocturnal in early spring and late fall than in summer. Phenological patterns of seven key food plants appeared to govern bear movements and habitat preferences. Bears occupied well-defined home ranges that remained stable from year to year. Home range areas of adults varied from 16.6 to 130.3 km2. Daily movements and home range areas of males were usually larger than those of females. Overlap of home ranges was extensive. Bears entered dens between 9 October and 27 November, and emerged in April. J. WILDL. MANAGE. 40(2):340-348 Reports of previous studies of black bears have not included data concerning the nature, time, and duration of their activities (Black 1958, Erickson and Petrides 1964, Jonkel and Cowan 1971). Craighead and Craighead (1965) demonstrated that radiotelemetry permits collection of such data. However, little radiotracking of black bears has been reported. In 1973 the Idaho Department of Fish and Game and the Idaho Cooperative Wildlife Research Unit initiated a cooperative study of the ecology of the black bear. One phase of that study, determination of movements and activities of black bears between June 1973 and December 1974, is reported here. Beecham did the trapping and marking, and Amstrup was responsible for the radiotelemetry studies. We are especially grateful to M. G. Hornocker and L. Oldenburg, without whose administrative and supervisory assistance this project could not have begun. We thank the personnel of the Council Ranger District, Payette National Forest, for providing maps and background information about the study area and for their continuous support.