• Version
• Download 13
• File Size 1.31 MB
• Create Date 1 January 1983
• Download

A minimum population of 34 black bears (Ursus americanus) visiting and feeding at the town dump in Jasper National Park, Alberta, were observed for over 750 hours on 141 days in 1968. Females with young of the year visited the dump more than any other group. Their average litter size of 2.67 for regular dump visitors suggests that food from the dump contributed to reproductive success. Social interactions between bears were characterized by tolerance, avoidance, and spacing, but we did observe 141 intraspecific agonistic interactions. In 89 out of 91 agonistic interactions, females with young of the year dominated all other age/sex classes, including adult males. These females, even when not with their young, used agonistic behaviour to maintain an individual distance of 3 to 30 m. Twelve postural and 4 vocal components of the agonistic repertoires are described and frequency of use is given for each identified bear. Agonistic signals were stereotyped but not invariant; physical contact was rare. Agonistic interactions were more frequent early in the season than later. The dump was visited by 7,500 to 10,000 tourists; despite hundreds of close approaches, including 57 situations in which people threw rocks or chased bears, a bear never struck, bit, or touched a person. Bears on 15 such occasions directed agonistic signals toward people; these were similar to signals used in intraspecific encounters. Subadults and females with their young climbed trees, where they appeared to find safety from harassment. Bears in trees were seen nursing, playing, sleeping, sheltering, relaxing, or cooling. The dump offered a food source which was concentrated, high-quality, predictable, and prolonged in time. Bears exploited this resource by forming social aggregations, tolerating other bears at shorter distances when at the dump than when away.