Resource Partitioning Among Brown Bears at Brooks River in Katmai National Park and Preserve, Alaska

• Main Author: Olson, Tamara L.
• Format: Text
• Language: unknown
• Published: Utah State University 1993
• Subjects: Ursus arctos; Alaska
• Online Access: https://dx.doi.org/10.26076/b4b7-90f5; https://digitalcommons.usu.edu/etd/6967

A quantitative study of the behavior of brown bears (Ursus arctos) was undertaken in areas of differing human activity at Brooks River in Katmai National Park and Preserve, 1988-1990. The research was conducted to determine whether the activity of any particular classes of bears using the river were differentially affected by human activity, activity of conspecifics, or availability of salmon. Approximately 1643 hours of systematic observation were recorded, 781 between June 26 and July 29 and 862 hours between August 26 and October 12 of all three years. Comparisons of fish capture rates by bears and distributions of bear use among observation zones were made by grouping individually identified bears according to both their age-sex class and tolerance of people (habituation). Differences in distributions of use among age-sex classes were apparent only during June-July; during that time subadults and females with young favored use of the river below Brooks Falls to a greater degree than other bears. Fish capture rates recorded during July 1990 showed a more than three-fold increase over those observed 1988-1989. The apparent increase in fish availability to bears that year was accompanied by the only observed differences in fish capture rates among age-sex classes. During July 1990 salmon availability in the observation zones near Brooks Camp increased significantly over the previous two years; habituated bears (tolerant of people atm) showed nearly three times as much use of those zones as in 1988-1989. In contrast, nonhabituated bears (61.5%-76.3% of all adult bears observed among observation years and seasons) showed minimal use of these areas despite the high availability of salmon. During the fall of each year fish capture rates appeared highest in the observation zones near Brooks Camp. Habituated bears used these zones significantly more than did nonhabituated bears, and overall rates of river use were higher for habituated than nonhabituated bears. Depending on their habituation class, females with young showed distinctly different use patterns through the fall season and across observation zones. All nonhabituated females with young (50.0% of females with young of known habituation class) favored use of the observation zone nearest Brooks Camp, and their activity was highest late in the season when human activity was minimal. The implications of patterns of use by age-sex class and degree of habituation to people are discussed.