Dynamics of a grizzly bear population during a period of industrial resource extraction. I. Density and age–sex composition

• Published in: Canadian Journal of Zoology
• Main Author: McLellan, Bruce N.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1989
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Ursus arctos
• Online Access: http://dx.doi.org/10.1139/z89-264; http://www.nrcresearchpress.com/doi/pdf/10.1139/z89-264

The characteristics of a grizzly bear (Ursus arctos) population in southeastern British Columbia were studied between 1979 and 1986, a period of timber harvest, gas exploration, and outdoor recreation, including grizzly hunting. I investigated the hypothesis that collectively these activities were detrimental to the grizzly population. I predicted a low density of bears compared with other interior populations and (or) a negative rate of increase. The sex ratio of cubs and yearlings captured was 50:50 and they represented 21.5 and 17.5% of the population, respectively. Although more adult males than adult females were captured, I estimated that there were more adult females than males in the population. I used two methods of population estimation and assumed saturation trapping : one method was based on home range characteristics and the other on the proportion of aerial locations in the study area. The average estimated bear density was 6.4/100 km 2 , which was high for an interior population, and increased from approximately 5.7/100 km 2 in 1981 to 8.0/100 km 2 in 1986, for an average annual observed rate of increase of r = 0.07.