Dynamics of a grizzly bear population during a period of industrial resource extraction. II. Mortality rates and causes of death

• 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/z89-265; http://www.nrcresearchpress.com/doi/pdf/10.1139/z89-265

The causes and rates of grizzly bear (Ursus arctos) mortality in a radio-marked population in southeastern British Columbia were studied for 9 years during a period of timber harvest, gas exploration, and outdoor recreation, including grizzly hunting. During 110 bear-years of radio tracking 55 radio-collared grizzly bears and their dependent offspring, one bear with a functioning radio collar died from natural causes and eight others from human intervention; in addition, four dependent offspring were thought to have died. Excluding trap-related mortalities, the best estimate for the annual survival rates were as follows: 0.82 for cubs, 0.88 for yearlings, 0.93 for subadults, and 0.93 for adults. Of the eight bears killed by human intervention, two were killed by legal harvest, five by illegal harvest (one of these in a trap), and one was killed in a trap by another bear. No mortalities were directly attributable to industrial activities. Resource extraction industries do contribute to grizzly bear mortality indirectly through the construction of roads, which provide easy access to hunters, poachers, and settlers. Road access planning and postoperational control of vehicles are recommended management actions.