POPULATION-DYNAMICS OF SELKIRK MOUNTAIN GRIZZLY BEARS

We investigated population dynamics of grizzly bears (Ursus arctos) in the Selkirk Mountains Grizzly Bear Ecosystem (SMGBE) of Idaho, Washington, and British Columbia to assist grizzly bear recovery from threatened status. We captured and radiomonitored 28 bears from 1985 to 1990. Estimated densities were 1.41 +/- 0.14 (95% CL) and 2.33 +/- 0.36 bears/100 km2 for the U.S. and Canadian portions of the SMGBE, respectively. Litter size (cubs less-than-or-equal-to 1.5 yr) was 2.22 +/- 0.26 and mean birth interval was 3.0 +/- 0.5 years for an estimated reproductive rate of 0.74 +/- 0.10 cubs/adult female per year. Age at first parturition was 7.3 +/- 0.38 years. Estimated annual survival rates were 0.96 +/- 0.05 for adult females, 0.81 +/- 0.20 for adult males, 0.78 +/- 0.22 for subadult females, 0.90 +/- 0.17 for subadult males, and 0.84 +/- 0.16 for cubs. The population appeared to be stable but growth was limited by illegal mortalities.