POPULATION TREND OF THE YELLOWSTONE GRIZZLY BEAR AS ESTIMATED FROM REPRODUCTIVE AND SURVIVAL RATES

The trend of the Yellowstone grizzly bear (Ursus arctos horribilis) population was estimated using reproductive rates calculated from 22 individual females and survival rates from 400 female bear-years. The point estimate of the rate of increase was 4.6%, with 95% confidence limits of 0 and 9%. Caution in interpreting this result is advised because of possible biases in the population parameter estimates. The main prospects for improving present knowledge of the population trend appear to be further study of possible biases in the parameter estimates, and the continued use of radiotelemetry to increase the number of samples on which the estimates are based.