Estimating survival rates of black bears

Capture-recapture, radiotelemetry ton a monthly and a yearly basis), and age-distribution methods were used to estimate annual survival rates for black bears (Ursus americanus) in the southern Appalachians from 1981 to 1996. Using capture-recapture data, the Jolly-Seber estimator calculated the annual survival rate for all bears over all years to be 0.64 +/- 0.04 (mean +/- SE). Because of small sample sizes, this method did not produce yearly estimates or allow separation of the data into age or sex classes. Both the Kaplan-Meier estimator (using monthly telemetry data) and the percent survival estimator (using yearly telemetry data) computed an overall annual survival rate of 0.76 +/- 0.04. Survival rates for the early years of the study (1981-1987) were significantly lower than in the late years (1988-1996). No significant difference in survival rate was detected between the sexes or among age-classes. Because it is difficult to capture and recapture large numbers of animals, radiotelemetry methods are preferable for large mammals such as black bears. If bears wear their collars for at least a year, calculating survival from yearly telemetry data provides a good estimate of bear survival. Using monthly telemetry data, however, provided the most detailed understanding of bear survival. Survival estimates produced by the age-distribution method were unreliable.