Mark–resight density estimation for American black bears in Hoopa, California

Abstract

Accurate and precise population estimates are necessary to answer many management questions, but these estimates are generally unavailable for large carnivores because of their extensive movements, low densities, and secretive natures. These traits also often prevent the bounding of occupied areas necessary to estimate densities. We used a modified Petersen mark–recapture methodology to estimate black bear density in 1998 at 2 study sites on the Hoopa Valley Reservation, California, from mark–resight data. We used culvert traps to capture, radiocollar, and eartag bears, radio telemetry to establish closure, and remote cameras to collect resighting data. We calculated bear densities (90% confidence intervals) of 0.18 (0.09–0.32) and 1.33 (0.54–3.29) bears/km2 on the 2 sites. Knowledge of bear densities can now be incorporated into forest management actions and associated bear control measures on the Hoopa Valley Reservation.