Survival of rehabilitated yearling American black bears

Abstract

Abstract: Scant information regarding the fate of rehabilitated American black bears (Ursus americanus) postrelease exists in the literature. We estimated survival of 28 rehabilitated bears that were released between 2015 and 2018 in North Carolina, USA, and investigated what biological, landscape, and behavioral factors influenced their survival in their first year postrelease. Sixty-one percent of the bears died within 1 year and 65% of the mortalities were from legal hunter harvest. Bear survival declined rapidly with increasing road density. Few mortalities were attributed to vehicular incidents; therefore, road density likely acts as proxy to hunting accessibility, especially in rural areas. Home ranges of bears in our study included 0–11% development and we estimated our bears had a 90% survival rate within their first year postrelease if their home range included 6–11% of developed land. In urban areas, ordinances and small parcels tend to restrict the opportunity for hunting, which may create a refugia for some black bears. Our results also indicate that female rehabilitated bears may be more susceptible to hunting pressures than are wild females. Release weight had a positive effect on survival; heavier bears were likely less attracted to anthropogenic food sources (e.g., crops, bird feeders) that would have made them susceptible to hunters compared with more reliable, natural food sources. Individuals that moved slightly more tortuous paths than average in our study had a lower survival probability, likely from remaining in the same area. We recommend that managers select release sites for bears that limit harvest via accessible roads. We also recommend ensuring 1.25–1.5-year-old bears are ≥71 kg at release to enhance survival probability. Our results add to the growing body of bear rehabilitation research and can inform programs in which rehabilitation is critical to species restoration efforts.