Use of fecal DNA to estimate black bear density in an urban‐wildland interface

Abstract

AbstractAmerican black bears (Ursus americanus) commonly habituate to human resources in regions of urban‐wildland interface, which frequently leads to human‐wildlife conflict. Monitoring bear densities is important to inform management, yet traditional density estimation methods may not be practical in such areas. Minimally or noninvasive genetic tools offer a potential solution, but the most common sampling method employs barbed‐wire hair snares and scented lure, which can pose dangers to people and pets. Fecal DNA, which is less invasive, has been used successfully for many species, but has not been commonly used for ursids in the United States. We conducted a pilot study from July–September 2018 to assess the feasibility of using fecal DNA in a spatial capture‐recapture analysis to estimate black bear density in the Lake Tahoe Basin in California, a region of high‐human density compared to other urban‐wildland interface localities in the United States, where bears pose significant nuisance problems. The use of fecal DNA allowed us to sample in both urban and wildland areas with minimal disturbance to the surrounding community. Based on 142 genotyped samples from 101 distinct individuals, we estimated an abundance of 0.84 bears/km2(95% CI = 0.58–1.21 bears/km2), which was similar to a previous capture‐recapture estimate in the study area and represents one of the highest densities reported for black bears. More generally, our findings indicated that fecal DNA capture‐recapture approaches provide a feasible means of estimating black bear densities in areas where hair sampling may be impractical.