Human-Wildlife Interactions (May 2017)
Best management practices in counting urban black bears
Abstract
DNA-based capture-mark-recapture (CMR) techniques are commonly used to obtain population parameters of black bears (Ursus americanus) in rural and wildland landscapes; however, these techniques have not been implemented in urban clusters (i.e., 2,500 to 50,000 residents). Black bears can readily habituate to urban clusters, and wildlife managers need to monitor and manage these urban bear populations. We modified DNAbased CMR for black bear using hair-snares to take into account the small home ranges of urban bears, urban bear behavior, and human safety within Mammoth Lakes, California, USA. We conducted this study for 3 fi eld seasons in 2010, 2011, and 2012 from June to July. Each fi eld season, we implemented a CMR with 6 encounter occasions, each 7 days in length. We used the traditional corral hair-snare design modified for human safety and chose multiple non-consumable and minimally consumable lure types to prevent food conditioning and a trap-happy response. In 2012, we also tested 3 additional hair-snare designs more appropriate for urban areas: natural rub, haphazard-wire snare, and tennis ball snare. In 2010, we collected an insufficient number of hair samples for CMR by putting hair-snares in the periphery of the urban cluster, which we call the urban–wildland interface. However, in 2011 and 2012, when we put hair-snares in the city center as well as the surrounding urban–wildlife interface and increased hair-snare density, we obtained a sufficient number of hair samples to estimate population density using closed capture CMR models. These adjustments to hairsnaring study design in urban areas helped increase capture and recapture rates to be similar to our wildland area. To achieve high capture rates using hair-snares in the urban area, we put out hair-snares at a density approximately 4 times greater than in our wildland study area and distributed them throughout the entire urban area, and not just on the urban–wildlife interface. In addition, setting hair-snares near anthropogenic features used by bears in urban areas (e.g., culverts, utility poles, dumpsters) and adding spent cooking oil to lures also increased our capture rate. Finally, the corral hair-snare had the highest capture rates of our 4 hair-snare designs. After adapting a study design for hair-snaring wildland bears, our methods were efficient for urban areas, having high capture and recapture rates (>0.30) and good precision for abundance estimates (coefficient of variation
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