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Evaluation of 2-soft-release techniques to reintroduce black bears

January 1, 2002

Black bear (Ursus americanus) were extirpated from most of their range by the early 1900s by habitat destruction and unregulated hunting. Since then, bear habitat has recovered in many areas, but isolation may prevent natural recolonization. Black bear translocations often have limited success because of high mortality rates and low site fidelity. We tested 2 reintroduction techniques designed to overcome those problems. The first technique used a winter release whereby pre- or post-parturient female bears were removed from their dens and placed in new dens at the release area. The second technique involved translocating female bears to the reintroduction area during summer and holding them in pens for a 2-week acclimation period before release. We translocated 8 female bears with cubs with the winter-release technique and 6 female with the summer-release technique. After release, total distance moved, net distance moved, mean daily distance moved, and circuity for winter-released bears (x̄=18.3 km, 7.1 km, 1.4 km, and 0.36, respectively) were less than summer-released bears (x̄=97.6, 63.4 km 5.1 km, and 0.74; P=0.010, 0.040, 0.019, and 0.038, respectively). Also, survival of winter-released bears (0.88) was greater than that for summer-released bears (0.2, P=0.001). Population modeling indicated that the least one additional stocking of 6 adult females with 12 cubs would greatly increase chances of population reestablishment. the winter-release technique has distinct advantages over the summer-release technique, limiting post-release movements and increasing survival of translocated bears.

Publication Year 2002
Title Evaluation of 2-soft-release techniques to reintroduce black bears
Authors Rick Eastridge, Joseph D. Clark
Publication Type Article
Publication Subtype Journal Article
Series Title Wildlife Society Bulletin
Index ID 1015014
Record Source USGS Publications Warehouse
USGS Organization Leetown Science Center; Northern Rocky Mountain Science Center