American Black Bear Ecology in Southeastern Oklahoma: Population Status and Capture Methodology
Abstract
Black bears (Ursus americanus) were extirpated from Oklahoma in the early 1900s but have since recolonized eastern portions of the state after successful reintroductions in Arkansas. After initial demographic studies were completed, the Oklahoma Department of Wildlife Conservation approved a hunting season for the southeastern population in 2009. To investigate the population-level impacts of the hunting season, we undertook a capture-based study of the population. We complemented the demographic analyses with a camera trap study of the capture efficiency of our trapping method. From May to August 2014 and 2015, we placed bucket snares along trap lines in southeastern Oklahoma. During 1,975 trap-nights, we handled 123 individual bears (58M, 65F) 171 times. The sex ratio of captured bears did not differ significantly from 1:1. We visited 26 collared individuals (4M, 22F) in their winter dens to collect reproductive data and handled 40 cubs (22M, 18F). We calculated fecundity to be 0.56 female cubs/adult female/year. Average litter size was 2.5 � 0.4 cubs with an over-winter survival rate of 83%. Average annual survival rate of adult bears was 0.90 � 0.07 during the study period. Average annual harvest rate was 8.7 � 1.67% and accounted for 87% of adult mortality. The population estimate for the core area was 175.0 � 79.2 bears (95% CI) using only live captures. When we included camera trap captures in the calculations, abundance was estimated at 175.8 � 49.4 bears. Using a Lefkovitch population model, the estimate of the asymptotic growth rate (?) was 1.04.During 1,285 camera trap-nights in 2015, we recorded 712 bear visitation events and 106 successful captures. Of the 403 visitation events in which the trap was active, 26.3% resulted in a successful capture (n = 106). By-catch was limited to 1 species, northern raccoons (Procyon lotor). The results of our capture models indicate that it is important to keep capture heterogeneity in mind when characterizing population demographics and calculating abundance using this capture method because sex, previous capture, and weight characteristics appeared to affect the capture process.
Collections
- OSU Theses [15752]