Denning Ecology of Black Bears in the White River National Wildlife Refuge, Arkansas

Abstract

Lack of adequate den sites may adversely affect cub survival and reproductive success in black bears (Ursus americanus). Management of remnant bear populations in the lower Mississippi floodplain necessitates understanding denning ecology. We monitored 23 radiotagged black bears for 33 den years from 1993 to 1995 in White River National Wildlife Refuge, Arkansas to investigate denning chronology and den requirements. Bears entered dens between 1 January-20 February and emerged between 12 March-28 April. Mean (±SE) denning duration was 92.9 ± 6.6 days and varied between sex-age classes (P = 0.002). Pregnant females denned longer (117.8 ± 5.2 days, P = 0.029) than males and non-pregnant females (84.2 ± 7.7 days). More than 44% of the bears that denned (n = 27) used >1 den during a denning season, and one female used 4 dens. Most (90.2%, n = 51) dens were elevated tree cavities with a hollow opening on the top or middle of the main trunk. Three species of trees were used with 77.8% (n = 46) being overcup oak (Quercus lyrata). Basal area of trees ≥10 cm diameter at breast height (dbh; P < 0.001) and number of stems ≥84 cm dbh (P < 0.001; the min. dbh of den trees documented in this study) differed among vegetation plots with and without den trees. For seasonally flooded habitats, our results suggest the need for maintenance or augmentation of trees ≥84 cm dbh to increase the number of potential dens and to enhance the quality of den microhabitat in the lower Mississippi Alluvial Valley.