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During May 1984, we initiated a study of black bear (Ursus americanus) ecology on the 410 km2 Great Dismal Swamp Wildlife Refuge, a forested wetland in eastern Virginia and North Carolina. Two male bears (ages 3 and 4) and 2 females (ages 3 and 7) remained active during winter 1984-85. Eight other bears (5 males, 3 females) denned for 70-131 days in excavated ground cavities (N = 3), ground-level tree cavities (N = 2), and ground nests (N = 3). Winter home ranges, determined by the modified minimum area method, were 1.9 km2 for males and 2.4 km2 for females. Annual home ranges for these bears, based on monitoring for 7-12 months, averaged 29.6 km2 and 17.8 km2 for males and females, respectively. Distance between consecutive-day relocations, an index of movement, was less in winter than in fall and spring. We observed 3 of the winter-active bears primarily in pocosin-type habitat dominated by evergreen shrubs and vines and the 4th in an inundated cypress-gum swamp. Preliminary analysis of scats, evidence of feeding activity, and visual observation indicated that bears were consuming fruits of greenbriar (Smilax spp.) and holly (Ilex spp.). Serum levels of urea nitrogen and creatinine for a 3-year-old female captured on 4 February 1985 were not indicative of a physiologically hibernating condition. Although occasional instances of nondenning behavior in black bears have been reported from areas with mild climates, the high frequency of winter activity we observed is unprecedented. Mild winter temperatures, lack of persistent snow cover, and diverse food items in the Great Dismal Swamp may be factors contributing to the high degree of bear winter activity.