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From 1979 to 1982, dormancy behaviors of black bears (Ursus americanus) were studied in a bottomland hardwood forest in Arkansas, an area with relatively mild winters. Mean activity level of radio-collared bears declined from 53% to 29% between mid-October and early December, before the denning period began. In 40 of 42 (95%) cases, bears denned for extended periods, ranging from 37 to 141 days. The transition to dormancy began before den entry, and a shift in behavior toward activity commenced before den emergence. Mean level of activity of denned bears (5.5%) was significantly lower than that of bears before denning (37%) and following den emergence (34%). Most activities of denned bears were momentary movements. Activity bouts occurred at a mean rate of 1.8/hour, but short bouts often appeared in series and probably were parts of longer activity periods. Most bears observed in dens were in a hibernating posture and did not react to my presence. Nine of 14 cases of den abandonment were attributed to research activities, 4 to flooding, and 1 case was unexplained. The likelihood of den abandonment was related to the timing of disturbances in relation to den entry and to den type. Dormancy behaviors of black bears in Arkansas are similar to those reported in other portions of the species' range. Differential denning chronology and probability of den abandonment between geographic regions may be explained by phenological development and exposure of denned bears, respectively.