HOME RANGES OF SLOTH BEARS IN NEPAL - IMPLICATIONS FOR CONSERVATION

Sloth bears (Melursus ursinus) are the only myrmecophagous ursid. Ursi ds generally have large home ranges, often with widely separated seaso nal ranges, whereas myrmecophagous mammals tend to have relatively sma ll ranges for their body size. During 1990-93, we captured and radioco llared 18 sloth bears in Royal Chitwan National Park, Nepal, and track ed their movements for less-than-or-equal-to 3 years to assess whether sloth bears have large ranges like other bears, or if, as a result of their myrmecophagous foraging habits, their home ranges are smaller. Six of 8 males tracked greater-than-or-equal-to 1 year exhibited seaso nal home range shifts from grasslands and riverine forests of the allu vial floodplain to upland sal (Shorea robusta)-dominated forest during the onset of the monsoon (median movement date = 1 Jun); however, the 2 smallest males and most females did not make seasonal range shifts to sal forest. After the wet season (May-Nov), males returned to the a lluvium (median return date = 14 Nov). Alluvial dry season ranges were smaller (P < 0.05) than wet season ranges, for bears that had moved t o the sal and for those that did not, suggesting that alluvium offered a plentiful food supply during the dry season. We propose that diggin g for termites (sloth bears' primary food) was difficult in alluvium w hen the ground was saturated, prompting large males to move to better drained uplands. Home ranges of sloth bears in Chitwan were small comp ared with those of other ursids, and unlike typical ursids, sloth bear s were not attracted to croplands outside the park, where they would h ave been subjected to risks of human-related mortality. Sloth bear pop ulations may subsist in sanctuaries smaller than would be expected for an ursid, given sufficient alluvial habitat.