THE ECOLOGY OF MALAYAN SUN BEARS (Helarctos malayanus) IN THE LOWLAND TROPICAL RAINFOREST OF SABAH, MALAYSIAN BORNEO

Abstract

Six Malayan sun bears (Helarctos malayanus) were captured and radio-collared from June 1999 to December 2001 in Ulu Segama Forest Reserve, Sabah, Malaysia to study food habits, home-range characteristics, movement patterns, activity patterns, and bedding sites. Food habits were studied by analyzing scats, examining feeding sites, and making direct observations. Invertebrates such as termites (Isoptera), beetles (Coleoptera), and beetle larvae (Coleoptera), were the predominant food items with 57% frequency of occurrence in scat samples. Figs (Ficus sp.) were the most common fruit consumed (61% frequency of occurrence) during the non-mast fruiting season. A total of 343 locations of radioed bears were recorded using ground triangulation. Home range sizes, calculated by the 95% adaptive kernel method, averaged 14.8 + 6.1 (SD) km. Daily movement distances from these bears averaged 1.45 + 0.24 (SD) km, and were affected by food availability. Male Malayan sun bears were primarily diurnal, but a few individuals were active at night for short periods. The first peak of activity occurred early morning, the second started 1300 h, and activity remained high until dusk. A total of 26 sun bear bedding sites were found in the study area. The majority of the bedding sites consisted of fallen hollow logs. Other bedding sites included standing trees with cavities, cavities underneath fallen logs or tree roots, and tree branches high above ground. We observed a period of famine in the study area from August 1999 to October 2000 when all six radioed Malayan sun bears were in poor physical condition, and two were later found dead. We surmise that the famine resulted from prolonged scarcity of mass fruiting in the study area. Lowland tropical rainforest trees of Borneo display supraannual synchronized mass fruiting. We believe that the starvation we observed and the generally low density of large animals in Borneo forests is a consequence of a history of prolonged food scarcity during non-mass fruiting years.