Five-year study on the autumn food habits of the Asiatic black bear in relation to nut production

We studied the autumn food habits of the Asiatic black bear (Ursus thibetanus) from 1993 to 1997, based on 202 fecal samples in the Chichibu Mountains, central Japan. Nuts occupied the highest proportions of autumn foods (59.9-85.8% important values). Although the proportion of nuts of Quercus crispula, Fagus crenata and Fagus japonica varied greatly between the years, acorns of Q. crispula were most prevalent in four of the five years. We also determined the relative nut production of these three species by counting the number of nuts or cupules on the ground. Black bears consumed the nuts according to their relative availabilities. Nuts of Q. crispula appeared to be the most important food because: (i) these nuts were eaten in the highest proportion in four of the five study years; and (ii) even in poor years the bears consumed acorns of Q. crispula, whereas nuts of Fagus spp. were not consumed. We discuss the significance of alternative foods for black bears in relation to food tree diversity in the forest and the necessity for long-term studies examining the food habits of Asiatic black bears.