FORAGING ON BUDS AND BARK OF MULBERRY TREES BY JAPANESE MONKEYS AND THEIR RANGE UTILIZATION

The Japanese monkey (Macaca fuscata) winter range utilization and the effects of foraging on mulberry trees (Morus bombycis) were studied in the Shimokita Peninsula during four winter seasons. The monkeys ate m ainly winter dormancy buds when they visited the mulberry tree clumps for the first time within the winter, but they ate mainly bark when th ey visited for the second or third times. In the areas utilized by the monkeys over the recent three years, the mulberry trees compensated f or the decrease in their number of shoots by producing longer shoots w ith more buds against the monkey foraging. In the areas used every yea r for more than four years, however, the mulberry trees were unable to compensate for the foraging pressure. Thus, although the monkeys had apparently operated prudent herbivory within three years, they did not do so on a longer time-scale. They shifted their utilization ranges a fter having over-exploited the mulberry trees.