AGE DIFFERENCE IN ACTIVITY PATTERN OF JAPANESE MONKEYS - EFFECTS OF TEMPERATURE, SNOW, AND DIET

Air temperature, snow depth, and diet composition were found to affect the activity budgets of 1 similar to 2-year-old, 3 similar to 4-year- old and adult female (> 5 years old) Japanese monkeys (Macaca fuscata) in the Shimokita Peninsula. They spent more time resting as the air t emperature decreased. They spent less time moving on the ground, so th at they moved shorter distances, where the snow was deep. However, the y spent more time moving on the ground as they fed more on fruits and seeds. Adult females moved mainly on the ground, while 1 similar to 2- year-olds moved on the tree branches as well as on the ground. Adult f emales increased their time moving on the tree branches where the snow was deep but 1 similar to 2- and 3 similar to 4-year-olds did not. Th e 1 similar to 2- and 3 similar to 4-year-olds but not adult females i ncreased their feeding time as they fed more on buds and barks contain ing abundant fiber. We hypothesize that the large body size of adult f emales may constrain them to move mainly on the ground, and might enab le them to choose energy saving tactics more easily.