Vertical distribution of wild Yakushima macaques (Macaca fuscata yakui) in the western area of Yakushima Island, Japan:: Preliminary report

A census of wild Yakushima macaques (Macaca fuscata yakui) was carried out in a 23-km(2) area of the western coast of Yakushima Island, Japan. We analyzed the census data to investigate changes in monkey distribution associated with the vertical distribution of vegetation. In the lowland coastal zone of 0-300 m above sea level (a.s.l.), 4.8 troops and 62.4-99.8 monkeys are estimated to have existed per km(2). In the mountainside zones of 300-900 m a.s.l., the troop density decreased to 1.3-1.6 troops/km(2). Since there was no difference in size between the coastal and mountainside troops, population density should decrease with altitude to about 30-36 monkeys per km2. On the other hand, 2.4 troops and about 36 monkeys were estimated to have inhabited per km(2) in the mountain summit zone of 900-1,323 m a.s.l.