Population Study of Japanese Monkeys at Takasakiyama I

The methods used in the census are described, giving population size and age-sex compositions of these unusually large troops of Japanese monkeys at Takasakiyama, which are the largest troops of non-human primates known to exist.

Abstract

Population censuses of Japanese monkeys at Takasakiyama were taken three times from 1970-1972. Because the population has become very large confirming exact troop sizes presents many practical problems. This paper, the first in a series of reports on demography at Takasakiyama, describes the methods used in the census, giving population size and age-sex compositions of these unusually large troops. Provisioning began at Takasakiyama in 1953. The Takasakiyama troop split three times since then, and four troop were made. The fourth troop was trapped and removed after the last division. The first three troops, A, B, and C, now have populations of 880-900, 250-260, and 250-260 respectively. Over the twenty years since provisioning began the size has increased 6 1/2 times, from 220 to 1400 individuals. These are the largest troops of non-human primates known to exist, and the population is still increasing linearly.