Socio-ecological study ofPresbytis aygula in West Java

Field studies of the Sunda Island leaf monkey,Presbytis aygula, were made in the montane forests of West Java at an altitude of 1,400–1,800 m between September 1976 and August 1981. The troop size ofP. aygula varied from 3 to 12 animals and the population density was about 35 animals/km² in Patenggang and 11–12 animals/km² in Kamojang. They were organized essentially in one male troops, though the troops in the Patenggang area usually consisted of only an adult pair and its offspring. Home range size was about 14 ha in Patenggang and about 35–40 ha in Kamojang. Some of those ranges overlapped with each other. The differences between these two areas were considered to be the result of recent habitat destruction and human impact in Patenggang. Animals spent more time in resting than other activities during a day.P. aygula in Java, consumed mainly leaves, eating less fruits and other parts of plants. Troop cohesion was tight, but social interactions between troop members were rather infrequent. The patterns of intertroop encounters and vocal sounds were described.