Bioacoustics of Trachypithecus leucocephalus

Activity patterns. The White-headed Languris diurnal, crepuscular, arboreal, and terrestrial. Daily activity starts with them leaving a sleeping cave at 05:30-06:10 h in summer and 06:45-07:00 h in winter. They enter their caves at 19:45-20:00 h in summer and 17:30-17:45 h in winter. Luminosity is 0-3-0-9 lux when they begin leaving their caves and 2:6-7-5 lux when they enter them at night. A group may use at least three caves, each for a period of 2-4 days. During a year, White-headed Langurs spent an average of 11-5 hours/day outside and 12-5 hours/day inside their caves, accounting for 48% and 52% of their time, respectively. The peak in morning feeding occurs upon leaving caves. There are two feeding peaks per day, one in the morning (c.05:00— 10:00 h) and one in the afternoon (c.16:00-17:00 h). Timing of feeding is considered to be the result of adaption to living in the karst area. On sunny days in summer, temperatures of the surfaces of bare rocks are very high, which results in a higher air temperature over karst areas. During this time, a long rest period at ¢.10:00-16:00 h is common. In winter, White-headed Langurs keep the same regime and use the resting time to sunbathe on bare rocks. Different subpopulations obviously have different time budgets. In Bapen Nature Reserve, ¢.50% of the day is spent resting, 15% each for feeding, traveling, and engaging in social behavior, and ¢.5% playing. In the Longling area, six groups spent an average of 70% resting, 15% feeding, and 10% traveling. In summer, resting time is higher, up to ¢.80%, while feeding time is lower, ¢.10%. In winter, resting time is reduced to ¢.50%, and feeding time increases to 23%. During a study in Hua Shan Nature Reserve in January-May, resting time was 33-6%, feeding time 20-8%, playing 20-2%, moving 13-6%, social behavior 7-3%, vocalization 4-1-%, and sexual activity 0-4%.