Seasonal Variation in Activity Budget of Assamese Macaques in Limestone Forest of Southwest Guangxi, China

The activity budget is important for understanding behavioural variability and adaptation in primates. Assamese macaques (Macaca assamensis) found in the limestone forest of Guangxi Nonggang National Nature Reserve, Southwest China, primarily feed on young leaves ofBonia saxatilis(a shrubby, karst-endemic bamboo). To understand how a specific bamboo leaf-based diet and ecological factors affect activity budget, one group of Assamese macaques was studied using instantaneous scan sampling for 1 year. The macaques spent most of their time feeding (32.7 +/- 5.4%), followed by resting (28.6 +/- 6.3%), moving (28.6 +/- 5.3%), grooming (8.0 +/- 3.0%), playing (1.7 +/- 1.6%) and other activities (0.4 +/- 0.2%). Their activity budget was similar to that of typical frugivorous primates and bamboo-dominated primates, which spent more time on active behaviours (feeding and moving, 61.3 +/- 6.0%) than on inactive behaviours (resting and grooming, 36.6 +/- 6.4%). The macaques spent significantly more time resting during the fruit-lean season and more time moving during the fruit-rich season. Their activity budget was significantly affected by diet. Resting time increased with decreased fruit consumption, whereas moving time decreased with the increasing mature leaf consumption. Playing time decreased when the macaques consumed more young bamboo leaves. The activity budget was also influenced by food availability and climatic factors. Resting time increased with decreasing temperature, whereas moving time increased with increasing day length and young leaf availability. Grooming time increased with decreasing day length and increasing temperature, and playing time increased with increasing day length. Our findings provide evidence of the importance of diet, food availability, temperature and day length in coping with seasonal variation in ecological factors, highlighting the need to increase knowledge of the behavioural ecology of the Assamese macaques living in the unique limestone forest and to understand the influence of a bamboo-dominated diet and ecological factors on their survival.