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Comparative studies of sympatric species are essential in understanding those species' behavioral and ecological adaptations as well as the mechanisms that can reduce resource competition enough to allow coexistence. We collected data on diet, activity budget and habitat use from two sympatric macaque species, the Assamese macaque (Macaca assamensis) and the rhesus macaque (M. mulatta), in a limestone seasonal rainforest of Nonggang Nature Reserve, southwestern Guangxi, China. Our results show that the two sympatric macaques differ in diet, activity budget, and habitat use: (1) out of the 131 plant species that were used by both macaque species as food over the year, only 15 plant species (11 %) were shared. Rhesus macaques used more plant species as major foods, and had higher dietary diversity and evenness indexes than Assamese macaques. (2) Assamese macaques fed predominantly on leaves, whereas rhesus macaques fed more selectively on fruits. The rhesus macaques' diet varied according to season, and was significantly correlated to season fluctuation in fruit availability. (3) Assamese macaques devoted more time to resting, and less time to feeding than rhesus macaques (4) Assamese macaques were present mostly on the cliff, and tended to stay on the ground, whereas rhesus macaques were present mostly on the hillside, and showed preference to lower and middle canopy. The observed differences in diet and habitat use between the two macaque species represent behavioral patterns enabling their coexistence.

Limestone forests are an unusual habitat for primates, but little information is available for the genus Macaca in such habitats, making a comparative understanding of extant limestone primates' behavioral adaptation incomplete. We collected data on the diet of rhesus macaques (Macaca mulatta) in a limestone habitat at Nonggang Nature Reserve, southwestern Guangxi, China, and examined the effects of forest seasonality on their diet. Our results indicated that a total of 114 species of plants are consumed by macaques. Young leaves are a preferred food, accounting for 48.9 and 56.9% of the overall diets. One group significantly increased young leaf consumption in response to availability. Fruits contributed to only 27.3 and 28.7% of overall diet. The macaque diet varied according to season. They fed on more fruits in the rainy season. Consumption of mature leaves increased when the availability of young leaves and fruits declined in the dry season, indicating that mature leaves are a fallback food for macaques in a limestone habitat. Similar to sympatric Assamese macaques, Bonia saxatilis, a shrubby, karst-endemic bamboo was consumed by rhesus macaques throughout the year, and was the top food species through most of the year, suggesting that bamboo consumption represents a key factor in the macaque's dietary adaptation to limestone habitat.

The activity budgets of primates reflect their survival strategy. Despite existing data on the activity budgets of Yunnan snub-nosed monkeys (Rhinopithecus bieti), little is known about how activity budgets vary between age-sex classes. This study provides the first detailed activity budgets subdivided by age-sex class, based on observations of the largest habituated group of R. bieti at Xiangguqing in Baimaxueshan Nature Reserve. This study was conducted from June 2008 to May 2009. We found that adult females spent more time feeding (44.8%) than adult males (39.5%), juveniles (39.1%) and infants (14.2%). Females allocated significantly more time to feeding than to any other activity. Adult males allocated more time to miscellaneous activities (12.5%) than adult females (3.8%). Juveniles allocated less time to grooming than adults. Infants were being groomed 6.9% of the time, the highest proportion among all age-sex classes. Adults spent more time feeding, while immature individuals allocated more time to moving and other activities. There are several reasons why activity budgets can vary by age-sex class: (1) differential reproductive investment between males and females; (2) developmental differences among the age categories, and (3) social relationships between members of different age-sex classes, particularly dominance. These variations in activity budgets among the different age-sex classes may become a selective pressure in this species.

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