Assamese macaques in limestone forests of southwestern China do not support ecological constraints model

Abstract

The ecological constraints model predicted that increased group size represents longer daily path length and feeding time. In this study, we compared behavior ecological data from different group sizes of Assamese macaques (Macaca assamensis) in karst limestone forests with low fruit production to test whether the limestone primates met the predictions of the ecological constraints model. Results of generalized linear mixed models indicated that the dietary composition, food diversity, daily path length, movement rate, and activity budgets of large groups did not significantly differ from those of small groups. High habitat quality, continuous vegetation, and low intensity of human disturbance may be the reasons why large groups do not need to exert more feeding effort than small groups. During the dry season when food resources were scarce, large groups did not spend more time and travel further than small groups in searching for foods, which may be related to their energy conservation strategy. However, further analyses revealed that small groups significantly took more Garcinia paucinervis and foraged more frequently on hillsides than large groups, suggesting that large groups may have monopolized some high-quality food resources. Overall, this study highlights the importance of habitat protection and vegetation restoration for animal conservation and endangered species protection.