Authors: Bach Thanh Hai, Jin Chen, Hoang Minh Duc, Kingsly Chuo Beng, and Nguyen Van Thuan.
The southern yellow-cheeked crested gibbon (Nomascus gabriellae) is an endangered species that lives exclusively in undisturbed tropical forests and consumes a highly frugivorous diet. To date, the ecology of this species is poorly known. In this study, over a one-year period, we collected over 1,390 hours of observation of the yellow-cheeked crested gibbon in the Cat Tien National Park, Vietnam. The gibbons were found to consume over 69 different plant species. Fruits were the main dietary item (43.3%), followed by leaves (38.4%), flowers (11.6%) and other plant parts (6.0%). A significant seasonal shift in diet was observed; fruit generally dominated the diet in the rainy season and leaves in the dry season. Averaged over the annual cycle, the gibbons spent 45% of their time feeding, 31.9% resting, 14.1% traveling and 9.0% socializing. The percentage of time allocated to different activities varied significantly across months and between the dry and rainy seasons. In addition, this study provides information relevant to the conservation and management of this endangered species by identifying important habitat conditions for reintroducing captive animals into the wild and provides insight into southern yellow-cheeked crested gibbon food preferences, which is important to the maintenance of these primates in rescue centers.