Seasonal variation in diet and activity budget of the northern yellow-cheeked crested gibbon Nomascus annamensis, North-eastern Cambodia
Victoria University Of Wellington
Jackson Frechette, Alison Behie, Naven Hon, Benjamin Rawson
Introduction: What conservation problem or question does your study address?
Most of gibbons are listed as endangered. Gibbons are now threatening due to habitats destruction and hunting. These lead to decling of population. The northern yellow-cheeked crested gibbon Nomascus annamensis is a newly described gibbon species. It is expected to be classified as Endangered. Populations of the species remain largely unknown. This study presents the daily, monthly, and seasonal activities and feeding pattern of a habituated group of N. annamensis.
Methods: What were the main research methods you used?
Study site: Data were collected from November 2007 – December 2012 in North-eastern Cambodia. The site is mostly semi-evergreen/evergreen tropical forest. The wet season occurs from May through October, with the dry season beginning in November and lasting through April. We habituated and followed one gibbon group for this study. The group consisted of an adult male and adult female, and two immature individuals, the youngest of which we estimate to have been born sometime in 2007.
Results: What are your most important results?
Inactivity, travelling and feeding accounted for the most daily activity budget. Feeding behaviours were significantly higher in the dry season. Fruit comprised over half of the diet, followed by young leaves and flowers. Fruit consumption was significantly lower in the dry season. This decrease in fruit consumption was negatively correlated with time spent on feeding. This indicated that when fruit consumption decreases, animals spend more time feeding.
Discussion: What are your important discussion points and what is the relevance of your results to conservation (if any)?
This is the first study report on the behaviour and ecology of N. anamensis. The activities and feeding patterns of this species are similar to other gibbon species. Although other gibbons are highly frugivorous, this species consumed less fruit in the dry season, but they consumed more young leaves and flowers. However, this species need more time to consume leaves as the energy of leaves is limited.