Test of the activity budget hypothesis on Asiatic ibex in Tian Shan Mountains of Xinjiang, China

Asiatic ibex (Capra sibirica) is a threatened species in China and is distributed in the mountains of Central Asia. It is a sexually dimorphic ungulate. The males are much larger than females, and except for the breeding season, both sexes live in separate groups. Many hypotheses have been developed to explain the sexual segregation in sexually dimorphic ungulates. These hypotheses are not mutually exclusive, and in recent years, the activity budget hypothesis has received special attention. To test this hypothesis, we studied the activity budget of Asiatic ibex in the autumn of 2005. According to the activity budget hypothesis, females should spend more time feeding than the males, and the degree of activity synchronization should be higher in same-sex groups than in mixed-sex groups. Our results are consistent with the hypothesis. Both sexes of the Asiatic ibex spent most of the time feeding, and females spent a significantly longer time feeding than males, and males spent a significantly longer time standing. Activity synchronization indexes of both the female groups and males groups were significantly higher than mixed-sex groups. These results indicated that in Asiatic ibex, the activity budget hypothesis about sexual segregation is supported.