Unpredictability of vigilance in two sympatric Tibetan ungulates

Abstract

Vigilance is important for anti‐predation, and different animals adopt different vigilance strategies. Instantaneous and sequential randomness in vigilance behavior are two main principles for the classic Pulliam model (1973). Given this context, we studied the vigilance behaviors in two wild cloven‐hoofed animals, the Tibetan antelope (Pantholops hodgsonii) and the Tibetan gazelle (Procapra picticaudata) on Qinghai–Tibet Plateau, to explore if the two randomness principles work across species. The results showed that the distribution of inter‐scan intervals of both Tibetan antelope and Tibetan gazelle followed the negative exponential distribution; inter‐scans of both Tibetan antelope and Tibetan gazelle were unrelated with their previous scan, and most sequences of inter‐scan intervals could be considered as random organized or unpredictable. In conclusion, the vigilance patterns of Tibetan antelope and Tibetan gazelle followed instantaneous randomness and sequential randomness of Pulliam model. A random vigilance strategy might be the best choice for Tibetan ungulates, and how to distinguish the social vigilance from anti‐predator vigilance is an important issue for future research.