关键词: 捕食风险, 高原鼠兔, 集群, 洞口距离

Abstract: The effects of group size and distance to refuge on foraging of plateau pikas ( Ochotona curzonize) under predation risk were examined in the paper. Under predation risk environment vigilance increases significantly at the cost of decreasing feeding. The effect of group size on foraging is complex. In the highest level of risk environment, plateau pikas prefer to feeding near one other pika feeding-site is as close to burrow as possible in response to the predation risk. However in the safe environment they are willing to feeding alone the feeding-site in the environment is more wide than that in the risk environment. The effect of distance to refuge on vigilance is also complex in response to the predation risk. Vigilance increases as the distance to refuge increases it occur mainly within 2 m from refuge, and it does not appear again in the risk environment when feeding far from refuge ( >3 m) reflecting a tradeoff between the possibility of fly back refuge successfully and the efficiency of early detecting.

Key words: Predation risk, Plateau pikas (Ochotona curzoniae), Group size, Distance to refuge