Abstract: The population density and vegetation community structure affect the predation risk level of individuals within the population. Vigilance,vigilance frequency and alert distance are indicators for assessing the predation risk level of small rodents. The individual’s predation risk of plateau pika was studied by video recording in different population densities and vegetation structures in 2017. The results showed that the vigilance time of plateau pika decreased significantly with increasing population density;the vigilance frequency of plateau pikas decreased as population density increased,but the alert distance had no significant difference among different population densities;The alert distance showed a significant increase with population density. The linear regression analysis showed that the proportion of vigilance was significant positively correlated with vegetation height and coverage. There was no significant correlation between vigilance frequency and vegetation height and coverage,while alert distance had significantly negative correlation with vegetation height and coverage;multiple linear stepwise regression analysis found that the vegetation height had a greater impact on the vigilance and alert distance than the vegetation coverage. The above results indicate that the higher pika population density,the lower the vegetation height and the coverage,the lower the predation risk level of the plateau pika individuals in the population.

Key words: Plateau pika, Predation risk, Vigilance time, Vigilance frequency, Alert distance

摘要： 种群密度和植被群落结构决定着种群内个体捕食风险水平的高低。警戒时间、警戒频次和警戒距离是评价小型啮齿类动物捕食风险水平高低的三个指标。2017年采用录像法对不同种群密度和植被结构中高原鼠兔个体的捕食风险进行了研究。结果表明：高原鼠兔警戒时间比重随种群密度的增加呈显著下降趋势；高原鼠兔警戒频次随种群密度的增加呈下降趋势，但警戒频次差异不显著；而高原鼠兔警戒距离随种群密度的增加呈显著增加的趋势。一元线性回归分析表明，高原鼠兔的警戒时间所占比重与植被群落高度和盖度呈显著正相关性，警戒频次与植被群落高度和盖度无显著相关性，而警戒距离与植被群落高度和盖度呈显著负相关性；多元线性逐步回归分析发现植被群落高度对鼠兔警戒时间和警戒距离的影响要大于植被盖度。以上结果说明，种群密度越大，植被高度越低，盖度越小，种群内高原鼠兔个体的捕食风险水平就越低。

关键词: 高原鼠兔, 捕食风险, 警戒时间, 警戒频次, 警戒距离