集群数量和采食距离对储草期布氏田鼠警戒频次的影响

警戒行为是动物对环境中潜在危险做出的反应。为探究影响警戒行为的因素,作者在内蒙古锡林郭勒典型草原区进行了集群数量和采食距离对储草期自由生活状态下布氏田鼠(Lasiopodomys brandtii)警戒频次影响的实验。通过标志重捕法和人工去除法设定3个集群数量梯度(11只、6只和3只),利用人工食物站设置4个采食距离梯度(5 m、10 m、20 m、30 m),共12个梯度组合,每个组合分别观察60次采食过程,共计观察720次,并记录采食过程中的警戒频次。对数据进行双因素方差分析,集群规模和采食距离对布氏田鼠警戒行为频次均有极显著影响(P0.01)。随着集群数量减小,布氏田鼠单次采食的警戒频次显著增加;采食距离越远,单次采食的警戒频次越高;集群数量和采食距离之间还存在极显著的交互作用(P0.01)。集群数量增大意味着采食距离的增加,为保证储草效率,布氏田鼠种群会在增加集群数量和减小采食距离之间权衡,最终集群数量维持在中等水平,支持了最优集群理论。

Influence of Group Size and Foraging Distance on Vigilance Frequency of Brandt's Vole (Lasiopodomys brandtii) in Food Storing Period

Vigilance behavior,affected by many factors,is animals' response to potential dangers.To study the vigilance behavior of Brandt's vole (Lasiopodomys brandtii),we examed the effects of group size and foraging distance on the vigilance behaviour frequency of Brandt's vole during the food storing period in typical steppes in Xilingole League,Inner Mongolia.We manipulated the group size of the voles in three levels (11,6,and 3 individuals) and foraging distance in four levels (5 m,10 m,20 m,30 m) in this study.The vigilance behaviour frequency was taken counted in the same time (Fig.1 and Appendix).Two-way ANOVA shows that the frequency of vigilance behaviour significantly related to both group size and foraging distance.Moreover,the interaction between group size and foraging distance was extremely significant (Table 2).Vigilance behaviour frequency was higher with smaller group size and longer foraging distance.The result suggests that the group size effect of Brandt's vole well supports the many-eyes hypothesis.And the result also indicates that foraging efficiency of Brandt's vole rises with the increase of the group size.Combined with the study that with higher group size comes higher predation risk,the trade-off between predation risk and foraging efficiency makes us ensure that there is an optimum group size of Brandt's vole.