食物诱导长爪沙鼠集群贮食的野外实验设计及其在社群研究中的应用

长爪沙鼠为典型的群居性鼠类。在自然条件下该鼠的集群贮食活动随时可为人工投放的种子食物所导引。本文依据组群个体合作贮食的习性，并结合剪趾和染毛双重标记的重捕跟踪方法设计了着重观测社群结构、群内个体序位、领域边界及相关社群行为的野外实验。据2(X)2年5月对4个相邻洞群的观测结果分析表明，应用此法便于在复杂的社群环境中直接确认组群成员及其属性，亦便于分辨同一组群或不同组群成员之间发生的行为事件及相关过程，且能在重复实验中得以验证。为在野外条件下定量研究长爪沙鼠社群行为提供了一种便捷可靠的观测方法。

The Method of Group-hoarding Behavior Provoked in Nature and Its Application in Social Ecology of Mongolian Gerbils

Mongolian gerbils(Meriones unguiculatus)live in family groups. Under natural conditions, group-hoarding behavior among gerbils can be invoked by artificially supplying grain. All group members older than 20-day-old pups hoard grain by storing it in their burrows. During May 2002, we conducted mark-recapture experiments (double-marking individuals by toe-clipping as well as by dyeing fur) within a fenced pasture in Touzhijian township, Taibusi Banner, Inner Mongolia. We conducted two field experiments: (1) To induce hoarding and thereby identify the size and composition of each gerbil group, we supplied grain in four petri dishes placed randomly around the central burrow area, and (2) To determine individual social status and judge the location of territorial borders, we placed eleven dishes containing grain along a line that traversed adjoining territories, such that some dishes were within the territory of the subject gerbil group and others required trespassing onto neighboring territories for the subjects to access them. Supplying grain confirmed the existence of four neighboring groups which operated as social units by group hoarding. In our second experiment, gerbils displayed individual differences in both hoarding and chasing behavior within groups. Based on observations of these chases, we identified the dominant gerbils within each group as those individuals most motivated to chase strangers and defend their investments. Resident gerbils had clear priority of access to grain placed in their own territory, and chased other gerbils from these grain stations. We found that territorial borders had an overlap zone of 1-2 m. These experiments provided a straightforward and repeatable method to quantify the complex social behavior of free-ranging Mongolian gerbils.