Number of neighbors instead of group size significantly affects individual vigilance levels in large animal aggregations
Number of neighbors instead of group size significantly affects individual vigilance levels in large animal aggregations
复制标题
大型动物聚集体中，邻居数量而非群体规模显着影响个体的警惕水平
DOI：
10.1111/jav.02065
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发表时间：
2019
影响因子：
1.7
通讯作者：
Zhou Li Zhi
中科院分区：
文献类型：
--
作者：
Zhao Jin Ming;Lyu Nan;Sun Yue Hua;Zhou Li Zhi
群体规模效应表明，随着群体规模的增加，生活在群体中的动物通过降低警惕水平来获得反捕食者的好处。群体规模效应的一个基本假设是，所有个体对于焦点个体来说都是同等重要的，焦点个体可以根据从他们那里获得的社会信息来调整其警惕水平。然而，一些研究表明，邻居对个人的警惕决策的影响比其他群体成员更大，尤其是在大型群体中。研究还发现，警惕性既针对捕食者（反捕食警惕性），又针对同种动物（社会警惕性）。中心个人可能比外围个人更依赖社会警惕。为了检验这些假设，我们研究了群体规模、邻居数量和群体内位置对冬季形成大型觅食群体的大白额鹅的警惕性和竞争的影响，并控制了其他变量（群体身份、冬季时期和地点）的影响。我们发现个体的警惕性水平受到邻居数量和群体内位置的显着影响，而群体规模则没有影响。人们对附近的群体伙伴投入了大量的警惕。与外围个体相比，中心个体对邻居的警惕性比例相对较高，这表明中心个体更依赖从邻居获取的社会信息，这可能是由于中心个体的视野受到更多遮挡所致。此外，由于竞争强度与邻居数量呈正相关，因此某些社会警惕性可能起到引导或防止竞争性互动的作用。因此，我们的研究表明，在决定大型动物群体中个体的警惕性时，邻居的数量比群体规模更重要。哪些邻居对个体警惕性影响较大，以及哪些因素影响个体从邻居处获取信息以调整警惕行为，仍需要进一步研究。
The group size effect states that animals living in groups gain anti‐predator benefits through reducing vigilance levels as group size increases. A basic assumption of group size effect is that all individuals are equally important for a focal individual, who may adjust its vigilance levels according to social information acquired from them. However, some studies have indicated that neighbors pose greater influences on an individual's vigilance decisions than other group members, especially in large aggregations. Vigilance has also been found to be directed to both predators (anti‐predation vigilance) and conspecifics (social vigilance). Central individuals might rely more on social vigilance than peripheral individuals. To test these hypotheses, we examined the effects of flock size, number of neighbors and position within a flock on vigilance and competition of greater white‐fronted gooseAnser albifronsthat form large foraging flocks in winter, controlling the effects of other variables (group identity, winter period and site). We found that individual vigilance levels were significantly affected by number of neighbors and position within a flock, whereas flock size showed no effect. Individuals devoted a large component of vigilance to nearby flock mates. Central individuals directed a relatively larger proportion of vigilance to monitor neighbors than peripheral ones, indicating that central individuals more relied on social information acquired from neighbors, possibly caused by the more blocked visual field of central individuals. Moreover, some social vigilance may function as conducting or preventing agonistic interactions since competition intensity was positively correlated with number of neighbors. Our study therefore demonstrate that the number of neighbors is more important than group size in determining individual vigilance in large animal groups. Further studies are still needed to unravel which neighbors pose greater influence on individual vigilance, and the factors that influence individuals to acquire information from their neighbors to adjust vigilance behaviors.