Changes in vigilance with group size under scramble competition
Changes in vigilance with group size under scramble competition
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DOI：
10.1086/368225
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发表时间：
2003-04-01
影响因子：
2.9
通讯作者：
Ruxton, GD
中科院分区：
文献类型：
--
作者：
Beauchamp, G;Ruxton, GD
动物经常中断觅食来扫描周围的环境。在一些分类群中，这种警惕性随着群体规模的增加而降低（Elgar 1989）。警惕性的下降通常被解释为大型群体中个体捕食风险的降低。提高检测能力和风险的数值稀释等机制可能会为大型群体中的觅食者提供更多保护，从而降低警惕性（Pulliam 1973; Roberts 1996; Bednekoff and Lima 1998）。然而，最近的工作表明，警惕性与群体规模的下降可能会减轻对，如果在大群体中的个人扫描更多，以避免位移的侵略性同伴（Slotow和Coumi 2000年; Treves 2000年）或找到其他群体成员的食物发现（Beauchamp 2001年）。在早期的警戒模型中，警戒的降低会使觅食者减少积累固定数量资源所需的总时间（Pulliam et al. 1982），或者在给定的时间范围内增加摄食率（McNamara and Houston 1992）。在这两种情况下，都假设不存在资源竞争。然而，当资源有限时，警惕性的降低可能会使个体分配更多的时间来觅食，从而获得更大份额的重新分配。
Animals often interrupt foraging to scan the surrounding environment. In several taxa, such vigilance decreases with group size (Elgar 1989). The decline in vigilance is usually interpreted as a decrease in the predation risk to an individual in large groups. Mechanisms such as increased detection ability and numerical dilution of risk may provide more protection to foragers in large groups, thus leading to lower vigilance (Pulliam 1973; Roberts 1996; Bednekoff and Lima 1998). Nevertheless, recent work indicates that the decrease in vigilance with group size may be mitigated against if individuals in large groups scan more to avoid displacements by aggressive companions (Slotow and Coumi 2000; Treves 2000) or to locate the food discoveries of other group members (Beauchamp 2001).We explore the role of resource availability on vigilance patterns. In earlier vigilance models, a decrease in vigilance would allow foragers either to decrease the total amount of time needed to accumulate a fixed amount of resources (Pulliam et al. 1982) or to increase feeding rate over a given time horizon (McNamara and Houston 1992). In either case, no competition for resources is assumed to take place. However, when resources are limited, a reduction in vigilance may allow individuals to allocate more time to foraging and so obtain a greater share of the re-