领燕■繁殖群体的集群觅食(英文)

Flock foraging at a breeding colony of collared pratincoles Glareola pratincola

集合点假说(Assembly-point hypothesis)认为动物局部地区聚群数量的增加有助于不同的繁殖地的个体聚集成群体,然后一起寻找食物斑块觅食,这种聚群有助于个体从集群觅食中获得利益。本文通过领燕■(Glareola pratincola)离开和回到繁殖地的先后顺序来验证以上假说。我们在29天的观察中,发现有4天该群中个体离开繁殖地的先后顺序不是随机分布的,尽管这种策略会随着环境条件而改变,但仍然表明领燕■的觅食群体在繁殖地就已经聚集形成了。食物资源(飞虫)的短暂性和波动性以及由繁殖地到觅食地的距离均与所验证的假说的假设相一致。

A variety of hypotheses has been adduced to explain why avian coloniality evolves （Wittenberger and Hunt, 1985 ）. The information center hypothesis （Ward and Zahavi, 1973） argues that species that benefit from social foraging should also be able to benefit by following others from a central colony site. According to this hypothesis, the main function of coloniality is transfer of information about the spatial location of food sources. Thus, an unsuccessful forager could follow a successful forager when leaving a communal roost or colony, and will in turn be fol- lowed on the occasions when it foraged successfully. However, the empirical evidence available for testing the hypothesis is incomplete and a majority of authors have not been able to confirm it （e. g. , Stutchbury, 1988; Caccamise, 1991; Buckley, 1997; but see Sonerud et al., 2001 ）. There are also serious theroretical problems derived from possible assumptions based on group selection （e. g. , Richner and Heeb, 1996）.