Why do birds participate in mixed-species foraging flocks? A large-scale synthesis

摘要: Mixed-species flocks of foraging birds have been documented from terrestrial habitats all over the world and are thought to form for either improved feeding efficiency or better protection predators. Two kinds flock participants recognized: those that join other species ('followers') therefore likely be recipients benefits participation joined ('leaders'). Through comparative analyses, using a large sample around world, we show (1) 'followers' tend smaller, more insectivorous, feed in higher strata than matched participate lesser extent (2) 'leaders' cooperative breeders often not known lead flocks. Furthermore, meta-analyses published results across showed bird mixed-species increase rates reduce vigilance compared when they solitary conspecific groups. Moreover, is seen only with followers leaders. These findings suggest role predation evolution flocking. Species vulnerable follow whose can exploit. By doing so, able their own forage at rates. (C) 2009 The Association Study Animal Behaviour. Published by Elsevier Ltd. All rights reserved.