The composition and spatial organisation of mixedspecies

Abstract

Mixed-species flocks are a prominent form of social organisation of foraging birds, particularly in the tropics (Powell 1985). In general, the occurrence of such flocks has been explained in terms of adaptations to reduce predation and increase foraging efficiency (reviewed in Morse 1977, Terborgh 1990). Flock systems vary widely in the numbers of species and individuals involved, with some of this variation explained by factors related to predation, including the openness of the vegetation and the density of avian predators (Thiollay 1999). More studies from different regions and habitats in the world are needed to further document the diversity of flock systems and better understand the applicability of the hypotheses that explain flocking.