Structure and dynamics of mixed-species flocks in a Hawaiian rain forest

The Auk
By:  and 



Mixed-species flocks of native and introduced birds were studied for four years in an upper elevation Hawaiian rain forest. Those flocks were characterized by strong seasonality, large size, low species richness, high intraspecific abundance, a lack of migrants, and a general lack of territoriality or any sort of dominance hierarchy. There was high variability among years in patterns of occurrence at the species level, and high variability within years at the individual level. These flocks are loosely structured social groupings with apparently open membership. The fluid, unstable movement patterns, high degree of variability in size and composition, and lack of positive interspecific associations are not consistent with the “foraging enhancement” hypothesis for flocking. Two resident, endangered insectivores, the Akepa (Loxops coccineus) and Hawaii Creeper (Oreomystis mana) served as “nuclear” species. Flock composition was compared between two study sites that differed significantly in density of these two nuclear species. Flock size was similar at the two sites, primarily because the nuclear species were over-represented relative to their density. This observation suggests that birds are attempting to achieve a more optimal flock size at the lower density site.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Structure and dynamics of mixed-species flocks in a Hawaiian rain forest
Series title The Auk
DOI 10.1642/0004-8038(2003)120[0082:SADOMF]2.0.CO;2
Volume 120
Issue 1
Year Published 2003
Language English
Publisher American Ornithological Society
Description 14 p.
First page 82
Last page 95
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