Agonistic behaviour of Japanese White-eyes Zosterops japonica on Miyake Island

Abstract

1) The Japanese White-eye Zosterops japonica was studied on Miyake Island (Izu Islands) in winter to record agonistic behaviour and associated behaviour.2) The winter population consisted of the island race Z. j. stejnegeri and the mainland race Z. j. japonica (about 9%), distinguishable in size and weight. Both races exhibited agonistic behaviour at sources of concentrated food supply, and in territorial contexts, with motor patterns similar to those known for other species of Zosterops. Wing fluttering, supplanting with bill clattering and head turning, which are components of aggressive behaviour unique to the genus Zosterops, have now been observed in Z. japonica.3) Foraging flock size, feeding habits and prey hunting behaviour were also typical of Zosterops, with generalized food niche and a large repertoire of foraging behaviour.4) The frequency of wing flicking was related to restlessness and not to dominance behaviour.5) Dominance classes of birds, based on the proportion of wins in total aggressive encounters in which birds were observed, reflected their ranks in a hierarchy derived from individual relatoins. Dominace classes were not related to any of the size attributes measured. Some small mainland birds were dominant over large island birds.