Mixed specks bird flocks its dipterocarp forest of north central Burma (Myanmar)

We studied the bird community in deciduous, dipterocarp forest of north-cen tral Burma (Myanmar) during December 1994, March 1996, and January 1997 and 1999. Most members of this community participated in mixed-species flocks. Seventy-three flocks were encountered during our study, containing 52 spec ies. Of these, 25 species occurred in more than 10% of flocks, and were inc luded in our analyses. There were 26 significant correlations among species pairs, 25 of which were positive. Cluster analysis indicated that there we re three principal types of flocks: one consisting mostly of small passerin es and picids, commonly including Common Wood-Shrike, Small Minivet and Whi te-browed Fantail, among others; a second type consisting mainly of sylviid s, e.g. Arctic, Dusky and Radde's Warblers; and a third type which generall y centred around Greater and Lesser Necklaced Laughingthrushes. Bird-eating hawks were numerous at these sites, and we witnessed several attacks on fl ocks during the study. Thus we infer that enhanced protection from predatio n is an important benefit conferred by flock membership. In contrast, there was little overlap in foraging behaviour among species, suggesting that fo raging facilitation is a relatively minor benefit enjoyed by flock members, although we did observe White-browed Fantails and Greater Racket-tailed Dr ongos kleptoparasitizing other species on occasion.