Mixed flocks of birds are two or more species groupings whose formation and cohesion depend on behavioral responses among members in the group. This study investigated the composition of mixed flocks in Atlantic Rain Forest at Parque Estadual Intervales (24º12' a 24º25'S; 48º03' a 48º30'W), in Serra de Paranapiacaba high elevation, SP, Brazil. Field work was conduced from April 1990 to March 1991. Flock size, species composition and high distribuition in vegetation were recorded for each mixed flock. Number of bird species per flocks was positively correlated with flock size (r = 0,8). A total of 120 bird species were registered in 388 records of flocks; only three species were categorized regular species: Basileuterus culicivorus, Philydor rufus e Sittasomus griseicapillus. The species and flock size averaged numbers, respectively 6,71 and 17,26 birds per flock. The numbers, however, showed significant seasonal variation. During the wet season (November to March) mixed flocks presented their richest number of species and greatest number of individuals.
mixed flocks of birds; Atlantic Rain Forest; foraging behaviour
