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INTRODUCTION
Mixed-species flocks are multispecific associations found in taxonomic groups as
diversified as birds (Moynihan 1962, Munn 1985, Powell 1985, Stotz 1993, Develey
and Peres 2000), primates (Peres 1992, Bshary and Noë 1997, Chapman and Chapman
2000), marine fishes (Robertson et al. 1976), and miscellaneous (e.g., between birds and
primates, Ferrari 1990, Passos 1997). A typical trait of these ecological associations is
the close moving of individuals pertaining to distinct species, independently of some
resource aggregation. So, the motivation for an individual to integrate these associations
is the group by itself (Powell 1985). In this aspect, the mixed flocks differ from
aggregations, where the individuals are attracted by a resource distributed in patches, as
fruits, seeds, or water (Powell 1979, 1985).
Mixed flocks are conspicuous components of forest bird assemblages, both in
temperate and tropical regions (Winterbotton 1949, McClure 1967, Morse 1970,
Partridge e Ashcroft 1976, Munn 1985, Hutto 1994, Yaukey 1995, Hino 2002), being
more stable and complex in the last situation (Munn e Terborgh 1979, Powell 1985,
Greenberg 2000). In the Neotropics, these interactions were studied in Central America
(Moynihan 1962, Powell 1979, Hutto 1987, 1988, 1994, Latta and Wunderle, 1996,
Gram 1998), Patagonia (Vuilleumier 1967, Ippi and Trejo 2003), Amazon Basin (Munn
and Terborgh 1979, Munn 1985, Terborgh et al. 1990), Cerrado (Alves 1990, Alves and
Cavalcanti 1996, Ragusa-Netto 2000, Tubelis 2004) and southeastern Atlantic Forest.
Bird flocks studies in Atlantic Forest focused mainly on structure (Davis 1946, Moraes
e Krul 1995, Aleixo 1997, Ghizoni-Jr. and Azevedo 2006), seasonality (Davis 1946,
Develey and Peres 2000, Maldonado-Coelho and Marini 2004), effects of fragmentation
and successional stage (Maldonado-Coelho and Marini 2000, 2003, 2004), and possible
adaptive reasons (Machado and Rodrigues 2000).