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ABSTRACT.
-We describe three successful predation events by the Barred Forest Falcon (Micrastur ruficollis) in the Atlantic Forest of coastal southeast Brazil. The prey items were a Plumbeous Pigeon (Patagioenas plumbea), a Brown Tinamou (Crypturellus obsoletus), and a large toad (Chaunus ictericus). This is the first report of successful attacks on prey heavier than the forest falcon, of which none was successfully carried away. These large prey items represent a trade-off between high nutrient value and safety of carrying prey to a secure perch. Received 16 November 2005. Accepted 23 July 2006.
The Barred Forest Falcon (Micrastur ruficollis) is a small neotropical falconid weighing an average of 168 g for males and 233 g for females (Thorstrom 2000). It lives in dense primary or secondary forest where it is known to feed on a variety of small vertebrates and large invertebrates (Sick 1993). Studies of its diet are few (del Hoyo et al. 1994), the most detailed of which (405 prey identified) found reptiles to be the most important group, in terms of frequency, followed by birds. However, both were equal in biomass captured and delivered to nests during the breeding season (Thorstrom 2000). There is one example of predation on a hummingbird (Nunnery et al. 2002) and fruit consumption has been reported (Thorstrom 1996). Hilty and Brown (1986) reported the forest falcon is believed to specialize mostly on small birds, but are not specialists on them (Thorstrom 2000).
Forest falcons are regularly captured in Amazonian forest mist nets attacking small birds already caught in the nets (Mario Cohn-Haft, pers. comm.). They also follow swarms of army ants at times, presumably hunting either fleeing insects or other birds that follow the ants (Willis et al. 1983). The largest prey described weighed 160 g, roughly the minimum weight of the predator (Thorstrom 2000). We describe three cases in the Brazilian Atlantic rainforest of M. ruficollis successfully taking prey larger than itself, and briefly discuss the implications...