Bats as predators at the nests of tropical forest birds

Nest predation is one of the main causes of bird mortality, and the development of nest anti‐predatory defenses can mold many aspects of bird evolution. Here we report that bats can attack nests in incubation and nestling stages in the Atlantic Forest, Brazil. Although other types of interactions between birds and bats have been reported, including predation of adult individuals and the co‐occurrence in cavity nests, bats may have been underestimated as nest predators. The combination of flying and olfactory skills makes bats functionally different compared to other predators, opening new perspectives on the interpretation of nesting‐birds anti‐predatory strategies. They represented 8% of all recorded potential predations in the bird community studied, being more important than reptiles, and were responsible for 33% of nest losses for at least one bird species. Our data suggest the potential for nest depredation by bats to be an important selective factor in shaping anti‐predatory strategies of nesting birds. Then, the use of devices capable to detect bats will be essential for reliable interpretations of birds nest defense mechanisms in future works.