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ABSTRACT. Identification of the predators of bird nests is essential to test ecological and evolutionary hypotheses and to make practical management decisions. A variety of nest monitoring devices have been proposed but many remain difficult to set up in the field. The aim of this study was to test camera traps as a potential tool to study predation of natural nests in a tropical rainforest environment. Specifically, we registered the predators, assessed their size range, and we compared the use of one and two cameras per nest. Of 122 nests from 24 bird species, 45 (37%) were depredated, and the cameras recorded the predator species in 29 of the total of depredated nests (64%). We identified predators in eight of 16 depredated nests (50%) in which we used one camera trap per nest, and we identified predators in 21 of 29 depredated nests (72%) when we used two camera traps per nest. The predators included six species of birds and six species of mammals, with body masses varying from 20 g to 16.5 kg. Causes for 10 of the 16 detection failures were identified and are discussed. These results suggest that camera traps are viable tools to investigate nest predation in a tropical rainforest area.

No abstract

Identification of the predators of bird nests is essential to test ecological and evolutionary hypotheses and to make practical management decisions. A variety of nest monitoring devices have been proposed but many remain difficult to set up in the field. The aim of this study was to test camera traps as a potential tool to study predation of natural nests in a tropical rainforest environment. Specifically, we registered the predators, assessed their size range, and we compared the use of one and two cameras per nest. Of 122 nests from 24 bird species, 45 (37%) were depredated, and the cameras recorded the predator species in 29 of the total of depredated nests (64%). We identified predators in eight of 16 depredated nests (50%) in which we used one camera trap per nest, and we identified predators in 21 of 29 depredated nests (72%) when we used two camera traps per nest. The predators included six species of birds and six species of mammals, with body masses varying from 20 g to 16.5 kg. Causes for 10 of the 16 detection failures were identified and are discussed. These results suggest that camera traps are viable tools to investigate nest predation in a tropical rainforest area.

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.