Predadores de ninhos em uma comunidade de aves da Mata Atlântica do estado de São Paulo

Abstract

The loss of nests is the main cause of failure in the birds reproduction, so predation becomes an important component in the events related to life history adaptations. An adaptation widely recognized is the smallest cluth size in tropics than temperate areas. One of the main hypotheses that try to explain this fact is the Skutch’s hypothesis, which predicts that predation rates are higher in the tropics and increase according visitation rate of parental in nest. Predation is also commonly associated with decline of birds population in fragmented areas, the mesopredators release hypothesis is widely used to explain this fact. This hypothesis predicts that in fragmented areas the top predators are the first to become extinct, leading to an increase in the density of mesopredators, which increases the nests predation rate, resulting in a decline of birds. Thus, the main goal was to identify nest predators in Atlantic Forest using cameras trap, allowing to infer about some assumptions of Skutch’s hypothesis and "mesopredators release". During two breeding seasons 2013/2014 and 2014/2015 were found 154 nests of 28 species of birds, of which 41 were preyed (26.62%). The contribution of each type of predator (day x nocturnal) can be evaluated and corroborated with the premise of Skutch’s hypothesis, they are mainly diurnal predators. There were no differences between the stages of the nesting cycle (incubation and nestling), so it was not possible to relate the predation with the activity of parents. The predation rate for the study area was low when compared with other studies, this can occur due to the area be well preserved and continuous, unlike most studies that are conducted in disturbed areas. Mostly identified nest predators are part of the diet of top predators, but there is indirect evidence (diet) that the smaller cats are probably more important to control density of nest predator, like small marsupials. Although the birds are not commonly quoted in these studies, they contributed greatly to the predation rates presented, reinforcing the importance of further studies on the birds fit in this context.