Experimentos com ninhos artificiais são utilizados para testar hipóteses ecológicas e comportamentais que influenciam na predação de ninhos naturais. O tamanho do ovo, a textura da casca e a cor podem influenciar na taxa de predação, porém poucos estudos avaliam qual modelo de ovo é o mais adequado para simular a predação de ninhos em áreas tropicais. O objetivo deste trabalho foi comparar a predação de diferentes modelos de ovos (ovos de codorna, massa de modelar e canários) no solo e a 1,30 m de altura no sub-bosque. O experimento foi realizado Ilha Anchieta, Ubatuba, São Paulo, Brasil. Foi encontrada uma diferença significativa na taxa de predação entre os ovos de codorna (71,87%) e sintéticos (93,75%) e entre os ovos de codorna e de canário (100%) no solo. Entretanto, não houve diferença significativa entre os ovos sintéticos e de canário. Os ninhos no sub-bosque apresentaram um padrão diferenciado do solo quando se refere aos ovos de codorna (25%) e sintéticos (28,1%), mas houve diferenças significativas quando os ovos de canário foram comparados com os ovos sintéticos e de codorna. Nosso trabalho demonstrou que diferentes tipos de ovos sobre uma mesma pressão de mesopredadores apresentaram taxas de predação diferentes. Portanto, estudos que avaliam o sucesso reprodutivo da avifauna baseado na predação de ninhos artificiais devem considerar a utilização de diferentes tipos de ovos e estratos na vegetação.

ABSTRACT. Islands can serve as model systems for understanding how biological invasions affect native species. Here we examine the negative effects of mesopredator mammals on bird richness at Anchieta Island, an 826 ha offshore island in the coast of Brazil. Anchieta Island has the highest density of mammals of the entire Atlantic forest, especially nest predators such as marmosets and coatis, introduced more than 20 years ago. This indiscriminate introduction of mammals may have affected directly the bird community, nowadays represented by 100 species comprised mainly by watercrossing birds, being 73 forest-dwelling species. A small component of these remnant bird species nests in tree holes and on the forest floor, null model analysis suggest that birds within these two nest types are under-represented on Anchieta Island. All guilds were affected negatively, but "opportunist insectivorous/omnivorous". Experiments using artificial nests showed a predation of 73% of nests on the floor while only 26% on the mainland. Camera traps recorded predation by coatis, agoutis, and opossums. The restoration of the bird community on this island is highly constrained by the high density of hyper abundant nest predators.

Threatened species are frequently difficult to monitor, leading to a lack of information for the selection of the best conservation strategies. A case in point is the Red-billed Curassow (Crax blumenbachii, Cracidae, Galliformes), whose populations have declined due to deforestation of the northern Atlantic Forest and increased poaching in the late 1960s. The species is presently absent from most forest frag- ments within its geographic range, occurring only in forest remnants on the states of Bahia and Espírito Santo, Brazil. In this study, we esti- mated encounter rates and recorded the periods of activity of the Red-billed Curassow in three large Atlantic Forest fragments in the north- eastern Brazilian state of Bahia, using line-transect sampling. The northern region of Serra do Conduru State Park (0.29 sighting/10 km) and Descobrimento National Park (0.27 sighting/10 km) presented slightly greater encounter rates of this endangered cracid, compared to the Una Biological Reserve (0.13 – 0.20 sighting/10 km). We recorded Red-billed Curassows throughout the day, mainly between 10:00–11:00 h and 14:00–17:00 h. Our study is the first step for long-term monitoring of the Red-billed Curassow. These findings serve as baseline infor- mation, which may contribute to future assessments of the conservation status and support future conservation actions for the species.