The identification of predators of birds' nests, crucial to a better understanding of predator-prey interactions, remains poorly known. Here we provide evidence that birds, and especially passerines, may depredate birds' nests in the Cerrado (Neotropical Savannah) of Central Brazil. Data was collected primarily in a Conservation Unit (Estação Ecológica de Águas Emendadas) during the breeding season, between 2003 and 2007. We report and discuss details on 14 events of nest predation, 12 of which by passerines, mostly by curl-crested jays - Cyanocorax cristatellus (Temminck, 1823). The results of our study suggest that the role of birds as nest predators in the Cerrado has been underestimated and needs to be further investigated.

The Cerrado is still one of the most important ecosystems in Brazil, even though more than 50% of its area has been altered or converted to pastureland and plantations. Despite its intense degradation, few ecological processes that might affect its biodiversity have been evaluated. The goal of this study was to test the edge effect on the predation rates at natural and artificial nests, at the Ecological Station of Águas Emendadas, Federal District, Brazil. Natural nests were found and monitored every three to four days from September to December of 2004 in the interior and at the edge of the reserve. Artificial nests were placed at four distances from the edge (0, 500, 1000 and 2000 m) in three spatial replicates in September and again in December of 2004. Each nest received one Japanese Quail and one plasticine egg and was monitored every five days, for 15 days. There was no difference between the rates of predation either in the natural nests or in the artificial nests between treatments. For one bird species, Elaenia chiriquensis (Lawrence, 1865), Tyrannidae, daily survival rates in the incubation and in the hatchling period had opposite values between the edge and the interior. Marks on plasticine eggs suggest that birds are the main predators. Estimates of the abundance of two potential nest predators, Cyanocorax cristatellus (Temminck, 1823), Corvidae and Canis familiaris (Linnaeus, 1758), Canidae, revealed no relationship with distance to the edge, nor with predation rates. Brood parasitism of natural nests was similar between the interior (0%) and the edge (3.8% of the nests). The results described here do not support the edge effect hypothesis for nest predation rates on either natural or artificial nests, nor for brood parasitism rates.

Elaenia chiriquensis (Lawrence, 1865) é um Passeriforme abundante nos cerrados do Planalto Central entre os meses de setembro e dezembro, quando se reproduz. Este trabalho tem por objetivo descrever alguns aspectos de sua biologia reprodutiva. O estudo foi desenvolvido na área da Estação Ecológica de Águas Emendadas, Planaltina, Distrito Federal durante o período de agosto de 2002 a dezembro de 2003. Ninhos (n = 110) foram monitorados a cada 1-5 dias. Adultos (n = 285) foram individualmente marcados. O tamanho das ninhadas variou entre um (n = 14), dois (n = 88) ou três ovos (n = 1). Elaenia chiriquensis constrói ninhos abertos em forma de "taça", com ovos de coloração branco gelo a rosado e pequenas manchas de cor ferrugínea no pólo obtuso. Dimensões e forma dos ninhos foram comparáveis aos da mesma espécie na América do Sul. A reprodução ocorreu entre meados de setembro a fins de dezembro, com dois picos de ninhos ativos, meados de outubro e novembro. Estes dois picos podem ser explicados por uma segunda tentativa após o sucesso ou insucesso da primeira nidificação. Trinta e dois ninhos (30%) obtiveram sucesso, 70 foram predados (67%) e 4 abandonados (4%). O sucesso dos ovos foi de 28% e a taxa de eclosão de 0,96 ± 0,02. A produção anual de filhotes (0,48 filhotes/ninho), a taxa de fecundidade (1,1 filhotes/fêmea), bem como as demais taxas encontradas foram semelhantes para outros estudos sobre a espécie e para outros Passeriformes neotropicais em países da América do Sul.

Elaenia chiriquensis (Lawrence, 1865) is a very common passerine abundant during the reproductive season (September-December) in the cerrados of Central Brazil. Since its breeding biology is still poorly known, this study had the aim to describe several aspects of its reproduction. We conducted the study at the "Estação Ecológica de Águas Emendadas", Federal District, Brazil, between August 2002 and December 2003. Birds were banded (n = 285) during this period. Nests (n = 110) found were monitored every 1-5 days. Clutch sizes had one (n = 14), two (n = 88) or three eggs (n = 1), which were pinkish with small reddish dots around the obtuse end. Nest characteristics were comparable to other records of this species. Breeding occurred between mid September to the end of December with two peaks of active nests, one in mid October and one in mid November. These two peaks may be explained by a second breeding attempt after a successful nest or a second breeding attempt after an unsuccessful first attempt. Thirty-two nests (30%) were successful, with most of the nests being depredated (n = 70%) and few abandoned (n = 4%). Egg success was of 28% and the hatching rate was 0.96 ± 0.02. Fledgling production was of 0.48 fledglings/nest and fecundity was 1.1 fledglings/female. All these values are similar to the ones already reported for this species and similar to other Neotropical passerines.

O tamanho do território é um importante atributo ecológico das populações, sendo considerado um fator que pode determinar densidades populacionais. Os Thamnophilidae formam um grupo diverso de pássaros insetívoros, usualmente representativos nas comunidades de aves em florestas da região Neotropical. Neste estudo estimamos o tamanho de território de três espécies de Thamnophilidae, Thamnophilus caerulescens (Vieillot, 1816) (Choca-da-mata), Dysithamnus mentalis (Temmink, 1823) (Choquinha-lisa) e Pyriglena leucoptera (Vieillot, 1818) (Papa-taoca-do-sul), através do método de polígono convexo, em um fragmento de Mata Atlântica no sudeste do Brasil. Os territórios foram pequenos (< 2 ha) para as três espécies e não variaram significativamente entre as estações não reprodutiva e reprodutiva. Os territórios sobrepuseram-se consideravelmente entre as três espécies, mas não em cada espécie. O tamanho dos territórios aumentou com a massa corporal das três espécies (P. leucoptera > T. caerulescens > D. mentalis). Não foi observada nenhuma relação entre o tamanho do território e sua distância à borda da mata e à estrada para as três espécies.

Territory size is an important ecological attribute of populations that has been considered a factor determines population density. Antbirds is a large group of mainly insectivorous Neotropical passerines, usually well represented in bird communities from forested landscapes in Neotropical region. Territory sizes for three Antbirds, Thamnophilus caerulescens (Vieillot, 1816) (Variable Antshrike), Dysithamnus mentalis (Temmink, 1823) (Plain Antvireo) e Pyriglena leucoptera (Vieillot, 1818) (White-shouldered Fire-eye), were mapped and their area estimated by the convex polygon method in a 50 ha forest fragment, in southeastern Brazil. The three species presented small territories of similar sizes (< 2 ha) both during the non-reproductive and the reproductive seasons of 2000-2001. Territories overlapped considerably among species but not intraspecifically. Territory sizes increased with body mass of the three species studied (P. leucoptera > T. caerulescens > D. mentalis). We failed to find any effect on territory size for the three species associated with forest edge or distance to the dirt road.

Para espécies de aves coloniais a sincronia de eclosão dos ovos tem sido considerada um fator que influencia o sucesso reprodutivo. O Guaxe, Cacicus haemorrhous (Linnaeus, 1766), é uma espécie de Passeriformes (Icterinae) que se reproduz em colônias com grupos de fêmeas fazendo a postura em diferentes períodos ao longo da estação reprodutiva. O objetivo deste estudo foi avaliar se há uma variação no sucesso reprodutivo de C. haemorrhous entre esses grupos de fêmeas que fazem a postura em diferentes períodos ao longo da estação reprodutiva. Quatro colônias totalizando 192 ninhos foram monitoradas no Parque Estadual do Rio Doce, Minas Gerais, Brasil, calculando-se a probabilidade de sobrevivência dos ninhos em relação a diferentes períodos (cedo e tardio) ao longo da estação reprodutiva de 2001. Constatou-se que fêmeas que reproduziram mais cedo na estação reprodutiva obtiveram maior sucesso reprodutivo do que fêmeas que reproduziram mais tarde. A predação foi a principal causa de perda de ninhos (48,4%), sendo observado um aumento nas taxas de predação com o avanço da estação reprodutiva.

For colonial bird species, egg hatching synchrony has been considered an important factor in their reproductive success. The Red-rumped Cacique, Cacicus haemorrhous (Linnaeus, 1766), is a Passeriformes species (Icterinae) that reproduces in colonies in which groups of females lay their eggs at different periods during the reproductive season. The objective of this study was to evaluate if there was a variation in the reproductive success among C. haemorrhous females groups that lay eggs in different periods along the reproductive season. A total of 192 nests from four colonies were monitored at Parque Estadual do Rio Doce, Minas Gerais state, Brazil, and used to calculate the nest survival probability in different periods (early and late) of the 2001 reproductive season. The results showed that females that reproduced at the beginning of the reproductive period had higher reproductive success than those that reproduced later. Predation was the main cause of nests loss (48,4%), and an increase in predation rate was observed as the reproductive period advanced.

Five hundred and eigh body masses of 74 forest birds, and measurements of wing, tail, tarsus and beak of 14 poorly known species mist-netted at two sites in the Atlantic Forest of eastern Paraná State, southern Brazil, are presented.