Sobrevivência e tamanho populacional do Tiê-preto Tachyphonus Rufus (aves: thraupidae) em fragmento de restinga no extremo Norte da Mata Atlântica

For a long time, we believed in the pattern that tropical and south hemisphere species have high survival. Nowadays results began to contradict this pattern, indicating the need for further studies. Despite the advanced state of the study of bird population parameters, little is known about their variation throughout the year and the factors affecting them. Reproduction, for example, is one factor that may alter adult survival rates, because during this process the breeding pair allocates resources to maintain itself to maintain offspring, making itself more susceptible to diseases and predation. The aim of this study was to estimate survival and population size of a Central and South America passerine, Tachyphonus rufus (Boddaert, 1783), testing hypotheses about the factors that define these parameters. We performed data collection between Nov/2010 and ago/2012 in 12 ha plot, in a fragment of Atlantic Forest in northeastern Brazil. We used capture-mark-recapture methods to generate estimates using Closed Design Robust model in the program MARK. We generated Multi-state models to test some assumptions inherent to Closed Robust Design. The influence of co-variables (time, rain and reproductive cycle) and the effect of transient individuals were measured. Capture, recapture and apparent survival parameters were defined by reproductive cycle, while temporary dispersal was influence by rain. The estimates showed a higher apparent survival during the non-breeding period (92% ± 1%) than during breeding (40% ± 9%), revealing a cost of reproduction and suggesting a trade-off between surviving and reproducing. The low annual survival observed (34%) did not corroborate the pattern of high rates expected for a tropical bird. The largest population size was estimated to be 56 individuals in Nov/11, explained by high recruitment of juveniles, while the lowest observed in May/12: 10 individuals, probably as a result of massive influx of competitor species. Results from this study add to the growing literature on life history of Neotropical species. We encourage studies like this especially in Brazil, where there are few information, and suggest that covariates related to habitat quality and environmental changes should be tested, so that we can generate increasingly reliable modelsCoordenação de Aperfeiçoamento de Pessoal de Nível SuperiorPor muito tempo, acreditamos no padrão de que espécies e populações de aves provenientes de regiões tropicais e do hemisfério sul apresentavam elevadas taxas de sobrevivência. Atualmente existem resultados que contradizem esse padrão, indicando a necessidade de mais estudos nessas regiões. Ainda que um grande progresso tenha acontecido no estudo de parâmetros populacionais em aves, pouco se sabe a respeito de suas variações ao longo do ano e dos fatores que os afetam. A reprodução, por exemplo, é um fator que pode alterar as taxas de sobrevivência de adultos, uma vez que durante este processo o par reprodutor aloca recursos da própria manutenção para a manutenção da prole, tornando-se mais susceptíveis à predação e doenças. O objetivo deste estudo foi gerar estimativas de sobrevivência e tamanho populacional de Tachyphonus rufus (Boddaert, 1783), um passeriforme restrito a América Central e do Sul, testando hipóteses acerca dos fatores que influenciam esses parâmetros. Realizamos a coleta de dados entre nov/2010 e ago/2012, em um quadrante de 12 ha, num fragmento de Mata Atlântica no nordeste do Brasil. Através do método de captura-marcação-recaptura elaboramos históricos de captura e geramos estimativas utilizando modelos de Desenho Robusto Fechado com o uso do programa MARK. Por originar modelos menos complexos, utilizamos modelos de Multi-estratos para testar alguns pressupostos inerentes aos modelos de Desenho Robusto. Avaliamos a influência de co-variáveis (tempo, chuva e ciclo reprodutivo) e o efeito de indivíduos transitórios. As probabilidades de captura e recaptura e a sobrevivência aparente foram definidas pelo ciclo reprodutivo, enquanto a dispersão temporária pela chuva. As estimativas mostraram uma maior chance de sobreviver durante o período não reprodutivo (92% ± 1%) do que durante a reprodução (40% ± 9%), revelando um custo reprodutivo e evidenciando um trade-off entre sobreviver e se reproduzir. A baixa sobrevivência anual observada (34%) não corrobora o padrão de altas taxas esperado para os trópicos. O maior tamanho populacional estimado foi de 56 indivíduos em nov/11, explicado pelo alto recrutamento de jovens para a população adulta, enquanto em mai/12 observamos o menor: 10 indivíduos, provavelmente resultante da entrada em massa de espécies competidoras. Acreditamos que nossos resultados contribuem para o entendimento da história de vida de aves de regiões tropicais, ainda pouco conhecida. Sugerimos que mais trabalhos como este sejam desenvolvidos nos neotrópicos, em especial no Brasil pela escassez de estudos com esse caráter, e que sejam testadas co-variáveis relacionados com qualidade do habitat e alterações ambientais, de forma a podermos gerar modelos cada vez mais confiávei

Richness, composition and trophic groups of an avian community in the Pernambuco Endemism Centre, Alagoas, Brazil

In northeastern Brazil, the reduction of the natural forest cover to a series of small, isolated fragments has had negative consequences for the local avian fauna, in particular, a loss of the more specialized species, while the populations of some generalists have tended to increase. The present study focuses on the composition and trophic groups of a bird community on a farm in the northeastern Brazilian state of Alagoas. Monthly surveys were conducted between November 2008 and October 2009, based on mist-netting and systematic observations. Overall, 112 species were recorded, of which 76 were associated with the two forest fragments surveyed, while all the others were observed exclusively in the surrounding matrix of pasture and orchards. The bird community presented a predominance of insectivorous species, followed by omnivores. However, specialized trunk-creeping and understory insectivores accounted for only around 15% of the species in this feeding category. The reduced diversity of other guilds and species with more specialized diets, and the complete absence of sensitive species such as large parrots and raptors, reflects the severe fragmentation and degradation of the local forests, which has greatly reduced the availability of dietary resources and breeding sites

Apparent survival and cost of reproduction for White-lined Tanager (Tachyphonus rufus, Thraupidae) in the northern Atlantic Rainforest, Brazil.

Understanding latitudinal variation in avian life-history traits has been a focus of many demographic studies around the world. However, we still know little about annual or intra-annual demographic variation within tropical regions or about how factors such as breeding season and precipitation influence demographic rates. In this study, we estimated intra-annual apparent survival of the White-lined Tanager (Tachyphonus rufus) using capture-mark-recapture data from northeastern Brazil. We tested whether survival varied seasonally (breeding vs. non-breeding), with rainfall, by age and residence status in our study area. Intra-annual apparent survival was correlated with the reproductive cycle, being lower during the breeding (0.65 ± 0.16 SE) vs. the non-breeding season (0.97 ± 0.05 SE). The annual apparent survival (~0.6) was relatively low for a tropical species. In both years, we observed highest abundance in spring (November, 3.1-3.7 birds/ha) and lowest abundance in autumn-winter periods (May-August, 1.1-1.4 bird/ha). The low survival during the breeding season probably reflects the trade-off between survival and reproduction and the cost of reproduction. Our findings represent an advance in the understanding of the demography of tropical birds because we did not find a predicted high annual apparent survival, and we elucidated some aspects of intra-annual variation in survival. Further exploration of latitudinal variation in demographic traits, especially in diverse, but poorly known habitats is needed to fully vet and develop life history theories

Richness, composition and trophic groups of an avian community in the Pernambuco Endemism Centre, Alagoas, Brazil

In northeastern Brazil, the reduction of the natural forest cover to a series of small, isolated fragments has had negative consequences for the local avian fauna, in particular, a loss of the more specialized species, while the populations of some generalists have tended to increase. The present study focuses on the composition and trophic groups of a bird community on a farm in the northeastern Brazilian state of Alagoas. Monthly surveys were conducted between November 2008 and October 2009, based on mist-netting and systematic observations. Overall, 112 species were recorded, of which 76 were associated with the two forest fragments surveyed, while all the others were observed exclusively in the surrounding matrix of pasture and orchards. The bird community presented a predominance of insectivorous species, followed by omnivores. However, specialized trunk-creeping and understory insectivores accounted for only around 15% of the species in this feeding category. The reduced diversity of other guilds and species with more specialized diets, and the complete absence of sensitive species such as large parrots and raptors, reflects the severe fragmentation and degradation of the local forests, which has greatly reduced the availability of dietary resources and breeding sites.</div