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

Bird communities in three forest types in the Pernambuco Centre of Endemism, Alagoas, Brazil

The Pernambuco Center of Endemism (PCE) in northeastern Brazil is highly fragmented and degraded. Despite its potential conservation importance the bird fauna in this area is still relatively unknown and there are many remnant fragments that have not been systematically surveyed. Here, we report the results of bird surveys in five forest fragments (one pioneer, two ombrophilous and two seasonal). In total, 162 taxa were recorded, 12 of which are endemic to the PCE. The frequency of endangered species was lower than what has been reported in studies from the same area and most of the taxa considered to be at risk of extinction were sub-species of uncertain taxonomic validity. The comparatively low number of endemic/threatened species may be due to the small size of the fragments in the present study - a consequence of the high levels of habitat loss in this region. Analysis of species richness patterns indicates that ombrophilous forest fragments are acting as refuges for those bird species that are most sensitive to environmental degradation

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

<div><p>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 (<i>Tachyphonus rufus</i>) 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.</p></div

Estimates of intra-annual apparent survival based on Huggins robust design models for the White-lined Tanager (<i>T</i>. <i>rufus</i>) in northeastern Brazil.

<p>Estimates of intra-annual apparent survival based on Huggins robust design models for the White-lined Tanager (<i>T</i>. <i>rufus</i>) in northeastern Brazil.</p

Top nine Huggins robust design models for a population of White-lined Tanager (<i>T</i>. <i>rufus</i>) in northeastern Brazil.

<p>These nine represent 99% of the weight in the entire model set. The global model and the constant model (23^rd and 61^st ranked model in the set respectively) are shown for comparison.</p

Average annual estimates of apparent survival (Φ; mean ± SD) and the maximum and minimum values estimated for Neotropical birds.

<p>Average annual estimates of apparent survival (Φ; mean ± SD) and the maximum and minimum values estimated for Neotropical birds.</p

Model-averaged estimates of capture (<i>p</i>) and recapture (<i>c</i>) based on Huggins robust design models for the White-lined Tanager (<i>T</i>. <i>rufus</i>) in northeastern Brazil.

<p>The vertical bars represent standard error estimates.</p