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How are personalities maintained in wild animal populations? A possible mechanism is the existence of trade-offs between fitness components (survival and reproductive success) among behavioural types. We investigated this trade-off in white-rumped swallows (Tachycineta leucorrhoa) by capturing adults and monitoring their reproduction over time. We focused on the personality trait of nest defence against a human. We found that swallows with different levels of nest defence had similar probability to return from migration between two years (a proxy for survival). In one year, swallows that defended their nests more boldly were also more likely to succeed. However, nest defence was not linked to nestling weight or number of fledglings. Thus, we found no evidence of a trade-off between fitness components. It is possible that the investigated relationships become relevant only in extreme years that severely alter the costs and benefits of this behaviour.

Theory predicts that, even within the same population, birds may vary their breeding investment with age. This may be due to an improvement in individual quality of old birds in body condition, foraging and in nesting experience. Birds commonly signal age and individual quality to potential mates and competitors through plumage colour. Young male and female breeders of Saffron Finches (Sicalis flaveola) have dull plumages that change to yellow with age. We asked whether older, yellow birds are in better condition and invest more in breeding than dull, younger birds. In southern Brazil, we monitored Saffron Finches breeding in nest-boxes over three breeding seasons. We found that yellow birds were in better condition: females had more furcular fat and males were heavier. Yellow parents bred earlier, had larger clutch sizes, shorter incubation periods, re-nested more and ultimately fledged twice as many offspring as dull parents. Egg mass, nestling mass and nest survival probability were similar bet...

Nest prospecting, that is, visiting potential future nest sites, may be a widespread bird behavior. Here we describe apparent prospecting while nesting by white-rumped swallows (Hirundinidae, Aves). In southern Brazil, birds tagged with passive-integrated transponders (PIT-tags) and breeding in nest boxes with PIT-tag readers: (1) often visited nest boxes that were in use by apparently unrelated birds (54 % of nests were visited at least once), (2) visited other boxes while caring for their own nestlings, (3) tended to have smaller broods than birds that were not recorded visiting, and (4) did not have a preference for any particular box. These patterns do not indicate any clear explanation for nest visiting, but they do show that prospecting is done by floaters (non-breeders) as well as actively breeding individuals. We suggest that these visits occur when time is available and that visitors may be assessing the availability of future nest sites.

Scientists have long been trying to understand why the Neotropical region holds the highest diversity of birds on Earth. Recently, there has been increased interest in morphological variation between and within species, and in how climate, topography, and anthropogenic pressures may explain and affect phenotypic variation. Because morphological data are not always available for many species at the local or regional scale, we are limited in our understanding of intra- and interspecies spatial morphological variation. Here, we present the ATLANTIC BIRD TRAITS, a data set that includes measurements of up to 44 morphological traits in 67,197 bird records from 2,790 populations distributed throughout the Atlantic forests of South America. This data set comprises information, compiled over two centuries (1820–2018), for 711 bird species, which represent 80% of all known bird diversity in the Atlantic Forest. Among the most commonly reported traits are sex (n = 65,717), age (n = 63,852), body mass (n = 58,768), flight molt presence (n = 44,941), molt presence (n = 44,847), body molt presence (n = 44,606), tail length (n = 43,005), reproductive stage (n = 42,588), bill length (n = 37,409), body length (n = 28,394), right wing length (n = 21,950), tarsus length (n = 20,342), and wing length (n = 18,071). The most frequently recorded species are Chiroxiphia caudata (n = 1,837), Turdus albicollis (n = 1,658), Trichothraupis melanops (n = 1,468), Turdus leucomelas (n = 1,436), and Basileuterus culicivorus (n = 1,384). The species recorded in the greatest number of sampling localities are Basileuterus culicivorus (n = 243), Trichothraupis melanops (n = 242), Chiroxiphia caudata (n = 210), Platyrinchus mystaceus (n = 208), and Turdus rufiventris (n = 191). ATLANTIC BIRD TRAITS (ABT) is the most comprehensive data set on measurements of bird morphological traits found in a biodiversity hotspot; it provides data for basic and applied research at multiple scales, from individual to community, and from the local to the macroecological perspectives. No copyright or proprietary restrictions are associated with the use of this data set. Please cite this data paper when the data are used in publications or teaching and educational activities.

We describe a nest and nesting activity of the Cinereous Warbling Finch (Poospiza cinerea) in Paredao da Serra do Curral City Park, Minas Gerais State in southeastern Brazil. Little is known about the reproductive biology of this globally vulnerable species. The nest was built with fragments of grass spikes in an Australian pine (Casuarina equisetifolia). The clutch consisted of three eggs. We describe courtship feeding behavior of the Cinereous Warbling Finch and brood parasitism of the nest by the Shiny Cowbird (Molothrus bonariensis).

The Cinereous Warbling-finch Poospiza cinerea is a globally vulnerable Emberizidae passerine, patchily distributed and rare in the open savannah of central South America. Attributes of rare species include niche specificity such as feeding habits. To verify possible niche specialization in this species we aimed to describe its foraging habits related to substrate use, foraging and substrate height, attack maneuvers, and consumed food items. We monitored two groups at two study sites and sampled foraging events with intervals of 15 minutes. The substrates used in greater frequency were foliage and reproductive organs. Foraging and substrate height varied widely with study area. The attack maneuver adopted in greater frequency was glean. Most food items attacked were small invertebrates. Big invertebrates included Lepidoptera, Hemiptera, Coleoptera, Hymenoptera and Orthoptera. Poospiza cinerea was also recorded foraging in mixed bird flocks with seven other species. The generalist foraging behavior of the species cannot be associate to its rarity. O capacetinho-do-oco-do-pau Poospiza cinerea é um passeriforme da família Emberizidae globalmente vulnerável, irregularmente distribuído e raro no Cerrado do centro da América do Sul. Atributos de espécies raras incluem especificidades de nicho tais como hábitos de forrageamento. Para verificar possível especialização de nicho dessa espécie, buscamos descrever seu comportamento de forrageamento relacionado a uso de substrato, altura de forrageamento e do substrato, manobras de ataque e itens alimentares consumidos. Nós monitoramos dois grupos em duas áreas de estudo e amostramos eventos de forrageamento com intervalos de 15 minutos. Os substratos utilizados em maior frequência foram folhagem e órgãos reprodutivos. Alturas de forrageamento e dos substratos variaram amplamente com a área de estudo. A manobra de ataque adotada em maior frequência foi respigar. A maioria dos itens alimentares foi pequenos invertebrados. Grandes invertebrados incluíram Lepidoptera, Hemiptera, Coleoptera, Hymenoptera e Orthoptera. Poospiza cinerea foi registrado forrageando em bandos mistos com outras sete espécies. O comportamento de forrageamento generalista da espécie não pode ser associado com sua raridade.

Information on breeding biology of birds is fundamental for the understanding of life history evolution and conservation. This information is only beginning to accumulate for Neotropical birds but the southern subtropics are still overlooked. Here we describe the breeding biology of passerines in subtropical Brazilian Atlantic Forest. We monitored 265 nests of 38 species during the 2012–2013 breeding season. Breeding began in September, but some species started as late as December. Average breeding season length was 64 days, but varied broadly across species. Average clutch sizes ranged from two to five eggs. The breeding season phenology, clutch sizes, and nesting periods were similar to other two communities at the same latitude in Argentina. Our data contribute to the debate that the combination of small clutch sizes and short breeding seasons seen in subtropical South America challenges the tropical-temperate paradigm of life-history theory.