Miguel Ângelo Marini

Climate change is altering breeding phenology patterns in different ways across regions, periods and species. We examined spatial and temporal variation in the breeding phenology of four Neotropical birds, specifically testing whether the magnitude of phenological shifts increases with distance from the equator, as previously reported for Northern Hemisphere species. We used data from 1310 clutches from Pitangus sulphuratus, Zonotrichia capensis, Tyrannus savana and Troglodytes aedon, spanning 1901–2020 and latitudes 32°N to −54°S. Breeding dates were analysed in relation to time, latitude and climatic variables through Bayesian linear models. Species showed very contrasting responses. Temporal patterns differed among species: Ty. savana and Tr. aedon delayed breeding over time, P. sulphuratus advanced and Z. capensis showed no temporal effect. Latitude influenced breeding phenology in Z. capensis, and year–latitude interactions indicated spatial variation in temporal changes for Ty. savana and Tr. aedon. Although all species analysed exhibited latitudinal structure in breeding phenology, the magnitude and direction of temporal changes differ among species, with no evidence that phenological shifts become stronger at higher latitudes farther from the equator, and that the Northern and Southern Hemispheres show different patterns.

Description of molt patterns of large-bodied species, such as vultures, is difficult and scarce. The black vulture ( Coragyps atratus ) is the most common and abundant Neotropical vulture, though its molt pattern is not yet fully understood. Here we describe its primary molt pattern using images of citizen science platforms taken from 2014 and 2024 in southeastern Brazil. The black vulture undergoes a complete molt per cycle, with an average duration of 15.5 months. The molt extends throughout the year with a decline in the winter with fewer records of primary molt during this period. The apparent second molt wave starts before the replacement of external primaries is completed, a Staffelmauser -like pattern. By comparing molt data with average breeding records for the southern hemisphere, we verified a decrease in molt records during the peak of breeding activity in the winter. This molt pattern agrees with other Cathartidae, and might be related to seasonal changes in photoperiod, resource availability or climatic seasonality. Our study shows that citizen science data can be used as a supplementary tool to study molt patterns of large-bodied birds which spend a large amount of time flying, and which capture is logistically difficult.

Variation in avian clutch and egg sizes across geographical gradients has long been debated, particularly regarding the mechanisms underlying latitudinal clines in reproductive investment. These patterns are primarily driven by climatic conditions, with latitude acting as a proxy for environmental gradients. Here, we assembled a robust dataset of eggs and clutches of eight species of kingbird flycatchers ( Tyrannus ) covering a broad geographic range to test the hypothesis that clutch and egg size vary systematically along environmental gradients, and predict that egg and clutch size would (a) increase with latitude, (b) be larger in more seasonal climate categories, (c) be larger at sites with cooler winters, and (d) be larger at sites with warmer and wetter long‐term climatic conditions. We analysed clutch and egg data from 35 scientific egg collections representing the geographically widespread genus Tyrannus . After applying spatial, temporal and taxonomic data quality controls, we analysed the relationships between clutch and egg size and climatic variables. The analyses of 1332 clutches and 4680 eggs of eight species collected during 158 years (1858–2016) showed that clutch and egg sizes increased toward higher latitudes. Both traits varied according to major climate types, regional subclimates, and local temperature and precipitation conditions. More seasonal regions had the largest clutches, although sites with colder winters did not have the largest clutches. Egg size was larger at sites with less severe dry periods, and larger eggs were also associated with lower temperatures. Overall, residual variation in clutch and egg size is strongly associated with climatic conditions at both regional and local scales. These findings contribute to understanding how avian reproductive traits respond to climatic gradients and may help anticipate how species will respond to future climate scenarios.

Urbanisation is a powerful environmental force, negatively impacting the few organisms that persist in urban areas. Fluctuating asymmetry (FA), a recognised bioindicator of ontogenetic and environmental stress, may reflect such impacts, though its role in assessing urban intensification remains unclear. We investigated the relationship between urbanisation intensity and FA in birds, analysing 10 locally abundant species in Brasília city, Brazil. Our hypothesis posited that birds in more urbanised areas would exhibit higher FA. We measured bird tarsus and wing to assess asymmetry and also examined whether FA differed between traits. Neither wing nor tarsus FA increased with urban intensity. However, tarsus FA was consistently higher than wing FA. Notably, our FA values for both traits are comparable to or, in the case of tarsus, exceed those reported for birds in fragmented forests. These findings suggest that urbanisation (even at lower intensities) may impose stronger genetic and/or environmental stress on developmental stability than previously recognised.

Understanding how the urbanization process affects the lives of animals that live in these environments is relevant to conservation and management. In fact, the urbanization process has a direct impact on animals and can influence their health state. Thus, our objective was to investigate the immunological response of birds to the urbanization process. We recorded the H/L ratio of 723 birds of 10 species captured in Brasília (a large city in central Brazil), as a measure of chronic stress in birds. The H/L ratio was positively associated with the intensity of urbanization and negatively associated with body condition. However, body condition was not associated with intensity of urbanization. We confirmed our hypothesis that birds living in areas with greater urban intensity are more stressed. In addition, we demonstrated that the H/L ratio is negatively associated with body condition, and that this variable should be considered in studies that aim to assess the health of animals. These findings are relevant because they confirm that the urbanization process, along with all its environmental changes (increased artificial light, increased noise, suppression of vegetation, increased built-up areas, etc.), has a negative direct impact on wild populations, which have to deal with major urban changes.

Among the many changes associated with the urbanization process, changes in resource availability can directly impact local wildlife populations. Urban areas suppress native vegetation and convert natural environments into impervious surfaces, modifying the composition and quantity of available food resources. Understanding the food requirements of species is crucial, mainly because it is one of the main elements that characterize their ecological niche and structure local communities. Our aim in this study was to assess the impact of urbanization intensity on the isotopic niche space of birds commonly found in urban areas of Brasília, the capital of Brazil, a big city in central Brazil with approximately 3 million inhabitants. By analyzing the δ¹³C and δ¹⁵N isotopic metrics of feathers from bird species found along a gradient of urbanization intensity, we evidenced a simplification but not a displacement of the bird assembly isotopic space due to urban intensification. Bird assemblage access similar food resources in the higher urban intensification areas, although less diversified than in lower urban intensification areas. In most cases, the response to urban intensification is more specific than convergent among guild members. The studied species maintain themselves in highly intensified urban areas by restricting, changing, and expanding their access to resources. The trophic dimension is one of the key components of the species' ecological niche, and understanding the urban intensification impacts on this dimension is essential for maintaining biodiversity and ecosystem services in cities.