The Hudsonian whimbrel Numenius hudsonicus is a migratory shorebird that breeds in Arctic Canada and Alaska (USA) and occurs primarily in coastal habitats during the nonbreeding season in Latin America and the Caribbean. Inland records in South America are rare. Here we report the first documented record of Hudsonian whimbrel for Paraguay. A single individual was observed on a sandbank on 26 November 2025 during a boat-based survey of shorebirds along the Paraguay River in the department of Cordillera. The bird was identified based on its size, structure, plumage, and wing-tail proportions, which excluded other curlew species. This record also represents the first documented occurrence of Hudsonian whimbrel within the Paraná-Paraguay watershed and suggests that the species is a very rare inland vagrant in southern South America.
Understanding the mechanisms underlying habitat selection, occupancy, and population dynamics is essential to identify key habitat variables that support species persistence, shape spatial behavior, and guide effective conservation strategies. In the present study, we provide the first population estimates for six threatened avian taxa in the extreme north of the Brazilian Atlantic Forest and identify habitat-associated factors that may influence their occupancy within an isolated forest fragment located in one of the most threatened portions of this important biodiversity hotspot. Data were collected between September 2022 and February 2023. The occupancy probabilities of the study taxa were differentially influenced by environmental parameters—some were most affected by aspects of forest structure, such as tree height or density; others were associated with distance from the forest edge or proximity to watercourses; and in one case, we found a positive relationship with the forest’s relative humidity. We obtained the following population density estimates: Xiphorhynchus atlanticus (0.43 ind./ha); Platyrinchus mystaceus niveigularis (0.45 ind./ha); Momotus momota marcgravianus (0.60 ind./ha); Automolus lammi (0.67 ind./ha); Pyriglena pernambucensis (0.79 ind./ha); and Xenops minutus alagoanus (1.33 ind./ha). These densities are low compared to values reported in other studies. Based on these results, we recommend local-scale conservation actions including: (i) planting native late-successional species; (ii) restoring connectivity among forest fragments, with priority given to areas along watercourses; (iii) establishing ecological corridors and metapopulation mosaics; and (iv) promoting environmental education to engage local communities in forest management.
It is well known that birds can lay their eggs in nests of other species. Although obligate brood parasitism has been intensively studied over the past decades, the cases of facultative brood parasitism are harder to detect and confirm, and have received considerably less attention. Here, we report two rare cases of eggs of eared dove (Zenaida auriculata) found in nests of, and being incubated by, ruddy ground dove (Columbina talpacoti). The extreme rarity of this record (< 1
Seabirds play an important role in marine ecosystems as indicators of fish stock and oceanographic conditions. Understanding the diets of sympatric species is fundamental for clarifying their trophic positions and coexistence mechanisms. Therefore, our study describes and compares the diets of the black noddy (Anous minutus), brown noddy (Anous stolidus), and sooty tern (Onychoprion fuscatus) in Atol das Rocas, Brazil, based on regurgitated food samples collected between 1998 and 2006. We used randomized cumulative prey curves to assess sampling adequacy, and the Prey-Specific Index of Relative Importance (PSIRI) was calculated for each prey category. Similarities in the diets of the three species were evaluated using Principal Component Analysis (PCA) and Analysis of Similarities (ANOSIM). Fish were the primary prey of all species, followed by mollusks. Cumulative curves confirmed robust sampling for the brown noddies and sooty terns, although the black noddies did not reach a clear asymptote. The ANOSIM results did not reveal any taxonomic segregation in the dietary compositions of the three species. However, PCA indicated differences in prey item importance. Marked segregation was also observed for prey length. Halfbeaks (Hemiramphidae) and flying fishes (Exocoetidae) were dominant for black noddies, whereas cutlassfishes (Trichiuridae) and flying fishes were important for brown noddies. Sooty terns primarily consumed squid and cutlassfishes. Regarding prey size, sooty terns and black noddies consumed larger prey on average, whereas brown noddies exploited a wider size range. These findings highlight the resource partitioning that facilitates the coexistence of these sympatric tropical seabirds.
The white-tailed hawk (Geranoaetus albicaudatus), found across the Americas, is well-suited for studying spatiotemporal patterns due to its conspicuous soaring behavior, preference for open areas, partial migratory habits, and delayed plumage maturation (five age classes). Here, we investigate overall abundance and seasonal shifts in age class abundance across the Gran Chaco/Espinal and the Cerrado. We also examine single-season abundance and age class distribution in the Amazon Basin and Guianan Savanna. Our analysis is based on systematic surveys spanning 692 h and 20,755 km in 138 roads (193 h, 5,840 km in 42 roads during the austral winter, and 499 h, 14,915 km in 96 roads during the austral summer). We found that: (1) overall abundance increased during the austral summer, with a 3.7-fold increase in the Gran Chaco/Espinal and a 1.6-fold increase in the Cerrado compared to the austral winter; (2) in the Gran Chaco/Espinal, age class distribution shifted from left-skewed (oldest class most abundant) in the austral winter to a slightly right-skewed, more even pattern (younger classes more abundant) in the austral summer, while in the Cerrado it remained left-skewed in both seasons; and (3) the Amazon Basin and the Guianan Savanna, surveyed in a single-season, exhibited a left-skewed distribution during the austral summer, similar to that of the Cerrado. This study establishes a crucial baseline for understanding spatiotemporal patterns at the age-specific level across South America, emphasizing the need for further research into age class distribution and its relation to the breeding phenology in the white-tailed hawk.
Nest usurpation is a behavior widely reported in various bird species, in which adults occupy the nest of conspecifics or other species. We report the first record of nest piracy by the feral pigeon (Columba livia) from a nest of rufous-bellied thrush (Turdus rufiventris) during the nestling stage in an urban site. The usurpation caused the mortality of two thrush nestlings, after which the pigeon laid one egg in the usurped nest. Our study provides valuable information that contributes to the scarce records of nest usurpation by pigeons.
We compared observed bird species richness in the Brazilian Atlantic Forest with predicted richness derived from BirdLife International distribution data to evaluate the effectiveness of point-count surveys in representing local and regional species pools. Observed richness was obtained from seasonal point-count surveys conducted over two years in three forest types (dense ombrophilous, mixed ombrophilous, and seasonal semideciduous). Predicted species lists were derived by intersecting global species distribution polygons with the geographic coordinates of each sampling site and filtering species according to habitat affinity to reduce commission errors. For each site, we estimated species richness, sample completeness, and the proportion of observed to predicted species. A total of 270 species were recorded during point counts, whereas 366 species were predicted based on distribution data. Point counts detected 73.7
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.
Birds occasionally incubate inanimate objects, a behavior known as pseudo-egg incubation. This study documents the first case of pseudo-egg incubation by a black vulture (Coragyps atratus) in the Brazilian semi-arid region. An unbanded adult vulture exhibited nesting behavior and tolerance to close human approach while incubating an empty snail shell. A month later, an unbanded adult vulture was observed at the same location near the shell, consistent with the species’ incubation period. The most plausible hypothesis for this behavior is mistaken-egg, where birds misidentify objects as eggs due to visual similarities, given the shell’s morphological similarity to a vulture egg. This record expands knowledge on this behavior in birds of prey and, as it was observed during a birdwatching excursion, highlights the value of citizen science in generating novel ornithological discoveries.
This article examines the interactions between seabob shrimp trawling and six seabird species in Ilha Comprida, São Paulo, Brazil. The species studied include the brown booby, magnificent frigatebird, Cabot’s tern, royal tern, kelp gull, and Neotropic cormorant. Observations were conducted along a 70 km beach transect, with a width of 300 m from the waterline, by driving at an average speed of 20 km/h. The Pearson correlation coefficient was used to assess the relationship between seabird abundance and the number of shrimp fishing boats. The magnificent frigatebird showed a strong correlation, with the highest abundance within the first 20 km of the southernmost region, particularly between September and February, aligning with peak fishing season. The royal tern exhibited a moderate correlation, with consistent abundance up to kilometer 35 and peak concentrations within the first 5 km. Kelp gulls had a weaker correlation, with the greatest sightings within the first 40 km, predominantly from June to February. Brown boobies demonstrated a moderate correlation, with increased abundance starting from the 13th boat, primarily distributed within the first 20 km, peaking in September. The Neotropic cormorant had a very weak correlation, showing a uniform distribution mainly within the first 15 km, with presence during spring-summer, from August to February. This study highlights the spatial and temporal relationships between shrimp trawling activities and seabird distribution, emphasizing the varying degrees of dependency of each species on fishing activities.
The grey-cowled wood rail (Aramides cajaneus) is a widely distributed species in the Neotropics. However, its habitat requirements have not been thoroughly analyzed. The rail has expanded its presence in Argentina, particularly in urban areas. This study aimed to investigate habitat selection by Aramides cajaneus along an urbanization gradient in a tourist coastal resort. Point count surveys were conducted during the breeding season. The presence of rails was associated with the percentage cover of houses, lawns, shrubs, and trees, as well as pedestrian traffic and noise levels. Rail presence was positively correlated with lawn cover. The findings suggest that lawns provide a suitable foraging substrate that supports the presence of rails in tourist areas.
Habitat fragmentation in forest landscapes, often resulting from agricultural expansion, poses significant challenges to wildlife movement and persistence. The ability of forest-dependent species to traverse non-forested areas, such as sugarcane and Eucalyptus plantations (i.e. matrix), is crucial for maintaining population connectivity. This study investigates how matrix composition and gap distance influence the gap-crossing behavior of two understory bird species: the variable antshrike (Thamnophilus caerulescens) and the sooty-fronted spinetail (Synallaxis frontalis). We conducted playback experiments in ten sinuous forest fragments within the Brazilian Atlantic Forest, each surrounded by either sugarcane or Eucalyptus plantations. Birds were presented with two route options to reach the opposite edge: (1) a shorter path crossing the matrix or (2) a longer path along the forest edge. We hypothesized that: (a) birds would prefer routes within the forest edge over crossing the matrix; (b) the likelihood of gap crossing would decrease with increasing distance; and (c) Eucalyptus plantations would be more permeable than sugarcane. Edge-to-edge distances ranged from 30 to 130 m. Control trials within continuous forest were also conducted for comparison. Results indicated a strong preference for forested routes (T. caerulescens: 16
Natural Protected Areas (NPAs) constitute a conservation strategy that, in many cases, has effectively prevented local biodiversity loss. However, many NPAs lack detailed information on how different bird communities respond to changes in local vegetation characteristics and land use from human activities. In this study, we assessed the relationship between bird taxonomic diversity and changes in local vegetation abundance and height, as well as land cover types, in a human-modified landscape within the Barranca de Metztitlán Biosphere Reserve. We found 85 bird species, of which 54 were considered resident, 26 were winter migrants, and five were exotic. The Hill-Shannon diversity of the entire bird community was positively associated with plant abundance at the local scale and pecan tree cover at the landscape scale. Pecan tree cover was positively related to the abundance, richness, and Hill-Shannon diversity of migratory birds. In contrast, resident birds were not influenced by environmental factors. Exotic bird abundance declined with increases in local plants and native vegetation cover. We conclude that our study highlights the importance of local habitat and landscape characteristics as factors shaping bird communities in an agricultural landscape in Mexico.
Rivers and wetlands are one of the most biologically diverse ecosystems facilitating vital habitats for a wide range of species. However, the species within these ecosystems are increasingly threatened by climate change and anthropogenic pressures. The black-bellied tern (Sterna acuticauda), an endangered riverine bird endemic to the Indian subcontinent, is highly reliant on wetland environments. Once widespread in South and Southeast Asia, the species is now locally extinct in much of Southeast Asia. Despite being recognized as a threatened and endangered species in Asia, no comprehensive climate-based assessment has yet been conducted. Accordingly, the present study was conceptualized to address these critical knowledge gaps by evaluating species responses to climatic change under both present and projected future conditions. This study evaluates the potential impacts of climate change on habitat suitability and corridor connectivity of S. acuticauda across the Ganges–Brahmaputra–Mahanadi (GBM) River Basin, which remains a key refuge, harboring over 90
The Araripe manakin (Chiroxiphia bokermanni) is an endemic and “Critically Endangered” (CR) piprid restricted to the slopes of the Araripe Plateau in the municipalities of Crato, Barbalha, and Missão Velha in the state of Ceará, Brazil. The species is threatened primarily by habitat loss and degradation. Population monitoring and genetic analyses have indicated an accelerated loss of genetic variability, highlighting the urgent need for conservation strategies, such as translocation and adoption, to help increase genetic diversity. In this study, we report intraspecific translocation and successful adoption of Araripe manakin eggs and nestlings, including the application of artificial incubation and Ex situ artificial feeding techniques for nestlings. These interventions offer new insights for population management by integrating In situ and Ex situ conservation approaches aimed at reinforcing the population and enhancing genetic variability. Our findings contribute to the development of conservation protocols and demonstrate that translocation and adoption are promising tools for the recovery and long-term viability of the Araripe manakin.
The scaled dove Columbina squammata is a species with a broad distribution across South America. Nevertheless, in Argentina and in the Brazilian state of Rio Grande do Sul it remains scarce. Several authors have noted that the species is undergoing a range expansion. In this report, we document the presence of C. squammata in Uruguay. The species was first recorded on 3 December 2024 in Paso Farías, Artigas Department, northern Uruguay. It was identified by its distinctive vocalization and characteristic scaled plumage. The individual was observed in a garden adjacent to an old warehouse, within a landscape dominated by rice cultivation and extensive cattle ranching. The dove remained in the area at least until 10 October 2025. This record represents a new southern range-edge occurrence and supports the idea that the species is expanding its distribution in modified environments.
Knowledge of owls' vocal activity is essential for understanding their responses to environmental change. We investigated patterns of vocalizations in the tropical screech-owl (Megascops choliba) and the spectacled owl (Pulsatrix perspicillata) in forest patches in the far north of the Atlantic Forest, Brazil, from September 2022 to January 2023. We sampled 88 sites in 11 patches using autonomous recording units over three consecutive days. We used static occupancy modeling to estimate the detection probability and, consequently, vocal activity throughout the night, and to test the influence of biotic and abiotic variables on vocal activity. We obtained a total of 3,432 h of sound recordings. Megascops choliba vocalized more frequently at 07:00 p.m., 01:00 a.m., and 04:00 a.m., with most vocalizations occurring from four hours before sunrise until sunrise. We could not support variation in the vocal activity of P. perspicillata throughout the nighttime hours. The vocal activity of M. choliba was negatively influenced by air temperature and was positively influenced by understory density, while the vocal activity of P. perspicillata was negatively influenced by moonlight. Understanding peak owl vocal activity and species-environment relationships will enable more efficient monitoring with limited resources.
Sumatran laughingthrush (Garrulax bicolor) is a critically endangered passerine found only in the montane forests of Sumatra, Indonesia. This species remains the subject of only a modicum of scientific study, resulting in a paucity of fundamental knowledge of its natural history. In terms of its morphology, it is generally assumed to be sexually monomorphic. This study presents the first evidence of morphometric analysis in this species, evaluating five morphometric traits, including both wild-caught and captive-bred individuals (n = 49), to assess potential sexual dimorphism. Overall intersexual comparisons revealed a significant difference only in wing length, with males having 2.29
In this study, we evaluated hematological and plasma biochemical metrics in kelp gulls (Larus dominicanus) using an open-air landfill in Mar del Plata, Argentina, across two wintering seasons. Forty-nine gulls were captured during the winters of 2022 and 2023, and hematological and plasma biochemical parameters was analyzed. In general terms, hematological and biochemical values were broadly consistent with previous reports for Larus gulls that exploit anthropogenic food sources, such as fishery discards and urban waste. However, marked interannual, sex-, and age-related differences were detected, likely reflecting physiological variation associated with environmental conditions, dietary differences, or differential exposure to anthropogenic stressors. Males had lower globulins (and higher albumin-globulin ratio) than females. Adults had higher eosinophils and triglycerides than immatures. Total leukocyte counts were lower than in other populations but remained within physiological limits, with elevated heterophil and lymphocyte proportions indicating maintained immune function. Subtle shifts in immune and metabolic indicators, including reduced albumin-globulin ratios and elevated glucose, cholesterol, and triglycerides, suggesting physiological adjustments associated with the use of urban-derived food resources. These findings provide baseline health information for kelp gulls in urban-modified habitats, underscoring their ecological plasticity and the need for integrative monitoring, including contaminants, hormonal profiles, and oxidative stress markers, to assess the long-term effects of urbanization on coastal seabirds.
