Birds

AI tools like Passive Acoustic Monitoring (PAM) and apps like iNaturalist and Merlin are increasingly used in bird monitoring and species identification. The purpose of this study was to assess whether AI-assisted binoculars improve bird species knowledge, particularly in novice birders, and to examine users’ motivation and experience. This study focuses on the learning impact of users, not data quality or accuracy of the device itself. Participants were recruited via social media, mostly novices (10 women, 9 men, 1 diverse). Four experimental groups (A–D, with N = 5 participants each) were designated. Participants used AI-supported binoculars to identify 10 bird species and the same binoculars with AI function switched off to identify another 10 bird species based on two sets of different species (counterbalanced to avoid order effects). This allowed a between-group as well as a within-subject comparison. We used a pre-test/post-test design for learning. Significant knowledge gains occurred only when using AI binoculars (Wilcoxon tests, p = 0.008). Pooled data across the intervention groups showed strong learning effects for AI-assisted users (Z = −3.736, p = 0.001). No significant learning occurred under control conditions. As a conclusion, AI-assisted binoculars significantly enhance bird identification learning in novices, but as a cautionary note, the study needs to be extended to live birds and in longitudinal settings. Full article

The Central Valley of California provides critical wintering habitat for Sandhill Cranes (Antigone canadensis), which rely on wetlands, grasslands, and grain crops to meet their energetic needs. However, temporary row crops that support Sandhill Cranes and other wintering birds are ostensibly being replaced by permanent woody crops, which offer little value for wetland and grassland-dependent species. To better understand how landcover changes may be affecting habitat availability for these wintering cranes, we analyzed landcover trends within priority crane wintering areas from 2008 to 2023. We employed a mixed-methods approach that allowed us to describe both linear and non-linear trends over time and across regions. Our findings indicate a significant decrease in landcover types suitable as crane habitat over the 16-year period ($\tau$ = −0.90, p < 0.001), with an average annual decline of approximately −1.15 ± 0.21% (B± 95% CI). The best-fit trendline showed that habitat suitability in priority wintering areas decreased from over 81% in 2008 to under 65% in 2023. Specifically, grasslands, rice fields, and alfalfa acreage declined across priority wintering areas, while woody landcover—including orchards, vineyards, and riparian forest breaks—increased significantly ($\tau$ = 0.88, p < 0.001; B = 1.14 ± 0.20%). These landscape-level changes may constrain the regional carrying capacity for Sandhill Cranes and reduce their overall resilience. Full article

Urbanization reshapes bird communities by filtering species according to their ecological traits, often reducing richness, altering relative abundances, and favoring a subset of functionally tolerant species that dominate urban assemblages. Some native taxa are able to inhabit cities, even using them as stepping stones for range expansion. We examined urban habitat use, microhabitat selection, and potential niche partitioning between two range-expanding thrushes (Austral Thrush [Turdus falcklandii] and Rufous-bellied Thrush [Turdus rufiventris]) in two urban settlements in the Pampas region, Argentina. Using 131 transects across green areas and urbanized zones, we related abundance patterns to habitat features at the transect scale and evaluated microhabitat selection at the individual level. Austral Thrush abundance increased with herbaceous cover, tree cover, and even concrete surfaces, suggesting a relatively high tolerance to fragmented green spaces within dense urban matrices. In contrast, Rufous-bellied Thrush showed a positive association with tree cover, avoided tall buildings, and reached higher abundance in the smaller city, consistent with its recent arrival in the region and preference for less intensively urbanized environments. Microhabitat data revealed marked vertical stratification: Austral Thrush foraged almost exclusively at ground level on grassy or bare substrates, while Rufous-bellied Thrush used trees, shrubs, and vines more frequently. These differences reflect fine-scale resource partitioning that may contribute to reducing niche overlap and favor the coexistence of both species in recently colonized urban areas, while recognizing that such dynamics occur within broader bird assemblages where multiple species interact and compete for space and resources. Our findings highlight that even closely related species can respond divergently to urban structure, and that maintaining structural and substrate heterogeneity within cities may help support native bird diversity. Full article

The Red Kite (Milvus milvus), a Western Palearctic raptor, experienced a severe population decline across its range during the 19th and 20th centuries, nearly disappearing as a breeding species in Spain. Although conservation and reintroduction efforts have facilitated recovery, information on its wintering ecology remains limited. We evaluated the population size and habitat selection of wintering Red Kites in and around the La Mancha Húmeda Biosphere Reserve (MHBR), Central Spain, and assessed whether survey route type affected detectability. Surveys comprised 325 vehicle-based line transects along paved roads and dirt tracks during the winters of 2021–2022 and 2022–2023, and the 2022 breeding season. Detection rates and density did not differ between route types. Across 212 winter transects, we recorded 124 individuals, with none detected during 113 breeding season transects. Density estimates were consistent across winters (1.3–1.4 individuals/km²), yielding a population estimate of approximately 1430 individuals. Habitat analysis indicated clear selection for open agricultural mosaics dominated by fallow land and vineyards, while rugged terrain was avoided. These results identify MHBR as an important wintering area. Yet, super-intensive agriculture is a poor habitat due to its uniformity. Enhancing heterogeneous open landscapes, including farmland, is essential for Red Kite colonization and expansion. Full article

Antipredator behavior can vary consistently among individuals, yet links between proactive nest defense and passive fear strategies are rarely quantified in the wild. We tested whether hissing, a conspicuous, snake-like display at the nest, predicts tonic immobility (TI) and breeding success in female Great Tits (Parus major). In pine forests in southeastern Latvia (2023–2024), we presented a taxidermic Great Spotted Woodpecker (Dendrocopos major) at nest-box entrances during incubation and scored whether females hissed and how many calls they produced. The same females were later assayed for TI by brief supine restraint when nestlings were 3–4 days old. Of 141 incubating females, 105 (74.5%) hissed. TI duration differed sharply between groups: non-hissing females showed significantly longer TI than hissing females. Nest failure was significantly lower in hissing than non-hissing female nests. These results reveal a strong negative association between proactive defense and passive fearfulness, and they show that hissing can translate into higher reproductive success in a Woodpecker-dominated predator environment. We conclude that defense strategies covary within individuals along a personality axis and that predator community composition may shape selection on these strategies. Full article

Coronaviruses (CoVs) were first described in poultry in the early 1930s and formally recognized as pathogens of both animal and human populations in the late 1960s. They are now considered among the most abundant viral families in the world. Though their distribution and diversity remain understudied in wild animals, representatives from 13 orders of wild birds worldwide have tested positive for CoVs of the gamma and delta genera over the last 25 years. Many of these wild bird species are in the orders Charadriiformes (shorebirds and their relatives) and Anseriformes (waterfowl including ducks, geese, and swans). Waterfowl are particularly concerning as potential reservoirs for CoVs because they are globally distributed; often congregate in large, mixed-species flocks; and may exist in close proximity to humans and domesticated animals. This review describes the history and current knowledge of CoVs in birds, provides an updated list of global detections of CoVs in 124 species of wild birds as reported in the peer-reviewed literature since 2000, and highlights topics for future research that would help elucidate the role of waterfowl in CoV transmission. Our review reiterates the need for continuous surveillance to detect and monitor CoVs across all bird species and for standardization in data reporting and analysis of both negative and positive results. Such information is critical to understand the potential role of free-ranging birds in the maintenance, evolution, and transmission of the virus. Further, we believe that research on the potential impacts of coronavirus infections and coinfections on avian demographics, especially reproduction in waterfowl, is warranted given known consequences in domestic poultry. Full article

Environmental stressors, particularly agricultural pesticides, can influence both growth and physiology in developing birds, yet the relationship between morphometric condition indices and biochemical biomarkers remains poorly understood. We investigated body mass, beak length, tarsus length, and body condition index (BCI) alongside plasma and S9 biomarkers, including the activities of acetylcholinesterase (AChE), carboxylesterase (CES), and glutathione S-transferase (GST), as well as the levels of glutathione (GSH) and reactive oxygen species (ROS) in nestling White Storks (Ciconia ciconia) from Croatia. Bayesian undirected graphical model (BUGM) inferred a disconnected correlation structure composed of two communities, with a strong beak length–GSH association. Biomarkers further exhibited plasma-specific affinity: plasma markers reflected short-term adjustments, whereas S9 enzymes represented distinct metabolic pathways. Overall, morphometry and physiological status showed only limited integration, restricted mainly to plasma biomarkers, and residual body condition index did not serve as a reliable proxy for physiological stress. We conclude that integrated monitoring approaches, combining morphometric and biochemical profiling, provide a more nuanced assessment of nestling condition and strengthen the use of White Storks as sentinels of agroecosystem health. Full article

Wind energy development is a key component in the transition to sustainable clean energy. Collision probability depends on turbine dimensions and species-specific behaviour, and understanding these relationships is essential for effective Environmental Impact Assessment (EIA). We applied a simulation approach based on flight-height distributions of a medium-sized diurnal raptor, the Common Buzzard (Buteo buteo). Long-term Global Positioning System (GPS) tracking data from an area with over 200 operating wind turbines in Northeastern Bulgaria were combined with Monte Carlo simulations of the Band collision risk model, and the predictions were validated against 18 years of systematic carcass searches under 114 turbines. Importantly, collision probability of the Common Buzzard was season-dependent, being greater during breeding and wintering, when flights occurred at lower altitudes, and lower during migration, when birds flew higher. Both the simulations and the field data supported an overall relatively low collision probability, indicating a high avoidance rate in this species. These findings suggest that wind energy planning should account for seasonal variation in flight behaviour and community composition, while long-term monitoring remains essential to ensure that cumulative impacts are adequately assessed. Full article

Cooperative breeding, or helping behavior, has long been recognized in birds. An ignored dichotomy, however, separates the helping found in many individuals of some long-lived, sedentary species from the helping occasionally found in the territories of isolated breeding pairs of some short-lived, long-distance migrant species. Both types of helping are called “cooperative breeding” in the literature. However, recognizing a dichotomy of “frequent” versus “infrequent” cooperative breeding would help justify the study of infrequent helping as a distinct discipline. Cooperative breeding in Wilson’s Warblers is infrequent, and among the unique behaviors found during this study were (1) solicitations by helper males, which aborted host male attacks and apparently initiated territorial acceptance, (2) an absence of sexual aggression between helper males and fertile host females, (3) attacks by helper males on intruding males during host female nest building, (4) helper males singing with impunity when host males were absent from territories, but being attacked when host males were present, and (5) a single male simultaneously serving as a helper in four adjacent host territories. Infrequent helping has essentially been ignored in studies and summaries of cooperative breeding. However, recognizing and studying infrequent helping as a distinct behavioral process could reveal interactions between helping and population ecology. Thus, infrequent cooperative breeding detected in a breeding population could reveal territorial saturation and could indicate that the population is likely ecologically healthy. Full article

For three regions of South Africa (Greater Gauteng, Greater Cape Town and Greater Durban) with the greatest coverage by bird atlas (SABAP2) fieldwork, we related arrival timing and abundance in each region of a long-distance migrant bird, the Barn Swallow, from July 2007 to March 2024. Using monotonic regression, from the atlas data we derived (1) the “annual anomaly of arrivals” from the average multi-year pattern; (2) the “average maximum” reporting rate at the completion of arrivals, in each region. We related these measures of the Barn Swallow timing and abundance in each of the 17 seasons of arrivals (July–January) in each of three region, with the large-scale climate indices, and temperature and precipitation in the Iberian+Apennine Peninsulas, for the Balkan Peninsula, and for the Sahel, averaged for the months when Barn Swallow visits areas between where these climate indices operate, at their breeding grounds in Eurasia, and along four southwards migration routes to South Africa. We used multiple regression modes with no more than two climate indices at a time, out of 84 explanatory variables, allowed by 17 data points (seasons) for each region. Our exploratory analysis indicated that the timing and abundance of Barn Swallow arrivals were related to a selection of these climate indices. The related climate indices varied between three regions in a pattern corresponding with the proportions of Barn Swallows arriving there from different breeding areas along different flyways, derived from an earlier study based on ringing recoveries. The paper shows the potential of the SABAP2 database as an annual monitoring approach, primarily due to the strong fieldwork protocol. We recommend that the project be continued indefinitely. Full article

Anti-predator behaviour in birds is required by day and night but has barely been studied at night. For prey which detect predators visually, low light levels may diminish detection or monitoring of approaching threats. We conducted standardised approaches to Silver Gulls (Chroicocephalus novaehollandiae) by day and night along an urban foreshore in Melbourne, Australia, measuring light levels (Lux) experienced by the gull, Flight-initiation Distance (FID; the distance at which escape is initiated), and Starting Distance (the initial distance between the observer and the bird). We fitted models reflecting different conceptual possibilities for the relationship between Lux and FID. Support existed for a model with a stepwise effect of light on FID. Longer FIDs (i.e., earlier escape) in darker conditions suggest that gulls can detect an approaching threat in darkness at least as well as by day, but the tolerance of closer approaches may be diminished in dull and dark conditions, perhaps due to difficulty in monitoring an approaching threat and/or because nighttime represents a time of greater predator risk. Starting Distance was positively related to FID, a result commonly reported for many taxa by day. Full article

Urbanization affects bird communities by reducing habitat and fragmenting ecosystems. Urban parks can help counteract these effects. However, anthropogenic noise can further alter bird composition. We examined the distribution and abundance of bird species in nine urban parks in Mexico City. We used a ten minute fixed-radius (25 m) point-counting technique to count birds along their annual cycle, with ten minutes allocated for bird counts. The quality of green areas was analyzed in terms of vegetation (Normalized Difference Vegetation Index), park size, and mean noise level dB(A) (based on MIN and MAX values), and species were grouped into trophic guilds. A total of 108 bird species were recorded, 5 of which are under special protection; we grouped all species into 14 trophic guilds, showing different responses to environmental gradients. Redundancy analysis (RDA) explained 89.98% of the variance, with noise and park size being the most influential variables. Granivores and omnivores were more tolerant to noise, while insectivores and frugivores preferred quieter areas with more vegetation. A positive association was observed between the presence of winter resident species and the park size. On the other hand, mean noise level dB(A) was negatively related to permanent resident species, winter resident species, and those with protected status. Conservation efforts should focus on maintaining ample green spaces and reducing noise pollution, as recorded high mean noise levels (>53 dB(A)) exceed the recommended thresholds for avifauna conservation. Full article

Winter bird feeders provide high-energy food for birds when natural food resources are in short supply. We performed an experimental study including two treatments and a control to investigate the reactions of eight passerine species visiting a winter feeder to the presence of a predator or a food competitor, measured by the number of visits and foraging time. We included in analyses the age and sex of the most numerous species, the Great Tit (Parus major). Our results showed that the number of feeder visits per 30 min differed significantly among species, treatments (predator, competitor, or control), and time intervals of time elapsed from the start of the treatment. The presence of food competitors and predation risk significantly deterred the birds from feeding at the feeder. The number of visits to the feeder by Great Tits was significantly affected by age (more frequent visits by immatures), sex (more frequent visits by males), treatment (less frequent visits by immatures during predation risk and by adults during both experiments), and the time elapsed since the start of the experiment (more frequent visits by adult females during the first eight time intervals after the start of the experiment). Surprisingly, the duration of the foraging visits to the feeder was significantly influenced by species (lower for all tit species compared to the other visiting species) and the time elapsed since the start of the treatment (shorter foraging duration during the first nine time intervals for Hawfinch (Coccothraustes coccothraustes), European Greenfinch (Chloris chloris) and European Robin (Erithacus rubecula)), but not by the treatment itself. This suggests that the decision to use the feeder is risk-dependent, but when birds choose to forage, their foraging time is risk-independent. Full article

In order to determine the impact of urbanization on raptors in the semi-desert conditions of southwestern Kazakhstan, an analysis of the spatio-temporal distribution of raptors is presented for the first time based on the results of surveys of the avifauna of Kyzylorda. Eight species of raptors were recorded: field Hen Harrier (Circus cyaneus), Marsh Harrier (C. aeroginosus), Eurasian Sparrowhawk (Accipiter nisus), Long-Legged Buzzard (Buteo rufinus), Eurasian Buzzard (B. buteo), Steppe Eagle (Aquila nipalensis), Eurasian Hobby (Falco subbuteo), and Common Kestrel (F. tinnunculus). The probability of raptors being present was negatively associated with dense urban low-rise buildings with limited greenery in the bay and the new part of the city. At the same time, the dense urban development with little or no greenery in the old central part of the city provides adequate habitat (including a foraging base and nesting sites) for the Common Kestrel. Raptor presence was positively associated with the Syrdarya River floodplain and wasteland with small groups of trees and/or shrubs. The landfill site located on the north-eastern edge of the city serves as a feeding ground for the Long-Legged and Eurasian Buzzards, while the airport area is inhabited by the Eurasian Buzzard, Steppe Eagle, and Common Kestrel. Based on this study, we would recommend that enterprises (e.g., grain storage facilities, airports) and local executive bodies who are interested in the conservation of raptors and regulating the population of the pigeons around their territories should retain or plant more native vegetation and shrubs and preserve areas with green spaces. Full article

Urban landscapes have given rise to novel ecosystems (e.g., green areas), which differ in design and ecological quality depending on local planning strategies. Europe has the goal to increase conservation through increasing greenspace; however, urban wildlife health impacts, particularly on birds, are poorly studied. This study investigates associations between haemosporidians and intestinal coccidia in the Eurasian Tree Sparrow (Passer montanus), as well as their body condition and immunological status, from five urban green areas in Madrid, Spain, from 2019 to 2022. These green areas differ in green infrastructure, and because these birds are adapted to urban environments, they are a good model to evaluate how green area infrastructure may affect the birds’ health. We detected a 29% prevalence of haemosporidians (Haemoproteus being the most common, followed by Leucocytozoon and Plasmodium) and a 4% prevalence of intestinal coccidia. We found that haemosporidian prevalence was significantly higher in green areas with untreated stagnant water surrounded by muddy areas, ideal conditions for vector reproduction. Therefore, effective management strategies, especially related to water treatment, are essential for protecting urban wildlife and human health. This study provides valuable information for researchers and urban wildlife managers to incorporate appropriate management strategies into urban green area planning to preserve urban biodiversity and protect public health. Full article

The climate is expected to change substantially by the end of the current century. In response to climate change, species may disperse, adapt, or become locally extinct. We aim to assess how the climate changes predicted to occur by 2060 may affect the potential distribution of Tropical Mockingbird (Mimus gilvus antelius) and Chalk-browed Mockingbird (Mimus saturninus frater) within the Atlantic Forest domain, Brazil. Occurrence data for both species were compiled from the scientific literature and online biodiversity databases. A total of 118 georeferenced records were obtained for Tropical Mockingbird and 1080 for Chalk-browed Mockingbird. Species distribution models predicted that the two species would respond differently to the ongoing climatic changes. The Tropical Mockingbird will slightly expand its suitable habitat by 3.5% (3871 km²) under the optimistic scenario (minimum temperature increase by 2060; Representative Concentration Pathways-RCP 2.6) and 2.5% (2765 km²) in the pessimistic scenario (maximum temperature increase by 2060; RPC 8.5), relative to the 1960–1990 baseline. Chalk-browed Mockingbird will reduce its suitable habitat by 64% (70,780 km²) under RPC 2.6 and 65% (71,886 km²) under RPC 8.5. The two future climate scenarios suggest that sympatry between the two species will become increasingly rare, with a shift toward allopatry due to emerging climatically unsuitable areas separating their distributions. Our results highlighted the importance of environmental policies that incorporate local ecological contexts and species-specific traits to mitigate biodiversity loss under future climate conditions. Full article

Public health in a densely populated city is inextricably linked to the state of the urban environment. The microclimate, the condition of water sources and sanitary well-being are just some of the many environmental factors that have a strong influence on people’s health. The presence of urban green spaces and various birds in cities is extremely important, also to create a more favorable psychological atmosphere for the people who live and/or work there. At the same time, it should not be forgotten that the feces of synanthropic birds are a favorable environment for various potentially pathogenic species of microorganisms, including yeasts of the genus Candida. Here, we investigated the culturable, potentially pathogenic ascomycetous yeast microbiome in the fresh and dry feces of five synanthropic birds (Rock Pigeon, European Starling, White Wagtail, Great Tit and House Sparrow). The samples were collected in spring (May 2024). In total, 48 Rock Pigeon, 47 European Starling, 38 White Wagtail, 32 Great Tit and 30 House Sparrow droppings were collected and analyzed. The selective medium Brilliance Candida Agar was used for cultivation. A total of 638 strains were isolated belonging to 9 yeast species (Arxiozyma bovina, Candida albicans, Nakaseomyces glabratus, Clavispora lusitaniae, C. tropicalis, C. parapsilosis, Pichia kudriavzevii, Debaryomyces hansenii and D. fabryi). All detected yeast species were molecularly identified using the ITS rDNA region. The microbiome of potential pathogens in fresh feces proved to be significantly host-dependent. Most pathogenic yeasts (7 species)—A. bovina, C. albicans, N. glabratus, Cl. lusitaniae, C. tropicalis, C. parapsilosis and P. kudriavzevii—were only detected in fresh feces from pigeons. This list contains five out of six ascomycetous species from the list of critical, high and medium-important yeast pathogens published in the World Health Organization fungal list. Of the potentially pathogenic yeasts, two species were observed in the dry droppings of various birds: C. parapsilosis and P. kudriavzevii. No significant differences in the diversity of culturable pathogens in dry droppings were observed between the different hosts. Fresh droppings from synanthropic birds, especially pigeons (and to a lesser extent dry droppings), therefore pose a health risk. In this study, we did not find any feces from synanthropic birds in which potentially pathogenic ascomycetous yeasts were not detected. To maintain the sanitary safety and well-being of citizens, it is very important to regulate the number of synanthropic birds (primarily pigeons), especially in sensitive areas such as playgrounds, hospital territories, etc. Full article

This report presents the first complete natal dispersal trajectory of a female Montagu’s Harrier Circus pygargus, tracked in real time from fledging to first breeding using high-resolution continuous Global Positioning System (GPS) telemetry. The bird’s first flight occurred on 26 July 2024, initiating a 31-day post-fledging dependence phase (PFDP), followed by a 23-day pre-migratory phase (PMP), during which it explored areas up to 280.8 km from the nest and eventually settled ca. 190 km away in the Sirente-Velino Regional Park. From there, autumn migration began on 18 September 2024. The bird reached its first wintering site in Mali by 15 October. It used four wintering areas over 178 days, with a winter home range of 37,615.02 km². Spring migration started on 11 April 2025 and lasted 21 days, ending with arrival in the Gran Sasso e Monti della Laga National Park (Central Italy) on 2 May. The bird used two main sites during the pre-breeding phase (PRBP) before laying eggs on 2 June 2025. The natal dispersal distance, from birthplace to nest site, was 151.28 km. Over 311 days, it covered a total of 14,522.23 km. These findings highlight the value of advanced telemetry in revealing early-life movement ecology and are useful for understanding species-specific patterns of survival, reproduction, and space use and can inform conservation actions. Full article

This paper outlines a methodology to compile geo-referenced observational data of Australian birds acting as pollinators of Strelitzia sp. (Bird of Paradise) flowers and dispersers of their seeds. Given the absence of systematic published records, a crowdsourcing approach was employed, combining data from natural history platforms (e.g., iNaturalist, eBird), image hosting websites (e.g., Flickr) and, in particular, social media. Facebook emerged as the most productive channel, with 61.4% of the 301 usable observations sourced from 43 ornithology-related groups. The strategy included direct solicitation of images and metadata via group posts and follow-up communication. The holistic, snowballing search strategy yielded a unique, behavior-focused dataset suitable for analysis. While the process exposed limitations due to user self-censorship on image quality and completeness, the approach demonstrates the viability of crowdsourced behavioral ecology data and contributes a replicable methodology for similar studies in under-documented ecological contexts. Full article