Populations of the Short‐eared Owl Asio flammeus have declined across Europe and North America, probably in response to habitat degradation driven by agricultural intensification. However, long‐term evidence linking farmland habitat change to variation in breeding density and reproductive success remains limited. We investigated these relationships in an agricultural landscape in western Finland over a 30‐year period (1977–2006), focusing on owl breeding parameters and temporal changes in grassy habitats supporting their primary prey (voles). Annual breeding density ranged from 0.0 to 1.5 (mean 0.35) nests km −2 and increased with spring vole abundance. Mean clutch size varied between 2.5 and 8.2 eggs, and mean brood size between 0.7 and 4.4 nestlings per nest, with significantly higher values observed during years of high vole abundance. Nest failure was primarily attributed to agricultural activities and predation. To assess long‐term population trends, monitoring was extended to a broader 1000‐km 2 area through 2023. Over the 47‐year study period, the local breeding population declined by more than 50%, corresponding to an average annual decrease of 2.8%. This decline coincided with substantial agricultural intensification, including the conversion of pasture and hay fields to cereal, potato and oilseed cultivation, as well as the reduction in open drainage systems. These changes resulted in a 46% reduction in grassy habitats suitable for voles and, consequently, for owl foraging. Our findings provide long‐term empirical support for the hypothesis that farmland structural simplification associated with agricultural intensification is a primary driver of population declines in Short‐eared Owls occupying grassland and farmland habitats.
The Earth's biodiversity is changing rapidly due to human activities. Natural history collections could help us better understand how and why biodiversity is changing but are grossly under‐used in this respect. Artificial intelligence (AI) has the potential to transform this situation by enabling us to unlock data associated with museum specimens more rapidly and accurately than ever before, but this potential needs to be rigorously evaluated. Here, we develop, test and apply a workflow for extracting data from the labels associated with skin preparations of birds using large language models (LLMs) and illustrate how to generate historical species distributions from the resultant data. To do this, we used specimens from the Archbold‐Vernay Expedition that visited Madagascar from 1929 to 1931 and collected >7000 specimens as a case study. We collected images of 2576 specimen labels and then used ChatGPT‐4o to extract the data from these images. Testing against a manually transcribed set of 130 labels showed excellent levels of transcription accuracy (fuzzy‐matching scores >95). Further analyses showed that transcription accuracy varied between labels and data categories, and was significantly poorer if the location information was handwritten compared with typed. We geocoded each specimen using the location information from its label and GEOLocate, a web‐based geocoding application, and some manual processing. This process successfully geocoded 91.4% of the 4965 specimens for which we had label‐derived location information. We then used freely available software (MaxEnt) to generate historical species distributions from the geocoded specimen data for a small sample ( n = 4) of endemic species. Our workflow illustrates the potential of AI to generate valuable ecological data from natural history collections, and together with other recent work, suggests AI‐assisted workflows are likely to accelerate the availability of data from museum specimens over the next few years.
The internet hosts vast quantities of digital media across webpages, repositories and social media platforms, providing unprecedented opportunities for ecological research. The use of web‐sourced media (photographs and videos) in ornithology is rapidly expanding, forming part of the emerging field of iOrnithology, which applies internet‐derived data to the study of birds. In this context, birds are particularly well suited to photographic and video‐based studies due to their visibility, popularity and distinctive appearances. However, a comprehensive synthesis of this research is currently lacking. Here, we reviewed the peer‐reviewed literature and extracted data from 64 studies published between 2015 and 2024 that used web‐sourced media to study birds. We quantified research topics, media types, data sources, spatial scales and taxonomic coverage. Eight primary research topics were identified: moult and plumage patterns, avian distributions, behaviour, diets, species interactions, threats to birds, habitat use and lateralization—asymmetry of the brain and associated physiological behaviours. Photographs were used in most studies, with fewer using videos or both media types. Studies of moult and plumage patterns, as well as avian distributions, primarily relied on photographs, whereas behaviour studies more often used videos. Most studies were conducted at national and continental scales, with relatively few at local or regional scales. Spatial scale varied significantly among research topics, with studies of plumage and threats being conducted at broader scales relative to behavioural studies. In total, 1506 bird species were studied across 33 orders. By number of species, Passeriformes were the most studied order, representing more than half (52%, n = 785) of all studied species. When compared with the number of described bird species per order, among those with at least five species studied, Ciconiiformes were the most well represented order (95% coverage), followed by Gaviiformes (60%), Podicipediformes (44%), Pelecaniformes (36%) and Suliformes (35%). These studies demonstrate that web‐sourced media can support a wide range of ornithological research that would often be difficult or resource‐intensive to achieve using traditional field‐based approaches. As digital media archives continue to grow and analytical tools improve, this approach is likely to expand further. Future developments within iOrnithology may include greater applications in areas such as invasive species, disease surveillance, and demography, and the integration of machine learning and artificial intelligence to analyse large volumes of media. Together, these developments highlight the growing value of web‐sourced media as a powerful addition to the ornithologist's toolkit for studying the ecology, biology and conservation of birds.
Understanding dietary preferences and prey selection is pivotal for interpreting the ecology and conservation needs of threatened species. We investigated the diet composition and prey selection of the Red‐backed Shrike Lanius collurio in a montane grassland of the central Italian Apennines, with special regard to sex‐related differences and the relationships between prey use and local prey availability. Using a non‐invasive camera‐trapping protocol at artificial perches, we collected high‐resolution photographic records of predation events over three breeding seasons (2021–2023). This method allowed us to identify individual shrikes through colour‐ringing and enabled prey items to be identified to fine taxonomic resolution. From 2968 recorded predation events involving 18 individually identifiable shrikes, we identified prey belonging to 12 arthropod orders, 52 families, 55 genera and 48 species. Arthropods dominated the diet, with Orthoptera accounting for the majority of prey items, followed by Hymenoptera, Coleoptera, Araneae and Lepidoptera. Multivariate analyses revealed a significant effect of sex on prey composition, whereas perch location had no detectable influence. Males disproportionately consumed large Ensiferans, bumblebees and spiders, whereas females more frequently preyed upon smaller orthopterans and solitary bees. Comparisons between prey use and availability showed clear evidence of active prey selection patterns. Shrikes consistently selected Ensiferan orthopterans and melolonthid beetles over their local availability, whereas abundant taxa such as honeybees and pierid butterflies were avoided. These patterns indicate that prey profitability, handling efficiency and risk probably play a major role in shaping foraging decisions, rather than simple opportunistic feeding. Our results highlighted the importance of diverse arthropod assemblages, particularly Ensiferan communities, in sustaining breeding populations of this declining farmland bird. Methodologically, the study confirmed the effectiveness of camera trapping at fixed perches for obtaining individual‐level dietary data in small passerines. Maintaining structurally heterogeneous grasslands and traditional low‐intensity management practices is critical for preserving key trophic resources and supporting viable Red‐backed Shrike populations in upland landscapes.
Type specimens represent the crucial physical reference for any scientific bird name, but type material is scattered widely across the globe, and there is still no one comprehensive source documenting the presence, status and condition of all avian type specimens, as well as associated information on nomenclature and the validity of individual names. Indeed, many collections, including very large and globally important repositories, lack a published type catalogue. Where such works are available, they may exist solely in printed form, are only partial in extent or are now outdated and incomplete. Furthermore, many workers, even taxonomists, may be unaware of them because such catalogues often appear in more obscure or less ‘visible’ periodicals or as stand‐alone museum publications. As a result, we advocate creating a comprehensive online database/data portal for bird type specimen information, focused initially on material held in European institutions, to serve as a standard and dynamic reference for collection‐based systematic, taxonomic and nomenclatural research. Among the various benefits, principally we highlight that the findability of, and access to, type specimens and their associated data will be greatly improved, perhaps especially among researchers in the Global South, as will co‐operation and data‐sharing between different institutions. Furthermore, such a project will also promote greater integration between the museum community and umbrella‐style international database projects. It can also feed into even wider and more general collaborations surrounding biodiversity research and documentation, such as the disambiguation of people's names in biological collections.
Preen gland secretions are known to vary depending on sex, season and species and are thought to play essential roles in avian life history. However, their chemical composition and functions remain largely unclear in Procellariiform seabirds with well‐developed olfactory senses. Storm petrels, known for their distinctive body odour, may use preen gland secretions as cues for social communication. This study aimed to provide foundational insight into the function of the preen gland in storm petrels by examining the chemical composition and seasonal variation of secretions in male and female Tristram's Storm Petrels Hydrobates tristrami during the breeding season. Qualitative analysis using gas chromatography–mass spectrometry revealed that the major components were lipid esters, particularly octadecyl octanoate, along with hydrocarbons and aliphatic alcohols. The composition showed sex‐specific seasonal variation across breeding stages. While few compounds in females showed significant seasonal variation, a greater number of compounds in males changed significantly from the early breeding period to incubation. Notably, 1‐hexadecanol significantly increased from incubation to chick‐rearing in both sexes. The drivers of these changes remain unclear, whether related to diet, endocrine dynamics or breeding behaviour. Future integrative research, including the monitoring of prey composition and parent–offspring interactions, is needed to clarify these relationships. This study presents the first description of the chemical composition and seasonal variation of preen gland secretions in storm petrels, forming a basis for further investigation into the functional role of the preen gland during the breeding season.
In a context of global biodiversity loss, studying the processes underlying the recolonisation—whether natural or assisted—of expanding species provides essential insights for the development of effective conservation strategies. Since the 1980s, the Osprey Pandion haliaetus has naturally recolonized mainland central and eastern France, increasing from one breeding pair in 1985 to 83 in 2024. Between 2018 and 2021, a translocation programme was implemented in south‐western France, using as its donor population the one located in central/eastern France. We aimed to assess the viability of the Osprey population in mainland France, comparing demographic dynamics between the area of origin (Orleans region) in central France and the periphery, and analysing the effects of translocation on survival and on the growth of the donor population. Based on chick ringing and reproductive monitoring since 1995, we estimated survival and reproductive parameters. Population viability analysis showed that this population in mainland France was viable over time with an annual growth rate of 1.05. We detected no demographic differences, in terms of either survival or reproduction, between the peripheral area and the core area, suggesting that the carrying capacity of the environment has not yet been reached in either area. The translocation had no significant effect on the survival of the released individuals and the impact on the donor population remained very limited with a difference in population growth rate of only 0.005—equivalent to a 0.5% annual decrease. The retrospective and prospective analyses highlighted the major influence of adult survival on the variance and sensitivity of the population growth rate, identifying this parameter as a priority to maintain for future conservation actions.
The importance of considering historical data in developing conservation and restoration measures for individual species and for wider ecological restoration has been pointed out by recent reviews but often remains neglected in practice. This paper provides a case study illustrating the issue through a review of the former breeding distribution of the White‐tailed Eagle Haliaeetus albicilla in North Africa, Iberia, the Mediterranean Basin (excluding the Black Sea) and the Middle East. The species has a significant role in coastal and freshwater ecosystems as a scavenger and predator. Subfossil, historical and 19th/20th century ornithological sources indicate that it was formerly widespread in the region. Records of breeding in the ornithological literature from the 1840s to 1980 yield 103 definite and 37 probable breeding records (multiple records of the same pair not included). These records, especially earlier in the period, are biased towards areas more likely to be visited by ornithologists and to areas where significant breeding populations survived later, such as the Nile Delta, Albania/Greece/Montenegro, modern Turkey and Sardinia. Breeding also persisted in the Tigris/Euphrates river system in modern Syria and Iraq to at least the 1920s, Israel to the 1950s and in Algeria to around 1980. There are individual breeding records from elsewhere in the region. A critically endangered population persists in northeastern Greece and European Turkey. From these data and the known dispersal capacity, it can be securely inferred that the species formerly bred in suitable habitat throughout the region. Analyses based on current distribution would significantly underestimate the species' climatic tolerances and biogeographical scope for restoration.
The Amur Falcon Falco amurensis performs one of the world's longest raptor migrations, involving a non‐stop crossing of the Indian Ocean of approximately 2800 km. While the existence of this route is known, the mechanistic details of wind exploitation and seasonal navigation remain to be fully elucidated. We satellite‐tracked seven birds during prebreeding migration of 2010 (six of which arrived at breeding sites), with a subset of three individuals providing data for both directions. One individual was tracked between 2010 and 2013. We analysed the timing of migration resumption and the wind exploitation behaviour during pre‐ and post‐breeding oceanic crossings. We utilized Argos telemetry data and NCEP atmospheric reanalysis data to model flight conditions across isobaric levels and assessed route efficiency by comparing observed tracks with simulated shortest routes and wind‐optimal Correlated Random Walks (CRWs). The estimated wind‐optimal flight altitude was consistently around the 925 hPa level (median 1000‐m prebreeding; 886‐m post‐breeding). The resumption of prebreeding migration was synchronized with high tailwind speeds over the ocean. Prebreeding flights achieved high tailwind assistance (mean: 3.9 m s −1 ), with crossings lasting approximately 60 h. Crucially, we found a significant interaction effect between wind speed and angular deviation, showing that Falcons actively compensated for wind drift, particularly under high crosswind speeds. Consequently, prebreeding tracks remained close to the wind‐optimal routes. In contrast, post‐breeding tracks exhibited lower tailwind speeds (mean: 3.2 m s −1 ) over longer durations (~78 h), and showed increased drift tolerance. The Falcons' navigational success depends on a highly flexible, seasonally dependent interaction between wind conditions and route control, suggesting a state‐dependent strategy rather than simple drift. The prebreeding crossing is highly optimized for time minimization, while the post‐breeding phase appears less constrained. The reliance on specific wind corridors renders this unique migratory system potentially vulnerable to climate‐driven changes in large‐scale atmospheric patterns.
The Roseate Tern Sterna dougallii is a locally threatened seabird that breeds in four discrete metapopulations across the Atlantic Ocean Basin: Northwest Atlantic, Caribbean, Azores and Northwest Europe. While this species is well‐monitored and the focus of long‐term management efforts across the breeding distribution, significant knowledge gaps remain for the Northwest Europe and Azores metapopulations with regard to genetic diversity, population structure and connectivity outside the breeding season. Here, we address this gap by leveraging data collected as part of a long‐term mist‐netting programme in Senegal, West Africa. We genotyped 240 individuals sampled during the northward migration in 2021–2023, including 112 ringed or resighted in breeding colonies. We used a panel of 15 microsatellite loci to investigate genetic diversity and population structure for birds of known origin (determined by location of ringing or resighting), and compared them to individuals sampled from a site in the Northwest Atlantic. We found relatively low genetic diversity indices within the Northwest Europe and Azores metapopulations, consistent with previous reports from the Caribbean, Azores and Northwest Atlantic metapopulations. We found no significant genetic differentiation among sites within Northwest Europe, consistent with metapopulation modelling studies. Significant differentiation was detected among the Northwest Europe, Azores and Northwest Atlantic metapopulations. We used discriminant analysis of principal components to assign 79% of individuals of unknown origin to the Azores or Northwest Europe metapopulations with ≥ 80% probability, while no birds were assigned to the Northwest Atlantic metapopulation. These results contribute the first comprehensive documentation of the genetic diversity of Roseate Terns utilizing the East Atlantic Flyway and the Northwest Europe metapopulation, document gene flow within Northwest Europe and demonstrate the value of sampling birds during migration for population genetic studies.
Sympatric species are expected to use resources differently along one or more ecological dimensions. This can be complex when there is partial separation along multiple dimensions, such as where bird species exhibit similarities in habitat use and diet. We used DNA metabarcoding to examine the diet of three sympatric warblers: the migratory Eurasian Reed Warbler Acrocephalus scirpaceus and Great Reed Warbler Acrocephalus arundinaceus, and the resident Cetti's Warbler Cettia cetti , breeding in reedbeds in Catalonia, Spain. Although the diets of the three species partially overlapped, each consumed some distinct prey taxa, and/or key species at differing frequencies. Compared to the Eurasian Reed Warbler, the Great Reed Warbler consumed a greater proportion of larger prey, while Cetti's Warbler consumed a greater proportion of terrestrial species. Together, these results indicate a degree of dietary niche separation between warbler species, via species‐specific prey selectivity, which may explain their coexistence in Catalonian reedbeds. Our findings have implications for understanding future competitive pressure and coexistence of reedbed warblers under the dual, connected threats of climate change and global invertebrate decline.
The phenology of animals is closely tied to seasonal climatic patterns so, by altering temperature and precipitation regimes, climate change disrupts the phenological cycles of species. More specifically, the influence of rising temperatures on the phenology of bird migration has been long studied. Most of such studies focus on species performing long‐distance winter migration. However, much less is known about how short‐distance and partial migrants, with both winter and summer movements, respond to changes in climatic conditions. In this study, we analyse the migration phenology and strategy of the Little Bustard Tetrax tetrax , one of the most endangered farmland birds in Europe, and how it has changed over a 20‐year period in response to changes in temperature and precipitation. We used 117 annual trajectories from 63 GPS‐tagged Little Bustards between 2005 and 2024, collected across the species' distribution in Spain. These trajectories were classified as sedentary and migratory, and the latter into pre‐breeding and post‐breeding migrations. Our results revealed a trend for Little Bustards to advance both their pre‐ and post‐breeding migrations during the study period. The shift in post‐breeding migration is directly related to rising summer temperatures and declining summer rainfall, with birds departing earlier in hotter and drier conditions. The shift observed for the pre‐breeding migration is directly related to the temperature in their wintering grounds, with birds spending more time there with higher temperatures. This study underscores the sensitivity of Little Bustards to increasing temperatures during both breeding and wintering seasons and their adaptation capacity, which gives rise to their complex migration patterns.
Classical works show the adaptive importance of precise timing of egg‐laying in brood parasitic Common Cuckoos Cuculus canorus to ensure sufficient incubation time and successful hatching. Laying in the late afternoon has been suggested to increase the chance of secretive parasitism and therefore escape the aggressive mobbing by hosts, yet this hypothesis has not been examined in more detail. We therefore used continuous video recordings of Great Reed Warbler Acrocephalus arundinaceus nests to explore (1) the overall timing patterns of cuckoo parasitism and host nest attendance, (2) how variation in nest attendance, both throughout the time of day and stage of the host laying period, relates to the timing of parasitism, (3) whether parasitism timing influences the likelihood that a cuckoo is detected by the host and (4) whether the timing of parasitism is repeatable among individual cuckoo females. We found that parasitism predominantly occurs during the initial days of the host laying period, with most events occurring after 14:00 h (2:00 PM). We also found that hosts are more present at their nests during the mornings and less so in the late afternoon, particularly at the start of their laying period. Our findings show that the timing of cuckoo parasitism is negatively associated with host nest attendance, but only early in the laying period. The cuckoo's preference for afternoon laying remains relatively constant throughout the laying period, even though it appears most beneficial at the beginning as the likelihood of host–cuckoo encounters increases later in the laying period and towards the evening. Nevertheless, the increasing nest attendance of Great Reed Warblers and the higher probability of encountering a cuckoo at the nest are probably not sufficient to disrupt the cuckoo's successful afternoon parasitic timing in the later stages, even though we observed a decline in the number of parasitism events over the laying cycle. Finally, a genetic analysis revealed that individual cuckoo females exhibit moderate repeatability in timing of parasitism throughout the day and none throughout the host laying cycle. We discuss the relationship between parasitism timing and host nest attendance, and potential implications of the observed patterns.
The combined effects of climate and landscape change are likely to be contributing to widespread and pervasive declines in forest bird populations. Individual species responses vary across climatic niches and habitat requirements, but bird communities and populations in montane systems may be particularly vulnerable to climate anomalies. Previous syntheses have reviewed evidence for impacts of climate change on bird species in general, in temperate regions and in Holarctic mountain ranges. Here, we propose that the Appalachian Mountains of eastern North America serve as an instructive case study due to their distinct combination of extensive temperate broadleaf forest cover, predominantly northeast–southwest orientation that bridges two major biomes and a bird assemblage that contains trailing‐edge populations of species that predominantly breed in the boreal forest. Our goal was to review the contemporary and potential future effects of both climate and land cover change on forest birds breeding in the Appalachian Mountains. Specifically, we focused on synthesizing documented and predicted changes in bird species distributions, populations and communities in response to changes in climate and land cover across this mountain range. We further compared our findings with trends from other mountain ranges across the world to assess commonalities and differences. Although there was limited literature from the Appalachian Mountains that incorporated both climate and land cover variables in models of forest bird responses, several results were consistent with studies from other montane systems, including vulnerability of cold‐associated species to warming temperatures and stronger effects predicted for future scenarios with higher greenhouse gas emissions. In addition, there were no prevailing trends that differed greatly from other mountain ranges, but potential extirpations of cold‐associated species varied along latitudinal gradients within the Appalachian Mountains region, and there was nuance in how changes in land cover and habitat conditions modified forest bird responses to climate change. We concluded our review by identifying key knowledge gaps, suggesting future directions for research and highlighting the conservation implications for forest birds in the Appalachian Mountains.
In the animal kingdom, nests are essential structures and textbook examples of extended phenotypes. However, the relationship between builders, nest traits and the nest‐site remains poorly understood. We indirectly examine whether structures in the nest‐site influence nest‐building behaviour, specifically focusing on their effect on nest architecture. We hypothesized that pre‐existing structures at the nest‐site of Rufous Horneros Furnarius rufus could influence nest construction, thereby affecting nest architecture. To test this, we investigated the relationship between nest asymmetry, defined by the side on which the nest opening is located, and external lateral structures using a database of 12 504 nest photographs taken by citizen scientists across the species' entire breeding range. We found that in nests built in contact with a lateral structure, birds were more likely than expected by chance to place the nest entrance on the same side as the lateral structure. When lateral structures were incorporated into the nest (i.e. when the structures replace parts of the nest), this likelihood increased significantly. Our findings suggest that incorporating pre‐existing elements into nests leads to predictable asymmetric architecture, highlighting a strong interaction between birds' building behaviour and nest‐site properties. These results underscore the importance of understanding the behavioural mechanisms shaping avian nest architecture and their plasticity.
Reproductive success is an important component of life history and population ecology, influenced by factors intrinsic and extrinsic to organisms. In birds, where nest predation is the primary cause of reproductive failure, parent behaviours (e.g. nest visits) can increase nest detection and failure by attracting the attention of predators, but they can also deter predators through high nest attentiveness, active defence or selection of an optimal nest-site. We examine how reproductive behavioural bird traits and nest-site characteristics interact to influence nest survival in a taxonomically and functionally diverse assemblage of tree-cavity nesting birds. In 2016-2019, in the subtropical humid Chaco of Argentina, we monitored 342 nests of 21 species every 1-7 days, collected 2387 hours of observations to summarize seven reproductive behavioural bird traits and measured 11 nest-site characteristics. We used logistic exposure models to test non-exclusive hypotheses about how reproductive behavioural bird traits, nest-site characteristics and interactions among these factors influence daily nest survival during the incubation and nestling periods. Predation caused 90% of nest failures, and both behavioural bird traits and nest-site characteristics influenced nest survival. During the incubation period, nest survival increased with nest attentiveness (time an adult was present in the cavity) and cavity depth. During the nestling period, survival increased with nest tree diameter, cavity height and cavity depth and decreased with number of trees around the nest tree, nest tree crown contact, feeding frequency and aggressiveness. Survival was high regardless of cavity concealment for birds without feeding synchrony behaviour but decreased with concealment in birds with feeding synchrony behaviour. Trait variation in functionally diverse assemblages can help us understand the cost-benefit scenarios that animals face during breeding events and the diversity of strategies they employ to optimize lifetime reproductive success.
Individual variation in avian migration timing is still poorly understood, yet recent evidence shows that it is closely linked to personality traits and may also be affected by food availability. Here, we examined how the interaction of the personality trait exploration speed and food availability affected the departure timing of Red Knots Calidris canutus from their wintering grounds. Using experimental manipulations of food access and measures of exploration speed in captivity followed by tracking of released individuals, we show that fast‐exploring birds departed later but only when subjected to restricted food access in the experiment, whereas birds with unlimited food access showed no personality‐dependent differences in departure timing. Our results suggest that personality does not reflect intrinsic variation in spring migration timing, but rather interactions with environmental variation affecting the birds' ability to refuel body stores after food restrictions.
Life‐history theory predicts covariation among reproductive traits that maximize lifetime reproductive success. In birds, broad‐scale patterns including latitudinal gradients and the fast–slow pace‐of‐life continuum support this idea. Yet, most research has focused on tropical and northern temperate species, while subtropical regions remain poorly studied and are often less predictable than expected from these general patterns. We tested whether breeding timing and nest success exhibit interspecific convergence (i.e. sympatric species with similar life‐history patterns due to shared macro‐environmental conditions at intermediate latitude), as expected from ecogeographical gradients, or whether these traits are primarily shaped by local ecological filters and species‐specific traits. We analysed nest initiation dates from 1202 nests of 85 species using linear mixed‐effects models, and daily nest survival rates (DSRs) from 605 nests of 68 species using nest survival models. We found that community‐wide breeding season length was intermediate between tropical and temperate latitudes, but timing varied with ecoregion, diet, annual cycle strategy and clutch size. Overall DSR (0.957/day) was also intermediate, varying with ecoregion, nest habitat, nest age and seasonal timing. Our findings indicate that local ecological conditions and species' life‐history strategies shape breeding patterns, deviating from the primary predictions of broad‐scale gradients in subtropical South America. By providing the most comprehensive nesting dataset for the region, our results complement the limited regional literature and establish a baseline for long‐term monitoring of subtropical avian reproductive strategies under a changing climate.
