Journal of Avian Biology最新文献

{"title":"Complete egg clutches as memory template for host egg recognition","authors":"Fangfang Zhang,&nbsp;Jianping Liu,&nbsp;Jinmei Liu,&nbsp;Wei Liang","doi":"10.1002/jav.03645","DOIUrl":"https://doi.org/10.1002/jav.03645","url":null,"abstract":"<p>Egg recognition and rejection are among the most prevalent forms of host defense against brood parasitism. However, there is a lack of comprehensive data on the ability of hosts to update and modify their egg rejection strategy throughout the breeding cycle. Here we examined two cavity-nesting bird species, the green-backed tit <i>Parus monticolus</i> and coal tit <i>Periparus ater</i>, to investigate their egg rejection strategies at different breeding stages. The results revealed that neither of these tit species rejects foreign eggs during the egg-laying stage; however, both species exhibited egg rejection after starting incubation. During this stage, both the green-backed tit and the coal tit exhibited high rejection rates against foreign eggs, and the green-backed tit maintained a high egg rejection rate during the nestling period as well. There was no significant difference in foreign egg survival time between the two species. Additionally, there was no difference in egg survival time between the egg-laying treatment group (foreign egg addition during the laying period, rejection during the incubation period) and the incubation treatment group for either tit species. Our study revealed that both green-backed tits and coal tits use the entire clutch as a memory template for comparing and recognizing foreign eggs, and that both species share a consistent egg rejection strategy. This is the first reported case that coal tits do not reject foreign eggs during the egg-laying period.</p>","PeriodicalId":15278,"journal":{"name":"Journal of Avian Biology","volume":"2026 5","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jav.03645","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149205369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interacting moonlight, weather, and sex influence foraging in a nocturnal insectivore Caprimulgus europaeus","authors":"Lucy J. Mitchell,&nbsp;Piran C. L. White,&nbsp;Kathryn E. Arnold","doi":"10.1002/jav.03641","DOIUrl":"https://doi.org/10.1002/jav.03641","url":null,"abstract":"<p>Animals use a variety of environmental cues to identify profitable conditions and increase their foraging efficiency. Identifying environmental correlates of foraging behaviour can help to understand the drivers of animal foraging decisions, and the potential consequences should conditions change. We used GPS tracking devices to collect data from 2015 to 2018 on movement behaviour of 34 individual European nightjars <i>Caprimulgus europaeus</i>, which forage exclusively at night on aerial invertebrates. To understand how they allocated their time, and whether their behaviour was influenced by the lunar cycle, weather conditions, and environment, we analysed the environmental factors that influenced foraging within and across multiple nights. Nightjar fine-scale changes in behaviour were primarily driven by different aspects of the lunar cycle, and cloud cover, with a lesser influence from habitat type and temperature. At an hourly level, nightjars responded to cyclical cues most strongly, foraging more when lunar light levels were high and the moon was close to the earth. Birds foraged for longer when the moon was between 60 and 90% illuminated, but the strength of this relationship varied with lunar distance. Foraging was also influenced by the amount of cloud present and lunar altitude. Nightjars concentrated their foraging in nautical twilight, when light levels were still sufficient, and temperatures likely still higher, thus providing efficient foraging via increased visibility, as well as better prey availability, supporting the reduced effort hypothesis. Male nightjars foraged significantly more than females, representing their differing breeding roles and potentially their energetic requirements. We suggest that our results indicate a trade-off between prey availability and visibility that may reflect allocating more time to foraging in conditions that promote reduced effort and increased efficiency.</p>","PeriodicalId":15278,"journal":{"name":"Journal of Avian Biology","volume":"2026 5","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jav.03641","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microstructure determines the difference between the mechanical properties of melanized and non-melanized domestic pigeon feathers","authors":"Rongjie Cheng,&nbsp;Esther Appel,&nbsp;Eberhard Haase,&nbsp;Stanislav Gorb,&nbsp;Chuchu Li","doi":"10.1002/jav.03716","DOIUrl":"https://doi.org/10.1002/jav.03716","url":null,"abstract":"<p>Melanins are natural pigments widely found in various structures of organisms and are responsible for avian feather coloration, contributing to signaling and camouflage. It has also been suggested that they maintain and enhance the mechanical properties of keratinized structures, such as reducing feather wear. However, the underlying mechanism remains unclear. In this study, wear, cross-sectional area, breaking force, stress, strain, and tensile modulus of melanized and non-melanized feathers are experimentally quantified to assess how melanization-associated structural differences influence the mechanical performance of primary feathers of the pigeon <i>Columba livia domestica</i>. Bleaching treatment was applied to both melanized and non-melanized feathers to further investigate the role of melanin in feather mechanical performance. The results show that melanized feathers/barbs exhibit significantly greater resistance to wear and higher breaking force than non-melanized ones, while no significant differences occur in breaking stress, strain, or tensile modulus regardless of bleaching treatment. These findings suggest that geometrical properties, particularly the cross-sectional area, rather than melanin itself, predominantly affect feather mechanical performance. This study improves understanding of the relationship between feather structure, melanization, and corresponding mechanical properties and provides insights for the biomimetic development of lightweight, feather-inspired structures for aerospace applications.</p>","PeriodicalId":15278,"journal":{"name":"Journal of Avian Biology","volume":"2026 5","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jav.03716","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149145833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gut microbial taxa are associated with problem-solving success in house sparrows","authors":"Melanie R. Florkowski,&nbsp;Giridhar Athrey,&nbsp;Jessica L. Yorzinski","doi":"10.1002/jav.03542","DOIUrl":"https://doi.org/10.1002/jav.03542","url":null,"abstract":"<p>Behavioral innovations are important traits that allow individuals to adapt to novel situations and changing environments. These behaviors require cognitive skills and behavioral flexibility but the mechanisms behind them are still poorly understood. The gut microbiome is the collection of microorganisms that reside in the gut, and it can influence the brain of the host organism through the gut–brain axis. We hypothesized that the richness and composition of the gut microbiome would relate to birds' abilities to solve novel problem-solving tasks. For this study, we used wild-caught house sparrows <i>Passer domesticus</i>, a species that is invasive in many parts of the world in part due to its flexible behavior and preference for urban habitats. We presented individuals with two food extraction tasks and measured their ability to solve them. We also measured the richness and composition of the birds' microbiomes from fecal samples. While microbial diversity did not significantly differ between solvers and non-solvers, some microbial genera did differ between solvers and non-solvers. We also found that persistence in solving the task was correlated with problem-solving success. These results add to our understanding of the avian gut–brain axis; however, further research will be needed to understand how specific microbes impact the brain and behavior of birds.</p>","PeriodicalId":15278,"journal":{"name":"Journal of Avian Biology","volume":"2026 5","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jav.03542","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Migratory divides highlight intraspecific flexibility in the stopover tactic of black kites","authors":"Ugo Mellone,&nbsp;Ivan Literák,&nbsp;Alessandro Berlusconi,&nbsp;Giuseppe Bogliani,&nbsp;Giacomo Dell'Omo,&nbsp;Michelangelo Morganti","doi":"10.1002/jav.03617","DOIUrl":"https://doi.org/10.1002/jav.03617","url":null,"abstract":"<p>In migrating raptors, route choice can be influenced by multiple factors, including geography, weather conditions, energy constraints, and social interactions. The selected route may in turn be associated with different patterns of stopover habitat use, yet the relationship between the two remains poorly understood. Achieving optimal energy stores is critical for completing long migratory journeys, particularly for birds facing the crossing of major ecological barriers. The black kite <i>Milvus migrans</i> is a migratory raptor with opportunistic feeding habits, which often exploits anthropogenic food sources such as landfills. In this study, we investigated their use by juvenile black kites, according to their migratory flyway. We tracked 43 juveniles using GPS telemetry, from four European breeding areas, using three main flyways to cross the Mediterranean Sea, differing in ecological and geographical characteristics. Route choice primarily depended on natal location, with birds from central European populations spreading over all flyways, and with birds hatched west of 18°E invariably choosing the western one, similar to birds hatched in northern Italy. In contrast, central Italian birds migrated directly southward, crossing the Central Mediterranean. Stopover strategies differed markedly among and within flyways. Along the western route, northern Italian kites made extensive use of landfills in France and Spain, while Czech individuals – despite following partly overlapping routes – stopped mainly in agricultural landscapes. In contrast, birds crossing the Central Mediterranean performed prolonged stopovers (up to 3–4 weeks) in Sicily in semi-natural agricultural areas, probably exploiting abundant invertebrate prey. Eastern-route migrants made shorter stops in cultivated areas and wetlands, with minimal landfill use. These findings highlight the behavioural flexibility of black kites, which present a range of foraging strategies, varying between populations and migration routes. Feeding at landfills exposes them to health threats, potentially compromising their fitness and survival across populations nesting far from the original source of contamination.</p>","PeriodicalId":15278,"journal":{"name":"Journal of Avian Biology","volume":"2026 5","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jav.03617","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photoperiod modulates courtship behavior and plasma testosterone in a short-day passerine","authors":"Maricel Quispe,&nbsp;Benjamín Silva Rochefort,&nbsp;María José Rojas,&nbsp;Irene Alburquerque,&nbsp;Natalia I. Márquez,&nbsp;Camila P. Villavicencio,&nbsp;René Quispe,&nbsp;João F. Botelho,&nbsp;Manuel Maliqueo,&nbsp;Gonzalo Marín,&nbsp;Jorge Mpodozis,&nbsp;Macarena Faunes","doi":"10.1002/jav.03712","DOIUrl":"https://doi.org/10.1002/jav.03712","url":null,"abstract":"<p>Seasonal reproduction in birds is commonly regulated by photoperiod, and passerines are generally considered long-day breeders. The Java sparrow <i>Padda oryzivora</i> has been proposed as a possible exception, but experimental evidence for short-day photoperiodicity has remained limited. Here, we tested the effects of day-length manipulation on courtship behavior and plasma testosterone levels in male Java sparrows. Birds were exposed sequentially to long-day, short-day, and long-day conditions, and behavioral and hormonal responses were quantified at defined stages across the experiment. Courtship increased after the transition from long to short days and decreased after the return to long days. Plasma testosterone showed a related but more heterogeneous pattern: it did not increase significantly at the group level after transfer to short days, but declined markedly after re-exposure to long days. In addition, variation in plasma testosterone did not consistently predict variation in courtship across treatment stages. Together, these results provide experimental support for a short-day reproductive response in Java sparrows, particularly at the behavioral level, and identify increasing day length as a potent inhibitory cue for both courtship and circulating testosterone. More broadly, our findings refine current views of photoperiodic regulation in passerines and highlight the complexity of the relationship between environmental cues, endocrine responses, and reproductive behavior in birds.</p>","PeriodicalId":15278,"journal":{"name":"Journal of Avian Biology","volume":"2026 5","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jav.03712","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146940","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Models of Ashmole's Halo","authors":"Alasdair I. Houston","doi":"10.1002/jav.03710","DOIUrl":"https://doi.org/10.1002/jav.03710","url":null,"abstract":"<p>Ashmole's halo is an area of reduced food availability around a colony of seabirds caused by the feeding behaviour of the birds. A model of the halo based on time and energy budgets has been used to predict how the intake rate of a colony member depends on distance from the colony. On this basis, the density of seabirds as a function of distance is predicted. This relationship is then used to relate colony size to foraging range. In this paper, I give a critical review of this work. The validity of this approach is of more than academic interest because it is being used to assess the consequences of changes to the environment on seabird populations. I compare the approach to an alternative that includes the dynamics of the prey and make suggestions for future lines of research.</p>","PeriodicalId":15278,"journal":{"name":"Journal of Avian Biology","volume":"2026 5","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jav.03710","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149048588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of egg size on size of subsequent eggs: experimental evidence for performance-based feedback within the clutch of a wild bird","authors":"Keith W. Sockman,&nbsp;Nicolas C. Frasson,&nbsp;Emma M. Reinhardt","doi":"10.1002/jav.03651","DOIUrl":"https://doi.org/10.1002/jav.03651","url":null,"abstract":"<p>An egg's size should reflect the net benefit of its production, which itself should vary with the environment. Although the environment is often complex, performance-based feedback from the size of an egg could signal the cumulative effects of the environment and enable females to optimize size of subsequent eggs, as a recent model and experiment support. That experiment did not rule out the signaling role of size-correlates, however. Therefore, using free-ranging Lincoln's sparrows <i>Melospiza lincolnii</i>, we conducted an experiment in which we substituted the first-laid egg – on the day it was laid – with an artificial egg from one of two groups that were identical except in size. We discovered that, compared to a small substitute, a large substitute yielded a larger increase in size from a previous egg to a subsequent egg (egg 4 in the clutch). This was consistent with the model and with the hypothesis that the size specifically of an initial egg can affect the size of subsequently laid eggs. Under unpredictably variable environmental conditions, such performance-based feedback may contribute to the optimization of not only egg size but a diversity of organismal processes.</p>","PeriodicalId":15278,"journal":{"name":"Journal of Avian Biology","volume":"2026 5","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jav.03651","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149047873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterizing partial migration using GPS tracking: high individual consistency in greylag geese","authors":"Lauren K. Common,&nbsp;Varalika Jain,&nbsp;Arno Cimadom,&nbsp;Harald Grabenhofer,&nbsp;Sonia Kleindorfer,&nbsp;Petra Sumasgutner","doi":"10.1002/jav.03568","DOIUrl":"https://doi.org/10.1002/jav.03568","url":null,"abstract":"<p>Migration is a critical ecological strategy throughout the animal kingdom and can be either fixed or flexible at the species, population, and individual levels. In partially migratory species, where only some individuals migrate, individuals may show consistency in their migratory behaviour. Greylag geese <i>Anser anser</i> are considered partially migratory, with known population-level flexibility in migration strategy. We used GPS tracking data from 21 wild greylag geese over seven years (2018–2025) around Lake Neusiedl, Austria, to investigate partial migration and the individual consistency of movement behaviour across years. To do so, we developed a multi-metric framework combining 95% annual kernel density estimates, net squared displacement (NSD) profiles, segment-level distance and speed, and model-based classification with the ‘migrateR' package. As part of this framework, we introduce a novel summary metric – the duration-normalized area under the NSD curve – which integrates how far and for how long an individual displaces from its breeding ground into a single, individual-comparable value. Based on these metrics, we found that 20/21 geese were migratory, with only one studied individual remaining a year-round resident for their entire tracking duration. Four individuals changed their movement behaviour between migratory and resident across years. Migratory individuals varied significantly in their movement patterns, overwintering across a broad latitudinal gradient, from upper Germany to Sardinia. These findings highlight the coexistence of plasticity and consistency in greylag goose migration and offer valuable opportunities to investigate the ecological and intrinsic drivers shaping movement behaviour at both individual and population levels.</p>","PeriodicalId":15278,"journal":{"name":"Journal of Avian Biology","volume":"2026 5","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jav.03568","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149047872","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Using functionally representative bird species and passive acoustic monitoring to model ecological variation across a land use mosaic in a dryland system","authors":"Frowin K. Becker,&nbsp;Connor M. Wood","doi":"10.1002/jav.03670","DOIUrl":"https://doi.org/10.1002/jav.03670","url":null,"abstract":"<p>Birds, through their wide range of functional traits, can serve as useful indicators of ecological change. Monitoring them across spatial scales has been considerably enhanced through passive acoustic monitoring (PAM) and automated call identification. Reconciling PAM with avian functional ecology remains an underexplored domain and could be a useful ecological assessment tool – especially in dryland ecosystems. In this study, we followed a systematic selection process to identify functionally representative and acoustically compatible bird species across variably managed (fenced-in) land parcels in north-central Namibia. Following this selection process, we identified eight suitable species, and used variables relating to land management, soil and vegetation to construct alternative occupancy models to estimate our selected species' occupancy probabilities across our study area. For five species, models with our ‘core' variables outperformed the null model, with several species distributions influenced by different environmental variables. Our findings demonstrate a quantitative, PAM- and trait-based approach to indicator species selection and the ways in which landscape features can affect the occupancy probabilities of functionally representative bird species. While exploratory in nature, this study can help develop an ecological monitoring concept that not only integrates bioacoustics and trait-based assessments but presents an effective tool for more underrepresented regions.</p>","PeriodicalId":15278,"journal":{"name":"Journal of Avian Biology","volume":"2026 5","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jav.03670","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148878406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}