Journal of Avian Biology最新文献

{"title":"Effects of urban life on the gut microbiota and the susceptibility to avian malaria infection in a population of the house sparrow Passer domesticus","authors":"Daliborka Stanković,&nbsp;Hugo J. Eira Pereira,&nbsp;Marko Raković,&nbsp;Stefan Skorić,&nbsp;Nayden Chakarov","doi":"10.1111/jav.03303","DOIUrl":"10.1111/jav.03303","url":null,"abstract":"<p>Life in urban areas may alter the gut microbiota and host physiology, leading to a higher susceptibility to pathogens. In contrast, specific members of the gut microbiota community have been shown to mitigate the intensity of malaria infection. House sparrows, living in close proximity to humans, are exposed to a unique environment with human-shaped diets emerging as a particularly influential factor. In addition, sparrows host a significant number of avian haemosporidian and other blood parasites. We examined how the gut bacterial community of house sparrows varied across two close urban sites in the city of Belgrade and the potential impact of blood parasite infection on the gut microbiota. Our results show that diversity and composition of the gut microbiota were only influenced by the sampling location, likely due to variations in food resources, particularly the availability of bird feed at one of the sites (a zoo). In summary, our results suggest the local microbial adaptations to differing levels of urbanisation habitats, in this case most likely driven by artificial alterations in food resources, but not reaching to effects on the blood parasite fauna.</p>","PeriodicalId":15278,"journal":{"name":"Journal of Avian Biology","volume":"2025 3","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jav.03303","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143944554","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":"Chemical signatures in the preen oil of pied flycatchers: testing reproducibility and exploring ontogeny","authors":"Laurence Jeanjean,&nbsp;Barbara A. Caspers,&nbsp;Tim Schmoll,&nbsp;Marc Gilles","doi":"10.1111/jav.03365","DOIUrl":"10.1111/jav.03365","url":null,"abstract":"<p>Preen oil – the secretion from the uropygial gland of birds – may have diverse functions in avian reproduction: protection against eggshell bacteria, olfactory crypsis against nest predators and olfactory mate choice. To investigate such functions, we should first characterise variation in preen oil composition, but also confirm that previously described patterns are robust. Replication studies are crucial to test the reproducibility of previous findings, but are rarely undertaken in chemical ecology. Here, we conducted an almost exact replication of a previous study on the chemical composition of preen oil in a wild passerine bird, the pied flycatcher <i>Ficedula hypoleuca</i>. We aimed to estimate the reproducibility of the previous results using larger sample sizes and following a pre-registered analysis. In addition, we explored the ontogeny of preen oil composition by comparing nestling and adult preen oil. In line with previous findings, preen oil composition was similar between breeding partners and not repeatable within individual females across breeding stages. Female preen oil changed across breeding stages more clearly than in the original study (higher richness, diversity and volatility during incubation than nestling-rearing), further refuting a role of preen oil in olfactory crypsis in this species. Unlike the original study, we found no difference in chemical profiles between sexes (nestling-rearing), casting doubt on the proposed role of preen oil as a sex semiochemical in this species. Nestling preen oil differed from adults, was more similar to adult males than to adult females, but was not more similar to parents than to non-parents. We found family chemical signatures, which, along with the breeding pair signature, suggests an influence of the nest environment on preen oil composition. Our study highlights the importance of replication and provides novel insights into the function and development of preen oil.</p>","PeriodicalId":15278,"journal":{"name":"Journal of Avian Biology","volume":"2025 3","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jav.03365","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143944553","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":"Comparative analysis of the plasma metabolome of migrating passerines: novel insights into stopover metabolism","authors":"Adi Domer,&nbsp;Weronika Jasinska,&nbsp;Leah Rosental,&nbsp;Eyal Shochat,&nbsp;Saleh Alseekh,&nbsp;Alisdair R. Fernie,&nbsp;Yariv Brotman,&nbsp;Ofer Ovadia","doi":"10.1111/jav.03331","DOIUrl":"10.1111/jav.03331","url":null,"abstract":"<p>During long-distance migration, many birds experience periods of either prolonged fasting (during endurance flights) or extensive feeding (during stopovers). Despite decades of research on avian metabolism during migration, many questions have remained unanswered, as such research mainly focused on targeted metabolites and fat metabolism. Here, we examined the plasma-metabolome of two migrating passerine species before they crossed the Sahara Desert. Birds were sampled at two sites populated by Pistacia trees bearing fat-rich fruits and at an additional site dominated by blooming Eucalyptus trees. The blood samples were analyzed using both GC-MS and LC-MS, using an untargeted approach. Examination of metabolic pathways activated during stopovers indicated a crucial role for cycling glucose through the Cori and Cahill cycles in resting and recovery processes. This novel perspective, conducted on free-ranging birds, suggests the evolution of avian insulin resistance due to factors such as endurance exercise, fasting, and a preference for fatty acid oxidation during migration, akin to cell trauma recovery. We detected significant inter-site variations in birds' polar and lipophilic metabolic profiles. We interpret the differences in the polar metabolites to be associated with the physiological state of the birds, with birds that are considered to have landed during the night prior to capture showing different metabolic profiles compared to birds that have spent more time at the stopover site. In contrast, distinctions in the lipophilic profiles of birds were associated with variations in the primary food source that was available to them in the different sites. This study underscores the challenge of interpreting commonly used indicators for assessing migrating birds' physiological state, which was predominantly derived from lipid metabolism in complex ecological systems.</p>","PeriodicalId":15278,"journal":{"name":"Journal of Avian Biology","volume":"2025 2","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jav.03331","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143595081","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":"Migration of black terns Chlidonias niger and common terns Sterna hirundo between south Sweden and the Atlantic coast of Africa","authors":"Thomas Alerstam,&nbsp;Johan Bäckman,&nbsp;Johanna Grönroos,&nbsp;Patrik Olofsson,&nbsp;Roine Strandberg,&nbsp;Sissel Sjöberg","doi":"10.1111/jav.03348","DOIUrl":"10.1111/jav.03348","url":null,"abstract":"<p>Light-level geolocators were used to record the annual migration cycles of black terns <i>Chlidonias niger</i> (9 individuals, 11 journeys) and common terns <i>Sterna hirundo</i> (7 individuals, 11 journeys) breeding in southernmost Sweden. The black terns used two different non-breeding (Oct–Mar) regions along the Atlantic coast of Africa, either north of the equator between Senegal and Liberia (3 individuals) or south of the equator between Gabon and northern Namibia (5 individuals). All the common terns travelled to non-breeding quarters south of the equator, mainly along the coasts of Namibia and South Africa. One juvenile common tern was tracked during the first twenty months of its life. This bird spent its first northern winter in South Africa, after which it migrated north of the equator to spend the northern summer as a one-year-old non-breeder in tropical waters off Ghana, after which it returned to South Africa for its second northern winter. This record demonstrates that one-year-old terns may undertake extensive intra-African migration to distant over-summering areas. Comparing geolocator results from Swedish and Dutch black tern populations indicate that they have similar migration habits, with a possible tendency of relatively more individuals migrating south of the equator in the more northerly Swedish population (leap-frog migration). Comparing geolocator and ringing results among common tern populations indicates a fascinating and complex pattern of scale-dependent geographic segregation and intermixing along the coasts of Africa.</p>","PeriodicalId":15278,"journal":{"name":"Journal of Avian Biology","volume":"2025 3","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jav.03348","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143944667","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":"Stopover regions, phenology, and spatiotemporal group dynamics of adult and juvenile common terns Sterna hirundo from inland lakes in North America","authors":"Annie Bracey,&nbsp;Fred Strand,&nbsp;Alexis Grinde,&nbsp;Francesca Cuthbert,&nbsp;Ann E. McKellar,&nbsp;David Moore,&nbsp;Elizabeth Craig,&nbsp;Simeon Lisovski","doi":"10.1111/jav.03308","DOIUrl":"10.1111/jav.03308","url":null,"abstract":"<p>Understanding the behavior of migratory birds can help determine levels of connectivity and inform conservation actions for species of conservation concern. The common tern <i>Sterna hirundo</i> is a long-distance migratory seabird that is considered a species of conservation concern in the North American Great Lakes region and that has experienced significant declines in breeding numbers across large lakes in Manitoba. To better understand the movement ecology of common terns, we used data from multiple tracking technologies (solar geolocation, GPS tracking, and Motus radio tracking) obtained from individuals (n = 83) across five breeding colonies on four inland lakes in North America. We identified key stopover regions used during southward migration and explored how demographics and social interactions influence connectivity. We identified three key stopover regions (Lake Erie, the southern Atlantic Coast, and Florida) and documented, for the first time, differences in post-natal and post-breeding migration for inland nesting terns. Juveniles arrived, on average, three weeks later than unrelated adults to their first major staging area. Although adult female arrival to and departure from Lake Erie was similar to adult males, female schedules became significantly earlier than males as southward migration progressed. Using a graph network to describe the spatiotemporal associations among adults from the same inland lake, individuals appeared to be highly connected, meeting up in different regions throughout the non-breeding season, suggesting that social interactions may play an important role in maintaining spatial connectivity. Despite differences in migration schedules by sex and arrival to the first major staging area by age class, birds appeared to rely on the same key stopover regions during southward migration. The stopover regions identified in this study can help identify potential bottlenecks and guide future research aimed at assessing the impacts of climate change and human disturbance on common terns breeding in North America.</p>","PeriodicalId":15278,"journal":{"name":"Journal of Avian Biology","volume":"2025 3","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jav.03308","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143945040","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":"Translocation experiment of taiga bean geese Anser fabalis provides evidence for oblique social learning of moult migration","authors":"Kristaps Sokolovskis,&nbsp;Antti Piironen,&nbsp;Toni Laaksonen","doi":"10.1111/jav.03263","DOIUrl":"10.1111/jav.03263","url":null,"abstract":"<p>While there is ample evidence supporting genetic control of migratory behaviour in short-lived passerines, long-lived social species have been assumed to rely solely on cultural inheritance of migratory routes. Evidence from experimental studies supporting this idea is scarce. We tested whether the moult migration in taiga bean geese <i>Anser fabalis</i> has an inherited component or whether the birds need oblique social learning (where knowledge on migration is transferred from any experienced individual to any naïve individual conspecific) to carry out this journey. In many waterfowl species, non-breeders and failed breeders migrate to remote places for wing moult while successful breeders stay at the breeding grounds and moult with their chicks. We translocated one-year-old taiga bean geese before their first moult migration to sites outside of the breeding range to examine whether they display innate moult migration behaviour without experienced conspecifics or not. The birds were equipped with GPS-transmitters and released in randomly assigned groups of two. Wild control one-year-old birds were released immediately after capture with other non-breeding geese, while a procedural control group consisting of older birds was held in captivity until being released at the same time with the translocated one-year-old birds but in the place where they were captured. Most translocated birds found conspecifics and either joined locally moulting breeders or followed experienced birds to moulting sites in Russia. Two of the translocated birds did not find other bean geese and settled to moult together in southwest Finland. The wild control birds moult-migrated as expected, while only one of the procedural control birds moult-migrated to Russia and the remaining three stayed with locally moulting breeders in Finland. Our results support the idea that moult migration in geese is culturally inherited, highlighting the importance of the non-relative, experienced adult individuals in maintaining population-specific behaviours.</p>","PeriodicalId":15278,"journal":{"name":"Journal of Avian Biology","volume":"2025 3","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jav.03263","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143945039","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":"Introducing the mini-review article category and the Journal of Avian Biology review award","authors":"Michael Tobler,&nbsp;Theresa Burg,&nbsp;Dominique Potvin,&nbsp;Jan-Åke Nilsson","doi":"10.1111/jav.03423","DOIUrl":"10.1111/jav.03423","url":null,"abstract":"&lt;p&gt;Journal of Avian Biology (JAB) publishes hypothesis-driven, high-quality research from all parts of the globe that advances our understanding of the ecology, evolution and behaviour of birds. Findings can be disseminated in research articles, short communications, viewpoint articles and reviews. Reviews perform an important function as vehicles to convey critical information in a synthesized way; they not only aggregate information, but also identify current research gaps and pave the way for future investigation. Comprehensive review articles, however, are major undertakings that may quickly go out of date. To address this challenge and to offer a nimbler format to publish overviews of a particular field or aspect in avian biology, JAB introduced the ‘mini-review' article category in December 2022. As the name suggests, mini-reviews are shorter than standard reviews (about 6000 words) and can be used to highlight a sub-topic or ongoing debate within a broader research area. They provide a succinct and clear summary of the research topic and give readers a quick overview of the most recent and significant advances.&lt;/p&gt;&lt;p&gt;Journal of Avian Biology is an important outlet for young researchers. Of all the articles published in 2023, nearly 60% had a corresponding author with no more than 8 years of post-doctorate research experience. Most of the corresponding authors on these papers (close to 50%) were PhD students or early postdocs at the time of publication. To emphasize this and to highlight the mini-review category as a new outlet for early career researchers to synthesize their research, JAB announced the first ‘JAB review award' competition in spring 2023. The award is sponsored by the Nordic Society Oikos (NSO), the umbrella society for the ecological societies in the Nordic countries, who publishes JAB and four other scientific journals (Oikos, Nordic Journal of Botany, Ecography and Wildlife Biology).&lt;/p&gt;&lt;p&gt;The JAB review award is given to an early career research scientist who has an exceptional mini-review manuscript accepted for publication in JAB. The mini-review should focus on new developments and/or emerging concepts in the areas of avian research that fall within the scope of the journal. The winner of the JAB review award receives a 1000€ honorarium and the runner-up receives 500€. If the award is given for a paper with multiple authors (the lead and corresponding author(s) must be early career), those meeting the early career research criteria at the time of publication will share the monetary prize. All accepted papers that are entered in the competition will appear together in an issue in Journal of Avian Biology.&lt;/p&gt;&lt;p&gt;In this first ‘award issue', we briefly reiterate eligibility and submission criteria, and outline the assessment criteria for the award. We wish to be clear and transparent about these criteria as it recently has been highlighted that there is not enough transparency in scientific awards for early- and mid-car","PeriodicalId":15278,"journal":{"name":"Journal of Avian Biology","volume":"2024 11-12","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jav.03423","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664799","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":"Beware of hitchhiking ticks? Clarifying the variable roles of bird species in tick movement along migratory routes","authors":"Lars Burnus,&nbsp;Joe Wynn,&nbsp;Miriam Liedvogel,&nbsp;Robert E. Rollins","doi":"10.1111/jav.03275","DOIUrl":"10.1111/jav.03275","url":null,"abstract":"<p>Ticks are blood-feeding parasites which act as major vectors for various pathogenic microorganisms affecting both animal and human health. Hard ticks are known to move passively (i.e. ‘hitchhike') on migratory birds as they transit between breeding and non-breeding grounds. This potentially leads to exchange and establishment of non-endemic tick species in novel environments. However, it is not yet clear if all migratory bird taxa play an equal role in movement of specific tick species, especially outside of medically important tick taxa. To clarify these interactions, we performed a systematic literature review regarding primary data of ticks moving on migratory birds within the African–Western Palearctic flyways. In total, 35 studies were found which showed 123 bird species from 37 families and 12 orders connected to potential movement of 30 tick species representing six genera (<i>Amblyomma</i>, <i>Dermacentor</i>, <i>Haemaphysalis</i>, <i>Hyalomma</i>, <i>Ixodes</i>, <i>Rhipicephalus</i>). Most tick species did not show high abundance for any bird species, or, if they did, only on very few. Only <i>Ixodes ricinus</i> and <i>Hyalomma marginatum</i> were estimated to be carried at above average burdens by multiple bird species. This could indicate an increased likelihood of these species to be moved during migration. Specific tick species or whole genera were only found in certain migratory seasons as expected based on their geographic distributions. Even so, species found in both migratory seasons did not differ in their estimated abundances on birds between seasons. This result could suggest that tick abundance on migrating birds is not always a direct result of geographic distribution and may suggest an understudied importance of stopover sites towards potential tick introduction or turnover. Taken together, the results presented here provide guiding information for future analyses integrating individual level variation into the current understanding of tick movement with migratory birds.</p>","PeriodicalId":15278,"journal":{"name":"Journal of Avian Biology","volume":"2025 3","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jav.03275","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143944752","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 metabolic data to investigate the role of brood size in the development of endothermy","authors":"Elana Rae Engert,&nbsp;Fredrik Andreasson,&nbsp;Andreas Nord,&nbsp;Jan-Åke Nilsson","doi":"10.1111/jav.03301","DOIUrl":"10.1111/jav.03301","url":null,"abstract":"<p>Altricial songbirds transform themselves from naked poikilotherms to fully feathered endothermic homeotherms over a matter of days from hatching to fledging. The ontogeny of endothermy is a developmental milestone for birds that not only face warmer average temperatures, but also increasingly frequent cold snaps and extreme weather. The timing of development of endothermy has been studied in altricial birds for over half a century. However, the determinants and constraints of the onset of endothermy are not yet fully understood. We experimentally investigated whether brood size influences the ontogeny of endothermic heat production in 4–8 day-old nestling blue tits <i>Cyanistes caeruleus</i> in southern Sweden. The thermogenic response to a cooling challenge (15°C) increased with age overall. We found that 8-day-old nestlings from reduced broods had a slightly increased capacity for endothermic heat production compared to enlarged broods. This difference cannot be explained by body mass because this trait did not differ between brood size categories. Although a metabolic response was present in most nestlings by day 6, it was brief, not lasting more than a few minutes, and not sufficient to maintain a stable body temperature in any age group. Our study shows that incipient endothermy is present at an early age in nestling blue tits and may advance faster in reduced broods, but that individual nestlings lack sufficient insulation and thermogenic performance to maintain homeothermy independently during the first week of life.</p>","PeriodicalId":15278,"journal":{"name":"Journal of Avian Biology","volume":"2025 3","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jav.03301","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143944886","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":"The interplay of resource availability and parent foraging strategies on juvenile sparrow individual specialization","authors":"Natalia Ricote,&nbsp;Constanza Weinberger,&nbsp;Natalia Ramírez-Otarola,&nbsp;Sara Bustamante,&nbsp;María Lucía Málaga,&nbsp;Gonzalo Barceló,&nbsp;Pablo Sabat,&nbsp;Seth D. Newsome,&nbsp;Karin Maldonado","doi":"10.1111/jav.03391","DOIUrl":"10.1111/jav.03391","url":null,"abstract":"<p>Temporal variation in resource availability, amplified by global change, may have strong impacts on species breeding at temperate and high latitudes that cue their reproduction to exploit seasonal resource pulses. This study examines how resource availability and parental care influence niche partitioning between and within age classes in the rufous-collared sparrow, which provides extensive parental care. We hypothesized juveniles would exhibit narrower niches focused on high-quality resources compared to adults, regardless of resource availability. We used stable isotope analysis to quantify individual and population niches in juveniles and adults across the breeding season in two cohorts experiencing contrasting resource landscapes. Contrary to our initial hypothesis, juveniles exhibited greater among-individual diet variation and smaller total niche widths (i.e. higher levels of individual specialization, IS) during periods of high food availability in comparison to periods of food scarcity. Interestingly, total niche width and IS of adults remained stable across seasons despite a shift in trophic level, highlighting their potential role in providing a consistent diet for their young. These findings reveal a dynamic interplay between resource availability, parental care, and IS, with important implications for understanding population resilience under variable resource scenarios. The study also suggests that adult sparrows modify their provisioning strategies based on resources, potentially buffering offspring from environmental fluctuations. Understanding age-specific responses to resource variation is crucial for predicting species responses to ecological conditions, particularly in regions like central Chile where seasonal resource limitation is expected to become more variable in response to climate change.</p>","PeriodicalId":15278,"journal":{"name":"Journal of Avian Biology","volume":"2025 2","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jav.03391","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143595711","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}