Avian Research最新文献

{"title":"Beyond amplitude: Phase integration in bird vocalization recognition with MHAResNet","authors":"Jiangjian Xie ,&nbsp;Zhulin Hao ,&nbsp;Chunhe Hu ,&nbsp;Changchun Zhang ,&nbsp;Junguo Zhang","doi":"10.1016/j.avrs.2025.100229","DOIUrl":"10.1016/j.avrs.2025.100229","url":null,"abstract":"<div><div>Bird vocalizations are pivotal for ecological monitoring, providing insights into biodiversity and ecosystem health. Traditional recognition methods often neglect phase information, resulting in incomplete feature representation. In this paper, we introduce a novel approach to bird vocalization recognition (BVR) that integrates both amplitude and phase information, leading to enhanced species identification. We propose MHAResNet, a deep learning (DL) model that employs residual blocks and a multi-head attention mechanism to capture salient features from logarithmic power (POW), Instantaneous Frequency (IF), and Group Delay (GD) extracted from bird vocalizations. Experiments on three bird vocalization datasets demonstrate our method's superior performance, achieving accuracy rates of 94%, 98.9%, and 87.1% respectively. These results indicate that our approach provides a more effective representation of bird vocalizations, outperforming existing methods. This integration of phase information in BVR is innovative and significantly advances the field of automatic bird monitoring technology, offering valuable tools for ecological research and conservation efforts.</div></div>","PeriodicalId":51311,"journal":{"name":"Avian Research","volume":"16 1","pages":"Article 100229"},"PeriodicalIF":1.6,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143454292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Disentangling the relative effects of semi-natural habitats within different landscape agricultural intensities on bird communities","authors":"Wenyu Xu ,&nbsp;Yongshan Xu ,&nbsp;Zheng Han ,&nbsp;Jiyuan Yao ,&nbsp;Piotr Tryjanowski ,&nbsp;Haitao Wang","doi":"10.1016/j.avrs.2025.100228","DOIUrl":"10.1016/j.avrs.2025.100228","url":null,"abstract":"<div><div>The process of agricultural intensification has led to significant reductions in biodiversity globally. Previous studies examined the role of semi-natural habitats within agroecosystems in supporting bird communities, but few have considered the effects of landscape agricultural intensity on avian conservation potential of semi-natural habitats. Here, we disentangle the relative effects of semi-natural habitats within different landscape agricultural intensities on bird community composition in central and eastern Jilin Province, China. We established 322 sampling sites distributed across low, middle, and high landscape agricultural intensities, with 103, 118, and 101 sites respectively. Each sampling site was visited two times in May and June 2023 to test the dissimilarities in bird composition between different landscape agricultural intensities. We found that middle-intensity agriculture supported the highest bird diversity in most cases, but low-intensity plays an important role in maintaining insectivorous birds. We used generalized linear models and model selection to assess the relative impacts of semi-natural habitats on bird community along agricultural intensity respectively. Our results showed that the effects of agriculture on bird communities were predominantly influenced by the amount of semi-natural habitats, with effects that differ in accordance with the level of landscape agricultural intensity. Priority should be given to preserve or/and plant these semi-natural habitats in middle-intensity agriculture due to the stronger effect sizes on bird diversity. Specifically, we suggested preserving and promoting woodlands and shrubs in high-intensity agriculture, and simultaneously increasing crop diversity to protect bird diversity in agriculture landscapes in the context of increasing crop intensification globally.</div></div>","PeriodicalId":51311,"journal":{"name":"Avian Research","volume":"16 1","pages":"Article 100228"},"PeriodicalIF":1.6,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143429655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Does wetland degradation impact bird diversity differently across seasons? A case study of Zoige Alpine Wetland ecosystem","authors":"Chen Yang ,&nbsp;Siheng Chen ,&nbsp;Tianpei Guan","doi":"10.1016/j.avrs.2025.100227","DOIUrl":"10.1016/j.avrs.2025.100227","url":null,"abstract":"<div><div>Wetland degradation is an escalating global challenge with profound impacts on animal diversity, particularly during successional processes. Birds, as highly mobile and environmentally sensitive organisms, serve as effective indicators of ecological change. While previous studies have primarily focused on local community structures and species diversity during a specific season, there is a need to extend the research timeframe and explore broader spatial variations. Additionally, expanding from simple species diversity indices to more multidimensional diversity indices would provide a more comprehensive understanding of wetland health and resilience. To address these gaps, we investigated the effects of wetland degradation on bird diversity across taxonomic, phylogenetic, and functional dimensions in the Zoige Wetland, a plateau meadow wetland biodiversity hotspot. Surveys were conducted during both breeding (summer) and overwintering (winter) seasons across 20 transects in 5 sampling areas, representing 4 degradation levels (pristine, low, medium, and high). Our study recorded a total of 106 bird species from 32 families and 14 orders, revealing distinct seasonal patterns in bird community composition and diversity. Biodiversity indices were significantly higher in pristine and low-degraded wetlands, particularly benefiting waterfowl (Anseriformes, Ciconiiformes) and wading birds (Charadriiformes) in winter, when these areas provided superior food resources and habitat conditions. In contrast, medium and highly degraded wetlands supported increased numbers of terrestrial birds (Passeriformes) and raptors (Accipitriformes, Falconiformes). Seasonal differences in taxonomic, phylogenetic, and functional diversity indices highlighted the contrasting ecological roles of wetlands during breeding and overwintering periods. Furthermore, indicator species analysis revealed key species associated with specific degradation levels and seasons, providing valuable insights into wetland health. This study underscores the importance of spatiotemporal dynamics in understanding avian responses to wetland degradation. By linking seasonal patterns of bird diversity to habitat conditions, our findings contribute to conservation efforts and provide a framework for assessing wetland degradation and its ecological impacts.</div></div>","PeriodicalId":51311,"journal":{"name":"Avian Research","volume":"16 1","pages":"Article 100227"},"PeriodicalIF":1.6,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143471420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Three subspecies of Black-tailed Godwit share non-breeding sites in the world's largest river delta","authors":"Delip K. Das ,&nbsp;Wouter M.G. Vansteelant ,&nbsp;Bingrun Zhu ,&nbsp;Shariful Islam ,&nbsp;Naim Khandakar ,&nbsp;Marco van der Velde ,&nbsp;Chris J. Hassell ,&nbsp;Jesse R. Conklin ,&nbsp;Pierrick Bocher ,&nbsp;Jos C.E.W. Hooijmeijer ,&nbsp;Yvonne I. Verkuil ,&nbsp;Theunis Piersma","doi":"10.1016/j.avrs.2025.100226","DOIUrl":"10.1016/j.avrs.2025.100226","url":null,"abstract":"<div><div>During the non-breeding season (September–April), Black-tailed Godwits (<em>Limosa limosa</em>) are commonly seen in coastal and inland wetlands of the Ganges-Brahmaputra-Meghna Delta in Bangladesh. We hypothesize that the Ganges-Brahmaputra-Meghna Delta, at the overlap between the Central Asian and East Asian–Australasian flyways, may host three subspecies that breed in disjunct areas of temperate and northern Asia: <em>L. l. limosa</em>, <em>L. l. melanuroides</em>, and <em>L. l. bohaii</em>. We used mitochondrial DNA (mtDNA) haplotype network and biometric analysis to determine subspecies in captured individuals, and deployed GPS–GSM transmitters to verify breeding areas of individuals with subspecies assignments. To test for differential habitat preferences, we sampled birds at two ecologically distinct habitats known to host the largest concentrations of non-breeding Black-tailed Godwits in Bangladesh: Nijhum Dweep National Park, a tidal coastal habitat with brackish water on the south-central coast, and Tanguar Haor (‘backmarsh’), a seasonal freshwater floodplain in the north. During the non-breeding seasons of 2021–2022 and 2022–2023, we sampled and measured 93 Black-tailed Godwits, 54 of which were equipped with GPS–GSM transmitters. Our mtDNA haplotype network analysis confirmed the presence of <em>limosa</em>, <em>melanuroides</em>, and <em>bohaii</em> subspecies at the study sites. Thus, indeed, Black-tailed Godwits subspecies, despite having distinct breeding ranges, exhibit (partially) overlapping non-breeding ranges in Asia. The subspecies composition differed significantly between sites, with <em>limosa</em> and <em>bohaii</em> dominating in Tanguar Haor and <em>melanuroides</em> in Nijhum Dweep. Of the 21 individuals that were tracked to their breeding grounds, 18 migrated to the expected breeding range of their respective subspecies. However, one bird with a <em>limosa</em> haplotype migrated to a known breeding area of <em>bohaii</em>, whereas two birds with <em>melanuroides</em> haplotypes migrated to the supposed breeding range of <em>limosa</em>. Therefore, while ecological factors at both ends of the flyways may shape the morphological and behavioural differences between Black-tailed Godwit subspecies, their delineations and possible gene flow require further studies.</div></div>","PeriodicalId":51311,"journal":{"name":"Avian Research","volume":"16 1","pages":"Article 100226"},"PeriodicalIF":1.6,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"How does asymmetric sibling rivalry respond under environmental metal pollution? A case study of the Tree Sparrow (Passer montanus)","authors":"Jian Ding ,&nbsp;Shengnan Wang ,&nbsp;Wenzhi Yang ,&nbsp;Huijie Zhang ,&nbsp;Ni Wang ,&nbsp;Yingmei Zhang","doi":"10.1016/j.avrs.2025.100225","DOIUrl":"10.1016/j.avrs.2025.100225","url":null,"abstract":"<div><div>The imbalanced allocation of maternal resources to eggs and nestlings may significantly impact the phenotype and fitness of offspring. Moreover, anthropogenic metal pollution has been reported to exert adverse effects on avian offspring. Therefore, we herein evaluated the relationships among offspring characteristics, asymmetric sibling rivalry, and the resulting offspring phenotype in a small passerine bird, Tree Sparrow (<em>Passer montanus</em>), at a polluted site (Baiyin, BY) and a relatively unpolluted site (Liujiaxia, LJX). By initiating incubation before the completion of clutch, asymmetric sibling rivalry might create a core and marginal offspring within the brood. In this study, lower egg mass, fewer core offspring, and more marginal offspring were found at the polluted site. Although eggshell speckling and coloration were relatively similar between the two sites, higher eggshell spotting coverage ratio and lower eggshell lightness (<em>L</em>∗) and hue (<em>h</em>°) were observed in core eggs than in marginal eggs at the unpolluted site. The clutch size had a positive relationship with egg mass at the polluted site and with brood size at hatching at the unpolluted site. The differences in egg measurements across the laying orders in the samples were relatively large for larger clutch sizes. The core and marginal egg masses had a significant positive effect on the size of early core nestlings and late marginal nestlings at the unpolluted site. Fledgling rate was significantly positively related to the incubation period and nestling period, while negative relationship with mean spotting coverage ratio was found at the polluted site. Marginal nestlings at the polluted site showed a higher mortality rate. Overall, although asymmetric sibling competition strongly determines the variation of marginal offspring size, the effect is less dramatic in metal-polluted environments, providing some respite to wild birds that survive pollution-induced stress.</div></div>","PeriodicalId":51311,"journal":{"name":"Avian Research","volume":"16 1","pages":"Article 100225"},"PeriodicalIF":1.6,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143395148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Local song evolution after three decades in a complex songster, the Thrush Nightingale","authors":"Abel Souriau ,&nbsp;Jorma Sorjonen ,&nbsp;Adam Petrusek ,&nbsp;Tereza Petrusková","doi":"10.1016/j.avrs.2025.100224","DOIUrl":"10.1016/j.avrs.2025.100224","url":null,"abstract":"<div><div>Birdsong is an important secondary sexual trait which may vary between but also within species. Intraspecific variation is generally studied either on the geographical or on the temporal scale; most of the studies exploring the variation of song over time, however, focused on species with rather simple songs. In this study, we explored the temporal changes in song of a complex songster, the Thrush Nightingale (<em>Luscinia luscinia</em>), recorded after 33 years (in 1986 and 2019) at the same locality in south-eastern Finland. Our analysis revealed a complete turnover of song types over the study period, with no song type shared between the two recording years. In contrast, 40% of the originally recorded syllable types were still found in the repertoires of recently recorded males. Their song type repertoires were significantly smaller but the songs themselves were on average longer compared to the 1986 recordings. Repertoires of both syllables and song types were more shared between males recorded in 1986 than between those from 2019. We discuss the processes that may have contributed to these temporal changes in song and call for more detailed studies of song evolution in wild populations.</div></div>","PeriodicalId":51311,"journal":{"name":"Avian Research","volume":"16 1","pages":"Article 100224"},"PeriodicalIF":1.6,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Inter- and intraspecific variation in flight muscle fibers is associated with migratory timing","authors":"Shangmingyu Zhang ,&nbsp;Shane DuBay ,&nbsp;Yuwen Cheng ,&nbsp;Zhehan Dong ,&nbsp;Zhengwei Liu ,&nbsp;Yongjie Wu","doi":"10.1016/j.avrs.2025.100223","DOIUrl":"10.1016/j.avrs.2025.100223","url":null,"abstract":"<div><div>The life-history strategies of organisms are shaped by trade-offs among traits that influence survival, development, reproduction, and ultimately fitness. However, the specific physiological and environmental mechanisms driving population-level variation in phenotypic traits, particularly in relation to migratory adaptations, remain poorly understood. Elevational migration represents an adaptive behavior for mountain birds that offers a unique model to investigate adaptive phenotypes because of the diverse migratory strategies that have been observed within and between species. Flight muscles, as multifunctional organs, exhibit phenotypic variation that aligns with locomotor and thermoregulatory demands. Linking flight muscle phenotypes to migratory strategies can provide insights into inter- and intraspecific variation in migratory adaptations. In this study, we examined spring arrival dates at high-altitude breeding sites for three closely related high-altitude breeding birds in the mountains of Asia: Blue-fronted Redstart (<em>Phoenicurus frontalis</em>), Himalayan Bluetail (<em>Tarsiger rufilatus</em>), and Rufous-gorgeted Flycatcher (<em>Ficedula strophiata</em>). We analyzed relationships between arrival dates and phenotypic traits, including flight muscle physiology, morphology, and internal organ mass, alongside environmental effects on these traits. Our findings indicate that species arriving earlier encountered lower temperatures and exhibited reduced fiber cross-sectional areas coupled with higher fast oxidative glycolytic (FOG) fibers densities. Males displayed pronounced protandry and higher fast glycolytic (FG) fibers densities. Ambient temperature significantly influenced flight muscle phenotypes, highlighting intraspecific variation and the potential plasticity of flight muscle fibers as crucial mechanisms for adapting to migration strategies and environmental conditions. Additionally, this study underscores the potential role of sexual selection in shaping functional phenotypic variation, further advancing our understanding of adaptive strategies in high-altitude migratory birds.</div></div>","PeriodicalId":51311,"journal":{"name":"Avian Research","volume":"16 1","pages":"Article 100223"},"PeriodicalIF":1.6,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143395147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Distribution pattern and niche overlap of sympatric breeding birds along human-modified habitat gradients in Inner Mongolia, China","authors":"Xi Yang ,&nbsp;Lishi Zhang ,&nbsp;Piotr Tryjanowski ,&nbsp;Frédéric Jiguet ,&nbsp;Zheng Han ,&nbsp;Haitao Wang","doi":"10.1016/j.avrs.2025.100222","DOIUrl":"10.1016/j.avrs.2025.100222","url":null,"abstract":"<div><div>The transformation of natural habitats into human-modified landscapes has far-reaching consequences for species distribution and abundance. As species adapt to these changing environments, shifts in distribution patterns, niche dynamics, and interspecies interactions may occur, impacting biodiversity at multiple levels and potentially leading to ecosystem imbalances. This study aims to assess the impact of variations in vegetation composition and human disturbance on the distribution of sympatric breeding birds and to determine the extent of niche overlap or differentiation among these species. We conducted field surveys and collected data on bird distribution, vegetation composition, and level of human disturbance in eastern Inner Mongolian grasslands. We focused on the six most frequently co-occurring breeding birds, representing a mix of sparrows, larks, and corvids. Generalized Additive Models revealed varying responses of species occurrence along habitat gradients. Species like the Eurasian Skylark (<em>Alauda arvensis</em>), Mongolian Lark (<em>Melanocorypha mongolica</em>), and Asian Short-toed Lark (<em>Calandrella cheleensis</em>), increased in larger and more connected habitats, while others, like the Tree Sparrow (<em>Passer montanus</em>), Eurasian Magpie (<em>Pica pica</em>), and Barn Swallow (<em>Hirundo rustica</em>), adapted to more fragmented habitats. Niche analysis indicated habitat generalists tended to occupy larger niches than grassland specialists. Substantial niche overlap was also found among the six co-occurring bird species. Conservation efforts should consider the specific needs of specialist species and strive to maintain or restore critical grassland habitats. Additionally, promoting sustainable agricultural practices that balance the needs of birds and human activities can contribute to the coexistence of generalist and specialist bird species in modified landscapes.</div></div>","PeriodicalId":51311,"journal":{"name":"Avian Research","volume":"16 1","pages":"Article 100222"},"PeriodicalIF":1.6,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143099481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing the vulnerability of wintering habitats for the red-listed Asian Houbara (Chlamydotis macqueenii) using climate models and human impact assessments","authors":"Gulzaman William ,&nbsp;Zafeer Saqib ,&nbsp;Abdul Qadir ,&nbsp;Nisha Naeem ,&nbsp;Mehrban Ali Brohi ,&nbsp;Asim Kamran ,&nbsp;Afia Rafique","doi":"10.1016/j.avrs.2024.100221","DOIUrl":"10.1016/j.avrs.2024.100221","url":null,"abstract":"<div><div>The Asian Houbara (<em>Chlamydotis macqueenii</em>), a vulnerable species, is under significant threat from habitat degradation and anthropogenic pressures in Pakistan's arid landscapes. This study addresses the urgent need for conservation by identifying critical habitats, analyzing the influence of environmental and human factors on species distribution, and projecting future habitat shifts under climate change scenarios. Using the MaxEnt model, which achieves a robust predictive accuracy (AUC = 0.854), we mapped current and future habitat suitability under Shared Socioeconomic Pathways (SSP126, SSP370, SSP585) for the years 2040 and 2070. Presently, the suitable habitat extends over 217,082 km², with 52,751 km² classified as highly suitable. Key environmental drivers, identified via the Jackknife test, revealed that annual mean temperature (Bio1) and slope play a dominant role in determining habitat suitability. Projections show significant habitat degradation; however, under SSP585, highly suitable areas are expected to expand by up to 24.92% by 2070. Despite this increase, vast areas remain unsuitable, posing serious risks to population sustainability. Moreover, only 2115 km² of highly suitable habitat currently falls within protected zones, highlighting a critical conservation shortfall. These findings highlight the imperative for immediate, targeted conservation efforts to secure the species' future in Pakistan's desert ecosystems.</div></div>","PeriodicalId":51311,"journal":{"name":"Avian Research","volume":"16 1","pages":"Article 100221"},"PeriodicalIF":1.6,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143099055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Decreased basal thermogenesis is associated with the downregulation of cellular metabolic activity of organs and serum thyroid hormones in fasting Eurasian Tree Sparrows (Passer montanus)","authors":"Hong Jin ,&nbsp;Qi Xia ,&nbsp;Ziqing Gao ,&nbsp;Yujie XuanYuan ,&nbsp;Beibei Dong ,&nbsp;Ming Li ,&nbsp;Qingjian Liang ,&nbsp;Jinsong Liu","doi":"10.1016/j.avrs.2024.100220","DOIUrl":"10.1016/j.avrs.2024.100220","url":null,"abstract":"<div><div>Food is a critical environmental factor that influences animal survival, especially for small passerines due to their high mass-specific metabolic rates. Basal metabolic rate (BMR) reflects the energy expended by endothermic animals for basic physiological processes and constitutes a major part of their daily energy budget. Some birds have been shown to employ compensatory mechanisms during food shortages, temporarily reducing these self-maintenance expenditures without using hypothermia. However, the mechanisms of BMR adjustment remain unexplored. In the present study, we assessed the phenotypic variation in basal thermogenesis of Eurasian Tree Sparrows (<em>Passer montanus</em>) by comparing a control group to groups fasted for 6, 12, 18, and 24 h. We focused on the correlation between a reduction in energy metabolism and the alterations of cellular metabolic activities, mitochondrial substrate supply, and changes in serum thyroid hormones during fasting. Our data indicated that fasting groups had significantly lower body mass, BMR, body temperature, and body fat content. Furthermore, fasting groups had significantly lower glycogen levels, mitochondrial state 4 respiration and cytochrome <em>c</em> oxidase (CCO) activity in the liver, and CCO activity in pectoral muscle. The levels of avian uncoupling protein (<em>av-UCP</em>) mRNA were significantly reduced, while the levels of myostatin protein in pectoral muscle were significantly increased in the fasting groups. Furthermore, the groups subjected to fasting exhibited significantly lower levels of serum glucose, triglyceride, thyroxine (T₄), and triiodothyronine (T₃). Positive correlations were observed between the following pairs of variables: log BMR and log body mass, log body mass and log body fat, log BMR and log state 4 respiration in the liver, log BMR and log CCO activity in the liver and muscle, log BMR and log <em>av-UCP</em> mRNA expression, whereas a negative correlation was observed between log BMR and log myostatin level. In addition, a positive correlation was also detected between log T₃ and each of the following: log BMR, state 4 respiration, and log CCO activity in the liver. Our results suggested that decreased metabolic thermogenesis via down-regulation in cellular aerobic capacity of organs and serum thyroid hormones may be an important survival strategy for fasting Tree Sparrows to reduce energy expenditure.</div></div>","PeriodicalId":51311,"journal":{"name":"Avian Research","volume":"16 1","pages":"Article 100220"},"PeriodicalIF":1.6,"publicationDate":"2024-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143098987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}