摘要: 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.

摘要: 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(Phoenicurus frontalis), Himalayan Bluetail(Tarsiger rufilatus), and Rufous-gorgeted Flycatcher(Ficedula strophiata). 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.

摘要: 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 selfmaintenance 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（Passer montanus） 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 c oxidase（CCO） activity in the liver, and CCO activity in pectoral muscle. The levels of avian uncoupling protein（avUCP） m RNA 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 av-UCP m RNA 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.

摘要: The Asian Houbara（Chlamydotis macqueenii）, 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 Max Ent 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.

摘要: 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 seminatural 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 middleintensity 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.

摘要: Nest predation is the leading cause of reproductive failure in birds and a major driving force in the evolution of anti-predation strategies. Current studies on the anti-predation strategies of birds driven by predation pressure have mainly focused on adults. However, the detection and behavioral responses of nestlings toward predation risk require further investigation. In this study, we examined nestling responses to predator sounds. Two species of nestlings, the Reed Parrotbill(Paradoxornis heudei) and Vinous-throated Parrotbill(Sinosuthora webbiana),were exposed to the Sparrowhawk(Accipiter nisus, less common) and Oriental Magpie(Pica serica, more common), which are predator species, the Oriental Turtle Dove(Streptopelia orientalis), which is a commonly found harmless species, and background noise. Our findings revealed that compared to pre-playback of natural begging and playback of background noise and Oriental Turtle Dove sounds, playback of the two predator types decreased the total begging time and total number of calls of the two nestlings species, with the calls of the Sparrowhawk leading to greater suppression of nestling begging behavior than those of the Oriental Magpie.Therefore, our results indicated that these nestlings were able to distinguish predators from harmless species based on auditory cues.

摘要: Inclusive fitness theory posits that altruistic behaviors, which are directed more likely towards relatives, should be favored by natural selection. However, the prevalence of alternative parenting behaviors in offspring selection, including rejecting their own offspring and accepting the offspring of others, remains poorly understood within the context of parental care evolution. In order to investigate the factors that prompt the occurrence of alternative parenting behaviors, we designed a series of experiments in the Azure-winged Magpie(Cyanopica cyanus). By manipulating the nest spatial position or offspring age/number and parent-offspring familiarity, we addressed how parents provided parental care for the manipulated offspring. In the nest resettlement experiment, the probability of parents rejecting their own offspring significantly increased with nest-moving distances while decreased with offspring ages. In the cross-fostering experiments, the probability of parents provisioning unrelated young significantly decreased with the age difference between cross-fostered chicks. In the nest duplication experiments, where parents were given a choice between familiar offspring and unfamiliar unrelated chicks or between unfamiliar offspring and familiar unrelated chicks, the probability of both alternative parenting behaviors was significantly influenced by the time when parental association with their offspring was deprived. We conclude that as offspring phenotypic traits become individualized and fixed at a special developmental stage, parents gradually acquire the capacity for offspring recognition by associating with them. Any factors that disrupt parent–offspring association or introduce unrelated young into the nest prior to this critical timeline can result in the occurrence of alternative parenting behaviors.

摘要: Urban environments have challenging characteristics for bird acoustic communication. High levels of anthropogenic noise, as well as vegetation structure(e.g., in urban parks), can potentially affect the song frequency characteristics of several bird species. An additional factor such as the abundance of conspecific and heterospecific vocalizing birds may play an important role in determining the structure of bird songs. In this study, we analyzed whether noise levels, vegetation percentage, and abundance of conspecifics and heterospecifics influence the song characteristics of three syntopic songbird species: House Finch(Haemorhous mexicanus), Rufouscollared Sparrow(Zonotrichia capensis), and House Sparrow(Passer domesticus) living in urban sites. We recorded songs of these species and measured the peak frequency and entropy of their songs at 14 sites in the city of San Cristobal de Las Casas, Chiapas, Mexico. We found that the song peak frequency of House Finch and House Sparrow's songs was negatively related to the vegetation. The peak frequency of neither of the three species correlated with the average noise level. However, the abundances of conspecific and heterospecific were related to the peak frequency of the three species' songs. The entropy of the House Finch and House Sparrow songs was positively and negatively related, respectively, to noise levels. House Sparrow song entropy was negatively related to the percentage of vegetation. Song entropy of House Finches was negatively associated to conspecific and House Sparrow abundance. Song entropy of Rufous-collared Sparrows was positively related to conspecific abundance. In conclusion, the song peak frequency and song entropy of the three songbird species were differentially related to urban noise, vegetation, and conspecific and heterospecific abundance, suggesting these factors influence bird song characteristics.

摘要: 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(Luscinia luscinia), 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.

摘要: 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 MHARes Net, 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.