Environmental DNA (eDNA) methods have emerged as a promising tool for studying a broad spectrum of biological taxa. However, metabarcoding studies of avian biodiversity using eDNA have received little attention. In this study, we compared waterbird biodiversity derived from eDNA metabarcoding with that obtained from traditional point counting surveys at 23 sites in Tai Lake of eastern China and evaluated the accuracy of eDNA metabarcoding for waterbird community studies. The point counting method recorded a higher total number of waterbird species (22) compared to the eDNA technique (16). While eDNA achieved a 74.5% detection rate for waterbird species and was able to identify a significantly greater number of species (12.48 ± 1.97) at each sampling site than point counting method (6.13 ± 2.69), particularly highlighting several rare and elusive species, it failed to detect some species commonly observed by the point counting method. The alpha diversity analysis revealed no significant differences in waterbird diversity between the eDNA method and the point counting method, except that the eDNA method exhibited lower Pielou evenness. Waterbird eDNA sequencing abundance correlated significantly with species occurrence, whereas Spearman's analysis indicated no significant difference between eDNA sequence abundance and species abundance from the point counting method. eDNA method detected no significant difference in waterbird composition between sampling sites, while the point counting method revealed significant differences. Consequently, eDNA is an effective complementary tool for assessing the diversity of wintering waterbirds in lakes, though it is unable to capture the full diversity of waterbird communities. It is crucial to develop sampling strategies that comprehensively monitor species composition and integrate eDNA with traditional survey methods for accurate evaluation of community structure.

Bacterial infections of avian embryos can lead to an increase in embryo mortality, and the proliferation of antimicrobial-resistant bacteria aggravates the situation. A low hatching rate also poses a challenge to the population of artificially bred Crested Ibises (Nipponia nippon). This study aims to determine the potential association between bacterial infection and the death of Crested Ibis embryos, and whether there is convergence between antimicrobial resistance and virulence in strain. In this study, 13 Escherichia coli and 12 Proteus mirabilis isolates were recovered from dead Crested Ibis embryos. The pathogenicity examination confirmed the pathogenicity of all isolates, and multiple virulence genes detected by PCR-sequencing demonstrated the presence of irp2 and iucD (100%), fimC and iss (92.31%) in E. coli, and ucaA (58.33%) in P. mirabilis. Antimicrobial susceptibility test demonstrated that isolates were mainly resistant to amoxicillin (E. coli: 76.92%, P. mirabilis: 91.67%), cefazolin (E. coli: 76.92%, P. mirabilis: 91.67%), oxytetracycline (E. coli: 92.31%, P. mirabilis: 75.00%) and sulfamethoxazole-trimethoprim (E. coli: 53.85%, P. mirabilis: 33.33%), and more than 30% of isolates showed multidrug-resistance (MDR). Further analyses detected extended-spectrum β-lactamase (ESBL) genes, of which bla_TEM-1 (E. coli: 100%, P. mirabilis: 100%) had the highest frequency, followed by the bla_CTX-M-55 (E. coli: 92.31%, P. mirabilis: 50%), bla_CTX-M-14 (E. coli: 76.92%, P. mirabilis: 33.33%), bla_CTX-M-65 (E. coli: 15.38%, P. mirabilis: 16.67%), and all isolates were negative for bla_SHV and bla_OXA. Pearson’s correlation analysis showed a positive correlation between the presence of β-lactam resistance and ESBL genes, while mainly negative correlations were observed between the presence of ESBL genes and virulence genes. Furthermore, the conjugation experiment and PFGE revealed that the isolates were primarily polyclonal, and there was horizontal transfer of resistance or virulence genes by plasmids. Based on the results, E. coli and P. mirabilis were responsible for embryonic mortality of the ibises in this study. The co-presence and co-transfer of ESBL genes and virulence genes can pose a potential threat to the health of the Crested Ibis, and measures such as prudent use of antimicrobials, and constant surveillance of resistance and pathogenicity, must be implemented at the Crested Ibis breeding base.

In brood-parasitic Cuculus cuckoos, male vocalizations are species-specific and easily distinguishable, whereas female calls are remarkably similar across species, making species identification challenging. In this study, we examined the structural characteristics and variability of female bubbling calls among four Cuculus species (Common Cuckoo C. canorus, Oriental Cuckoo C. optatus, Indian Cuckoo C. micropterus, and Lesser Cuckoo C. poliocephalus) breeding in South Korea. Comprehensive acoustic analyses of seven call parameters, using recordings from 2021 to 2023, were conducted to quantify the characteristics of their calls and compare within- and between-individual variability across species. Significant differences were found across all call parameters, with the Common Cuckoo producing the highest number of notes and the Oriental Cuckoo the lowest-frequency calls. Despite these differences, the overall structure of the calls remained acoustically similar, with overlapping characteristics across species. Furthermore, female Common Cuckoos exhibited greater within-individual variability in their calls, while the other species showed higher between-individual variability, which may further complicate species identification based vocalization alone. These findings highlight the complexities of female vocalizations in Cuculus cuckoos and suggest that ecological, social, and evolutionary factors may contribute to this vocal variability.

Tracking and mating data of Common Terns (Sterna hirundo) breeding in a single colony in north-eastern Germany were used to test for assortative mating in regards to migratory phenotypes. These birds use the eastern and western African migration routes and three different wintering areas along the African coast. However, no assortative mating was found for either migratory route or wintering area, as birds using both flyways and all three wintering areas paired randomly, which might be explained by a lack of difference in the arrival date at the colony between the groups. These results might indicate a low degree of genetic fixation of migratory route and wintering area in the Common Tern, which might hint that migratory direction and wintering sites could be passed to young terns via social learning, either by joining the parents or migratory flocks of conspecifics. If migratory phenotypes are passed on by a parent, it seems more likely that it is passed from father to young, as female Common Terns tend to leave the colony earlier and males provide the majority of post-fledging care.

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.

Passerine mimics often imitate various vocalizations from other bird species and incorporate these sounds into their song repertoires. While a few anecdotes reported that wild songbirds imitated human-associated sounds, besides captive parrots and songbirds, systemic and quantitative studies on human-made sound mimicry in wild birds remain scarce. In this study, we investigated the mimetic accuracy and consistency of electric moped sounds imitated by an urban bird, the Chinese Blackbird (Turdus mandarinus). We found that: (1) Only one type of electric moped sound was imitated, i.e., 13 of 26 males mimicked the first part of the antitheft alarm, a phrase containing a series of identical notes. (2) The mimicry produced by male Chinese Blackbirds had fewer notes and lower consistency within phrases compared to the model alarms. (3) The mimicry of male Chinese Blackbirds was imperfect, i.e., most of the acoustic parameters differed from the model alarms. Additionally, mimetic notes were lower in frequency than the models. Mimetic notes from two areas were also different in acoustic structures, suggesting Chinese Blackbirds might learn mimicry mainly from conspecific neighbors within each area respectively rather than electric mopeds, namely the secondary mimicry. Imperfect mimicry of human-made sounds could result from cost and physical constraints, associated with high consistency, frequency, and repetitions. Consequently, Chinese Blackbirds copied a simplified version of electric moped alarms. We recommend further attention to mimic species inhabiting urban ecosystems to better understand vocal mimicry's adaptation to ongoing urbanization.

Climate change can affect rainfall and temperature worldwide, and the ability of birds to react to these changes can be mirrored by studying population phenology and their breeding success. Some European species have advanced arrival and breeding dates in response to local spring advancement, but conditions experienced during winter seasons may also affect arrival dates and subsequent breeding success. We utilized data collected from 1983 to 2020 in four colonies of Common Swift (Apus apus) in Northern Italy (5486 breeding attempts) to examine the variations of laying date and breeding success in relation to non-breeding conditions (previous winter in Africa) and local conditions in breeding period (spring). Climatic conditions were monitored using the North Atlantic Oscillation (NAO) and El Nino Southern Oscillation (ENSO) indices to describe conditions experienced in winter quarters and the local temperature and rainfall conditions of the breeding area. Common Swifts laid their eggs earlier in warmer springs, and this in turn had a positive effect on breeding success. We did not find evidence for any effects of African winter conditions on laying date nor on breeding success. However, because studies made in the same area have demonstrated a relationship of winter conditions (NAO) on individual survival, our data highlight the importance of considering environmental variables across the annual life cycle to understand variation in Common Swift populations.

Carotenoid-based plumage coloration may signal individuals’ overall body condition, influencing reproduction and survival of birds. In tropical species, little is known about the influence of color on social interactions and mate attraction. We evaluated the chromatic variation of 136 adult Saffron Finches (Sicalis flaveola) in Cali and Jamundí, Colombia. Our aim was to determine whether plumage coloration in this social, abundant, and widely distributed species is a signal used in mate choice and establishment of hierarchies. We predicted that there was intrasexual chromatic variation in crown and throat, and that individuals with higher saturation, regardless of sex, would be preferred by opposite sex and they would be dominant in intrasexual aggressive interactions, reflecting better condition. We quantified the reflectance of the crown and throat with visible and ultraviolet light (300–700 nm) subsequent to the molecular sex determination of each individual. Our results suggest that the chromatic variation in the crown and throat is explained by the perception of medium and long wavelengths in both sexes. Additionally, saturation is the color characteristic that best explains the chromatic variation. We formed duos of individuals based on chromatic contrast and conducted 23 mate choice experiments and 21 dominance experiments. The analysis of spectra and experiments revealed that dominance in males was associated with less saturated crowns. Our results reveal that in the Saffron Finches the “negatively correlated handicap” is a plausible hypothesis. Crown color appears to mediate dominance interactions, with less saturated males potentially taking greater risks to gain access to resources.

Abundant food supply is crucial for the survival of long-distance migratory birds. The continued population decline of the Spoon-billed Sandpiper (Calidris pygmeae), a critically endangered shorebird, is primarily attributed to habitat loss and degradation. However, significant gaps remain in research on their diet and foraging habitat selection, limiting effective conservation and restoration efforts. In this study, we investigated the composition of macrobenthic communities, analyzing habitat and prey selection at the main foraging area of SBS in Tiaozini, Jiangsu Province of eastern China—their most critical staging site during southward migration. Our findings revealed 25 species of macrobenthos in foraging areas, with mobile epibenthos comprising the largest group by biomass, accounting for 73%, and having higher density and biomass nearshore. Observations of foraging Spoon-billed Sandpiper individuals indicated that shallow water habitats were their preferred foraging environments, where mobile epibenthos, which thrive in these habitats after the tide recedes, made up 81% of their biomass intake. We propose that shallow water habitats in intertidal mudflats serve as essential refuges for mobile epibenthos after tidal retreat, thereby providing Spoon-billed Sandpipers with access to high-quality food resources. Habitat protection efforts should prioritize habitats harboring extensive microhabitats with shallow water, especially the nearshore area, and further research is needed to explore the mechanisms underlying the formation of these microhabitats, with the ultimate goal of restoring more high-quality habitats for the Spoon-billed Sandpiper.

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 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.

During the non-breeding season (September–April), Black-tailed Godwits (Limosa limosa) 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: L. l. limosa, L. l. melanuroides, and L. l. bohaii. 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 limosa, melanuroides, and bohaii 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 limosa and bohaii dominating in Tanguar Haor and melanuroides 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 limosa haplotype migrated to a known breeding area of bohaii, whereas two birds with melanuroides haplotypes migrated to the supposed breeding range of limosa. 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.

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), Rufous-collared 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.

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.

Avian brood parasitism is a unique reproductive behavior in which parasitic birds depend on other species to incubate their eggs and raise their offspring. In China, there are 20 species of cuckoos in the family Cuculidae, order Cuculiformes, of which 17 species are parasitic cuckoos. This makes China one of the countries with the largest number of parasitic cuckoo species worldwide. Understanding the host utilization of cuckoos provides fundamental data for studying the coevolution of cuckoos with their hosts. We collected information on cuckoo hosts from the literature, photographs provided by birdwatchers, and online short video platforms, combined these data with our field observations, and summarized the parasitic cuckoos and their host species in China. A total of 1155 parasitism events were counted, involving 12 parasitic cuckoo species and 87 bird host species. These hosts belonged to 26 families, among which Muscicapidae was the most diverse with 19 species, accounting for 21.8% of the total hosts, followed by the families Phylloscopidae and Leiothrichidae with 8 species each, accounting for 9.2% of the total hosts recorded. The Common Cuckoo (Cuculus canorus) had the largest number of host taxa with 38 species, accounting for 43.7% of the total host species. This study adds 14 host species that have not been reported in China. However, for five species, the Jacobin Cuckoo (Clamator jacobinus), Banded Bay Cuckoo (Cacomantis sonneratii), Violet Cuckoo (Chrysococcyx xanthorhynchus), Common Hawk-cuckoo (Hierococcyx varius), and Whistling Hawk-cuckoo (Hierococcyx nisicolor), information regarding host utilization is still lacking.

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 (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 (av-UCP) 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 av-UCP 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.

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.

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.

Illegal hunting and trafficking of wildlife and their derivatives extort unprecedented population decline of relatively many species pushing them towards extinction. Notwithstanding contemporary counteracting interventions at international, regional, national and local levels, wildlife farming is advocated as an alternative approach to minimize pressure on wild populations. For wildlife farming to be an effective conservation tool, the integration of wildlife forensics is inevitable to allow distinction between captive-bred and wild-caught species. To this end, we analyzed methylation rates of skeletal muscle samples (pectoralis major, triceps brachii, gastrocnemius, biceps femoris, and neck muscles) from 60 captive-bred and 30 wild-caught Common Pheasant. A total of 13,507 differentially methylated regions were identified between five wild-caught and five captive-bred individuals through whole-genome methylation sequencing (WGBS). Based on the selected five methylation sites, LOC116231076, LOC116242223, ATAD2B, EGFL6, and HS2ST, quantitative detection technique was developed using methylation-sensitive high-resolution melting curve (MS-HRM) to measure methylation rates. The results showed significant differences in methylation rates at all differential sites between wild-caught and captive-bred individuals (|t| = 0.67–33.10, P = 0.000–0.042). The discrimination accuracy rate of each locus was highest in the gastrocnemius muscle and lowest in the neck muscle. The discrimination accuracy rate on LOC116231076, LOC116242223, ATAD2B, EGFL6, and HS2ST methylation sites for gastrocnemius muscle was 64.98%, 100.00%, 68.54%, 63.79%, and 63.70%, respectively; and for neck muscle it was 67.42%, 68.06%, 83.61%, 65.04%, and 68.85%, respectively. The united discrimination accuracy rate of the five loci were 100.00% for gastrocnemius muscle, 99.78% for biceps femoris muscle, 97.52% for pectoralis major muscle, 93.96% for triceps brachii muscle, and 91.63% for neck muscle, respectively. The panel also revealed excellent repeatability, reproducibility, sensitivity and universality to mammals and avian species. This study establishes an effective, accurate and low-cost identification technology for the identification of wild and farmed Common Pheasant, and also provides a reference for the development of identification methods for other species.

Passive acoustic monitoring (PAM) technology is increasingly becoming one of the mainstream methods for bird monitoring. However, detecting bird audio within complex natural acoustic environments using PAM devices remains a significant challenge. To enhance the accuracy (ACC) of bird audio detection (BAD) and reduce both false negatives and false positives, this study proposes a BAD method based on a Dual-Feature Enhancement Fusion Model (DFEFM). This method incorporates per-channel energy normalization (PCEN) to suppress noise in the input audio and utilizes mel-frequency cepstral coefficients (MFCC) and frequency correlation matrices (FCM) as input features. It achieves deep feature-level fusion of MFCC and FCM on the channel dimension through two independent multi-layer convolutional network branches, and further integrates Spatial and Channel Synergistic Attention (SCSA) and Multi-Head Attention (MHA) modules to enhance the fusion effect of the aforementioned two deep features. Experimental results on the DCASE2018 BAD dataset show that our proposed method achieved an ACC of 91.4% and an AUC value of 0.963, with false negative and false positive rates of 11.36% and 7.40%, respectively, surpassing existing methods. The method also demonstrated detection ACC above 92% and AUC values above 0.987 on datasets from three sites of different natural scenes in Beijing. Testing on the NVIDIA Jetson Nano indicated that the method achieved an ACC of 89.48% when processing an average of 10 s of audio, with a response time of only 0.557 s, showing excellent processing efficiency. This study provides an effective method for filtering non-bird vocalization audio in bird vocalization monitoring devices, which helps to save edge storage and information transmission costs, and has significant application value for wild bird monitoring and ecological research.

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.

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 (Alauda arvensis), Mongolian Lark (Melanocorypha mongolica), and Asian Short-toed Lark (Calandrella cheleensis), increased in larger and more connected habitats, while others, like the Tree Sparrow (Passer montanus), Eurasian Magpie (Pica pica), and Barn Swallow (Hirundo rustica), 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.

In recent years, environmental DNA (eDNA) has garnered significant attention as a novel tool in biodiversity monitoring, recognized for its efficiency, convenience, and non-invasiveness. Despite its extensive application in various ecological studies, such as conservation, invasion biology, biomonitoring and biodiversity survey assessment, its use in avian monitoring remains in its infancy. This review critically examines the potential and limitations of eDNA technology for avian monitoring, focusing on current advancements and ongoing challenges in this emerging field. Water and air are the primary environmental media for collecting avian eDNA, although other sources like spider webs and plant flowers have been explored as well. Notably, airborne eDNA has been reported to capture the highest diversity of avian species. While avian eDNA technology has shown promise for monitoring rare and endangered species and assessing avian diversity, significant challenges remain, particularly in sampling strategies, DNA extraction methodology, primer selection, and ascertain abundance. Additionally, we discussed the factors influencing the production, transportation, and degradation of avian eDNA in the environment. Finally, we suggested future research directions, including optimizing sampling strategies, developing avian-specific universal primers, expanding avian DNA barcode databases, enhancing eDNA detectability, and integrating environmental RNA (eRNA) and eDNA approaches.

The number of secondary feathers varies among orders of birds with some orders exhibiting a positive relationship with ulna length, whereas in other orders secondary number is invariant. This difference has implications for scaling of the width of the feather vane within orders. In those species where the number of secondary remiges is invariant with ulna length, vane width should scale isometrically with ulna size to maintain an aerodynamic flight surface. Where feather count increases with increasing ulna length then vane width should exhibit negative allometry. Vane length should also correlate with ulna length, irrespective of the number of feathers. Data were compiled from an online library of images for the vane length and the width of the vane at 50% of the vane length for the fifth secondary feather for 209 bird species from 24 different orders. The results supported the hypotheses that vane width is a function of ulna size, and the number of secondary feathers as associated with different orders. Vane length was unaffected by the number of secondaries but varied between orders. The results suggest that birds have solved the problem of maintaining the aerodynamic surface of the proximal wing in two ways. Hence as ulna length increases the first solution involves more feathers that exhibit negative allometry for vane width, or in the second where feather count doesn’t change, the vane width simply scales isometrically. The implications for the mechanical properties of the vane, and how it affects wing function, have not yet been explored in a range of birds.

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.

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 (Passer montanus), 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 (L^*) and hue (h°) 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.

Avian vocal communication represents one of the most intricate forms of animal language, playing a critical role in behavioral interactions. Both peripheral and central auditory-vocal pathways are essential for precisely integrating acoustic signals, ensuring effective communication. Like humans, songbirds exhibit vocal learning behaviors supported by complex neural mechanisms. However, unlike most mammals, songbirds possess the remarkable ability to regenerate damaged auditory cells. These capabilities offer unique opportunities to explore how birds adjust their vocal behavior and auditory processing in response to dynamic environmental conditions. Recent studies have advanced our understanding of the plasticity of avian vocal communication system, yet the vocal diversity and neurophysiological mechanisms underlying vocalization and hearing have often been examined independently. A comprehensive overview of how these systems interact and adapt in birds remains lacking. To address this gap, this review synthesizes the peripheral and central features of avian vocalization and hearing, while also exploring the mechanisms that drive the remarkable plasticity of these systems. Furthermore, it explores seasonal variations in bird vocalization and hearing and adaptations to environmental noise, focusing on how hormonal, neural, and ecological factors together shape vocal behavior and auditory sensitivity. Avian vocal communication systems present an exceptional model for studying the integration of peripheral and central vocal-auditory pathways and their adaptive responses to ever-changing environments. This review underscores the dynamic interactions between avian vocal communication systems and environmental stimuli, offering new insights into broader principles of sensory processing, and neuroplasticity.

The Natural Forest Protection Project (NFPP), initiated by the Chinese government in 2000, is a crucial ecological construction project that has played a significant role in forest restoration in China. Forests in the Qinghai-Tibet Plateau (QTP) serve as important habitats for many rare and endemic birds. Understanding the conservation efficiency of NFPP implementation on these birds holds significant practical significance. In this study, we utilized land use change matrices to analyze the forest changes in the QTP before and after NFPP implementation, predicted the potential spatial distribution of 16 nationally protected birds using Species Distribution Models (SDMs), and compared the impacts of this project on bird habitats under different carbon emission scenarios. Mann-Whitney U tests were employed to analyze the adaptation of different birds to forest changes during NFPP implementation. Our results showed that NFPP protected 172,398 km² of primary forests and added 6379 km² of secondary forests in our study area. The potential spatial distribution and sympatric species richness of the 16 protected birds slightly increased after NFPP implementation under different climate change scenarios, and NFPP implementation contributed to improving the potential spatial distribution of birds. Compared to newly established secondary forests, protected primary forests exhibited enhanced conservation for forest birds (Z-value > 0 for six bird species, P < 0.1), while being less suitable for non-forest birds (significantly unsuitable for three non-forest bird species, Z-value < 0, P < 0.05; non-significantly unsuitable for four non-forest bird species, Z-value < 0, P > 0.1). This indicates that the protection of primary forests during NFPP implementation benefits forest bird conservation while the addition of secondary forests is beneficial to non-forest birds. To enhance the role of NFPP in avian conservation in the QTP, it is suggested to increase the landscape heterogeneity of forest, particularly in newly established secondary forests.

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.

Assessing individual differences and variability in animal movement patterns is essential to improve our understanding of the evolution and ontogeny of migratory strategies. In long-distance migratory species, fledged juveniles often rely on an extremely restricted time span to learn the essential skills for survival and to prepare for migration, possibly the most risky phase of their lives. Collecting detailed information on the dynamics of the movements during the crucial pre-migratory phase is hence essential to understand the solutions developed by migratory species in different environmental contexts. Here, we used high-resolution GPS/GSM transmitters to collect information on the movement ecology of seven juvenile Montagu's Harriers (Circus pygargus) born in central Italy, investigating their early life stages, namely the post-fledging dependence period (PFDP) and the pre-migratory phase (PMP), until autumn migration. After fledging, individuals showed high variability (both in space and time) in home range size, daily distances covered (6.88 ± 11.44 km/day), distance from the nest (1.45 ± 2.8 km) and PFDP length (23.3 ± 5.3 days). Residence time at the natal site significantly decreased, while time interval between revists in the natal area significantly increased, as the PFDP progressed. During the PMP, explored areas and distance from the nest (max value up to 320.8 km) varied among individuals, despite daily distances covered (27 ± 40 km/day) and time allocation between traveling (60.7%) and foraging (39.3%) were similar across individuals. The PMP lasted 38 ± 14 days. Land cover composition of foraging locations was mostly represented by agricultural lands (~78.2%), though habitat use differed among individuals. More than 76% of such locations were outside protected areas. This individual-based tracking study represents a novel approach that improves previous knowledge based on field studies on the early life stages of the Montagu's Harrier. High inter-individual variability in movement patterns, broad-range exploratory movements and foraging locations outside the protected area network make the application of standard conservation measures difficult, raising concerns about the long-term preservation of this vulnerable migratory species in Italy.

Free-ranging yak grazing is a regime specially adapted to high-elevation environments across the Pan-Tibetan Highlands, yet its impacts on alpine birds remain poorly understood. The Chinese Monal (Lophophorus lhuysii) is a rare pheasant species that serves as a representative and umbrella species for alpine meadow ecosystems in the mountains of Southwest China, and has long been regarded as threatened by free-ranging yaks. However, the actual impacts and specific mechanisms through which yak grazing influences Chinese Monal have not been empirically tested. Here, we conducted infrared camera monitoring in alpine meadows within the Wolong National Nature Reserve, Sichuan, China, from 2019 to 2022. We analyzed the effects of free-ranging yaks on habitat occupancy, activity pattern, and population density of the Chinese Monal using multispecies occupancy models, kernel density estimations, avoidance attraction ratios, and random encounter models. We found that interactions with yaks affect monal habitat occupancy in conjunction with other ecological factors. Specifically, the presence of yaks alters monals’ occupancy responses to variations in grass cover and elevation, causing monals to use habitats with lower grass cover and elevation more frequently. Additionally, the activity patterns of the Chinese Monal and yaks are significantly different, and the presence of yaks significantly prolongs the time until monals re-occupy the same habitats. As an outcome of the cumulative effects of spatial and temporal avoidance, the population density of the Chinese Monal negatively correlated with increasing grazing intensity. This study provides the first empirical evidence of the negative impacts of free-ranging yaks on the Chinese Monal and elucidates the underlying mechanisms, highlighting great risks to conservation of this vulnerable species. Our findings inform the optimization of grazing management that balances production with conservation. Strict control over yak numbers and grazing areas in critical habitats for Chinese Monal and other threatened species could be a feasible compromise to mitigate these pressures.

Evaluating the habitat suitability of flagship species and its key influencing factors is vital for understanding potential conservation issues and developing coping strategies. We surveyed the wintering population size and distribution of the Black-necked Crane (Grus nigricollis) in the Yarlung Zangbo River Basin (YZRB) from 10 to 29 January 2022, and predicted the current potentially suitable habitat distribution and its effective factors using the MaxEnt model. A total of 9337 wintering Black-necked Cranes were recorded in the YZRB in 2022, 76.58 % of which were primarily found in Lhunzub, Samzhubze, Namling, and Lhaze. Compared to 2018, the crane population has exhibited a notable decline in Samzhubze and Taktse, likely due to farmland plowing, winter irrigation, changes in agricultural practices, road construction and hydraulic projects. The crane population within various counties exhibited a significant positive correlation with the suitable habitat area (r = 0.70, P = 0.002, n = 17). We also found that the currently suitable habitat area covered 17,204 km², of which only 3244 km² (18.86 %) was effectively protected at the national level, which was predominantly distributed in farmland and rangeland habitats characterized by gentle slopes, altitudes not exceeding 4500 m, and proximity to human settlements along rivers, where suitable isothermal values (51) and less seasonal precipitation (20 mm) prevail. Our study will be helpful for formulating reasonable conservation strategies to protect the core population of this threatened highland flagship species.

Moult is an essential event in the annual cycle of birds. Moult patterns and strategies of birds are crucial for understanding their life-history trade-offs and adaptations to the environment. However, moult knowledge is still lacking for many Eastern Palaearctic birds, especially large endangered species, mainly because of the difficulty in data collection. Here, we used field photography, a non-invasive method, to detect and score moult in the endangered Crested Ibis (Nipponia nippon) and explored the moult timing variations and moult-breeding trade-offs. The adult Crested Ibis sequentially moults its primaries outward, and secondaries inward from three foci from April to October. Age (adult versus sub-adult) and breeding status (breeding or not) have a significant effect on moult timing. Moult timing does not differ between the sexes, likely because of similar parental investments in breeding. Crested Ibis exhibits significant moult-breeding overlap, because moult is time constrained and needs to finish before the season of food scarcity in winter. Breeding timing (first egg laying date) has a strong impact on moult duration, with late breeders experiencing a longer moult duration, indicating that the moult intensity is slowed down during the breeding period because of trade-offs between moult and breeding. This reflects that energy allocation of late breeders is challenging during extensive periods of moult-breeding overlap, which might partly contribute to their high breeding failure. Our results strongly suggest the existence of a negative relationship between breeding time on one hand, and fitness and moult on the other: early breeders show higher reproductive output and higher quality plumage, whereas late breeders show lower reproductive output and lower quality plumage.