摘要: Environmental DNA(e DNA) methods have emerged as a promising tool for studying a broad spectrum of biological taxa. However, metabarcoding studies of avian biodiversity using e DNA have received little attention. In this study, we compared waterbird biodiversity derived from e DNA metabarcoding with that obtained from traditional point counting surveys at 23 sites in Tai Lake of eastern China and evaluated the accuracy of e DNA metabarcoding for waterbird community studies. The point counting method recorded a higher total number of waterbird species(22) compared to the e DNA technique(16). While e DNA 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 e DNA method and the point counting method, except that the e DNA method exhibited lower Pielou evenness. Waterbird e DNA sequencing abundance correlated significantly with species occurrence, whereas Spearman's analysis indicated no significant difference between e DNA sequence abundance and species abundance from the point counting method. e DNA method detected no significant difference in waterbird composition between sampling sites, while the point counting method revealed significant differences. Consequently, e DNA 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 e DNA with traditional survey methods for accurate evaluation of community structure.

摘要: In recent years, environmental DNA(e DNA) 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 e DNA 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 e DNA, although other sources like spider webs and plant flowers have been explored as well. Notably, airborne e DNA has been reported to capture the highest diversity of avian species. While avian e DNA 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 e DNA in the environment. Finally, we suggested future research directions, including optimizing sampling strategies, developing avian-specific universal primers, expanding avian DNA barcode databases, enhancing e DNA detectability, and integrating environmental RNA(e RNA) and e DNA approaches.

摘要: 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.

摘要: 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 tradeoffs. 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.

摘要: 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.

摘要: 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.

摘要: 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 ffiaveola) 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.

摘要: 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.

摘要: 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(mt DNA) 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 mt DNA 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.

摘要: 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 Shorttoed 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.