Search Results (91)

Bird migration routes across North America, which are often speculated upon at the microscale, are now subject to scrutiny using the ‘eBird’ database, the world’s largest data repository for the North American continent. This database has steadily accumulated data on resident and migratory birds, with annual data on both potentially revealing regional trends. Through analysis of eBird data accumulated since 1980, we identified regional trends indicating bird migration patterns across North America, delineating three primary regions within the North American flyway: the western, central and eastern flyways, with the latter further subdivided into three regions. These findings refine previous categorisations of the four major flyways, deepening our understanding of bird migration dynamics in North America. Full article

A key challenge is how to effectively conserve habitats and biodiversity amid widespread habitat fragmentation and loss caused by global urbanization. Despite growing attention to this issue, knowledge of the seasonal dynamics of habitats remains limited, and conservation gaps are still inadequately identified. This study proposes a novel integrated framework, “Habitat Suitability–Risk–Quality”, to improve the assessment of the seasonal bird habitat quality and to identify priority conservation habitats in urban landscapes. The framework was implemented in Wuhan, China, a critical stopover site along the East Asian–Australasian Flyway. It combines the Maximum Entropy (MaxEnt) model to predict the seasonal habitat suitability, the Habitat Risk Assessment (HRA) model to quantify habitat sensitivity to multiple anthropogenic threats, and a refined Habitat Quality (HQ) model to evaluate the seasonal habitat quality. K-means clustering was then applied to group habitats based on seasonal quality dynamics, enabling the identification of priority areas and the development of differentiated conservation strategies. The results show significant seasonal variation in habitat suitability and quality. Wetlands provided the highest-quality habitats in autumn and winter, grasslands exhibited moderate seasonal quality, and forests showed the least seasonal fluctuation. The spatial analysis revealed that high-quality wetland habitats form an ecological belt along the urban–suburban fringe. Four habitat clusters with distinct seasonal characteristics were then identified. However, spatial mismatches were found between existing protected areas and habitats of high ecological value. Notably, Cluster 1 maintained high habitat quality year round, spanning 99.38 km², yet only 46.51% of its area is currently protected. The remaining 53.16 km², mostly situated in urban–suburban transitional zones, remain unprotected. This study provides valuable insights for identifying priority habitats and developing season-specific conservation strategies in rapidly urbanizing regions, thereby supporting the sustainable management of urban biodiversity and the development of resilient ecological systems. Full article

Globally, coastal wetlands are among the most dynamic and important environments due to their wide range of environmental services, from which coastal communities benefit. Mexico has coastal wetlands that are a priority in the Pacific Flyway in America, since every year millions of shorebirds use these wetlands to reproduce and rest during their migration, in addition to various species that live there and are under some protection standard or in danger of extinction. In addition, these Mexican wetlands are also spaces from which important growing coastal communities benefit. However, the conservation of these coastal sites will be compromised in the coming decades by sea level rise and increasing pressure derived from coastal development, which directly impact the potential loss of space and consequently the decrease in migratory bird populations. This work identifies hydrodynamic changes and the effects of sea level rise in five coastal wetlands in Mexico and the Pacific Flyway in America, focusing on the future availability of space and the potential loss of ecosystem services under projected scenarios. The results generated give us a knowledge base to design strategies focused on the conservation and resilience of these wetlands in the face of sea level rise. Full article

Accurate information on species distributions and population sizes is essential for effective biodiversity conservation, yet such data are often lacking at national scales. This study addresses this gap by assessing the distribution and abundance of 111 bird species across Croatia, including breeding, wintering, and migratory flyway populations. We combined Species Distribution Models (SDMs) with expert-based population estimates to generate spatially explicit predictions. The modeling framework incorporated high-resolution Earth observation (EO) data and advanced spatial analysis techniques. Environmental variables, such as land cover, were derived from satellite datasets, while climate variables were interpolated from ground measurements and refined using EO-based co-variates. Model calibration and validation were based on species occurrence records and EO-derived predictors. This integrative approach enabled both national-scale population estimates and fine-scale habitat assessments. The results identified critical habitats, population hotspots, and areas likely to experience distribution shifts under changing environmental conditions. By integrating EO data with expert knowledge, this study enhances the robustness of population estimates, particularly where species monitoring data are incomplete. The findings support conservation prioritization, inform land use and resource management, and contribute to long-term biodiversity monitoring. The methodology is scalable and transferable, offering a practical framework for ecological assessments in diverse regions. We integrated expert-based population estimates with species distribution models (SDMs) by applying expert-derived density values to areas of suitable habitat predicted by SDMs. This approach enables spatially explicit population estimates by combining ecological modeling with expert knowledge, which is particularly useful in systems with limited data. Experts provided species-specific density estimates stratified by habitat type, seasonality, behavior, and detectability, aligned with habitat suitability classes derived from SDM outputs. Full article

Birds are hosts to a diverse assemblage of vector-transmitted haemosporidian parasites. However, the true genetic diversity and many host–parasite interactions are still unknown, particularly in under-represented species groups such as wild doves and pigeons (Columbiformes). In this study, we examined the prevalence and lineage diversity of haemosporidian genera Plasmodium, Leucocytozoon, and Haemoproteus in three species of wild columbids, sampled in Germany. Examinations were performed by applying molecular methods (nested PCR and one-step multiplex PCR) and blood smear examination, and their respective advantages and disadvantages are discussed. In the case of the European Turtle Dove Streptopelia turtur, samples were collected along a west–east gradient throughout Germany, covering migratory birds from the Western and Central-Eastern flyway of this species. Although no infection was detected in the Stock Dove Columba oenas samples, 53% of Turtle Dove and 86% of Common Woodpigeon Columba palumbus harbored a parasite of at least one haemosporidian genus, revealing previously unknown lineage–host interactions. We were not able to demonstrate a correlation between infection status (presence or absence of infection based on PCR results) and parasitemia with condition based on the heterophil to lymphocyte ratio (H/L ratio). Neither lineage occurrence nor prevalence of infection followed any geographically specific patterns. Thus, haemosporidian lineages found in Turtle Doves could not be used as a marker of geographic origin that would allow the tracking of their nonbreeding distribution. Full article

The Yancheng coastal wetlands serve as a crucial stopover site along the East Asian–Australasian Flyway. The rapid expansion of aquaculture has led to a significant decline in natural wetlands, impacting both the distribution and quality of waterbird habitats. Following the designation of the region as a World Natural Heritage site in 2019, the local government has prioritized the protection of waterbird habitats, leading to the large-scale withdrawal of aquaculture from the region. Nevertheless, the impact of the fishing withdrawal on waterbird habitat selection and the ecological benefits it brought remain unknown. In this study, based on the identification of fishing withdrawal zones in the Yancheng coastal area, six waterbird groups, Anatidae, Ardeidae, Charadriiformes, Laridae, Gruidae and Ciconiidae, were selected to construct an evaluation index system for habitat suitability. The Biomod2 ensemble model was employed to analyze the spatial differences of suitable habitats for waterbirds within the fishing withdrawal zones. The result revealed the following: (1) As of 2022, the area of fishing withdrawal zones had reached 2.23 × 10⁴ ha, primarily distributed in Beihuan and Nanhuan. Among these, the area of fishing withdrawal zones in Nanhuan was the largest, reaching 6.78 × 10³ ha. (2) Unsuitable area for waterbirds was largest in the fishing withdrawal zones, with a proportion of 60% and 58% for Gruidae and Ciconiidae, respectively. (3) The rich nutrients, high coverage and tall stature of emergent vegetation in the fishing withdrawal zones led to a reduction in water surface area, resulting in significant adverse effects on the suitable habitats for Charadriiformes and Gruidae. Therefore, the results suggest that most areas after fishing withdrawal were still not suitable habitats for waterbirds. The implementation of scientific fishing withdrawal practices, along with ecological restoration and management, is crucial for improving the habitat suitability in fishing withdrawal zones. This study provides valuable insights for more purposeful selection of fishing withdrawal sites, and more scientific management and restoration of these areas to enhance their ecological benefits. Full article

Coastal wetlands provide critical ecological services but are threatened by the human, climatic, and hydrological changes impacting these ecosystems. Several key ecosystem services and functions rely on aquatic macrophyte plant species. We integrate 10 years of seasonal monitoring data (2014–2024) and climatic and hydrological datasets to assess how environmental variability influences two dominant aquatic macrophytes—the invasive and non-indigenous Elodea densa Planch. Casp. (Hydrocharitaceae) and the native Schoenoplectus californicus (C.A.Mey.) Soják—in Chile’s first Ramsar site, Carlos Anwandter, and a Nature Sanctuary. We modeled suitable habitat areas using MaxEnt software with Landsat 8 spectral bands and indices as predictive layers. We found significant recent decreases in temperature, river flow, and water level, with a nonsignificant shift in precipitation. We also observed marked spatial and temporal fluctuations in areas with suitable habitat areas for both macrophytes. Stepwise regression analyses indicated that Elodea densa expanded with increasing temperature over time but declined with water level variability. Schoenoplectus californicus showed contrasting effects, declining with rising temperature and water levels but expanding with higher precipitation. These findings emphasize the complexity of coastal wetland ecosystems under environmental stress and climate change and the need for further research for the conservation and management of coastal wetlands along migratory flyways such as the Southeastern Pacific Flyway. Full article

Despite increasing conservation efforts for shorebirds, there are widespread declines in many shorebird species in North America. Climate change is causing significant shorebird range shifts and population declines. This study investigates the relationship between meteorological variability and shorebird population dynamics over ten years (2014–2023) at Fish Haul Beach, Hilton Head Island, South Carolina, USA. Shorebirds, reliant on specific habitats for breeding and foraging, are increasingly vulnerable to climate-driven changes, including shifts in temperature, precipitation, and wind speed. Using Generalized Additive Models with Poisson distribution, we analyzed species-specific count data for 12 shorebird species in relation to annual meteorological variables. Additionally, the Mann–Kendall test and Sen’s slope were employed to assess decadal trends in population counts. The results reveal significant declines in Black-bellied Plover (Pluvialis squatarola), Marbled Godwit (Limosa fedoa), and Willet (Tringa semipalmata). In contrast, Semipalmated Plover (Charadrius semipalmatus) and Piping Plover (Charadrius melodus) showed increasing trends, indicating potential habitat benefits or conservation success. Temperature emerged as a key driver affecting the abundance of several species, while precipitation and wind speed also played crucial roles in shaping population dynamics. Our findings underscore the sensitivity of shorebird populations to weather fluctuations, emphasizing the need for integrating meteorological variability into management strategies to ensure shorebird conservation. This study provides critical insights into the impacts of meteorological variables on migratory shorebird populations along the Atlantic Flyway. It highlights the importance of maintaining healthy coastal ecosystems in South Carolina. Full article

Poyang Lake, the largest freshwater lake of China, serves as a crucial wintering site for migratory birds in the East Asian–Australasian Flyway, where habitat quality is essential for maintaining diverse bird populations. Recently, the frequent alternation of extreme wet years, e.g., 2020, and dry years, e.g., 2022, have inflicted considerable perturbation on the local wetland ecology, severely impacting avian habitats. This study employed the spatiotemporal fusion method (ESTARFM) to obtain continuous imagery of Poyang Lake National Nature Reserve during the wintering seasons from 2020 to 2022. Habitat areas were identified based on wetland classification and water depth constraints. The results indicate that both extreme wet and dry conditions have exacerbated the fragmentation of migratory bird habitats. The shallow water habitats showed minor short-term fluctuations in response to water levels but were more significantly affected by long-term hydrological trends. These habitats exhibited considerable interannual variability across different hydrological years, affecting both their proportion within the overall habitat and their distribution within the study area. This study demonstrates the ability of ESTARFM to reveal the dynamic changes in migratory bird habitats and their responses to extreme hydrological conditions, highlighting the critical role of water depth in habitat analysis. The outcomes of this study improve the understanding of the impact of extreme water levels on migratory bird habitats, which may help expand knowledge about the protection of other floodplain wetlands around the world. Full article

The wetlands of Sardinia (Italy) supply food and shelter for many waterbird species that migrate along the central–eastern Mediterranean bird flyway. Despite many different policies and laws (the Birds and Habitats Directives, the European Water Framework Directive, and the Ramsar Convention), the Sardinian wetlands are seriously threatened by human activities and climate change, which in turn menace the associated avifauna. In this study, we (a) inventoried (four sampling dates) the avian metacommunity of the largest coastal wetlands in Sardinia during the crucial period of the year for the avifauna (August–September), (b) explored the spatiotemporal dynamics in bird species assemblage, and (c) used results to refine planning for bird habitat management and bird diversity conservation. We recorded 60 bird species, of which 54 were migratory and 21 belonged to Annex I of the Birds Directive. During August–September, (a) α, β, and γ avian diversity showed no significant temporal trends, (b) the contributions of space (wetlands) and time (dates of sampling) in determining the presence/absence of the waterbird species were comparable, (c) wetlands formed three statistically significant clusters with regard to the species richness, (d) a significant increase in the number of the species belonging to the “mixed” migration guild, and “divers from the surface” foraging guild, occurred, (e) there was a statistically significant chronological succession of the occurrence of waterbird species, (f) twenty-five species made use of the Sardinian wetlands all summer long, while ten further species were present in three sampling dates out of four, (g) the spatial distributions of the waterbird species in the Sardinian wetlands were significantly different between the sampling dates, (h) the Little Egret, the Grey Heron, and the Greater Flamingo were primarily responsible for the observed difference in the spatial distributions of species between the sampling dates, (i) Is Brebeis, Pilo, and S. Giovanni were the wetlands that changed their species composition the most during the studied period, (j) twenty-two waterbird species resulted at high priority for conservation, and thirteen species at medium priority. Based on these results, we have proposed new strategies for the conservation of the waterbird species of the Sardinian wetlands during the post-breeding migration period. Full article

Avian influenza subtype H5N1 has caused outbreaks worldwide since 1996, with the emergence of the Guandong lineage in China. The current clade 2.3.4.4b has evolved from this lineage, with increased virulence and mass mortality events in birds and mammals. The objective of this study was the analysis of 17 viral genomes of H5N1 avian influenza isolated in Venezuela during the 2022–2023 outbreak. The eight viral genomic segments were amplified using universal primers and sequenced via next-generation sequencing. The sequences were analyzed to confirm the H5 hemagglutinin clade, identify possible genetic reassortments, and perform a phylogenetic and docking analysis of the viral isolates. The viruses found in Venezuela belonged, as expected, to clade 2.3.4.4b and formed a monophyletic clade with North American influenza viruses, with no evidence of further reassortment. The introduction of the virus in South America is associated with bird migration through the Atlantic (Venezuela), Atlantic/Mississippi (Choco, Colombia), and Pacific migratory flyways, with the emergence of several viral lineages. Several mutations were found in all segments of the genome, although none of the key mutations was involved in mammalian adaptation. Moreover, in silico structural analysis suggests, as expected, that the viral hemagglutinin maintained a predilection for avian α2,3-linked sialic acid. The unprecedented pathogenic outbreak of avian influenza disease in South America was associated with the circulation of three different lineages, which maintain a lower affinity for the mammalian receptor. Full article

Highly pathogenic H5N1 (HP H5N1) influenza A virus (IAV) has been detected annually in North American ducks since its introduction during 2021, but it is unknown if this virus will follow the same seasonal and geographic patterns that have been observed with low-pathogenicity (LP) IAV in this reservoir. We monitored blue-winged teal in the Mississippi flyway prior to the detection of HP H5N1 and during two post-introduction migration cycles from spring 2022 to spring 2024, testing birds for infection and antibodies to IAV nucleoprotein (NP), hemagglutinin subtype H5, and neuraminidase subtype N1. Antigens representing clade 2.3.4.4b HP H5 and LP North American H5 were used for hemagglutination inhibition (HI) and virus neutralization (VN) tests for H5 antibodies. Virologic results were consistent with historic seasonal and geographic patterns reported for LP IAV with peak infections occurring in pre-migration staging areas in Minnesota during fall 2022. However, the high prevalence of the H5 subtype was exceptional compared to historic prevalence estimates at this same site and for the Mississippi flyway. HP H5N1 was detected on wintering areas in Louisiana and Texas during the fall of that same year and this was followed by an increase in estimated antibody prevalence to NP, H5, and N1 with no HP H5N1 detections during the wintering or spring migration periods of 2022/2023. HP H5N1 was not detected in Minnesota during fall 2023 but was detected from a single bird in Louisiana. However, a similar increase in antibody prevalence was observed during the winter and spring period of 2023 and 2024. Over the two migration cycles, there was a temporal shift in observed prevalence and relative titers against the H5 antigens with a higher proportion of ducks testing positive to the 2.3.4.4b H5 antigen and higher relative titer to that antigen compared to the representative LP North American H5 antigen. The seasonal and geographic patterns observed appear to be driven by population immunity during the migration cycle. Results support an initial high infection rate of HP H5N1 in blue-winged teal in the Mississippi flyway followed by a high prevalence of antibodies to NP, H5, and N1. Although prevalence was much reduced in the second migration cycle following introduction, it is not known if this pattern will persist in the longer term or affect historic patterns of subtype diversity in this reservoir. Full article

The duck Tembusu virus (DTMUV), an emerging flavivirus, has led to severe neurological disorders and substantial economic losses in the duck industry throughout Asia. Considering South Korea’s increasing duck production and its strategic location along the East Asian–Australasian Flyway, this study aimed to assess the presence of DTMUV in South Korea to evaluate potential risks to the poultry industry. We performed a comprehensive serological survey of 1796 serum samples from broiler and breeder ducks collected between 2011 and 2023, alongside molecular detection tests on 51 duck flocks exhibiting suspected clinical signs of DTMUV infection. The absence of serological and molecular evidence for DTMUV or other flavivirus infections suggests that these viruses have not yet affected South Korean duck populations. These findings underscore the critical need for ongoing surveillance, given the virus’s potential to disrupt agriculture and pose public health risks. The study also emphasizes the importance of maintaining stringent biosecurity measures and conducting further research to monitor and prevent DTMUV transmission, particularly due to the possible role of migratory birds and other vectors in spreading zoonotic diseases. Full article

Protected areas are essential for the conservation of biodiversity. However, the rapid expansion of urbanization and the intensification of human activities have significantly disrupted environmental integrity, leading to a continuous deterioration in both the quantity and quality of large ecological patches. This has further diminished the connectivity among ecological patches, leading to significant consequences for regional biodiversity conservation. Taking Poyang Lake as a case study, which serves as a crucial wintering habitat for migratory birds along the East Asia–Australasia flyway, this research employs ArcMap technology. It considers various factors including land use type, slope, and elevation to evaluate habitat quality and degradation through the application of the InVEST model. Additionally, the study utilizes the minimum cumulative resistance (MCR) model alongside circuit theory to delineate ecological corridors within the area and to establish a comprehensive ecological network system. The research results in this paper are as follows. (i) During the period from 2000 to 2020, there was an overall decline in habitat quality within the study area, indicating a clear trend of habitat degradation. However, it is worth noting that there was an increase in habitat quality in certain local areas within the protected area. (ii) The ecological resistance values in the core area of the migratory bird reserve in Poyang Lake are generally low. However, the ecological resistance values of the habitats have shown a consistent increase from 2000 to 2020. Additionally, there has been a significant decrease in the density of ecological corridors during this time period. (iii) Over the period from 2000 to 2020, both the number and connectivity of ecological corridors decreased and their integrity and functionality degraded. Consequently, this weakened role of the ecological network has had implications for maintaining regional biodiversity and ecosystem service functions. The findings indicate two conclusions. (i) Ecological connectivity is essential for the conservation of migratory bird habitats. Strengthening control measures aimed at expanding ecological corridors can effectively safeguard flagship and umbrella species, thereby promoting biodiversity conservation. (ii) The establishment of ecological corridors can help reconcile conflicts between conservation efforts and development objectives. This reconciliation carries significant theoretical implications for fostering a harmonious coexistence between humans and birds in Poyang Lake’s migratory bird sanctuary. Full article

The coast of Dalian in Liaoning Province, China, is one of the most important habitats for migratory shorebirds along the East Asia–Australasian Flyway. However, the coastal areas of Dalian have been modified extensively by various projects, including reclamation and the construction of aquaculture and port facilities, embankment buildings, cross-sea passages, and wind farms, which have led to significant damage to the coastal habitats of shorebirds. Assessing the spatiotemporal distribution and habitat characteristics of shorebirds is of great importance to biodiversity conservation. The present study involved a 15-month-long survey of shorebirds in nine coastal wetlands of Dalian from August 2021 to October 2022. In total, 31 species of shorebirds, belonging to five families, were recorded. Migratory shorebirds were the most frequently observed, accounting for 77% of the recorded shorebirds. Dunlin (Calidris alpina), Kentish plover (Charadrius alexandrinus), Eurasian curlew (Numenius arquata), and Far Eastern curlew (Numenius madagascariensis) were the most abundant species. Both species richness and species abundance peaked in May and again in September. The Zhuanghe Estuary boasted the highest species diversity, while the Huli Estuary wetland exhibited the greatest species abundance. The type of habitat and the spatial extent of natural wetlands were the main variables influencing the spatial distribution of waterbirds. By identifying the population characteristics and habitat status of shorebirds in Dalian, the results provide support for shorebird conservation and habitat management. Full article