The Eastern population of the Lesser White-fronted Goose (EPLWFG) Anser erythropus is shared between Russia and China. The summer range of the EPLWFG has been recognised as a continuous area extending from the Olenyok River in the west to the Anadyr River in the east and northwards from 64°N. The aim of this study was to provide information on breeding behaviour; nest-sites, nesting habitats, and time of nesting; nesting success; timing of summer movements including moult migration; moult timing, duration, and moulting habitats; site fidelity; and the effect of human presence. To accomplish this, we combined the results from field surveys with GPS/GSM tracking. A total of 30 summer tracks from 19 individual EPLWFG were analysed. We estimated breeding propensity in 93.8% of adult LWFG, and this factor did not seem to depend on breeding success in the previous season. Reproductive success was 13.3% in all nesting attempts. Non-breeders arrived three-week later and departed a week earlier. The EPLWFG are highly mobile during the summer. The core moulting site for the entire EPLWFG was discovered by this study and is located along the lower reaches of the San-Yuryakh and Kyuanekhtyakh rivers flowing towards the Omulyakhskaya Bay of the East Siberian Sea. The EPLWFG flightless period was 24.8 ± 2.8 days. A part of failured EPLWFG (43.7 %) migrated back to its early summer breeding/staging site after having completed moult. The strong site fidelity (100%) of adult birds to both nesting and moulting sites promotes the formation of local breeding populations, which could be considered conservation units if genetic studies support this differentiation. The EPLWFG selects the remotest and least human-accessible area for their remigial moult, and the main site was discovered with the help of tracking.

South-west China, particularly between the Himalayas and the Beibu Gulf, constitutes an important corridor for migratory raptors along the East-Asian continental flyway. However, a lack of ornithological assessment and the common practice of illegal hunting in this region emphasize the need for research and conservation actions. To investigate the ecology of migration and scale of persecution, we launched one of the first citizen-science projects in mainland China to record southward-migrating raptors and hunting gunshots from 2015 to 2019 on Guantouling, a well-known raptor site in South-west China. A total of 42,891 raptors were recorded, belonging to 30 diurnal raptor species. Grey-faced Buzzard Butastur indicus, Oriental Honey Buzzard Pernis ptilorhynchus and Amur Falcon Falco amurensis were the three most abundant species recorded. The bulk of Grey-faced Buzzard and Amur Falcon migrated through Guantouling from mid-October till early November, while Oriental Honey Buzzard migrated throughout October and early November. Precipitation slowed down migration significantly while increasing cloud cover was favoured by the three most abundant species. We found hunting mostly occurred in the afternoon, coinciding with an increasing number of Oriental Honey Buzzard, which may become a major victim of hunting. It is thus suggested to prioritize peak raptor migration period for law enforcement actions, especially on cloudy days and after passage of cold fronts, when Oriental Honey Buzzards and other species are likely to migrate. The annual counting scheme on Guantouling is not only an ecological survey, but also an effective way of engaging the public to counter raptor persecution.

During their northward migration, Red Knots Calidris canutus rufa stop at the Lagoa do Peixe National Park in the extreme south of Brazil to build up fat reserves for their journey to their Canadian breeding grounds. We tracked five Red Knots with PinPoint Argos-75 GPS transmitters to investigate differences in migration strategies from this stopover. Tracked birds used two different routes: the Central Brazil route and the Brazilian Atlantic Coast route. One bird flew 8,300 km straight from Lagoa do Peixe to the Delaware Bay (USA). Another bird stopped in Maranhão (north-east Brazil) and a third one used a yet unknown environment for the species, the mouth of the Amazon River at Baía Santa Rosa, Brazil. These two birds made short flights, covering stretches of 1,600 km to 3,600 km between stop-overs, where they stayed from 4 to 18 days. Our study highlights the occurrence of intrapopulation variation in migratory strategies and reveals the connectivity of environments that are essential for the viability of rufa Red Knot populations.

Detecting factors causing the decline of wildlife populations provides essential knowledge for their effective conservation. Populations of Black Stork Ciconia nigra are decreasing in northern Europe; however, there are no detailed analyses of its survival, which frequently is a key demographic parameter affecting population dynamics in long-lived species. We used long-term data from re-sighted colour-ringed birds and satellite-tracked birds to estimate age- and sex-specific survival in a rapidly declining Black Stork population in the Baltic region at the northern end of the European range. Apparent survival (0.89) among colour-ringed birds older than one year was not significantly different from the previously reported estimates in Central Europe and the estimated real survival of GPS-tracked birds (0.77). However, the apparent survival of first-year (1y) birds was only 0.04, which is remarkably lower than earlier estimates in Central Europe. The real survival of GPS-tracked 1y birds was somewhat higher (0.11), but still much lower than estimates in other long-lived species. Apparent survival was three times lower in 1y females (0.013) than 1y males (0.045); this could be explained in part by a higher mean natal dispersal of females (189.1 km), compared with that of males (72.0 km), as well as by sex-specific mortality due to poor foraging conditions. There were no significant differences in apparent survival between the male and female storks older than one year. To better address the population decline, further research is needed to determine the factors causing low survival in young Black Storks, including the roles of food availability and climate change.

Birds show considerable spatial and temporal fluctuations in their abundance due to variations in habitat conditions. The lowland wetlands of the Pampas region in Argentina are key wintering areas for two flamingo species. The Chilean Flamingo Phoenicopterus chilensis is a year-round resident, while the Andean Flamingo Phoenicoparrus andinus is a partial altitudinal migrant that uses these wetlands in winter when some of the wetlands in the high Andes freeze over. We studied the association between the annual abundance of both flamingo species, wetland condition (water surface area and water salinity), and environmental conditions (flooding) driven by the El Niño Southern Oscillation (ENSO) over 15 consecutive winters (July–August 2008–2022) in 24 lowland wetlands in central Argentina. There were notable differences in wetland surface area and water conductivity between years, with some wetlands ranging from flooded to almost dried out. For any given year, there were also large differences in water surface area and water conductivity between wetlands. Both flamingo species showed marked fluctuations in abundance over the study period. Each year, the Chilean Flamingo was more abundant than the Andean Flamingo. The Chilean Flamingo was recorded at least once in every wetland, while the Andean Flamingo was absent from three wetlands and was not observed in two years during the study. The Chilean Flamingo was recorded in wetlands covering a larger range of water conductivity values than the Andean Flamingo (2.53–58.23 ms/cm vs 2.94–16.20 ms/cm, respectively). The abundance of both flamingo species was higher at intermediate water conductivity values and decreased at higher or lower values. These results show that these lowland wetlands are subjected to strong interannual variation in climatic conditions which affect lake conditions, and thus the abundance of both flamingo species, highlighting the importance of conserving wetlands encompassing a broad range of environmental conditions.

The hypersaline Lake Urmia, located in Iran, has undergone a significant reduction in size and is currently facing the risk of desiccation. The decrease in water levels, coupled with elevated salinity levels, has initiated ecological degradation, leading to a substantial decline in the region’s waterbird population. This study employs breakpoint analysis to determine the year when the drought event affecting the lake commenced. Additionally, canonical correspondence analysis (CCA) is utilised to elucidate the interaction between environmental parameters and the waterbird assemblages in Lake Urmia over the period 1970–2018. Our investigation identifies the year 2000 as the initiation of the water crisis in Lake Urmia, synchronously coinciding with the decline in the waterbird populations. This finding highlights a significant connection between the majority of waterbird species and the axes of CCA, intricately linked with water availability within Lake Urmia. This revelation underscores the pivotal role of fluctuations in water levels in shaping the dynamics of the lake’s waterbird assemblages. Furthermore, our observations emphasise the importance of even minor improvements in hydrological conditions of the lake, resulting in substantial positive impacts on waterbird populations.

Understanding the movement ecology of threatened species is fundamental to improving management and conservation actions for their protection, mainly during the pre-adult stage and particularly when a species is subject to population reinforcement or reintroduction projects. An example is the case of the Cinereous Vulture Aegypius monachus on the Iberian Peninsula, an endangered species that has been reintroduced in different regions during the last two decades. Here, we explore differences between the spatial ecology of reintroduced pre-adult Cinereous Vultures, according to age-class, sex, and season (breeding and non-breeding). We used GPS-tag data from 51 pre-adult individuals reintroduced into Catalonia (north-east Spain) to describe their use of space, i.e. home-range size, core area, and minimum convex polygon (MCP) and movement patterns, i.e. cumulative distance, maximum displacement, maximum daily dispersal, and maximum annual dispersal. Our study showed significant variation in the use of space and movement patterns among pre-adult birds and the influences of age, sex, and season. Age was the most influential factor, determining range areas and movement patterns. Similar to other vulture species, home range and core areas increase with age, with subadult vultures exhibiting larger ranges than young first year, juveniles, and immature birds, but the MCP measures were larger for juveniles. Movement patterns were also influenced by age-class, with juveniles making longer movements, followed by immatures and subadults (with similar values), and shorter movements for birds during their first year of life. Overall, males made shorter movements and explored smaller foraging areas than females. Season had an important effect on movement patterns, and the daily and dispersal movements were longer during the breeding period (February–August). Our findings fill a knowledge gap regarding the dispersal behaviours of Cinereous Vultures, information that will enable the improvement of management and conservation decisions.

A previously unknown raptor migration hot spot has been identified in southern Greece. During the post-breeding migration of 2024, a total of 11,790 individuals were recorded in 15 days, including 11,606 European Honey Buzzards Pernis apivorus. GPS tracking data from Finnish and Hungarian populations further highlight the site’s significance, suggesting that it could become the third migration hot spot for the species in the Mediterranean, alongside the Straits of Gibraltar and Messina. Plans to develop a wind farm in the area raise concerns due to its crucial role in the beginning of the long sea crossing to Libya.

Migratory birds are experiencing widespread population declines, underscoring the urgency of effective conservation actions. Long-term monitoring of migratory birds, especially during migration, is crucial for such actions yet remains technically challenging. Bioacoustic monitoring of nocturnal flight calls (NFCs) constitutes a promising technique to monitor migratory birds during migration. Such monitoring has increased in North America and Europe, but its application on the East Asian–Australasian Flyway (EAAF) remains limited. Here, we present findings from an NFC monitoring project conducted at a recording station in central Beijing, China over four migration seasons. From around 3,350 hours of recording effort, we manually extracted and identified 84,135 NFCs, involving at least 111 species or species groups that are associated with a wide range of habitat types. We also found that NFCs provided additional information on species’ migration phenology in comparison with citizen science observation data. To our knowledge, this study is the first formal investigation of bird migration using NFC monitoring on the EAAF, serving as a proof-of-concept case for wider, long-term monitoring efforts in this traditionally understudied region. Our findings also highlight the significance of incorporating migratory bird conservation into urban planning and land management practices.

Collision with powerlines is a major cause of mortality for many bird species, including bustards and sandgrouse. In this work, we used GPS tracking data to identify the hour of collision of three threatened steppe birds, i.e. Little Bustard Tetrax tetrax, Black-bellied Sandgrouse Pterocles orientalis, and Pin-tailed Sandgrouse Pterocles alchata. Out of a data set of 160 GPS-tracked individuals collected over a 13-year period, we detected eight collision events with powerlines or fences. Of these, we were able to determine the timing of 87.5% of the collision events with a resolution accurate to within two hours. Our results reveal that collisions occurred throughout the year and at different hours of the day, presenting a challenge for implementing effective mitigation strategies. The use of dynamic and reflective or luminescent devices may therefore be appropriate to prevent collision of steppe birds with powerlines during the day and night. Overall, this study adds evidence to the utility of using tracking data to better understand anthropogenic mortality in birds.

Knowledge of the status of ecosystems is vital to help develop and implement conservation strategies. This is particularly relevant to the Arctic where the need for biodiversity conservation and monitoring has long been recognised, but where issues of local capacity and logistic barriers make surveys challenging. This paper demonstrates how long-term monitoring programmes outside the Arctic can contribute to developing composite trend indicators, using monitoring of annual abundance and population-level reproduction of species of migratory Arctic-breeding waterbirds on their temperate non-breeding areas. Using data from the UK and the Netherlands, countries with year-round waterbird monitoring schemes and supporting relevant shares of Arctic-breeding populations of waterbirds, we present example multi-species abundance and productivity indicators related to the migratory pathways used by different biogeographical populations of Arctic-breeding wildfowl and wader species in the East Atlantic Flyway. These composite trend indicators show that long-term increases in population size have slowed markedly in recent years and in several cases show declines over, at least, the last decade. These results constitute proof of concept. Some other non-Arctic countries located on the flyways of Arctic-breeding waterbirds also annually monitor abundance and breeding success, and we advocate that future development of “Arctic waterbird indicators” should be as inclusive of data as possible to derive the most robust outputs and help account for effects of current changes in non-breeding waterbird distributions. The incorporation of non-Arctic datasets into assessments of the status of Arctic biodiversity is recognised as highly desirable, because logistic constraints in monitoring within the Arctic region limit effective population-scale monitoring there, in effect enabling “monitoring at a distance”.

Marbled Teal Marmaronetta angustirostris is a globally threatened species that has been undergoing population declines across much of its range in recent years. This is particularly true in the Middle East and the Caucasus, where the species once commonly bred across much of the region. However, there is a dearth of recent literature and population-level assessments of the species in the countries in this region. For example, the last update of conservation status for Marbled Teal in Armenia was undertaken in 2009 and in Türkiye in 2008. Therefore, this study addresses the urgent need for an updated evaluation of the species’ status in both Armenia and Türkiye. For Armenia, the current population estimate is 8–11 breeding pairs, with a steep decline of 87% between 2003 and 2019. In Türkiye, the species appears to be functionally extirpated from the country due to an absence of breeding in almost a decade and multiple years without any records, with only a handful of wandering individuals detected in recent years. This study highlights the threats facing the species, particularly changes to wetland habitat and quality as well as hunting pressures and illegal poaching. Based on our findings, we propose that the conservation status of Marbled Teal in both countries be updated from “Endangered” to “Critically Endangered”. Finally, we note the conservation requirements for the species in the region and provide a set of recommendations for its protection, including a species recovery plan. Without urgent conservation measures such as the creation of new protected areas and establishment of new populations from released birds, the long-term viability of Marbled Teal populations in the region is in jeopardy.

Reintroduction includes the captive propagation and movement of extirpated animals or plants into areas of historical and native distribution. Many biotic or abiotic factors can affect a founder population when small numbers are released into unfamiliar novel environments, particularly at the early stage of reintroduction. The inclusion of behavioural and ecological components plays a crucial role in the decision-making process of endangered species conservation efforts such as reintroduction. Since the resident population of Oriental Storks Ciconia boyciana was locally extirpated in South Korea in 1971, its founders have been established through reintroduction since 2015. The aim of this study was to investigate the demography, habitat use, and movement patterns of stork founders using the first two-year demographic and tracking data. Stork founders maintained their population size, which slightly increased in the long term. The patterns of habitat use and movement depended on rice paddy fields for foraging and breeding along with mixed effects of breeding status and season. Considering ecological and life history-related perspectives, we also discuss the potential adaptiveness of founder Oriental Storks as a resident population in a novel environment in South Korea.

The population changes in waterbirds are recognised as a global issue. Many waterbird species, especially migratory ones, are undergoing population changes. Monitoring these changes is crucial for waterbird conservation. However, the lack of data to quantify these populations hinders comprehension of the factors responsible for these changes. Although a few studies have investigated the long-term trends of waterbirds in the Republic of Korea (ROK), most have concentrated on a limited number of species and groups. Understanding these changes enables us to identify which species are vulnerable and develop more effective conservation measures accordingly. This study aimed to investigate the population dynamics of waterbirds in the ROK from 2000 to 2024. Data from the Winter Waterbird Census of Korea were used to analyse trends across various waterbird groups and species. The results showed diverse population trajectories, with some species experiencing notable increases while others underwent severe declines. Among the observed trends, several globally threatened species, such as the White-naped Crane Grus vipio and Oriental Stork Ciconia boyciana, exhibited significant population growth. This is largely a testament to the effectiveness of conservation interventions aimed at these species. However, the study also identified population declines of some species, such as the Tundra Swan Cygnus columbianus and Common Pochard Aythya ferina, indicating pervasive threats due to habitat loss and degradation. Lastly, several recommendations are made regarding the identified population trends that should be used to guide future conservation efforts in the East Asian–Australasian Flyway. This study, with its comprehensive and detailed findings, reiterates the importance of long-term monitoring data for developing effective conservation measures.

We report the non-breeding range of an adult Rapa Shearwater Puffinus myrtae, as estimated from data collected by one light logger deployed from 31 August 2019 to 22 July 2020. The Rapa Shearwater is classified as “Critically Endangered”, with a strong decline in breeding numbers reported recently. As the species is threatened by various introduced mammals on the breeding colonies, the main objective of this tracking essay was to identify the oceanic regions where the birds forage during the non-breeding season. The non-breeding range of this bird was located south-east of Rapa Island, where fishery activities are limited. The conservation efforts for the Critically Endangered Rapa Shearwater should first focus on securing mammal-free sites for breeding colonies.

Owing to habitat loss, the entire breeding population of the globally threatened Aquatic Warbler Acrocephalus paludicola, a flagship bird species of fen mires, is now limited to scattered areas in east-central Europe. The breeding biology of the Aquatic Warbler was studied between 2012 and 2015 in calcareous fens dominated by the Cladietum marisci sedge community at the south-western range limit of the species, near Chełm, in south-east Poland. Two nesting peaks were observed during the breeding season, corresponding to first and second breeding attempts. Nest densities were greater during the first- rather than the second-brood period but singing male densities did not differ between the brood periods. Clutch size and post-hatching fledging success were significantly lower during the second-brood period. Total nest fledging success (whether or not a nest fledged at least one young) was 76.6% in 124 nests with known outcomes with an average of 2.7 (± SE 0.2) fledglings per nest. Mayfield probability of nest survival was 56.9% with losses mainly due to predation (55%), nest desertion or female predation (28%), and changes in water level (14%). Nest survival to fledging increased along the gradient of increasing levels of litter layer thickness, stagnating water, and vegetation height at the nest, and increasing height of the nest above the soil. Fledgling production tended to be lower than in the Biebrza Marshes (north-east Poland) habitats, assumed to be optimal for breeding. Otherwise, the reproductive success estimates did not deviate from nests found in the core breeding areas in north-east Poland or Belarus. Brood feeding frequency (15.5 ± 1.0/hour) was similar to that observed in the Biebrza Marshes. Our results suggest that the calcareous fens at the margins of the current species’ range provide a suitable breeding habitat. However, as the nesting area has contracted, management programmes tailored to the ecological requirements of the Aquatic Warbler are required.

Many Afro-Palearctic songbird migrants have declined, with conservation efforts mainly focused on the restoration of breeding habitat. However, pressures outside the breeding season might play a role. This includes the possibility that local relict populations no longer maintain the original phenotypic variation in migration patterns, with a loss of flexibility. The Great Reed Warbler Acrocephalus arundinaceus kept stable population levels in central and eastern Europe, but was almost extinct in the western part of the breeding range. In the Rhine delta the population declined from 10,000 individuals around 1950, to fewer than 100 at present. Here we document migratory timing, routes, and destinations of members of this remnant songbird population. It turned out that the remaining adults still showed high diversity in migratory phenotypes. This is even true in each of the two last tiny subpopulations in the Netherlands (of 50 and 15 pairs). So, even very small populations maintain the possible adaptive phenotypic variation, and with hindsight this justifies the breeding habitat restoration efforts currently underway.