Waterbird hunting is to be performed sustainably with respect to conservation status and animal welfare. Birds that are hit but not killed by shotgun pellets suffer what is called crippling. Here, we present data on crippling rates., i.e., the proportion of x-rayed birds with embedded shotgun pellets, of x-rayed individuals of nine waterfowl species in six European countries during 2017–2022. We x-rayed 3,843 individuals, of which 17

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".

Drone use has increased sharply worldwide over the past decade, leading to more frequent interactions with wildlife. The rapid advancement of drones for ecological monitoring and research has further contributed to these encounters, which may disturb animal behavior, such as triggering flight responses in birds. Therefore, best-practice guidelines are urgently needed to help operators and site managers minimize disturbances. This study aimed to establish safe operating distances for seven common colonial breeding bird species: black-headed gull (Chroicocephalus ridibundus), herring gull (Larus argentatus), lesser black-backed gull (Larus fuscus), Sandwich tern (Thalasseus sandvicensis), common tern (Sterna hirundo), Eurasian spoonbill (Platalea leucorodia), and great cormorant (Phalacrocorax carbo). We assessed the effects of professional and consumer-grade drones flying at altitudes between 5 and 50 meters on the flight responses of these species at breeding sites in the Dutch Wadden Sea. Of 1492 drone flights, 7.4% caused disturbances, defined as more than 10% of birds becoming airborne. Flight initiation distance (FID), the distance between a bird and the drone at the moment of flight response, varied by species. Sandwich terns and common terns had the largest FID (>170 m), followed by black-headed gulls (>160 m), herring gulls and lesser black-backed gulls (>60 m), while great cormorants and Eurasian spoonbills had the shortest (~5 m). When selecting drone flight locations, we recommend considering species-specific FID and using the maximum diagonal FID as a guideline. Disturbance decreases with altitude, so flights should be conducted at 50 meters or higher whenever possible. These findings provide concrete guidelines to inform policy and promote the responsible use of drones in wildlife research and management.

The 39.4% decline in numbers in the Northeast/Northwest European population of Bewick's Swan Cygnus columbianus bewickii between 1995 (29,780 birds) and 2010 (18,057 birds) was of major conservation concern, alleviated by a partial recovery to 20,149 recorded in the January 2015 census. The most recent census, in January 2020, however found that the recovery was not sustained. The results described in this paper found a further 29.7% decline between 2015 and 2020, with 12,702 individuals counted in 2020 and the population estimated at 12,930 birds. This represents a 56.7% decrease over the 25-year period from 1995-2020; an annual average decrease of 3.3% per year, with a higher rate of decline (8.5%/year) over the most recent 5year period. Changes in the Bewick's Swans distribution were evident, with a significant increase in the proportion of the population recorded in countries in the northeastern part of the wintering range compared with those further south and west. More sites of international importance for Bewick's Swans in mid-winter (i.e. with >= 1% of the total population) consequently were found in Germany during the 2020 census than in previous censuses. Moreover, the swans were found to be more widely dispersed, rather than being concentrated at key sites, in 2015 and 2020. Annual productivity data, based on the percentage of cygnets (first-winter birds) recorded in wintering flocks, indicate that the recruitment to the population was consistently lower than estimated survival rates between 2010 and 2020, and moreover this has continued up to and including winter 2024/25. A population model predicts that a further reduction in population size to an estimated 11,068 Bewick's Swans will be found during the next census scheduled for January 2026, unless the swans have a good breeding season in summer 2025, which would represent a decrease of 14.4% since 2020.

Small uninhabited islands form important roosting and breeding habitats for many coastal birds. Previous studies have demonstrated that guano can promote ecosystem productivity and functionality on island ecosystems. Here, we assess the role of external nutrient input by coastal birds on the vegetation structure and coverage on sandy biogeomorphic islands, where island-forming processes depend on vegetation-sedimentation feedbacks. As a first step, we investigated whether breeding birds affect vegetation productivity on sandy back-barrier islands in the Wadden Sea. Using a combination of bird observations and plant stable isotope (δ15N) analyses, we demonstrate that (i) breeding birds transport large quantities of nutrients via their faecal outputs to these islands annually and that (ii) this external nitrogen source influences vegetation development on these sandy, nutrient-limited, islands. Based on these results we discuss how this avian nutrient pump could impact island development and habitat suitability for coastal birds and discuss future directions for research. In general, we conclude that avian subsidies have the potential to affect both the ecological and biogeomorphic functioning of coastal soft-sediment systems. However, the strength and scale of especially these biogeomorphic interactions are not fully understood. For the conservation of both threatened coastal birds and sandy back-barrier islands and the design of appropriate management strategies, we argue that three-way interactions between birds, vegetation and sandy island morphodynamics need to be further elucidated.

Trends in abundance and changes in the distribution of the Northeast Europe/ Northwest Europe Bewick's Swan Cygnus columbianus bewickii population have been studied in detail since the second half of the 20th century, but much less is known about the Northwestern Siberia/Caspian population which was estimated at 1,000- 1,500 individuals at the turn of the century. Here, we describe the results of the first species-specific mid-winter International Bewick's Swan Census (IBSC) covering the East Mediterranean to Central Asia, made in January 2020. We also use longer-term data collated by Wetlands International through the annual International Waterbird Census (IWC) programme to construct trends in wintering numbers in the region. Results from the IBSC and IWC both showed a marked increase in population size for the Northwestern Siberia/Caspian Bewick's Swans over the past two decades. A total of 6,819 was recorded during the IBSC and there was a five-year mean of 9,111 +/- 4,300 swans reported to the IWC (for the years 2018-2022) with a peak count of 13,775 in 2019. An aerial survey of the Volga Delta in the northern Caspian Sea in 2020, rarely covered because of the logistical difficulties of carrying out midwinter counts in the region, found an estimated 551 Bewick's Swans wintering at the site. There was marked annual variation in the IWC counts recorded from 2017 onwards, although the reasons for these fluctuations remain unknown. Trends analysis suggested a slow increase over time from 2000-2015, followed by a period of rapid increase during 2015-2017, then a weak decline in 2017-2022. Given that the IBSC and the IWC have provided totals of > 6,000 Bewick's Swans in five of the last six years, however, we propose that the new population estimate should be increased to 6,000-13,000 birds, pending further comprehensive surveys of the whole region.

The release of captive-bred or translocated individuals is a strategy used worldwide to support threatened animal populations. By capture-recapture analysis, we examined the survival of released individuals when reinforcing a critically endangered Lesser White-fronted Goose population. Our analysis includes data from 646 birds, released 1984-2017, including two different age classes, divided in two distinct periods when different techniques were used. Fledglings were released with foster parents of Barnacle Geese in the first period and by a soft release without support of foster parenting in the second period. Yearlings were released by soft release in both periods. We find that use of foster parents enhances survival rates, but these differences were detectable only in the first year of life. Fledglings supported by foster parents showed significantly higher survival compared to yearlings released by soft release, but this difference was not clear when soft release was applied to both groups. Resighting data suggest that most losses occurred during the acclimation period following the release. Foster parenting may enhance survival rates due to social learning enabling the transfer of crucial behaviors (e.g. feeding, anti-predator, and migration) to released individuals. However, these conservation benefits need to be balanced against costs and potential inherent risks related to foster parenting, including the imprinting of undesired behaviors in released individuals, such as hybridization. Based on our results, we advise conservationists to carefully consider foster parenting as one method to improve survival probability, especially if capacity to produce individuals to be released is a limiting factor.

Data on the breeding success of several characteristic coastal breeding bird species in the Wadden Sea have been collected each year since 2015. Ten bird species considered representative of specific habitats and food groups are being monitored. The monitoring scheme on breeding success in coastal breeding birds is run as an ‘early warning system’ to follow the reproductive capacity of the bird populations in the Wadden Sea and understand the processes underlying fluctuations in populations. It is a valuable addition to the monitoring of population numbers and is carried out under a trilateral agreement with Germany and Denmark (TMAP). The data are also included in the OSPAR biodiversity indicator B3 under the Marine Strategy Framework Directive. The 2019 results indicate that little has changed in the poor breeding success observed in previous years, although there were some positive exceptions locally and for some species, partly related to special conservation measures.

The problem we address is motivated by the desire to regulate the size of the NW/SW European population of greylag geese Anser anser to meet a number of management objectives, including providing sustainable harvests and minimizing agricultural impacts and conflicts. Using simple models of population dynamics along with observed allometric relationships in birds, we have concluded that reported estimates of greylag goose population size and/or offtake at the flyway level are likely biased, perhaps severely so. Recognizing that resources are limited, we suggest that the most pressing need may be to investigate and strengthen monitoring protocols for offtake. We also describe a simple information-gap ('info-gap') decision model that could allow decision makers to make informed choices about changes in offtake until such time that more reliable monitoring information is available for greylag geese. With the info-gap decision model we were compelled to use a management criterion based on the growth rate of the flyway-wide population because true levels of abundance and offtake are unknown. Moreover, we emphasize that in the face of deep uncertainty about greylag goose abundance and offtake, decisions concerning management of the population carry a high risk of failing to meet conservation objectives, whatever they may be. While the info-gap analysis suggests an increase of offtake beyond the nominal level of 450 000 reported in the International Single Species Management Plan may be necessary to stabilize the population, we do not know the current level of offtake (i.e. whether it has recently changed from that last reported). Moreover, recent counts conducted by the range states and the International Waterbird Census suggest that the winter flyway population may no longer be increasing. For these reasons, management implications of the info-gap analysis must be viewed with caution.

Following the use of Barnacle Geese Branta leucopsis as foster parents in a conservation program for the endangered Lesser White-fronted Goose Anser erythropus in Sweden 1981–1999, mixed breeding pairs of the two species were established in the wild. We find indications that this was related to shared moulting habits of the two species in the Bothnian Sea during late 1990s. Starting in 2003, five mixed pairs produced at least 49 free-flying hybrid offspring until 2013, when the last breeding was confirmed. Reported numbers of hybrids did not increase in parallel to the production of young hybrids over time. After 2013, the number of hybrids started to decrease in Sweden and the Netherlands. Lower numbers of hybrids than expected can partly be explained by management actions taken, but may also be associated with low survival due to genetic outbreeding. Mixed pairs and their offspring entirely adopted the migratory habits of Barnacle Geese, overlapping very little with sites used by Lesser White-fronted Geese. We find no evidence that the hybrids ever posed a serious threat to Lesser White-fronted Geese breeding in Fennoscandia.

Species distribution models (SDMs) are frequently used to understand the influence of site properties on species occurrence. For robust model inference, SDMs need to account for the spatial autocorrelation of virtually all species occurrence data. Current methods do not routinely distinguish between extrinsic and intrinsic drivers of spatial autocorrelation, although these may have different implications for conservation. Here, we present and test a method that disentangles extrinsic and intrinsic drivers of spatial autocorrelation using repeated observations of a species. We focus on unknown habitat characteristics and conspecific interactions as extrinsic and intrinsic drivers, respectively. We model the former with spatially correlated random effects and the latter with an autocovariate, such that the spatially correlated random effects are constant across the repeated observations whereas the autocovariate may change. We tested the performance of our model on virtual species data and applied it to observations of the corncrakeCrex crexin the Netherlands. Applying our model to virtual species data revealed that it was well able to distinguish between the two different drivers of spatial autocorrelation, outperforming models with no or a single component for spatial autocorrelation. This finding was independent of the direction of the conspecific interactions (i.e. conspecific attraction versus competitive exclusion). The simulations confirmed that the ability of our model to disentangle both drivers of autocorrelation depends on repeated observations. In the case study, we discovered that the corncrake has a stronger response to habitat characteristics compared to a model that did not include spatially correlated random effects, whereas conspecific interactions appeared to be less important. This implies that future conservation efforts should primarily focus on maximizing habitat availability. Our study shows how to systematically disentangle extrinsic and intrinsic drivers of spatial autocorrelation. The method we propose can help to correctly identify the main drivers of species distributions.

In western Europe, the majority of wild goose populations have increased exponentially over the last decades. Such increase is the source of many socio–ecological conflicts. The need for coordinated management actions to handle the goose-related conflicts at the European scale has led to the establishment of a specific European Goose Management Platform (EGMP) under the auspices of the Agreement on the Conservation of African–Eurasian Migratory Waterbirds (AEWA). The northwest/south-west (NW/SW) European population of greylag goose Anser anser has been considered as a priority concern, and an AEWA international single species management plan has been recently adopted. Because of the complex structure of the greylag goose population (e.g. spatial differences in migration strategies), and management (e.g. different hunting schemes among the range states), delineation of management units (MUs) based on goose movement characteristics was deemed necessary to further implement effective management actions. Based on neckband marking in various breeding regions and subsequent resighting locations, we conducted spatio–temporal analysis based on kernel methods to infer spatio–temporal and migratory movements of greylag geese in the NW/SW European flyway. The results highlight the existence of contrasted migratory behaviour, dispersal patterns and phenology within the flyway. From these results three international management units could be delineated. The first MU would include migratory birds from Norway. Birds from breeding grounds in Sweden and Denmark would represent the second MU. Finally, a third central MU was delineated, including primarily breeding birds from the Netherlands and northwestern Germany, which do not show migratory behaviour at the flyway scale. The delineation of these MUs has to be considered within an adaptive process, and future studies will enable a refinement of the definition of such units in order to continuously improve the efficiency of management plans.

Coordinated international censuses of the Northwest European Bewick's Swan Cygnus columbianus bewickii population have been undertaken across the swans' wintering range at c. 5-year intervals since 1984. During the early years of the study, numbers increased steadily to a peak of 29,780 individuals in January 1995, but then declined by 39.4% to 18,057 swans counted in January 2010 before showing a partial recovery to 20,149 recorded in January 2015. Changes in distribution across the wintering range were also recorded; a higher proportion of the population now remains in more easterly countries (notably Germany) in mid-winter, whilst only a handful of birds migrated to Ireland (at the western edge of the range) during the 2000s compared to >1,000 wintering there at the start of the study. Variation between censuses in the proportion of swans recorded in different parts of the range were attributable to weather conditions, with more swans wintering further north in warmer years. The overall percentage of cygnets recorded in each of the census years ranged from 9.6% in 2010 to 13.2% in 2005, with no obvious consistency over time in the distribution of cygnets across the wintering range. There were however changes between 1990 and 2015 in the swans' use of feeding habitats, with a decline in the proportion of birds on pasture and a corresponding increase in those on arable land. Decreases in the total population size and changes in distribution in the 21st century have implications for the designation and resultant protection of sites of international importance for the species.

Many bird populations are made up of social units with differences in size and social status. Of these, the family and flock structure of geese Anserini are among the better known. However, how the association of juvenile geese with their parents in families influences the migration timing and space-use of populations, as well as the events leading to juvenile independence are not well understood. We focus on family size dynamics of the Greater White-fronted Goose Anser a. albifrons on its wintering grounds in the Netherlands and northern Germany, where we gathered 17 years of observation data on foraging flocks and tracked 13 complete families with GPS transmitters. We explored how social status and family size affected wintering site choice and migration timing as well as how and why family sizes decreased. We found that family size decreased strongly during autumn migration, likely from juvenile death due to insufficient fuelling. It further decreased through the winter, here seemingly by juveniles accidentally splitting off during strong disturbance events. Different from previous findings, a large proportion of juveniles became independent during winter. Large families generally arrived later to the wintering grounds, wintered further from the breeding grounds and departed later for spring migration than adults without young. Independent young left for spring migration last. Thus, White-fronted Geese are differential migrants by social status. In combination with the observation of low breeding success in this population in recent years, our findings improve the understanding of its spatial and temporal patterns during winter, and their apparent changes. This can support conservation and management decisions for both White-fronted Geese as well as other large migrants with complex age and social structure.

Data have been collected on the breeding success of several characteristic coastal breeding birds in the Wadden Sea each year since 2005. Ten birds species considered representative of specific habitats and food groups are being monitored. The monitoring scheme on breeding success in coastal breeding birds is run as an ‘early warning system’ to follow the reproductive capacity of the bird populations in the Wadden Sea and understand the processes underlying fluctuations in populations. It is a valuable addition to the monitoring of population numbers and is carried out under a trilateral agreement with Germany and Denmark (TMAP). The data are also included in the OSPAR biodiversity indicator B3 under the Marine Strategy Framework Directive. The 2017 results indicate that there has been little improvement in breeding success compared with previous years and that most species, especially Eurasian Oystercatcher, Pied Avocet and Arctic Tern, raised far too few young to maintain a stable population.