Data on species’ demography are essential to detect changes in population size, identify drivers of population change, motivate conservation plans, or evaluate the effectiveness of management. The Arctic Skua Stercorarius parasiticus is a seabird with a circumpolar distribution, which is listed as “Endangered” on the International Union for Conservation of Nature (IUCN) European Red List, although listed as “Least Concern” globally. It is both a predator and a kleptoparasite reliant on marine and terrestrial prey, and undertakes migrations from northern breeding habitats to temperate and tropical marine environments. Most studies of breeding populations originate from North Atlantic populations where Arctic Skuas are primarily kleptoparasitic. However, a large proportion of the global breeding population occupies remote coastal and inland tundra of Arctic regions where Arctic Skuas are more generalist in foraging modality and the range of prey taken. Here, we collated and summed national/regional population estimates to provide an updated global estimate of breeding population size and trends. We reviewed drivers of population change and knowledge gaps, and their implications for the conservation of this species. We estimated a minimum breeding population of 185,131–395,315 pairs combining Alaska, Canada, Greenland, and Europe; we extrapolated that at least 40,000 pairs could be found in Asian Russia, where no estimates were available. We noted differential trends, with substantial declines in typically kleptoparasitic populations of the North Atlantic where data quality was higher, whereas for populations in the Nearctic, trend data were scarce and geographically restricted. Various threats were identified as potential drivers of population change, including bottom-up processes, fisheries, heat stress, and interspecific competition/predation. Given the large uncertainty around abundance and population trends for much of the Arctic Skua’s range, the current global conservation status of Least Concern may be better designated as “Data Deficient”, and we encourage the implementation of a range of approaches to improve monitoring of population trends and demography globally.

To assess mitigation measures for habitat loss, it is important to understand the function of artificial wetlands as alternative wader habitat. In the Netherlands since 2016, a 1,000-ha freshwater archipelago called Marker Wadden has been constructed 3 km offshore in lake Markermeer. This artificial ecosystem provided a unique opportunity to study the impacts of construction designs and development of habitats on waders. Over a seven-year period, we studied Pied Avocets Recurvirostra avosetta because they used habitats in the constructed basins right from the start for feeding, and they are of conservation concern in the Netherlands. Between 2017 and 2023 we counted staging Pied Avocets and monitored habitat development in basins that varied in the time of construction (age) and design (closed or open, i.e. with breached levees connecting to the surrounding lake). Annual habitat changes were assessed with satellite images, and with pictures taken monthly at 20 fixed locations. With negative binomial zero-inflated models, we tested the effects of habitat characteristics, basin age, size and design, and raptor presence on bird numbers. The maximum number of Pied Avocets declined from >500 in 2017 to <100 in 2023. Basin age captured all habitat variation caused by natural succession and had the strongest negative effect on bird numbers. Open basins, allowing permanent flooding, were used less than closed basins. Avocet numbers remained highest in basins containing a mosaic of water and mud, with no or sparse vegetation. We concluded that Pied Avocets decreased due to two reinforcing processes: vegetation succession and breaching of levees leading to a rise in water level. Future developments targeting Pied Avocet conservation in freshwater wetlands should create and maintain shallow and muddy habitats with the closed basin and size concept as guidelines.

Long-distance migratory birds rely on pre-migratory fuelling to complete extensive flights. Global change and invasive species may threaten food resources critical for this process. The Bristle-thighed Curlew Numenius tahitiensis breeds in Alaska and winters across Pacific islands. Its population in French Polynesia has halved in the past two decades, raising conservation concerns. Introduced Pacific rats Rattus exulans are suspected to deplete terrestrial food resources on atolls, potentially impacting curlew fuelling. This study characterises the diet of Bristle-thighed Curlews during April, their pre-migratory fuelling period, using DNA metabarcoding of 61 faeces collected across rat-infested and rat-free islands in the Tuamotu Archipelago – of which 38 provided dietary data. Several molecular operational taxonomic units (MOTUs) were identified, covering arthropods, annelids, nemerteans, molluscs, reptiles, and plants. The curlew’s diet was dominated by crabs (45.8% MOTUs, 66.1% reads), particularly Pachygrapsus fakaravensis and Grapsus albolineatus, followed by insects (35.8% MOTUs, 11.5% reads), notably Pycnoscelus cockroaches. Plant material, mainly from coconut trees, represented 17.4% of reads. The diet was significantly more diverse on rat-infested islands, with higher MOTU richness and a predominance of crabs (73.7% reads). In contrast, rat-free islands showed a more balanced intake among crabs, insects, and plants. Rat presence shifts dietary diversity and composition, possibly by altering prey availability. Despite greater diversity on rat-infested islands, optimal fuelling appears to be associated with abundant crabs and insects on rat-free islands. Findings highlight the importance of managing invasive rats to maintain key food resources for this Endangered migratory bird. Further research on prey availability and nutritional quality across islands is recommended to inform conservation strategies.

Wetlands are critical ecosystems for many species of conservation concern, including migratory birds. These species face resource depletion and unpredictability in the context of global change and are expected to adjust their space use accordingly. Understanding how waterbirds use space and identifying their foraging needs are essential for guiding conservation efforts. Here, we present preliminary results on the fine-scale space use of a wetland flagship species, the Whiskered Tern Chlidonias hybrida, in La Brenne, a historical French breeding stronghold. The species is listed as ‘Vulnerable’ in France and breeds in only a few large wetlands. For the first time, we equipped four adult terns with miniature GPS tracking devices, providing unique, high-resolution data on their daily movements throughout the breeding season (i.e. pre-incubation, incubation, rearing, and post-breeding). Our results showed that most daily foraging trips did not exceed 2–3 km, resulting in relatively small home ranges (ranging from 2.00 km2 to 14.95 km2). Values were higher during the post-breeding period (up to 8 km from the nest and home range size up to 74.45 km2). Furthermore, we found that Whiskered Terns remained faithful to their foraging areas throughout the season and preferentially foraged in ponds – especially those near their colony – compared with other potential foraging habitats. On average, 91% of foraging positions occurred in ponds and 9% in grasslands. We also provide practical details on bird capture and device attachment methods. Finally, this pioneering bio-logging study offers promising prospects for future research on the movement ecology of Whiskered Terns, which could be invaluable for their conservation.

Survival is a key life history trait influenced by climate variability and resource availability in many bird species. Understanding the factors affecting survival in threatened species is critical for effective conservation management. However, we lack knowledge regarding survival rates and their annual variations for most threatened species. In this study, we use mark-recapture data collected in eastern Spain between 2011 and 2019 to estimate the annual adult survival of the Endangered Dupont’s Lark Chersophilus duponti, a steppe specialist passerine. We also aim to assess whether survival rates are linked to plant productivity, as a surrogate of resources available, and climate variability during the post-breeding (autumn) and winter periods. A total of 113 adults (89 males and 24 females) were ringed, which yielded 43 recaptures. The average adult survival rate over the nine-year period was slightly higher than previous estimates for Dupont’s Lark and other related species. Nonetheless, we observed substantial annual fluctuations in survival (ranging from 0.34 to 0.80), largely driven by winter climate conditions. Survival rates decreased during winters with a higher number of frost days (below 0ºC) and increased accumulated rainfall. These findings provide new insights into the population dynamics of the species and suggest that factors other than adult annual survival may be contributing to its declining status. Among those factors, a critical area for further research is to study and characterise the dispersal patterns and survival of juvenile birds, which remain largely unknown for this species.

Interactions between seabirds and fisheries, such as collisions or entanglement with fishing gear and bycatch, occur in all oceans and most fisheries. These interactions primarily occur as seabirds attempt to feed on bait, resources in nets or fisheries’ by-products such as discards and offal. The Black-browed Albatross Thalassarche melanophris is the most abundant albatross species on the Argentine Continental Shelf. This species is currently listed as ‘Least Concern’ by the International Union for Conservation of Nature (IUCN) but it is considered to be threatened in Argentina where it is known to interact significantly with diverse fisheries. Little is known about how these interactions vary with intrinsic factors such as age, a key knowledge gap. This study aimed to evaluate the effect of fishing effort by trawl and squid-jigging vessels on the foraging behaviour of adult and immature Black-browed Albatrosses wintering on the Argentine Continental Shelf. Our analysis used data from 15 satellite transmitters deployed on six adults (2011–2013) and nine immature individuals (2015). Foraging behaviour was identified using the Expectation Maximisation Binary Clustering algorithm. Generalised Linear Mixed Models (GLMMs) were fitted to determine the effect of fishing effort by different trawl and jigging fleets (measured as the number of fishing points per hour per grid cell) on the likelihood of albatrosses engaging in foraging behaviour. In both age classes, the probability of foraging behaviour was positively correlated with trawl fishing effort. For immature albatrosses, foraging behaviour was notably affected by double beam trawlers only. For adults, it was associated with fishing effort from double beam trawlers, coastal trawlers, and high-seas ice-trawlers, although the effect was of lesser magnitude. All mentioned trawl fisheries are known to produce significant amounts of discards. Identifying these associations can help to pinpoint potential conflict areas between albatrosses and fishing activities and facilitate the planning of effective conservation measures through an ecosystem-based approach to fisheries management.

National and continental-scale bird monitoring schemes, such as the Pan-European Common Bird Monitoring Scheme (PECBMS), are essential for tracking bird population trends across broad spatial scales. However, while these frameworks provide invaluable data for population monitoring, they may be less accurate in estimating species densities at small spatial scales, particularly for habitat-specialist species like the Red-backed Shrike Lanius collurio. This species is listed in Annex I of the EU Birds Directive, and its effective monitoring is a legal conservation obligation for EU Member States under the Natura 2000 framework. Ensuring accurate data on its population status is therefore critical for meeting international biodiversity targets. To evaluate this limitation, we compared density estimates from the Common Breeding Birds Survey (MPPL) with those obtained from intensive, targeted surveys across 53 study plots, each covering an area of 1 km², in eastern Poland. Although density estimates from MPPL and the targeted field study were correlated, a deeper analysis revealed that MPPL (2.1 individuals/km²) consistently underestimated densities recorded during targeted surveys (3.9 breeding pairs/km²). Using Generalised Linear Models (GLMs), we explored the habitat characteristics that may contribute to these discrepancies. Only two predictors, i.e. the proportion of buffer zones around arable fields and around mixed crops, were significantly associated with underestimation. In both cases, a higher share of buffer zones led to a greater difference between MPPL and targeted estimates, indicating that landscape structure influences detectability. Differences in survey timing between the two approaches, with MPPL visits conducted earlier in the breeding season, coupled with species-specific breeding behaviours (including peak activity later in the breeding season) may have influenced these differences. This study highlights that although bird surveys are an indispensable tool for analysing trends and comparing densities between surfaces over large spatial domains, their usefulness for studies at small spatial scales may be limited.

Understanding the causes and drivers of extinction is critical for mitigating future anthropogenic extinctions. This study explored the extinction process of the Crested Ibis Nipponia nippon in Japan, focusing on the last wild population on Sado Island. An integrated population model–population viability analysis (IPM-PVA) framework was applied to estimate demographic parameters and population dynamics using four historical data sources, i.e. population counts, records of dead or rescued individuals, reproductive data, and captures for captive breeding. The IPM estimated an average of 0.703 fledglings per breeding pair per season, with adult and juvenile survival rates of 0.870 and 0.730, respectively. Human disturbances were found to substantially reduce fecundity. PVA results indicated an extinction probability of 56.6% under observed historical conditions, which could have been reduced to 11.2% if human access to nesting forests had been restricted. The study identified low fecundity caused by human disturbance at nest-sites as a likely contributor to the species’ extinction. Despite the need for cautious interpretation due to data limitations, this study highlights the practical utility of the IPM-PVA framework in providing detailed insights into the extinction process.

The determinants of nest-site selection and nest success are important for conservation planning for endangered birds. Here we examine factors driving nest-site selection and success for the Mariana Crow Corvus kubaryi, also known as the Åga, across the entire range of the population, by comparing 370 nests that were found during surveys (2014–2021) against random points sampled from all forested areas on the island. Nest-sites were more likely to have high canopy cover than random points, while proximity to human infrastructure (e.g. roads, buildings) did not impact nest-site selection. None of our tested covariates impacted nest success, nor did the land-cover type in which the nests were found. Our results suggest that the Åga is able to nest successfully in close proximity to humans, and that nest success is not negatively affected by current land-use practices. Future research on the low nest success rate (23.9%) would be most fruitfully targeted towards local biotic stressors, such as nest predation or environmental factors, which may exacerbate the unknown inflammatory disease that afflicts many wild nestlings.

Green Peafowl Pavo muticus, a dry forest specialist, has experienced declines across its range in mainland South-East Asia due to habitat degradation, habitat loss, and hunting. In Thailand, the species’ remaining habitats have been grouped into four strongholds where long-term viable populations are thought to persist. For two of these strongholds, extensive population estimates are available, but for the other two (north-western and eastern Thailand), only a single site-based estimate currently exists. To address the gap, additional density estimates were derived from distance sampling in OpLuang National Park (north-western stronghold) and the Phnom Dangrek Range (north-eastern stronghold). Remaining suitable habitats were identified using a Generalised Linear Model (GLM) and the threats these populations face were assessed. In the north-western stronghold, density was estimated at 0.51 calling birds/km2 in OpLuang National Park, with suitable habitat covering 7,197 km2 (2,657 km2 within protected areas) and deforestation totalling 1,374 km2 (963 km2 consecutive hotspots, 377 km2 sporadic hotspots, and 34 km2 new hotspots). In the north-eastern stronghold, density was estimated at 0.93 calling birds/km2 in three of six protected areas across the Phnom Dangrek Range, with suitable habitat covering 9,917 km2 (3,518 km2 within protected areas) and deforestation totalling 3,407 km2 (1,954 km2 consecutive hotspots, 1,142 km2 sporadic hotspots, 309 km2 new hotspots, and 2 km2 persistent hotspots). Our results confirm the importance of both strongholds for the long-term survival of the species. However, they also highlight the need for improved management to systematically monitor larger portions of suitable habitat, enhance population growth, and mitigate threats from deforestation, fire, and hunting by feral dogs.

Effective conservation of declining migratory species requires identifying habitats used during each stage of the annual cycle and the links between them. The Little Blue Heron Egretta caerulea, a long-legged, colonial-nesting, wading bird species that primarily forages in shallow-water wetlands, is declining throughout much of its range. A lack of understanding of its annual cycle movements prevents identifying when and where populations face limiting pressures, hindering conservation efforts. This study quantifies Little Blue Heron annual cycle movements, including space use at wintering and breeding sites, colony locations, migration distances, phenology, and site fidelity of herons from two important wintering sites on Florida’s Gulf Coast that differ in availability of fresh water. Little Blue Herons tagged with GPS transmitters (n = 30) showed a partial migration strategy; however, the ratio of migrants to residents was substantially different between the two study sites. Additionally, these birds established breeding colonies in both inland (n = 10) and coastal (n = 12) wetlands throughout the south-east USA and western Cuba (n = 2) and travelled a mean of 4.46 (SE = 0.87) km from their colony to forage. About 95% of individuals established colonies within freshwater wetland habitats, regardless of their wintering site, providing support that availability of fresh water during the breeding period is a key element of the habitat for this species. The results of this study suggest that management decisions aimed at minimising the threats to high-value wintering sites will benefit this species. The coastal systems examined supported wintering individuals for at least half of the full annual cycle. During this period, individuals maintained small home ranges (mean = 153.71, SE = 17.4 ha), did not make any significant within-season movements to other locations, and displayed strong inter-year site fidelity (0.49–0.85 BAI overlap), suggesting that these are areas that provide high quality habitats, justifying continued protection.