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.

Species’ declines are caused by a combination of factors that affect survival and/or breeding success. We studied the effects of a set of environmental and anthropogenic variables on the disappearance of Canarian Houbara Bustards Chlamydotis undulata fuertaventurae on Fuerteventura (Canary Islands), once the main stronghold of this endangered bird. Of 83 male display sites detected in 1997–1998, only 29 remained occupied in 2020–2021 (a 65% decrease in only 23 years). We compared habitat quality, density of conspecifics, other steppe birds and crows, presence of human infrastructure, and degree of environmental protection between these 29 extant sites and the 54 extinct sites using univariate analyses and generalised linear models (GLMs). The most influential variable in the abandonment of display sites was the Normalised Difference Vegetation Index (NDVI), an indicator of green vegetation productivity, which suggests a strong effect of habitat aridification due to climate change on the population’s extinction process. Powerline density was the second most important factor. This suggests that houbaras have survived where a greater abundance of food resources has enabled a higher breeding success, and where powerline fatalities have caused lower mortality over the years. Higher densities of houbaras, and other steppe birds and crows at extant display sites confirmed the better habitat quality in these areas. Extant display sites, located generally in protected areas, also had lower densities of human infrastructure (e.g. buildings, roads). We discuss the conservation implications of these results and provide management recommendations for this endangered subspecies.

As a result of increasingly intensified agricultural practices in Europe over the last century, agroecosystems have experienced severe biodiversity declines. Among the species experiencing negative population trajectories in agricultural habitats are meadow and farmland birds, which have suffered a loss in both habitat and food availability in cultivated fields. In Denmark, biotope plans (a requirement to establish small agro-environmental habitats on properties with stocking of game birds) have been implemented as a measure to mitigate biodiversity declines in the agricultural landscape and, in this paper, we investigate to what extent these initiatives fulfil the intended purpose with respect to birds in the breeding season. We demonstrate that some initiatives like hedgerows, areas of open vegetation, scrub, and lakes seemed to increase avian diversity locally, but also that other measures such as vegetation strips, grass strips, and bare soil strips had little effect given the current implementation of these initiatives. Benefitting species were mostly scrub- and woodland species that now inhabited previously open landscapes after the establishment of suitable habitats, and the initiatives failed to show clear positive effects on meadow birds and farmland birds for which they were originally intended. The most commonly registered species in our data set was (released) Pheasant Phasianus colchicus, which emphasised that the stocking of game birds can have a clear effect on avian species composition in areas where this practice is exercised. Future studies are needed to clarify how this stocking may affect local biodiversity of different taxonomic groups.

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.

Forests of urban/suburban areas are being increasingly restored, but before/after-control/impact studies addressing effects on biodiversity in peri-urban forest restorations are virtually lacking. Using a before/after-control/impact (BACI) design, we explored the effects on birds (commonly used as indicators for restoration impacts) of small-scale restoration interventions in 2019 targeting residual forests north of Milan, in the largest Italian conurbation, with trees and shrub planting around existing patches or in formerly cultivated areas. Birds were surveyed in 2018, 2019, and 2021, at 20 intervention and 20 control sites. We evaluated the short-term effects of restoration by analysing changes in avian communities (i.e. richness, richness and abundance of forest specialists, single species’ abundance), considering the effect of year and intervention (i.e. before/during/after intervention). Species richness of breeding birds was largely unaffected by on-going interventions, while it was positively related to concluded restoration. The abundance of five individual species varied according to restoration: on-going interventions had positive effects on two species, Common Blackbird Turdus merula and Hooded Crow Corvus corone cornix, and negative effects on Barn Swallow Hirundo rustica, while concluded restoration positively affected two species, Common Blackbird Turdus merula again, and the forest specialist Marsh Tit Poecile palustris. Even small-scale interventions in peri-urban areas may provide tangible benefits to breeding birds in the short term: peri-urban forest restoration could contribute to biodiversity conservation.

Heat stress from high temperatures has been recognised as a threat to several bird species and one that is likely to increase in severity and frequency as a result of global environmental change. Many seabirds are particularly vulnerable as their adaptations to forage in cold water can make it hard for them to resist heat gain while on land. The African Penguin Spheniscus demersus forages in cool water (10–20°C) but breeds and moults on land where temperatures can exceed 30°C. Little is known about its thermal physiology and when heat stress will occur. Here, we provide the first account of changes in body temperature and behaviour in African Penguins in response to an experimental increase in ambient temperature from 20°C to 35°C. Surprisingly, the highest body temperature observed (39.2°C) was recorded at the start of the study. Presumably, this response in body temperature was due to the stress of transport and handling. Penguins returned to normal body temperature (37.3°C) after 3.5 hours and maintained normothermia for roughly an hour. We then observed the onset of heat storage at an ambient temperature of 29°C, whereafter body temperature increased steadily at a rate of ca.0.2°C per 1°C increase in ambient temperature. Panting commenced at an ambient temperature of 31.4°C, when body temperature was 37.8°C. In addition to panting, penguins changed their posture to facilitate heat dissipation by standing, raising their heads, and extending their flippers. Our results corroborate field observations and support the argument that African Penguins are highly vulnerable to heat stress in the near future as extreme heat events become more severe and frequent due to climate change. Our results also confirm that penguins are sensitive to handling, which elicits a hyperthermic response. Given the general sensitivity of penguins to disturbance, from a conservation perspective, we advise that cautionary measures be implemented at colonies during critical life-history stages.

Newly elevated to species rank, the Bahama Nuthatch Sitta insularis is or was a bark- and twig-gleaning insectivore only known in life from the pine forests of Grand Bahama in the Bahamas archipelago. It became increasingly difficult to find in the past 50 years, seemingly in part in response to multiple hurricanes in this century. In spring (June–April) 2018, when it was still known to be extant, we divided the island into seven sections and carried out point count transects with playback and measured habitat variables at 464 locations in pine forest across Grand Bahama. We made only six observations at six locations, all in the region of Lucayan North and each involving a single nuthatch (possibly all the same individual). Fourteen count points were within 500 m of the six locations, and tree size at these sites was greater in height and girth than at sites with no observations and indeed than at other sites within Lucayan North. Count points within 500 m of nuthatch records in 2004–2018 had larger trees and more snags than survey points over 500 m away from previous detections, while count points within 500 m of our 2018 nuthatch records tallied more snags than did those within 500 m of the 2004–2007 records. Declines in habitat quality, habitat extent, nesting substrate, and food availability (driven by logging, attritional island development, and the direct and indirect effects of hurricanes), plus speculated increases in populations of invasive predators/competitors and in major mortality events (hurricanes, increasing in force and frequency with climate change), are suspected to be the ultimate causes of the decline of the nuthatch, with Hurricanes Matthew and Dorian the proximate causes of its evident extinction in 2019.

The Black-cheeked Lovebird Agapornis nigrigenis has a highly restricted range in dry south-western Zambia, where its distribution is clumped and localised in association with mopane Colophospermum mopane woodland and permanent water pools. Fieldwork and monitoring over 30 months between December 2018 and October 2021 established that the lovebirds’ usage of pools for drinking was higher towards the centre of the bird’s distribution and influenced by the pools’ proximity to mopane woodlands, surrounding tree cover, and level of human activity. Of the four pool types available for use by lovebirds (i.e. mopane, grassland, river, and artificial), mopane and grassland pools were disproportionally susceptible to drying out in the dry season, hence showed greater variation in numbers of visiting birds compared with the other two types. Lovebirds showed a preference for pools with a perimeter of <50 m and tended to avoid those with a perimeter >100 m, consistent with a positive association between pool size and human activity. Convergence between humans and lovebirds in dependence on water resources and mopane woodland points to the need to find ways to overcome potential conflicts. Such ways include creating small, shallow-sided, undisturbed pools in or near mopane woodland, extending water retention in existing mopane pools, and enhancing the capacity of artificial pools to meet the needs of the lovebirds.

Spix’s Macaw Cyanopsitta spixii, extinct in the wild since 2000, was successfully reintroduced in Brazil in 2022, leading to significant progress, including the hatching of wild chicks. However, recent restrictions on further releases by the Brazilian government have put the reintroduction programme into jeopardy. This study updates our 2023 population viability analysis (PVA) to assess the impact of these delayed releases on the wild population. Using six modelled scenarios, we confirm that without annual supplementation of captive-bred birds, the probability of extinction in the wild remains at 100%. Even a one-time release is insufficient to secure population stability. Our results highlight that those annual releases of at least 20 individuals are necessary to ensure long-term viability, with reduced but still essential growth achievable with 10 birds per year. Supplementation of the wild population does not compromise the long-term viability of the well-established captive population. We urge immediate action to resume the release programme in 2024 to prevent the species from once again facing extinction in the wild.

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.

Assessing the conservation status of a species is important for designing effective conservation measures. Consequently, it is often vital to review it to update biodiversity management initiatives. The Parana Antwren Formicivora acutirostris is a bird found in pioneering formations (coastal marshes) of Brazil’s southern flood plains. It is considered threatened in Brazil but near threatened globally. In 2007, its distribution, habitat, and population size were estimated based on aerial photographs from 1978 and 1980. Since the species is threatened and occupies a small area across a region under pressure, we aimed to reassess its conservation status and assess its Green Status. We compiled new records, conducted new density estimates, and compared them with the previous mapping with satellite imagery to estimate the current distribution in terms of extent of occurrence (EOO), area of occupancy (AOO), area of habitat (AOH), habitat loss, and population size, and review its conservation status. The species is distributed across 10 populations, including two new populations further south. We estimated the EOO at 26,655 km², AOO at 320 km², AOH at 41 km², and the population as 6,285 mature territorial individuals. The previously mapped AOH decreased by 15.35 km² due to ecological succession. The loss of habitat due to invasion by exotic grasses is the main anthropogenic impact. We recommend that the species be considered “Vulnerable”. The Green Status indicates that the Conservation Legacy of actions taken thus far and the Conservation Dependence of ongoing actions are inefficient due to their small scales, but it highlights the importance of future actions for species conservation. We propose the establishment of exotic-free zones as small areas with a significant amount of minimally invaded environments, which we suggest as priority areas for the conservation of the species due to their cost-effective management potential. We also propose assisted colonisation to enhance its long-term conservation.

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.

In Europe, population estimates of breeding birds are produced nationally and are periodically compiled at EU or pan-European scales. Until now, no other source was available to explore the robustness of these estimates. In this study, we compared population sizes reported in the latest edition of the European Red List of Birds (ERLoB) with those produced using data from the second European Breeding Bird Atlas (EBBA2) to assess their consistency and determine parameters behind variability in population estimates that deserve further attention in the future. In general, European population estimates derived from summing local abundance data from EBBA2 were similar to those obtained from ERLoB, although for some species they differed considerably, particularly in those distributed mainly in southern Europe. National population estimates from EBBA2 also did not differ markedly from those in ERLoB. However, we found that EBBA2 provided larger national population sizes than ERLoB for widespread species, suggesting that spatial information is more relevant for properly assessing their population size than for localised species. Our analysis also showed that, in general, population estimates based on robust methodological protocols (e.g. complete counts, statistical inference) contributed to reducing differences between ERLoB and EBBA2 values. Interestingly, EBBA2 and ERLoB estimates were quite similar for species classified in Europe as “Threatened” or “Near Threatened”, whereas the values for “Least Concern” species were consistently different between these two sources. Our results indicate which type of species would benefit from additional efforts to improve national population estimates and their consistency across countries, issues that are of paramount importance for guiding conservation strategies in Europe.

The endemic Little Vermilion Flycatcher (LVF) Pyrocephalus nanus has suffered a drastic decline on Santa Cruz Island, Galapagos, where it was common 30 years ago. Currently, fewer than 40 individuals remain in the last remnants of natural humid forest in the Galapagos National Park on the island. This small population has low reproductive success, which is contributing to its decline in Santa Cruz. Previous studies have identified Avian Vampire Fly Philornis downsi parasitism, changes in food sources, and habitat alteration as threats to this species. In Santa Cruz, invasive plants may strongly affect the reproductive success of LVF because they limit accessibility to prey near the ground, the preferred foraging niche of these birds. Since 2019, we restored the vegetation in seven plots of 1 ha each by removing invasive blackberry plants and other introduced plant species. In all nests that reached late incubation, we also reduced the number of Avian Vampire Fly larvae. In this study, we compared foraging and perch height, pair formation, incubation time, and reproductive success between managed and unmanaged areas. As predicted, we found significantly lower foraging height and perch height in 2021 in managed areas compared with unmanaged areas. In 2020, the daily failure rate (DFR) of nests in the egg stage did not differ between management types; however, in 2021, the DFR in the egg stage was significantly lower in managed areas than in unmanaged areas. The DFR during the nestling stage was similar between managed and unmanaged areas in 2020, but in 2021, only nests in managed areas reached the nestling stage. Females brooded significantly more during the incubation phase in managed areas. Additionally, we found significantly higher reproductive success in managed areas compared with unmanaged areas in 2021, but not in 2020. Habitat restoration is a long-term process and these findings suggest that habitat management positively affects this small population in the long term.

Many European farmland bird populations are rapidly declining because of agricultural intensification and land-use changes. Robust estimates of population sizes and trends, habitat use, and protected area coverage within the distribution range are crucial to inform the conservation and management of threatened species. Here we report on the results of the 2019 Black-bellied Sandgrouse Pterocles orientalis (BBS) survey promoted and coordinated by SEO/BirdLife to update its breeding distribution, population size, and trends in continental Spain. A total of 660 grid cells, 10 × 10 km, Universal Transverse Mercator (UTM), were surveyed (81% of the distribution area), with 2,257 visits to 1,750 walked transects (7,001 km in total; 10.6 km per UTM). BBS was detected in 43% of sampled UTMs. At transect level, occupancy was 11% higher inside protected areas. At UTM level, occupancy was estimated at 0.58 (Bayesian credible interval [BCI] 95%: 0.55–0.61), revealing that BBS occupied about half of its previous breeding range (2003–2005). Using hierarchical distance sampling modelling, we estimated an average density of 1.33 individuals/km2 in occupied areas, and a population of 4,025 individuals (confidence interval: 1,840–7,609) within sampled areas, with an additional 697 individuals (confidence interval 461–1,075) in areas that were not surveyed. Further, the relative abundance of BBS (Kilometric Abundance Index) declined by 63% between 2005 and 2019 (annual decline rate of 4.5%). BBS used agricultural habitats (73%) and unprotected areas (54%) despite a higher occupancy within protected areas. Given the recent decline rate and persistent threats, the BBS conservation status should be upgraded to “Endangered” in peninsular Spain. Its future depends on land-use changes and agricultural practices, in particular the maintenance of fallows, semi-natural habitats, and pastures for extensive grazing. Better protection of important areas and targeted conservation initiatives should be promoted to halt and reverse the population decline in this key western Palearctic stronghold.

Land-use change for crop production is one of the key drivers of habitat loss and fragmentation and consequently biodiversity loss and change in tropical regions. This may impact biodiversity-regulated ecosystem services; birds are important to crop health regulating services (e.g. seed dispersal, pest control) and disservices (e.g. seed predation, grain herbivory). However, knowledge is limited on how birds use heterogeneous agricultural landscapes and the consequences for spatial distribution and flow of services and disservices. We studied crop and non-crop–habitat associations of birds in forest–agricultural landscapes of the Kilombero Valley, Tanzania. We focused on dietary preference as a key trait impacting bird responses to land-use change, services, and disservices to crops. We surveyed birds across four main habitat types using repeated point counts, recording a total of 148 species. We found that crop habitats supported higher species richness and larger communities of potentially beneficial species to crop health, whereby 34.5% of invertebrate-feeding species were recorded in cropland. We found that habitat heterogeneity within the landscape supports bird functional diversity and that each habitat type supported unique communities of species. Furthermore, the number of species unique to forest habitats increased with increasing forest canopy closure. Our findings suggest that management strategies for maintaining trees and shrubs, and enhancing tree cover within the crop production landscape, can be effective approaches for maintaining bird diversity and services. However, in-depth studies on trade-offs with disservices need further exploration to mitigate negative impacts of birds on crop yields.

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.

Gadfly petrels Pterodroma spp. are among the most threatened bird taxa. Conservation interventions have been successfully developed and applied for some gadfly petrel species, but a substantial gap remains in conservation science for this group in the tropical Pacific Ocean. The Vanuatu Petrel Pterodroma [cervicalis] occulta is an ideal exemplar to develop a pipeline for conservation science in tropical Pacific gadfly petrels as it is subject to many of the challenges facing other gadfly petrel taxa in the region. We review over 40 pelagic Vanuatu Petrel records and five research expeditions to the only known colony on the island of Vanua Lava, Vanuatu. These records provide a baseline from which to recommend conservation research actions for the taxon. The population status, taxonomy, distribution, and threat profile of the taxon are all poorly known, and these areas are high priorities for future research.

In 2022, highly pathogenic avian influenza (HPAI) A(H5N1) virus clade 2.3.4.4b became enzootic and caused mass mortality in Sandwich Tern Thalasseus sandvicensis and other seabird species across north-western Europe. We present data on the characteristics of the spread of the virus between and within breeding colonies and the number of dead adult Sandwich Terns recorded at breeding sites throughout north-western Europe. Within two months of the first reported mortalities, 20,531 adult Sandwich Terns were found dead, which is >17% of the total north-western European breeding population. This is probably an under-representation of total mortality, as many carcasses are likely to have gone unnoticed and unreported. Within affected colonies, almost all chicks died. After the peak of the outbreak, in a colony established by late breeders, 25.7% of tested adults showed immunity to HPAI subtype H5. Removal of carcasses was associated with lower levels of mortality at affected colonies. More research on the sources and modes of transmission, incubation times, effective containment, and immunity is urgently needed to combat this major threat for colonial seabirds.