Seabirds are highly threatened, including by fisheries bycatch. Accurate understanding of offshore distribution of seabirds is crucial to address this threat. Tracking technologies revolutionised insights into seabird distributions but tracking data may contain a variety of biases. We tracked two threatened seabirds (Salvin’s Albatross Thalassarche salvini n = 60 and Black Petrel Procellaria parkinsoni n = 46) from their breeding colonies in Aotearoa (New Zealand) to their non-breeding grounds in South America, including Peru, while simultaneously completing seven surveys in Peruvian waters. We then used species distribution models to predict occurrence and distribution using either data source alone, and both data sources combined. Results showed seasonal differences between estimates of occurrence and distribution when using data sources independently. Combining data resulted in more balanced insights into occurrence and distributions, and reduced uncertainty. Most notably, both species were predicted to occur in Peruvian waters during all four annual quarters: the northern Humboldt upwelling system for Salvin’s Albatross and northern continental shelf waters for Black Petrels. Our results highlighted that relying on a single data source may introduce biases into distribution estimates. Our tracking data might have contained ontological and/or colony-related biases (e.g. only breeding adults from one colony were tracked), while our survey data might have contained spatiotemporal biases (e.g. surveys were limited to waters <200 nm from the coast). We recommend combining data sources wherever possible to refine predictions of species distributions, which ultimately will improve fisheries bycatch management through better spatiotemporal understanding of risks.

The Asian Golden Weaver (Ploceus hypoxanthus) occurs in Myanmar, Thailand, Laos, Vietnam, Cambodia, and Indonesia and inhabits marshes, grasslands, reeds and rice fields close to water in the lowlands (Robson 2000) and natural waterholes in lowland dry dipterocarp forest (Round 1998). It is globally ‘Near-threatened’ due to habitat loss through the conversion of wetlands to agricultural and settlement areas (BirdLife International 2007). In Thailand it is local and uncommon in the north, north-east and central regions (Lekagul and Round 1991, Robson 2000). However, no quantitative data are available regarding its ecological requirements. Our objectives were to collect basic ecological data on: i) population structure, ii) nesting habitat characteristics, iii) food selection and foraging behaviour, and iv) parental care at the nest.

The ‘Endangered’ Sakalava Rail Amaurornis olivieri is endemic to wetlands in western Madagascar, where it has been recorded between the Betsiboka river in the north and the Mangoky river in the south. Between August 2003 and November 2006, including dry and wet seasons, we surveyed 36 potentially suitable wetlands throughout its known range. We found Sakalava Rails at five sites: Lacs Kinkony, Ampandra, Amparihy, Sahapy and Mandrozo. At each site the population was small (12–39 individuals) and the highest density was 20 individuals km−2. We found up to 67 birds in each field visit and the total number of birds (sum of maxima at each site) seen was 100. We estimate the total population at the five sites to be 215 rails. We cannot confirm that the population lies within the range estimated in the current Red List (250–999 individuals), although this may yet be proven correct. The typical breeding habitat of Sakalava Rail is lotic marshes with a mixture of large areas of open water, reed Phragmites mauritianus and floating Salvinia hastata. The major threats to Sakalava Rail appear to be habitat loss caused by wetland conversion to rice fields and by fires, disturbance by fishermen and people from local villages, and hunting. Other processes that may alter the ecological character of wetlands and so affect their suitability for Sakalava Rails, such as hydrological change or the effects of exotic fish or vegetation, remain to be investigated.

Differences in the diets of urban and rural avian predators could indicate potential niche vulnerability in a particular habitat. This study compares the core-isotopic niche areas and diet disparity of a declining peri-urban Verreaux’s Eagle Aquila verreauxii population with a stable rural population in South Africa. In addition to stable isotope analyses, the diet of the peri-urban Verreaux’s Eagles was investigated using camera trap footage of prey delivered during the nesting season. Dominant prey consisted of species with a mixed diet of plants with a C3 and/or C4 photosynthetic pathway (browsers and grazers). Rock hyrax Procavia capensis contributed 60% of the total diet composition, scrub hare Lepus saxatilis 26% and Helmeted Guineafowl Numida meleagris 22%. The core-isotopic niche area for each population was calculated using bulk carbon (δ13C) and nitrogen (δ15N) stable isotope values chronological measured along the length of 18 feathers from 21 nests. The isotopic niche of the rural eagle population revealed that they consume prey from multiple trophic levels with a C3-plant-dominated prey base (browsers), likely including small carnivores. In contrast the isotopic niche of the peri-urban Verreaux’s Eagles correlated with the mixed mammalian and avian food-niche determined from camera trapping, confirming that the peri-urban population mainly hunted three abundant species that are all narrowly associated with modified human habitats. The decline in the Magaliesberg Verreaux’s Eagle population is, therefore, unlikely to be due to constraints in their dietary niche, as raptors benefit from the diversity and abundance of human-commensal prey associated with the peri-urban habitats.

New Britain in the Bismarck Archipelago of Papua New Guinea supports 14 endemic bird species and together with New Ireland, forms an Endemic Bird Area that supports 38 restricted range species. Extensive conversion of lowland forest to oil palm plantations resulted in the loss of over 20% of forest under 100 m altitude between 1989 and 2000. However the rate of loss has subsequently slowed (2.2% loss across all altitudes between 2002 and 2014), and much forest remains at higher altitudes: 72% of New Britain remained forested (including secondary forest) in 2014. Despite the ongoing high threat and rich endemic bird fauna, the state of knowledge of the conservation status of birds in New Britain is very poor. We use an unprecedented dataset based on 415 hours of bird surveys conducted in oil palm plantations, as well as primary and secondary forests at all altitudes, to revise the IUCN status of New Britain’s birds. These data indicate that six species of elevated conservation concern are less dependent on old-growth forest than previously assessed. We recommend reduced population size estimates for one species, New Britain Kingfisher Todiramphus albonotatus. We recommend increased population size estimates for seven species: Pied Cuckoo-dove Reinwardtoena browni, Yellowish Imperial Pigeon Ducula subflavescens, Green-fronted Hanging Parrot Loriculus tener, Blue-eyed Cockatoo Cacatua opthalmica, Violaceous Coucal Centropus violaceous, New Britain Boobook Ninox odiosa and New Britain Thrush Zoothera talaseae. Despite our comprehensive surveys, Slaty-backed Goshawk Accipiter luteoschistaceus, New Britain Sparrowhawk Accipiter brachyurus, New Britain Bronzewing Henicophaps foersteri and Golden Masked-owl Tyto aurantia remain very rarely recorded and require further assessment. With ongoing habitat loss, particularly in lowland areas, New Britain’s birds urgently require more attention.

Accurately demarcating distributions of biological taxa has long been at the core of ecology. Yet our understanding of the factors defining species range limits is incomplete, especially for tropical species in the Global South. Human-driven threats to the survival of many taxa are increasing, particularly habitat loss and climate change. Identifying distributional range limits of at-risk and data-limited species using Species Distribution Models (SDMs) can thus inform spatial conservation planning to mitigate these threats. The Madagascar Peregrine Falcon Falco peregrinus radama is the resident sub-species of the Peregrine Falcon complex distributed across Madagascar, Mayotte, and the Comoros Islands. There are currently significant knowledge gaps regarding its distribution, habitat preferences, and population size. Here, we use penalized logistic regression and environmental ordination to identify Madagascar Peregrine Falcon habitat in both geographic and environmental space and propose a population size estimate based on inferred habitat. From the penalized logistic regression model, the core habitat area of the Madagascar Peregrine Falcon extends across the central and northern upland plateau of Madagascar with patchier habitat across coastal and low-elevation areas. Range-wide habitat use in both geographic and environmental space indicated positive associations with high elevation and aridity, coupled with high vegetation heterogeneity and >95% herbaceous landcover, but general avoidance of areas >30% cultivated land and >10% mosaic forest. Based on inferred high-class habitat from the penalized logistic regression model, we estimate this habitat area could potentially support a population size ranging between 150 and 300 pairs. Following IUCN Red List guidelines, this subspecies would be classed as ‘Vulnerable’ due to its small population size. Despite its potentially large range, the Madagascar Peregrine Falcon has specialised habitat requirements and would benefit from targeted conservation measures based on spatial models to maintain viable 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.

The status of the ‘Endangered’ Fuerteventura Stonechat Saxicola dacotiae, a western Palearctic single island endemic, was assessed 22 years after the first population estimate of 1,300–1,700 individuals was made by Bibby and Hill (1987). Using GIS and Distance Sampling methodologies, the population on Fuerteventura in 2008 was estimated at 1,035 birds (832–1,287) with the species more abundant on hillsides than in gullies. Within the island's three main massifs (i.e. north, west and south) the highest encounter rate was recorded in the northern massif. This study supports the category of ‘Endangered’ for this species, which does face the obvious threat from development, particularly in the south of the island. The species is also on the endangered list nationally (Spain) and in Europe but has not as yet been evaluated by the Canarian Government. I suggest, based on results of this study, that serious effort should be put in to improving knowledge of the distribution range of this endemic (either by modelling or by systematic visits to sites). An official monitoring programme should be developed and implemented with special attention paid to the three main mountain ranges of this island and particularly to the southern massif which is suffering the highest rate of habitat loss.

Species reintroductions can be used in conservation management to increase biodiversity and aid in restoring ecosystem function. For reintroductions to be successful, it is important to identify the conditions required to establish a viable population. We developed a demographic model using Vortex10, an individual-based simulation software, to assess the long-term consequences of different management interventions on the success of the recent reintroduction of the white stork, Ciconia ciconia, to the UK. Demographic data obtained from this reintroduced population were supplemented with information from western European populations to build the models. The impact of incorporating different management actions (e.g. supplementing with captive-bred juveniles, provision of nesting platforms, and habitat improvement/supplementary feeding) on the stochastic population growth rate was assessed. Survival rates also differ depending on an individual’s migratory strategy, hence we tested the impact of having different proportions of the population as residents or migrants. Our models showed that if the British stork population adopts a fully migratory strategy, with its associated higher mortality rates, i.e. all individuals migrating to southern Europe or northern Africa, increasing the supplementation rate would not lead to a positive population growth rate. However, management actions which increased the number of fledglings per nest generated a slight positive growth rate that led to a 54.3% increase in population size after 50 years and, when combining all three management options, the population grew by 378.3%. Alternatively, if a minimum of 9% of individuals overwintered in Britain, which is likely based on field observations and tracking data, a positive growth rate can be achieved without additional management due to this behaviour’s lower mortality rates. We conclude that the British white stork population will likely be viable in the long term, but these models and projections should be updated as more demographic data on this novel population become available.

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.

Although birds are among the best studied taxa, many of the globally threatened species lack the information required to fully assess their conservation status and needs. One such species is the Anjouan Scops Owl Otus capnodes which was presumed extinct until its rediscovery to science in 1992. Based on the limited extent and decline of the moist forests in the highlands of Anjouan in the Comoro Islands, a population size of only 100–200 pairs was estimated and the species was classified as ‘Critically Endangered’. The current study is the first comprehensive survey ever conducted on this species, and aimed to establish the current distribution and population size. Point counts with distance sampling were conducted across the agroforestry and forest zones of Anjouan in both a dry and wet season. A niche suitability model predicted the species distribution to be wider than expected with owls observed as low as 300 m altitude and in highly modified agroforestry habitats. However, the encounter rate in natural relatively undisturbed forest was significantly greater than in other habitats. The wider than expected geographic range of O. capnodes supports a possible downlisting of this species on the IUCN Red List to ‘Endangered’. Population size was found to be far greater than previously thought, at approximately 3,450 individual owls in the dry season and 5,450 in the wet season. These results show the importance of investing in robust surveys of poorly known and cryptic bird species, and provide up to date and important information for landscape scale conservation planning in the Comoros Islands.

Setting Favourable Reference Values (FRVs) can assist the definition of the conservation status of a species. FRVs may consider population, habitat, and range. FRVs can indicate a range of values for different parameters, which should allow the long-term persistence of a species/population. We propose a method for the definition of reference values for the habitat (FRV-H or HRV) of breeding bird species. HRV should cover habitat extent and quality, both required to ensure long-term persistence. Extent HRV should express a measure of suitable area, whereas quality HRV could be defined as the range of values for habitat variables known to affect habitat quality. To define an extent HRV, we built species distribution models (SDMs) and set extent HRV as the extent of potentially suitable habitat under a conservative approach. Quality HRV should refer to environmental determinants/correlates of occurrence and breeding success, and should be defined by the identification of the habitat factors affecting occurrence and reproduction. When habitat selection is adaptive, habitat suitability may approximate habitat quality, being correlated with breeding success. In that case, fine-scaled habitat/distribution models may be used to identify determinants/correlates of reproductive output, and such species-habitat relationships may help define quality HRV. We show examples using the Red-backed Shrike Lanius collurio as a model. The use of habitat selection models, which can be made spatially explicit generating distribution models, may assist the definition of both extension and quality HRVs. Species-habitat models can allow the individuation of factors and relative values affecting species occurrence/reproduction (quality HRV), and the definition of the spatial distribution and quantity of potentially suitable habitat (extent HRV). Our approach is one of the possible ones, aiming at finding a “suitable” trade-off between affordable data and scientific precision. HRVs should be used together with population and range FRVs to assess the status of a species/population.

The Hadejia-Nguru wetlands in north-east Nigeria are of international importance for resident and migratory Anatidae but the construction of large dams upstream seriously threatens their continued existence. An analysis of waterfowl census data collected over the period 1988 to 1998 inclusive demonstrated that the extent of flooding had no effect on the species richness of waterfowl but had a significant impact on total numbers. White-faced Whistling Duck Dendrocygna viduata and Garganey Anas querquedula in particular respond to changes in flood extent. The present practice of releasing water from upstream reservoirs should therefore be continued.

The Giant Ibis Pseudibis gigantea was formerly more widespread in mainland South-East Asia, being found in Thailand, Cambodia, Laos and Vietnam. However, it has always been scarce throughout its range and has declined dramatically over the past 50 years as a result of habitat destruction, disturbance and hunting. This paper documents the species's decline with a review of all previous records including the recent sightings between 1993 and 1995, and suggests conservation measures to be taken for its continued survival.

The incidental mortality of seabirds in fisheries remains a serious global concern. Obtaining unbiased and accurate estimates of bycatch rates is a priority for seabird bycatch mitigation and demographic research. For measuring the capture risk of seabird interactions in fisheries, the rate of carcass retrieval from hauled gear is commonly used. However, reliability can be limited by a lack of direct capture observations and the substantial pre-haul bycatch losses known to occur, meaning incidence of seabird bycatch is underestimated. To solve this problem, a new measure (bycatch vulnerability) that links an observed interaction directly to the underlying capture event is proposed to represent the capture risk of fishery interactions by seabirds. The new measure is not affected by subsequent bycatch loss. To illustrate how to estimate and analyse bycatch vulnerability, a case study based on a long-term dataset of seabird interactions and capture confirmation is provided. Bayesian modelling and hypothesis testing were conducted to identify important bycatch risk factors. Competition was found to play a central role in determining seabird bycatch vulnerability. More competitive environments were riskier for seabirds, and larger and thus more competitive species were more at risk than smaller sized and less competitive species. Species foraging behaviour also played a role. On the other hand, no additional effect of physical oceanic condition and spatio-temporal factors on bycatch vulnerability was detected. Bycatch vulnerability is recommended as a replacement for the commonly used bycatch rate or carcass retrieval rate to measure the capture risk of an interaction. Combined with a normalized contact rate, bycatch vulnerability offers an unbiased estimate of seabird bycatch rate in pelagic longline fisheries.

Herewith the UNEP/AEWA Secretariat gives a response to the paper by Vernon G. Thomas and Raimon Guitart entitled “Role of international conventions in promoting avian conservation through lead toxicosis: progression towards a non-toxic agenda”.

Since their description in the first half of the 20th century by M. A. Carriker, Bolivian Recurvebill Simoxenops striatus and Yungas Antwren Myrmotherula grisea have been regarded as extremely poorly known endemics of the Bolivian Yungas and adjacent humid foothill forests. They are considered ‘Vulnerable’ under the IUCN criteria of small population, predicted population decline (criterion C2a) and, in the case of Bolivian Recurvebill, small extent of occurrence (criteria B1a+b). Here we summarise the information published to date and present extensive new data on the distribution (including the first records for extreme southeast Peru), natural history, population size and conservation status of both species based on field work in the Bolivian Andes over the past 12 years. Both species primarily inhabit the understorey of primary and mid-aged to older regenerating forest and regularly join mixed-species foraging flocks of insectivorous birds. Bolivian Recurvebill has a strong preference for Guadua bamboo, but it is not an obligate bamboo specialist and persists at often much lower densities in forests without Guadua. Yungas Antwren seems to have a preference for dense, structurally complex understorey, often with Chusquea bamboo. Both species are distributed much more continuously at altitudes of mostly 600–1,500 m, occupy a greater variety of forest types (wet, humid, semi-deciduous forest) and have a much greater population size than previously thought. Consequently, none of the IUCN criteria currently used to assign ‘Vulnerable’ status to both species actually apply, and we recommend them to be downlisted to ‘Near Threatened’.

The Eastern Imperial Eagle (Aquila heliaca), a vulnerable and declining species, is widely but sparsely distributed throughout its range. Because much of that range extends through the Russian-speaking world, relatively little on the species has been published in English. The world's easternmost population of Eastern Imperial Eagles, at Lake Baikal, Russia, is particularly well studied and, because of recent rapid population declines, is of great conservation concern. Here, using a data set covering more than 20 years evaluated in the context of historical accounts published in Russian, we assess recent severe declines in this population and the subsequent changes in its conservation status. In intensively surveyed areas near Lake Baikal, numbers of territories occupied by eagles have declined by 80–100% in the past 20–40 years. Likewise, throughout the entire region, the average number of known occupied and breeding territories were both more than 40% lower in 1998–1999 than they were in 1982–1983. These data suggest severe long-term declines in the population of Baikal's Imperial Eagles. Because we observed only limited decreases in reproductive output, our interpretation of the patterns in these data is that mortality of non-breeding birds (wintering adults and all pre-adults) is the most likely cause for this decline. Addressing the causes of this decline is critical to protect this severely threatened population from extirpation.

Восточный могильник (Aquila heliaca), уязвимый и сокращающийся в численности вид, широко, но разрозненно распространен по своему ареалу. В связи с тем, что большая часть его ареала находится в пределах русскоговорящей части мира, относительно мало опубликовано по этому виду на английском языке. Самая восточная группировка могильника находится в Прибайкалье. Она изучена особенно хорошо и из-за быстрого сокращения популяции вызывает особую тревогу и озабоченность природоохранников. Используя более чем >20 летние данные, рассмотренные в контексте исторических сведений опубликованных по-русски, мы оцениваем недавнее серьёзное сокращение этой популяции и последующие изменения в её природоохранном статусе. На территориях, находящихся под интенсивным обследованием в Прибайкалье, количество участков занятых орлами сократилось на 80–100% за последние 20–40 лет. Таким же образом, во всем регионе, среднее количество известных занятых территорий и гнездовых участков в 1998–1999 было на >40% меньше по сравнению с 1982–1983. Эти данные свидетельствуют о серьёзном долговременном сокращении прибайкальской популяции могильника. В связи с тем, что мы наблюдали лишь незначительное снижение результатов размножения, наша интерпретация модели по этим данным приводит к выводу, что смертность неразмножающихся птиц (зимующих взрослых и неполовозрелых птиц) является наиболее вероятной причиной этого сокращения. Выявление причин произошедшего падения численности очень важно для сохранения этой угрожаемой популяции от полного вымирания.

Diagnosing the causes of population declines of highly endangered species is vital to ensure that appropriate conservation measures are undertaken. Although experiments can provide critical information on potential causes, these can be time consuming and costly, and so it is important to determine the most plausible hypothesis for such tests. The last wild population of the Critically Endangered Mariana Crow Corvus kubaryi has been declining rapidly on Rota in the Mariana Islands. Because nest predation by introduced rats Rattus spp. has been implicated in the declines of other Pacific island birds, we tested for a correlation between breeding success of Mariana Crows and abundance of rats R. diardii surrounding their nest sites. If rats are a contributing factor in this species’s decline, we predicted that breeding success would be lower in areas where rats were more abundant. In complete contrast to this prediction, we found that breeding success was significantly higher where rats were most abundant, suggesting that rats are unlikely to be a major driving force behind the decline in this species. The positive association between crow breeding success and rat abundance suggests these species may be responding to similar habitat needs or a shared predator. This study illustrates the importance of gathering sufficient knowledge on the ecology of a species prior to undertaking costly, logistically difficult and time consuming experiments.