The declining-population paradigm holds that small populations are particularly vulnerable to anthropogenic influences such as habitat destruction, pollution and species introductions. While the effects of particular stressors, such as parasitism, may be unimportant in a large, healthy population, they can be serious and even devastating in situations characterised by a restricted geographic range, or by fragmented or reduced population sizes. We apply this idea to nest parasitism of threatened Neotropical bird species that exist in small populations, focusing on dipteran nest parasites in the genus Philornis. We review the literature on Philornis parasitism exerting negative pressure on bird populations that have become small and isolated due to human actions and present a new case of Philornis parasitism of a threatened hummingbird species. Our aim is to raise awareness about the exacerbating effect that nest parasites can have on small and declining bird populations; especially when biological information is scarce. The five reviewed cases involve two species of Darwin’s Finches in the Galápagos Islands attacked by the invasive P. downsi, two species of hawks on islands in the Caribbean attacked by the native P. pici and P. obscura, and the Yellow Cardinal Gubernatrix cristata in southern South America attacked by an unknown Philornis species. We also present new documentation of parasitism of a threatened hummingbird species in mainland Ecuador by an unidentified Philornis species. We recommend more field studies to determine the presence of nest parasites in bird populations worldwide to improve understanding how nest parasites affect bird fitness and population viability and to allow time to act in advance if needed. Parasitism by Philornis may represent a severe mortality factor in most already threatened bird species, putting them at greater risk of extinction. Therefore, parasitism management should be included in all threatened species recovery plans.

United Arab Emirates is an important range country for the ‘Vulnerable’ Socotra Cormorant Phalacrocorax nigrogularis and Abu Dhabi Emirate holds most of the remaining breeding colonies. Emirate-wide monitoring of all breeding colonies was undertaken annually for 11 breeding seasons from 2006–2007 to 2016–2017 to monitor the status of breeding colonies and estimate the nesting population. Breeding was recorded in 10 colonies that were used intermittently with an average of four (± 1.3 SD) colonies active each year. The highest number of eight active colonies was recorded in 2016–2017. Establishment of two new breeding colonies on Butinah and Digala in 2016–2017 and recolonisation of three previously inactive colonies during the monitoring period emphasised the ability of the species to relocate and colonise suitable sites. Continued threats at some breeding colonies caused abandonment and subsequent relocation, resulting in a gradual shift of breeding colonies to safer areas. Presently, most of the breeding sites (62%) with an increased number of breeding birds are found in colonies with restricted access. The Emirate-wide nesting population witnessed a 10-fold increase in the last decade; after an initial decline in 2006–2007 it increased from about 5,000 pairs in 2007–2008 to nearly 52,000 nesting pairs in 2016–2017. Combined with the nesting population from the Siniya colony, the overall UAE nesting population is estimated at 60,000 to 70,000 pairs, nearly half of the global breeding population. Further augmentation of the current breeding numbers is possible if breeding colonies remain safe from human disturbance and invasive predators. For long-term conservation of Socotra Cormorant, protection of all remaining colony sites, including inactive ones, is important in addition to minimising disturbance along with widespread public awareness to change the people’s perception of the species as a competitor to commercial fisheries.

The Japanese Murrelet Synthliboramphus wumizusume is a rare, globally ‘Vulnerable’ seabird, endemic to Japan and South Korea. However, little is known of its at-sea distribution, habitat or threats. We conducted several years of at-sea surveys around Japan to model Japanese Murrelet density in relation to habitat parameters, and make spatial predictions to assess the adequacy of the current Japanese marine Important Bird and Biodiversity Area (IBA) network for the species. During a five-year period, 3,485 km of at-sea surveys recorded 3,161 Japanese Murrelets around four breeding locations. Maximum murrelet group size was 90 individuals with a mean group size of 2.9 ± 4.2 individuals. Models of Japanese Murrelet at-sea density around the two largest breeding locations predicted that almost all murrelets occur within 30 km of the breeding colony and most within 10 km. Murrelets were predicted closer to the colony in May than in April and closer to the colony at a neritic colony than at an offshore island colony. Additionally, murrelets breeding on an offshore island colony also commuted to mainland neritic habitat for foraging. The marine habitat used by Japanese Murrelets differed between each of the four surveyed colonies, however oceanographic variables offered little explanatory power in models. Models with colony, month and year generated four foraging radii (9–39 km wide) containing murrelet densities of > 0.5 birds/km2. Using these radii the Japanese marine IBA network was found to capture between 95% and 25% of Japanese Murrelet at-sea habitat while breeding and appears appropriately configured to protect near-colony murrelet distributions. Given the range of marine habitats that breeding murrelets inhabit, our simple models offer an applicable method for predicting to unsampled colonies and generating ecologically-informed seaward extension radii. However, data on colony populations and further at-sea surveys are necessary to refine models and improve predictions.

The Chinese Crested Tern Thalasseus bernsteini (CCT) is likely the most critically endangered seabird species in Asia. The Matsu, Penghu, Jiushan, and Wuzhishan Archipelagos along the China coastline, plus Yeonggwang County in South Korea, are the five areas where this species is currently confirmed to breed. According to census and historical data collected in the Matsu Archipelago from 2004 to 2017, there was an average of 10 ± 4 adult CCT individuals at the Matsu Islands Tern Refuge (MITR) during the breeding season. CCT nested only in association with Greater Crested Terns T. bergii (GCT) among seven protected islands in the MITR, and the numbers of observed breeding individuals of the two species were positively correlated (r = 0.59, P < 0.001). We used generalized linear models to examine the effects of chlorophyll-a concentrations in surrounding marine habitats, typhoon frequency, and in-season shifts in colony location on inter-annual variation in numbers of breeding individuals and productivity (chick:adult ratios) of both CCT and GCT at the MITR from 2004 to 2017. Average chlorophyll-a concentrations during July-August obtained from the MODIS satellite were positively correlated with the annual maximum number of GCT at the MITR, but not that of CCT. In addition, we found that nest abandonment events during early incubation at the mixed-species colonies were associated with in-season shifts in colony location and delayed nesting chronology, thereby extending nesting into the peak typhoon season during July and August. The effects of in-season colony shifts on nesting chronology and the additive effects of typhoons caused a significant decline in CCT breeding success during the study period. We propose more rigorous monitoring to ascertain the root causes of in-season colony shifts of terns and then determine possible solutions. Additionally, creating educational programmes to increase public awareness towards seabird conservation could prove beneficial.

Timneh Parrots Psittacus timneh are a threatened species endemic to the moist forests of West Africa. In 2016, they were categorised as ‘Endangered’ on the IUCN Red List, due to suspected rapid population declines driven by habitat loss and heavy trapping for the pet trade. Systematic assessments of the status of populations are lacking for much of their range and addressing this knowledge shortfall has been identified as a priority action. We combined multiple research approaches to investigate the distribution, trends and threats to Timneh Parrots in Guinea Bissau, where the species is restricted to the islands of the Bijagós archipelago and Pecixe. Direct observational surveys were conducted along line transects on 19 islands. A total of 69 groups were observed on eight of these islands, with the majority (78%) seen on just two islands. Forty-two interviews were conducted with local community members on 24 islands. Interviewees reported the species to occur on 20 islands and that populations are generally perceived to have declined in recent decades. Based on these findings and existing data we conclude that Timneh Parrots occur on 22 of the 32 islands considered and estimate the national population in Guinea-Bissau to be in the order of several hundred individuals, with perhaps half of the parrots occurring on the islands of João Vieira and Meio. Investigations into the factors linked to inter-island variation in parrot densities indicate that densities are highest on the islands which are most remote from permanent human settlements. These findings suggest that human activities including habitat modification and trapping have been important in driving population declines in Guinea-Bissau. We consider the implications of these findings for the conservation of Timneh Parrots.

The near-threatened Lilian’s Lovebird Agapornis lilianae is a small parrot endemic to the Zambezi basin in south-east Africa. The species has a fragmented distribution predominantly within mopane woodlands and is widely referred to as a mopane specialist. The harvesting of mopane trees for charcoal production and timber are having widespread impacts on this woodland habitat, raising concerns over its capacity to support biodiversity. This study aimed to understand the key drivers determining the occurrence of Lilian’s Lovebird in the mopane woodlands of Zambia, focusing particularly on aspects of woodland structure, including the size and density of trees. We used a MaxEnt species distribution model based on historical species occurrence data, to inform selection of 116 survey plots in the Luangwa, Luano and Zambezi valleys. Each plot was sampled for Lilian’s Lovebirds and woodland structure described. Occurrence of Lilian’s Lovebird was found to be positively associated with the size of mopane trees (both height and diameter at breast height) suggesting that large ‘cathedral’ mopane trees provide a key resource for the species and that conservation efforts should focus on the protection of sites containing large trees. No Lilian’s Lovebirds were recorded in areas where they previously occurred to the west of Lower Zambezi National Park, and there was an absence of ‘cathedral’ mopane habitat in this area.

An analysis of the extent of overlap between habitats of the Egyptian Vulture Neophron percnopterus during summer and winter in Iran, and Iranian protected areas, discovered slight overlap between the two. Our study aimed to survey suitable habitats of the Egyptian Vulture during summer and winter in Iran using MaxEnt, a species distribution modelling method, and compare the results with the locations and span of protected areas. Model fitness was assessed using the area under the ROC-plot and True Skill Statistics. We found that habitat suitability in Iran varies for the Egyptian Vulture during summer and winter. Summer visitors are scattered in the north and west of Iran, concentrated along the Zagros and Alborz mountain ranges. Winter visitors and residents are scattered in coastal areas in the south. Habitat protection for winter visitors was the greatest, with 10% of suitable habitat covered, while less than 10% of suitable habitat for residents and summer visitors fell within protected areas. The Egyptian Vulture is categorised as ‘Endangered’ on the IUCN Red List. Different environmental factors influence the suitability of habitat for the species. While some factors such as NDVI and anthropogenic disturbance influence all visitors in a similar way, the effects of others such as elevation and distance from protected areas vary for summer and winter visitors. Since designation of protected areas in Iran is mainly determined by the distribution of mammal species, protection of bird habitats is often overlooked. Suitable habitat for the species should be considered when selecting protected areas in future.

Human-wildlife conflicts are often partly due to biased human perceptions about the real damage caused by wildlife. While Griffon Vultures Gyps fulvus are obligate scavengers, 156 complaint reports about vultures attacking livestock were officially recorded over eight years (2007–2014) in France. We investigated whether this conflict could be explained by a change in vulture behaviour, or by a biased perception by farmers. If vultures became predators, as a consequence of density-dependent processes, we predicted that reports would concern mostly ante-mortem consumption of healthy livestock and would be temporally and spatially correlated to vulture population size and space use. Under the hypothesis of perception bias of farmers, we predicted that reports would concern mostly post-mortem consumption, and would be more numerous in areas where farmers are less familiar with vultures and where herds are less attended by shepherds. The spatio-temporal distribution of reports was not correlated with the vulture’s population trend and was not centred on the core area of vulture home range. In 67% of reports, vultures consumed post-mortem an animal that had died for other reasons. In 18% of reports, vultures consumed ante-mortem an animal that was immobile and close to death before vulture arrival. The fact that 90% of complaining farmers did not own vulture supplementary feeding stations and that 40% of these farms were located outside protected areas (where most education programmes take place) suggests that most farmers had little familiarity or personal knowledge of vultures. There was no shepherd witness present in 95% of the reports. Therefore, the hypothesis of a perception bias due to lack of knowledge was most likely to explain this vulture-livestock conflict rather than the hypothesis of a recent change in vulture feeding behaviour. Environmental education should be better included in conservation programmes and enhanced in areas where vultures are expanding to recolonise their former distribution range.

The ‘Vulnerable’ Swinhoe’s Rail Coturnicops exquisitus is believed to occur in only two regions in Russia’s Far East and China’s Heilongjiang province, separated by more than 1,000 km. Recent observations suggest that the Amur region, situated between the two known populations, might be inhabited by this secretive species as well. As the species is rather similar in appearance and field characteristics to its Nearctic sister taxon, the Yellow Rail C. noveboracensis, and almost all field records relate to flushed individuals in flight, we aimed to complement the field observations by genetic evidence. Samples were obtained from four individuals and one eggshell and their mitochondrial cytochrome b genes were amplified and sequenced. The genetic analyses unequivocally confirmed that swab samples and eggshell were attributable to Swinhoe’s Rail, thus constituting the first known breeding record of this species for 110 years. It is therefore likely that the individuals observed in the field also belonged to this species. It seems possible that Swinhoe’s Rail is more widely distributed in the Amur region and was overlooked in the past, possibly due to a misleading description of its calls in the literature.

The ‘Critically Endangered’ White-winged Flufftail Sarothrura ayresi is regarded as one of the rarest and most threatened rallids in Africa. Due to the species’ low density, habitat preference, cryptic colouration, elusive behaviour and lack of auditory cues has resulted in it being one of the most challenging species to survey using traditional methods such as auditory surveys and rope dragging. Numerous data deficiencies exist regarding facets of the species’ ecology, distribution, habitat-use and population status. A stratified array of nine camera localities was used within high-altitude palustrine wetland habitat to ascertain if this non-invasive technique could successfully document the first estimate of site occupancy, fine scale habitat use and activity patterns of this very rare species. Our study accumulated a total of 626 camera days and eight independent sightings of White-winged Flufftail across the respective austral summer season. Furthermore, our study confirms the applicability of camera trapping to other rare and elusive rallid species. Our results confirm that White-winged Flufftail is a low-density habitat specialist species, with site occupancy influenced positively by basal and canopy vegetation cover and detection probability influenced negatively by water depth within associated wetland habitats. Activity pattern analyses displayed that peak activity occurred at dawn and dusk, which yielded the highest degree of activity overlap with the only other migratory rallid recorded, Spotted Crake Porzana prozana. Our study also recorded the first apparent territorial display behaviour noted for the species. Our study supports the need for conservation initiatives focused on securing contiguous sections of suitable wetland habitat in order to accommodate the persistence of this globally threatened species.

The north-west European population of Bewick’s Swan Cygnus columbianus bewickii declined by 38% between 1995 and 2010 and is listed as ‘Endangered’ on the European Red List of birds. Here, we combined information on food resources within the landscape with long-term data on swan numbers, habitat use, behaviour and two complementary measures of body condition, to examine whether changes in food type and availability have influenced the Bewick’s Swan’s use of their main wintering site in the UK, the Ouse Washes and surrounding fens. Maximum number of Bewick’s Swans rose from 620 in winter 1958/59 to a high of 7,491 in winter 2004/05, before falling to 1,073 birds in winter 2013/14. Between winters 1958/59 and 2014/15 the Ouse Washes supported between 0.5 and 37.9 % of the total population wintering in north-west Europe (mean ± 95 % CI = 18.1 ± 2.4 %). Swans fed on agricultural crops, shifting from post-harvest remains of root crops (e.g. sugar beet and potatoes) in November and December to winter-sown cereals (e.g. wheat) in January and February. Inter-annual variation in the area cultivated for these crops did not result in changes in the peak numbers of swans occurring on the Ouse Washes. Behavioural and body condition data indicated that food supplies on the Ouse Washes and surrounding fens remain adequate to allow the birds to gain and maintain good body condition throughout winter with no increase in foraging effort. Our findings suggest that the recent decline in numbers of Bewick’s Swans at this internationally important site was not linked to inadequate food resources.