Donald (2007) showed that the adult sex ratios of wild bird populations tended to be male-biased, and that this bias was stronger in threatened species than in those of least concern. Here we show that, in 2004, the world population of the Critically Endangered Raso Lark was 65 individuals, 70% of which were male (adult sex ratio 0.70). In 2008, the population numbered approximately 175 (including juveniles) and the adult sex ratio was 0.58. Both ratios were significantly different from parity. All adult females were observed to be both paired and holding a territory. The observations therefore support Donald’s (2007) suggestion that a shortage of females can be an important constraint on the growth of threatened bird populations, a constraint that needs attention in conservation planning.

Habitat loss, the primary driver for loss of biodiversity worldwide, is of special concern for species that have a small area of occurrence, such as those restricted to islands. The Forest Thrush Turdus lherminieri is a ‘Vulnerable’ (VU) species endemic to four islands in the Caribbean, and its population has declined dramatically over the past 15 years. Because this decline is poorly understood, we studied its habitat associations on Montserrat. We conducted three repeat point count surveys and measured forest structure and habitat at each of 88 randomly placed locations in the largest forest area remaining on the island. We related Forest Thrush abundance to habitat using binomial mixture models that account for imperfect detection. Detection probability was a function of survey time, survey date, location of the survey point, and wind. Local habitat structure had the greatest influence on Forest Thrush abundance, with birds being more abundant at mid-elevations under closed canopies. We conclude that the Forest Thrush prefers mature mesic and wet forests on Montserrat. Assuming similar habitat selection in the rest of its range, the species’s long-term future depends on good protection of these natural forests on all four islands where it occurs.

The Crested Argus Rheinardia ocellata nigrescens is endemic to Peninsular Malaysia and is threatened with extinction. It is known from elevations above 600 m and is limited to a few mountain ranges in Peninsular Malaysia. First described in 1902, this subspecies was only known from Gunung Tahan and Gunung Rabung for many years. Recent surveys have added several new sites: Gunung Mandi Angin and Gunung Gagau, Gunung Penumpu and Camp Kor. All known sites are in Taman Negara National Park.

Twenty Florida Snail Kite Rostrhamus sociabilis plumbeus nests in imminent danger of collapsing at four lakes in central Florida, U.S.A. during 1987-1993 were stabilized or artificially supported. Most nests (n=17, 85.0%) were in either cattail Typha spp. or bulrush Scirpus validus. Nine supported nests (45.0%) successfully fledged young; the remaining nests were either abandoned (n=8, 40.0%) or ultimately collapsed (n=3, 15.0%). The overall rate of 0.75 fledgling per nest for supported nests was similar to the 0.79 fledgling per nest for unaltered nests. If the 160 nests that collapsed during the study had been supported, 72 nests saved from collapsing could have produced an additional 54 fledgling kites. Nest support may be effective where kite populations are low or during drought conditions.

Megapodes: an action plan for their conservation 1995–1999) was published in 1995 by the Species Survival Commission of IUCN – The World Conservation Union. It is the twenty-eighth publication in its Action Plan series and the first for any group of birds. Action Plans published under the auspices of the Species Survival Commission are perceived as a means of making information on the status, threats and action required to safeguard species available to conservation planners and others in a position to take action. They are compiled by the appropriate taxon Specialist Group of the Species Survival Commission and their production and implementation is central to the Commission's activities. As well as the megapodes, Action Plans have recently been compiled for the partridges, quails, francolins, snowcocks and guineafowl, and for the pheasants. Stimulating interest in the conservation of these three groups of birds is the responsibility of three Specialist Groups which operate under the joint parentage of the World Pheasant Association, BirdLife International and the Species Survival Commission. The World Pheasant Association is the umbrella organization for five Galliformes Specialist Groups and was the driving force behind the production of these Action Plans, providing the means for the Specialist Groups to compile the information. This paper outlines the scope of these Action Plans and explains how they were compiled in the hope that this may assist the production of Action Plans for other bird groups.

The Dusky-legged Guan Penelope obscura is the southernmost species of the family Cracidae, reaching its southern distributional limit in the delta of the Paraná River. Habitat loss, together with uncontrolled harvest, has led to local-scale decreases or extirpation of the species, but no quantitative evaluation of habitat preferences has been made. We surveyed Dusky-legged Guans in the Delta del Paraná Biosphere Reserve, Argentina, by motorboat along 543.9 km of nine waterways during both January and July 2009 and used occupancy modelling to estimate habitat and seasonal effects on occupancy. Detectability was 21–22% on average and occupancy estimates were highly variable within habitats, but highest in secondary forest, followed by mature plantation, and lowest in occupied residences. There were no significant differences in occupancy or detectability among habitats or seasonally. There was a strong positive effect of length of riparian habitat segments on occupancy and detectability. Habitat management efforts should address increasing the suitability of mature plantation forest for guans by increasing their similarity to native forest in structure and composition. Furthermore, we illustrate that surveys by boat can be logistically effective for surveying cracids associated with riverine habitats and that it is important to account for incomplete detectability since in our case failing to do so would have underestimated occupancy by 78–79% on average. Given this, the use of commonly accepted methodologies for surveying cracids that do not account for incomplete detectability should be reconsidered and methodologies that can produce robust, reliable estimates applied.

The critically endangered Mariana Crow now exists in a single population on the island of Rota, Northern Mariana Islands. Targeted management requires an accurate measure of the population status of this species. In Mariana Crows the breeding population is both the easiest cohort to accurately survey and the most important segment of the population in terms of population recovery. The total number of Mariana Crow territorial pairs was estimated on the island of Rota using a direct count method, and total population size was calculated using a Chapman estimate. From September 2013 to April 2014, 46 crow pairs were found and up to an additional eight pairs were estimated in unsearched areas. The total population was estimated to be 178 individuals. This represents a 10–23% decline in pairs in the six years since 2007 and a 46–53% decline since 1998. This number is also considerably lower than the minimum 75 pairs recommended to maintain a viable population on Rota.

The Long-tailed Ground-roller (Uratelornis chimaera) is a globally Vulnerable, restricted-range species of dry forests in south-west Madagascar. We studied a population in 1997–2000, finding that nest-building was relatively synchronous and that pairs preferentially nested next to open areas, such as driveable tracks. By searching for trackside nests and for footprints, we conducted surveys throughout the known range of the species. Total transect coverage was 153 km, along which we encountered a minimum of 28 breeding pairs. By dividing the transects into 41 randomly distributed survey strips, each 1.2 km in length and 200 m broad, we intensively sampled an area of 9.84 km2. Using transect data, we made a tentative estimate of 5.7 mature adults km−2, from which we estimated a global population of 21,092 individuals, based on our calculation from satellite imagery that 3,706 km2 of suitable habitat remained. By comparing habitat data at points with and without ground-rollers we found that, contrary to previous statements, they prefer lower stature or degraded habitats, and have no direct association with the endemic cactus-like tree Didierea madagascariensis. We used a novel census technique to provide the first quantitative data on population size, population density, breeding behaviour and ecology in the Long-tailed Ground-roller, or any member of the family Brachypteraciidae, information that is crucial to the design of effective conservation programmes.

The Chocó-Tumbesian region of western Ecuador is one of the 25 global biodiversity hotspots harbouring high numbers of endemic species, which are heavily threatened by habitat loss and fragmentation. Moreover, ongoing climate change in the tropics drives species uphill as lower-lying areas are becoming constantly drier. Such upslope movement can pose major challenges for less mobile species, such as understorey birds which are confined to mature forests and unable to cross habitat gaps. Consequently, these species are threatened by a combination of upslope range shifts and forest fragmentation. In our study, we investigated population numbers and habitat requirements of the Ecuadorian Tapaculo Scytalopus robbinsi, which is endemic to the premontane cloud forests of south-western Ecuador. Comparing the microhabitat structure within territories with control sites revealed that Ecuadorian Tapaculos prefer old secondary forests. Moreover, connectivity between forest fragments was the strongest predictor of the presence of territories within them. We estimated the mean upslope shift of the distribution range as 100 m per decade and developed a model of habitat availability for the revised range. Extrapolating the number of territories from the study area to the distributional range of the Ecuadorian Tapaculo showed that the global population size is smaller than previously assumed. Our results suggest that the Ecuadorian Tapaculo is strongly affected by forest loss and degradation. Therefore, to prevent a continuing decline in population numbers or even extinction, conservation measures focusing on restoring connectivity between fragments and increasing habitat quality and quantity for the remaining populations need to be prioritised.

Taiwan has 145 breeding bird species, but so far no comprehensive attempt has been made to model their distributions. For the first time, we bring together various datasets to model the distributions of the 116 bird species with sufficient sampling coverage. We improved on previous limited modelling efforts by using ensemble modelling, based on five well-performing modelling approaches: multiple discriminant analysis, logistic regression, genetic algorithm for rule-set production, ecological niche factor analysis and maximum-entropy. We then used these ensemble models to improve our knowledge of the status of each bird species by (1) calculating each species’s coverage of Taiwan, (2) calculating each species’s coverage by Taiwan’s protected area network, and (3) comparing these two conservation-relevant measures with already established measures to highlight those species whose status may need to be reassessed. We categorised each species’s coverage of the entire study area as measured by their modelled distributions into four quartiles, thus establishing a new measure of rarity called ‘range quartile’ which we used to highlight the 22 species with a limited distribution on mainland Taiwan. We also calculated that overall, 29.8% of the distribution ranges of the 116 modelled species are covered by Taiwanese protected areas. We then identified those species whose status may need to be reassessed because of possible conflicts between the respective conservation-relevant measures. Thus we identified 10 species which are first-quartile species < 5% of whose distributions are protected, of which only five are considered threatened. We also identified another 12 species with limited distributions, 30 species with limited protection and 19 species whose status may need to be reassessed for various reasons. We recommend that range quartile and protected area coverage be incorporated into future assessments of the conservation status and protected area coverage of Taiwanese birds.

During 1998–2011, in an area of western Cyprus spanning about one-quarter of the global breeding range of the endemic Cyprus Warbler Sylvia melanothorax, the species declined at a rate of c.59% decade-1, suggesting that there is an urgent need to review its global conservation status. This decline has coincided with the recent, rapid colonisation of western Cyprus by the Sardinian Warbler S. melanocephala, whose numbers have increased substantially within the study area, as might be expected of a newly colonising breeding species. To identify possible causes of the Cyprus Warbler’s decline we compared its rate of change with measures of land-cover, vegetation density, altitude, rainfall and the presence of Sardinian Warblers at survey sites. The rate of decline in the Cyprus Warbler’s abundance was strongly correlated with land-cover and with the duration of site occupancy by Sardinian Warbler; Cyprus Warbler abundance had declined more steeply on sites colonised by Sardinian Warblers early in the survey period than on sites colonised later. Furthermore, on sites surveyed by BirdLife Cyprus in 2006–2014, Cyprus Warbler abundance had continued to decline significantly (also by c.59% decade-1) in western Cyprus, while Sardinian Warbler abundance had continued to increase. In contrast, Cyprus Warbler abundance showed no significant change in central and eastern Cyprus, where Sardinian Warblers were sparse or absent during the breeding season. These findings are consistent with at least two contrasting scenarios: that changes have occurred in land-cover or climatic conditions in Cyprus, to the detriment of Cyprus Warbler and to the benefit of Sardinian Warbler; or that in western Cyprus at least, the two species may compete for similar resources, despite a lack of evidence of this in an earlier, more detailed study. In either case, we suggest the need for a thorough, nationwide breeding survey of the two species.

The frequency and intensity of extreme weather events represent a threat for biological diversity and are expected to increase in many regions over the following decades due to climate change. Our current knowledge about the impact of extreme weather events on the population dynamics of bird species is very limited. Here, we evaluated the impact of an extreme winter snowstorm on the abundance of 14 populations of the threatened Dupont’s Lark Chersophilus duponti, a resident bird whose European population is restricted to Spain. We found a drastic and significant population decline in the next reproductive season following the extreme weather event. During the control period (2017–2020) the species suffered an overall annual decline of 19.4% (±5.0, SE). However, the overall annual decline after the storm was 67.6% (±9.4, period 2019–2021), with a mean decline of 66.5% (±15.9) for seven populations monitored both the year before and the year after the snowstorm (period 2020–2021). The snow covered the ground for over 10 days in central and eastern Spain, which together with a subsequent extreme cold wave could have reduced the species ability to find food resources and properly thermoregulate, forcing the species to move to unknown areas. Indeed a few days after the storm, several individuals were reported in areas typically avoided. Such displacements may increase the mortality risk for dispersing individuals, besides the direct effects of the extreme cold event, such as thermal challenges to energy balance or a reduced immune function. We discuss the potential role that extreme weather events may have on the population dynamics and conservation of the species.

The average population size of Capricorn Yellow Chat Epthianura crocea macgregori was estimated at 251 +/-31 (SE) by repeated surveys over seven years (2004–2010) using consistent search effort at known occupied sites. Because the survey period coincided with a mixture of dry and wet years (drought from 2004 to 2007 followed by flood rainfall in early 2008 and 2010), it is particularly valuable as a preliminary benchmark upon which to base management decisions. Most of the population (74.5%) was in the Broad Sound area in the north, with lower numbers in the Fitzroy River delta area in the south (22%) and at Curtis Island (3.5%). Sites on Torilla Plain in Broad Sound accounted for two-thirds of the estimated population, making it a priority for conservation efforts. Depending on habitat configuration, some Capricorn Yellow Chats showed a seasonal pattern of habitat use, moving from flooded breeding habitats as they dried to refuge sites such as salt fields or upper marine plains in the dry season; distances moved being < 10 km. Standard surveys from Torilla Plain showed that the chat count during a sequence of above-average rainfall years was almost double that of the average for drought years: 162 +/-28 (2008–2015) compared with 85 +/-15 (2004–2007) respectively. Low population size, large annual fluctuations in population with prior rainfall, rapid declines in low rainfall years, a fragmented distribution and almost half the population concentrated at one site point to a subspecies vulnerable to chance events. Increased climatic extremes predicted by climate change such as higher temperatures, evaporation rates, extended droughts and more intense rainfall events add to its vulnerability.

The Black-capped Petrel or Diablotin Pterodroma hasitata has a fragmented and declining population estimated at c.1,000 breeding pairs. On land, the species nests underground in steep ravines with dense understorey vegetation. The only confirmed breeding sites are located in the mountain ranges of Hispaniola in the Caribbean, where habitat loss and degradation are continuing threats. Other nesting populations may still remain undiscovered but, to locate them, laborious in situ nest searches must be conducted over expansive geographical areas. To focus nest-search efforts more efficiently, we analysed the environmental characteristics of Black-capped Petrel nesting habitat and modeled suitable habitat on Hispaniola using openly available environmental datasets. We used a univariate generalized linear model to compare the habitat characteristics of active Black-capped Petrel nests sites with those of potentially available sites (i.e. random pseudo-absences). Elevation, distance to coast, and the influence of tree cover and density emerged as important environmental variables. We then applied multivariate generalized linear models to these environmental variables that showed a significant relationship with petrel nesting activity. We used the top performing model of habitat suitability model to create maps of predicted suitability for Hispaniola. In addition to areas of known petrel activity, the model identified possible nesting areas for Black-capped Petrels in habitats not previously considered suitable. Based on model results, we estimated the total area of predicted suitable nesting habitat for Black-capped Petrels on Hispaniola and found that forest loss due to hurricanes, forest fires, and encroachment from agriculture had severely decreased availability of predicted suitable habitat between 2000 and 2018.

African White-backed Vultures were recently uplisted to ‘Critically Endangered’ by IUCN due to declines across their range. Poisoning is widely accepted as the major reason for these declines. Botswana supports a high number of this species (breeding pairs > c.1,200), but as yet no published information exists on their breeding success in the country. However, mass poisonings within Botswana and neighbouring countries have killed thousands of White-backed Vultures in recent years. We therefore expected that nesting numbers may have declined in this region if these poisoning events killed local breeding birds. We used information from aerial surveys conducted between 2006 and 2017 in Khwai and Linyanti, two important breeding areas for this species in north-central Botswana, to determine if there was any change in nesting numbers and breeding success of White-backed Vultures. Results showed an overall 53.5% decline in nesting numbers, with a greater decline in Linyanti than in Khwai. In both areas, breeding success was significantly lower in 2017 than it was 10 ten years earlier. We recommend that similar repeat surveys are continued to provide greater confidence in the trends of both nesting numbers and breeding performance. Population viability analysis suggested that if the productivity levels detected in 2017 were a true indication of current productivity levels for this population, and if recent high poisoning rates continue, this population could be extirpated from the area in the next 13 years.

Between April 2008 and July 2015, we conducted a total of 18 trips on five different side-haul trawlers fishing within the Argentine Exclusive Economic Zone, monitoring 486 hauls. We observed 100% of the hauls and monitored trawl cables for 136.7 hours, about 5% of the trawl effort, to identify the levels of seabird bycatch from net entanglements and collisions with trawl cables. A total of 35 net entanglements of White-chinned Petrels Procellaria aequinoctialis, Great Shearwaters Ardenna gravis, Black-browed Albatrosses Thalassarche melanophris and Southern Royal Albatross Diomedea epomophora were recorded, all of which occurred during the autumn and winter. Additionally, 656 seabird collisions against trawl cables were recorded including 39 heavy, 96 medium and 521 light. Further, we recorded nine Black-browed Albatrosses and two Great Shearwaters potentially dead. Although in the study fishery the number of deaths in the trawl cables could surpass the number of birds incidentally killed in nets, the mortality rate caused by the latter type of interaction far exceeds those observed in nets from other trawl fisheries operating in the Patagonian Shelf. Fortunately, 26% of the seabirds entangled in the net were recovered and released alive, which indicates that awareness and training in safe bird handling and release may improve captured seabird survival rates. The main objectives of this work is to highlight a little-studied source of seabird mortality by entanglement, to generate discussion on potential technical mitigation measures for side-haul trawl fisheries, and to propose crew training in safe handling and release of seabirds as an immediate mitigation measure.

The Rufous-throated Dipper Cinclus schulzi is endemic to the Southern Yungas of north-western Argentina and southern Bolivia. The species is categorised as ‘Vulnerable’ on the IUCN Red List on the basis of small population size and restricted range. The purpose of our study was to determine the distribution of potentially suitable habitat for the Rufous-throated Dipper, estimate its population size, and assess potential distribution within strict protected areas, in north-western Argentina. We surveyed 44 rivers in the Southern Yungas of Argentina from 2010 to 2013 to determine dipper density (i.e. the number of individuals detected per km surveyed). The dipper’s potential distribution was assessed using a maximum entropy modeling approach based on 31 occurrence points and eight bioclimatic and two topographic variables as predictors. The species is dependent on mountain forest rivers, so the potential distribution was restricted to rivers. We estimated dipper population size by multiplying density by the potential distribution along rivers. Finally, we calculated the extent of suitable habitat contained within the boundaries of Argentina´s National Parks. Dipper density was 0.94 ± 1.55 individuals/km. We estimate that within north-west Argentina there are ~2,815 km of river that are potential habitat, with an area of occupancy of 141 km2 and a population size of 2,657 ± 4,355 dippers. However, of this river extent, less than 5% is within National Parks. Our results highlight the need to create new and to enlarge existing National Parks that protect the potentially suitable habitat of the species. Although more information is needed for Bolivia, the country-level area of occupancy and population size of the dipper found in Argentina provides strong evidence that the IUCN Red List classification of this species as ‘Vulnerable’ is warranted.

Since i960 107 translocations of wild-caught Weka (genus Gallirallus) have occurred in New Zealand. Only four of these Weka liberations resulted in a population that persisted for more than 10 years and only one was successful on the North Island (the resultant population is now believed extinct). The reason for these failures was not known. In 1991 members of the Royal Forest and Bird Protection Society commenced breeding North Island Weka Gallirallus australis greyi in captivity for another liberation. Between 1992 and 1996 101 weka were released. We used radio telemetry to follow the fates of the first 17 Weka released in the Karangahake Gorge, near Paeroa, North Island, New Zealand to determine possible outcomes of the liberation. Only one of the 17 birds released survived until 242 days post release. Most newly released Weka were killed by predators, mainly dogs. Future Weka and flightless rail introductions should occur only in areas where predators are being removed to allow survival of released birds and production of young to exceed mortality.

Long-wattled Umbrellabirds Cephalopterus penduliger are restricted to the Chocó Biogeographical Region, an area with exceptional levels of avian diversity and endemism. Due to widespread habitat loss and hunting pressure, the species is considered globally Vulnerable and Endangered within Ecuador. Little is known of the species' basic biology. This paper presents data on the first confirmed nest recorded for the species. The nest was found in June 2002 atop a tree fern Cyathea sp. located in secondary forest near Mindo, north-west Ecuador, at 1,600 m in the subtropical zone of the Andean slope. Data collected during incubation and nestling provisioning suggest that females may be responsible for all parental care. At the nest, the female provided food an average of once per hour, and brought roughly twice as many invertebrate food items as vertebrate or regurgitated food items. A male was never seen at the nest. In addition to presenting data from the nest, we compare Long-wattled Umbrellabirds to congeners and discuss implications for the conservation of this species.

Mountain systems are often recognised as biodiversity hotspots; however, most montane forests are human-modified. Understanding the conservation value of human-modified forests is essential to mountain biodiversity conservation. In this study, mist-nets and point-counts were used to compare the bird communities of primary forests on ridges in the Ailao Mountains of Yunnan, China, and secondary forests, firewood forests, and pine plantations in nearby lower elevation zones. We found that community turnover among habitats was very high using both methods. Although the percentage of forest interior species and insectivores in each habitat was higher in the primary forests than in the human-modified forests, relatively high percentages of forest interior species and insectivores were recorded in the human-modified forests. Moreover, many bird species, forest interior species, insectivores and babblers were only recorded in the human-modified forests. Our study indicated that the primary forests are important for sustaining mountain bird diversity. However, given that primary forests are restricted to ridges, secondary forests, firewood forests, and pine plantations at lower elevations also play important roles in bird conservation in mountainous regions by increasing landscape diversity and partially offsetting species loss from primary forests. Therefore, conservation efforts should also be concentrated on human-modified forests at lower elevations in mountainous regions in south-west China.