The Bare-throated Tiger-Heron (Tigrisoma mexicanum) is a widespread Neotropical heron generally regarded as a generalist predator whose diet consists primarily of fish and large invertebrates. Amphibians, reptiles and a small rodent have also been reported as prey; however, no previous records exist of avian prey consumption by this species. Here, we document the first known record of a bird in the diet of the Bare-throated Tiger-Heron: a Great Kiskadee (Pitangus sulphuratus) in the Tropical Dry Forest of Costa Rica. The observation was made at an artificial water reservoir during the dry season, a period when water scarcity concentrates wildlife around permanent water sources. During the event, the heron repeatedly immersed the avian prey in water prior to consumption, a prey-handling behavior consistent with dunking and not previously reported for this species. This record expands the known dietary breadth and behavioral repertoire of T. mexicanum and underscores the importance of detailed natural history observations for documenting rare or overlooked ecological interactions.
This study examines the key threats facing overwintering Demoiselle (Grus virgo) and Common (Grus grus) Cranes along the Indus Flyway in District Bhakkar, Punjab, Pakistan. Field surveys conducted from September 2023 to March 2024 recorded 212 cranes that were either killed or captured. These incidents were primarily associated with household consumption by local residents (61%). A considerable proportion involved live capture for illegal trade and domestication (29%), while a smaller fraction was attributed to recreational sport hunting by visiting hunters (10%). Land-use analysis from 2000 to 2024 documented substantial land cover changes across District Bhakkar, including 1,333 km2 of urban expansion, fluctuating vegetation cover, and a critical wetland loss of approximately 75% (from 187 km2 to 46 km2) over the study period. Utility line collisions further contributed to crane mortality, with three Demoiselle Crane carcasses recorded along a 20 km survey route. These findings highlight the urgent need for stronger anti-poaching enforcement, wetland habitat restoration, and power line mitigation measures to safeguard migratory cranes along this critical corridor.
Understanding the dietary ecology of colonially breeding waterbirds is essential for evaluating reproductive success and habitat quality. We investigated the dietary composition of the Straw-necked Ibis (Threskiornis spinicollis) during a large breeding event in the Lowbidgee floodplain, Australia, using non-invasive methods. Prey items were identified visually from scat and regurgitate samples and complemented with stable isotope analysis (δ13C and δ15N) of scats and chick feathers to assess both short-term and assimilated diet. Samples were collected across ten time points throughout the breeding period. Orthoptera and Coleoptera dominated the diet, comprising over 87% of prey items, with consistent contributions supported by both visual and isotopic analyses. Mixed models indicated similar dietary composition across sample types, with minor contributions from other taxa. Our results demonstrate the robustness of combining visual and stable isotope approaches to assess diet in colonial waterbirds. The dominance of high-quality invertebrate prey highlights the importance of prey availability for sustaining large breeding colonies in dynamic floodplain environments.
The timing of the start of the annual reoccupation of Kittiwake colonies is an important ecological variable, but is poorly known because it is brief, involves few individuals and occurs in the early part of the year. A method for the accurate determining of the date of first arrival was developed and then used in two colonies in NE England over more than 50 years. It resulted in the recognition of large differences in the date of return, both within and between the colonies. The day that the first Kittiwakes landed on a nest site after a long period away was restricted to the morning and lasted for less than an hour, and involved a very small number of old individuals. The first returning birds first formed a raft on the sea about 100m off the colony and made brief visits passing close to the nesting cliffs before landing briefly on nests sites for the first time. Birds then returned to the colony daily but it was always deserted overnight until mid-April. First returning females were the first to lay eggs and laying was one day earlier for each four days that their return date was advanced.
Large, freshwater birds can be highly mobile, revealing important linkages between wetland systems. We sought to overview the present scientific knowledge on the movements of 34 large, freshwater bird species in Africa using a systematic literature review and summaries of ringing data. Our literature search found only 28 publications on the movement of our focal species, most of which were of European origin. Only eight species in 10 publications have been tracked using telemetry technology, and only four of these studies were African-based. We found that ringing in Europe has contributed substantially to an understanding of movement, possibly because of more directed colour marking, whereas movements of only a few species in southern Africa have been sufficiently elucidated from ringing. Ringing data in southern Africa was biased toward South Africa, and most waterbirds were ringed prior to the year 2000. Overall, the knowledge of waterbird movement in Africa, particularly southern Africa, has advanced little in decades. Ringing remains an important tool for research, but widely available telemetry technology must be applied to waterbirds for effective species-specific habitat conservation. However, funding and skills capacity are significant hurdles that must be addressed to overcome the scientific shortcomings highlighted in this study.
Seabirds are globally declining, and accurate surveys are essential in determining breeding population size. We estimated the breeding population of globally vulnerable Socotra Cormorants (Phalacrocorax nigrogularis) nesting on Rubud Al Sharqiyah, Hawar Islands, Bahrain. Direct ground counts were conducted in 05 November, 2023. A drone was used to take aerial photos on 20 November, 2023. Nests were either counted from the images using DotDotGoose or using an empirical threshold method. Ground counts totaled 17,108 ± 135 breeding pairs (b.p.), which was higher because they were done at peak nesting. Manual counts yielded 12,762 b.p., while the empirical threshold method yielded 11,640 b.p. The estimate using the manual count method was about 9% higher compared to the empirical threshold method, which is acceptable considering that it took six hours to complete manual counts compared to just 20 minutes for the empirical threshold method. Annual monitoring of all sites at peak nesting is urgently needed to better understand breeding and distribution patterns. The empirical threshold method offers a convenient way to efficiently count nesting birds from aerial images. This is urgently needed for transboundary conservation planning of the species across the region.
Cuba has one of the most important populations of American Flamingo (Phoenicopterus ruber) in the Caribbean region. However, current status and trends of the species have not been documented. The American Flamingo is a coastal habitat-specialist, increasing its vulnerability to habitat loss and climate change. It is also sensitive to disturbance and hydrological conditions. This study updates population trends of American Flamingo in Cuba, identifies and documents current and historical foraging and reproduction sites in the last 40 years, and provides an updated population size. We identified 48 foraging sites and nine breeding sites. The major foraging sites for American Flamingos were the faunal refuges R & imath;o Maximo, Tunas de Zaza, and Delta del Cauto. Currently, Delta del Cauto is the only documented nesting site. We estimate that the current number of American Flamingo in Cuba is about 64,000-87,000 individuals. We conclude that while Cuba still has a healthy flamingo population, the number of nests has declined drastically over the last 10 years, with 80% of reported sites having been abandoned. Our results provide information needed for improved management for this species in Cuba and the Caribbean and highlights the urgent need of nesting site conservation. Received 26 Oct 2024, accepted 27 Nov 2025.
The Salton Sea, a saline lake ecosystem in southern California that is critical for birds along the Pacific migratory pathway, is rapidly changing due to changes in water use and supply. This shrinking Sea supports over 300 species of birds and millions of migratory birds annually. Reduced water inflows since 2017 have lowered water levels and increased salinity, driving ecological change, yet the impacts to birds remain largely unexamined. We analyzed bird population trends (2016-2023), changes in the extent of preferred habitats under different water management regimes, the expansion of emerging vegetation on exposed lakebed, water quality, and macroinvertebrate diversity. Bird population trends reveal both winners and losers: populations of Northern Shovelers, Least and Western Sandpipers, and Black-necked Stilts increased, while populations of American White Pelicans, nonbreeding American Avocets, Double-crested Cormorants, and Ruddy Ducks declined. Increasing shorebird population trends aligned with the expansion of emerging wetland vegetation on exposed lakebed, while decreasing trends in deep water dependent species aligned with the loss of areas of preferred deep-water habitat. Water quality was associated with waterbird abundance, but the effect of biogeochemistry on birds and their prey are not well understood and warrant further research. These findings inform strategic management efforts to sustain and restore habitats at the Salton Sea, with the goal of achieving positive outcomes for birds as wetland and saline habitats across the Western United States remain threatened. Received 8 May 2025, accepted 4 Dec 2025.
Barrier island habitats are increasingly threatened by climate change, with potential consequences for the breeding success and habitat quality of beach-nesting birds. Understanding fine-scale habitat requirements is important for identifying risks and managing these environments to support reproductive success. We evaluated two key habitat features, vegetation density and elevation, to understand their influence on American Oystercatcher (Haematopus palliatus) nest-site selection, hatching success, and fledging success on two Virginia (U.S.A.) barrier islands (Assateague and Assawoman Island). Using long-term nest monitoring data (2007-2022) and three years of remotely sensed elevation and vegetation data (2015, 2016, and 2021), we found that American Oystercatchers consistently preferred nest sites with lower vegetation density and at higher elevation. However, neither factor predicted hatching or fledging success. These results suggest that vegetation encroachment may contribute to population declines not by reducing reproductive output directly, but by limiting the availability of suitable nesting habitat. Vegetation nonetheless plays a key role in stabilizing high-elevation dune systems. Effective beach management should prioritize the preservation and creation of sparsely vegetated, elevated sites to maintain nest-site availability under changing coastal conditions. Received 27 Feb 2025, accepted 09 Oct 2025.
To identify the key ecological factors influencing the foraging site selection of Black Storks (Ciconia nigra), a field survey was conducted in the Heihe Wetland, Zhangye, Gansu Province, China, during the autumn of 2018. Environmental variables, waterbird diversity, and community structure were analyzed using principal component analysis and a generalized linear model. Black Storks preferred reservoirs and river channels far from urban areas, with minimal human disturbance, low population density, and limited transportation access. However, they were significantly attracted to reservoir aquaculture and autumn water drainage for fishing operations, and to fish ponds near urban areas with minimal disturbance. Waterbird species richness, abundance, diversity, and the population size of dominant species were significantly higher in areas where Black Storks were present (P < 0.05). The linear model demonstrated strong predictive accuracy for Black Stork distribution, and principal component analysis revealed significant differences in environmental and community structure differences between areas with and without Black Storks. The presence of Black Storks and of certain other waterbird species were strongly correlated. These findings suggest that conservation management efforts should promote aquaculture and autumn water drainage to enhance foraging and roosting opportunities for migrating Black Storks.
is an important component of population ecology but has been little studied for many species. The Reddish Egret (Egretta rufescens) is a "near threatened" species worldwide and is under "special protection" in Mexico due to its small population size. The mangrove ecosystems in which it lives have declined in Mexico. Therefore, the aim of this study was to evaluate the nesting success, survival, and ecological factors associated with the breeding success of this species on Isla Pajaros, Oaxaca-Chiapas. An intensive search and monitoring for Reddish Egret nests was conducted from March to June 2024. The nests were recorded from the presence of the eggs until the fledglings fledged and variables associated with the nest (vegetation cover over the nest, location and position of the nest, and mortality). A total of 217 nests and 357 eggs were recorded. Hatching success was 15.13% (n = 54) and nesting success was 9.26% (n = five). Survival probability was 0.15 during incubation, 0.59 during chick growth, 0.31 during the pre-fledgling period and 0.09 during fledgling. The factor that determined nesting success was mortality. Nesting success of the Reddish Egret on Isla Pajaros was low, mainly due to mortality from egg and nestling predation. Received 29 Mar 2025, accepted 24 Nov 2025.
On May 5, 2023, three individuals of the Asian Openbill (Anastomus oscitans) were observed in flight near the Ahmad Yani Airport area, Semarang, Central Java. Since then, a total of nine sightings of this species has been documented. These findings provide information of range expansion for the Asian Openbill, which was previously only known in Indonesia from Sumatra as a visitor. Received 30 Nov 2024, accepted 20 Oct 2025.
site fidelity is a critical aspect of avian breeding behaviour, influencing reproductive success and population dynamics. This study presents preliminary evidence of nest site fidelity in the Ibisbill (Ibidorhyn-cha struthersii), a monogamous wader inhabiting riverine habitats of the Kashmir Himalayan region. Using leg flags, three individuals were tracked across two major rivers from February 2023 to May 2024. All tagged birds returned to the same nesting sites used in the previous breeding season, suggesting a possible tendency toward nest site fidelity over a short time frame. While fidelity may enhance breeding success through environmental familiarity, the implications of this behaviour for long-term recruitment or ecological risk requires extended studies across years and sites. We emphasize that conclusions regarding ecological traps or conservation planning should be drawn cautiously and only after longer-term, larger-scale research. Received 1 Aug 2024, accepted 20 Oct 2025.
King Rails (Rallus elegans) are secretive, obligate freshwater marsh birds. King Rail populations have declined range-wide, heightening concern for their persistence and leading to increased need for conservation measures on public lands. Freshwater coastal marshes were surveyed within a similar to 30 km radius of a well-studied breeding population on a national wildlife refuge. We used standardized broadcasts of species-specific calls to detect King Rails. Vegetation surveys were conducted to estimate wetland cover types and habitat structure. Model selection was conducted to identify factors that predict occupancy and abundance. King Rail occupancy and abundance was positively related to wetland management and negatively related to presence of woody vegetation. Based on a Royle-Nichols model, the number of breeding individuals among 58 plots (similar to 730 ha total) was estimated to be 437 +/- 218. Mean abundance and occupancy probabilities were higher at sites with more than ten years of management to maintain emergent marsh in an early successional state. A relatively stable breeding population of King Rails is resident in this region. Wetland management, primarily consisting of prescribed burns, has likely contributed to their success here. Sea level rise and salt-water intrusion threaten these marshes, highlighting the importance of monitoring King Rail populations to ensure their continued survival.
Dot-winged Crake (Laterallus spilopterus) is a wetland specialist with a highly restricted range in South America, reliant on environments increasingly threatened by habitat loss, urbanization, and climate change. This study used ecological modeling to analyze its current distribution, project future range shifts under varying climate scenarios, and identify key environmental drivers of habitat suitability. Occurrence data from the Global Biodiversity Information Facility (GBIF), supplemented by historical synonyms and literature records, underwent rigorous cleaning to remove duplicates, imprecise coordinates, and spatial autocorrelation. Eight bioclimatic variables with low multicollinearity were selected using VIF analysis and incorporated into MAXENT habitat suitability models. Current habitat suitability estimates range between 395,632.5 km(2) and 167,502.5 km(2). Future projections under climate change scenarios indicate severe range contractions, particularly in southern Brazil, Uruguay, and northern Argentina, with over 50% loss anticipated by 2061-2080 under the most pessimistic scenario. Nonetheless, potential expansions were identified along the Chilean coast, suggesting recent range shifts influenced by changing climatic conditions or previously undetected populations. The findings highlight the Dot-winged Crake's vulnerability to climate change and anthropogenic pressures, with key environmental dependencies including water range contractions highlight the urgent need for adaptive conservation strategies. The recent detections in central Chile suggest opportunities to investigate potential range expansions and population dynamics, critical for informed conservation efforts. Collaborative strategies and enhanced ecological understanding are essential to secure the long-term survival of this threatened species. Received 29 Mar 2025, accepted 4 Nov 2025.
islands in Virginia, U.S.A. support the most breeding American Oystercatchers (Haematopus palliatus) throughout their range; however reproductive success remains low. This study focused on how the food supply might influence reproductive success on two barrier islands in coastal Virginia. From 2022-2024, 821 observations were made on foraging adults and brood provisioning to assess food profitability, distances to foraging areas, diets of breeding pairs, and brood provisioning rates. Two hundred fifty-four nests were monitored, 102 of which hatched 215 chicks. Overall, foraging factors did not affect breeding success at the study site. Instead, daily nest survival was best explained by year. Interannual variation in predator and storm activity determined hatching success. In 2024, a lack of storm overwash and limited predator activity led to higher hatching success compared to 2023 and 2022 when nor'easters flooded nests and there was high nest predator activity by foxes, avian predators, and ghost crabs. Daily brood survival was best explained by age, where daily survival decreased with age. Older chicks tended to be of larger body size and hide less from predators, which likely increased their predation risk. Efforts to control predators and increase nesting habitat elevation can support American Oystercatcher reproductive success. Received 1 Mar 2025, accepted 20 Oct 2025.
