Search Results (33)

This report presents the first complete natal dispersal trajectory of a female Montagu’s Harrier Circus pygargus, tracked in real time from fledging to first breeding using high-resolution continuous Global Positioning System (GPS) telemetry. The bird’s first flight occurred on 26 July 2024, initiating a 31-day post-fledging dependence phase (PFDP), followed by a 23-day pre-migratory phase (PMP), during which it explored areas up to 280.8 km from the nest and eventually settled ca. 190 km away in the Sirente-Velino Regional Park. From there, autumn migration began on 18 September 2024. The bird reached its first wintering site in Mali by 15 October. It used four wintering areas over 178 days, with a winter home range of 37,615.02 km². Spring migration started on 11 April 2025 and lasted 21 days, ending with arrival in the Gran Sasso e Monti della Laga National Park (Central Italy) on 2 May. The bird used two main sites during the pre-breeding phase (PRBP) before laying eggs on 2 June 2025. The natal dispersal distance, from birthplace to nest site, was 151.28 km. Over 311 days, it covered a total of 14,522.23 km. These findings highlight the value of advanced telemetry in revealing early-life movement ecology and are useful for understanding species-specific patterns of survival, reproduction, and space use and can inform conservation actions. Full article

The eastern imperial eagle (Aquila heliaca) has shown a marked population increase in the past decades in Hungary. The breeding range is expanding towards homogeneous agricultural habitats of the Hungarian Plain, where the already existing and recently growing infrastructural network is thought to be one of the main factors limiting distribution. We used data from 508 breeding attempts between 1989 and 2008 to assess the effects of infrastructural networks on breeding distribution. We constructed a single cumulative infrastructure effect (CIE) variable based on the avoidance of different infrastructure types by eagles in the past 20 years. Conditional autoregressive models were built in a Bayesian framework to quantify the effects of infrastructures on the spatial breeding pattern in a pre-defined core study area. Both multivariate and CIE models were able to classify the presence of breeding attempts with high accuracy. The CIE variable was used to build a predictive distribution model for the Hungarian Plain. The results suggest that infrastructure has a significant local effect but does not necessarily hinder the future range expansion of imperial eagles, as two-thirds of the prediction area seems to be suitable for the species. The methods and results described enable conservation managers and policy makers to assess the trade-off between infrastructural development and nature conservation priorities. Full article

Our study investigates predation among sympatric owl species in the Judea Region, specifically focusing on the predation by Eurasian Eagle Owls (Bubo bubo) on smaller owl species. Field observations conducted between 2006 and 2009 revealed recurrent predation events, with 172 individuals documented as preyed upon by Eurasian Eagle Owls. These results align with previous studies, demonstrating the role of larger owl species as intraguild predators that affect the survival and reproduction of smaller owls. Our findings emphasize the need for further research on intraguild predation and its ecological consequences. This study contributes to a broader understanding of the complex interactions within nocturnal raptor communities and underscores the importance of incorporating such dynamics into conservation strategies to safeguard owl biodiversity in fragmented landscapes. Full article

The hen harrier, Circus cyaneus, is a migratory raptor that relies on open grasslands as key winter habitats in Central Europe, where it predominantly preys on common voles, Microtus arvalis. However, habitat loss due to agricultural intensification, land use change, and human disturbances increasingly threatens these landscapes. Using the framework of conservation behavior, this study examines how hen harriers respond to human-induced environmental changes, how behavior-based habitat management can support conservation, and how behavioral indicators such as territoriality inform conservation planning. Based on 278 h of field observations, we analyzed space use, foraging ecology, time and energy budgets, and territoriality of wintering hen harriers. Our results indicate that non-territorial females require ~20% more energy intake than territorial females, reflecting the advantage of defending vole-rich habitats. This corresponds to an estimated daily intake of up to 8 voles for non-territorial females, compared to 4–6 voles for territorial ones. Winter territory establishment was primarily driven by vole availability, and habitat degradation due to grassland loss impaired territory formation, influencing energy allocation and conservation prospects. Our findings highlight the role of territory establishment as a quantifiable behavioral indicator for habitat quality and conservation planning. At a landscape scale, habitat alteration and loss, anthropogenic disturbances and top-down effects further shape hen harrier distribution, emphasizing the need to account for these factors in conservation strategies. Finally, we identify open research questions, especially regarding large-scale environmental pressures and cross-seasonal effects. Full article

Seasonally dry mature and old-growth (MOG) forests in the western USA face increasing threats from catastrophic wildfire and drought due to historical fire exclusion and climate change. The Emerald Point forest at Lake Tahoe in the Sierra Nevada of California, one of the last remaining old-growth stands at lake level, is at high risk due to elevated fuels and tree densities. The stand supports huge trees and the highest tree diversity in the Lake Tahoe Basin and protects important raptor habitat. In this study, we simulate forest response to vegetation management and wildfire to assess the impacts of four fuel-reduction scenarios on fire behavior and stand resilience at Emerald Point. Results: Our results demonstrate that restorative forest management can greatly improve an MOG forest’s resistance to catastrophic fire. Thinning to the natural range of variation for density, basal area, and fuel loads, followed by a prescribed burn, was most effective at reducing large-tree mortality, maintaining basal area, and retaining live tree carbon post-wildfire, while reducing secondary impacts. Conclusions: Our findings highlight the value of proactive management in protecting old-growth forests in seasonally dry regions from severe fire events, while also enhancing their ecological integrity and biodiversity. Full article

Urban biodiversity is crucial for ecological security, balance, and important for fostering awareness on human-nature interconnectedness among the public. The diversity of birds, as an urban ecosystem indicator, reflects ecosystem services and is impacted by urban development. To explore the impacts of urbanization on bird diversity, stratified to songbirds, terrestrial birds, climbers, swimming birds, wading birds, and raptors, we specifically investigated the existing and potential distributions of selected bird species, analyzed different contributions of environmental factors, and compared these with urban biodiversity conservation policies. We used bird records from the China Birdwatching Record Center (over 1400 species of birds for querying) and remotely-sensed landcover data, based on the MaxEnt model, to analyze bird spatial distribution characteristics and potential habitat corridors throughout Beijing. The results showed that: (1) Songbirds and terrestrial birds were predominantly concentrated in water areas in urban areas. Wading birds, climbers, swimming birds, and raptors were gathered in forest-covered areas, near wetlands and farmland in suburban areas. Projections indicated that the raptor species Common Kestrel (Falco tinnunculus) showed a notable shift toward urban cores. (2) Among climbers, Gray-headed Pygmy Woodpecker (Dendrocopos canicapillus) occupied the highest proportion of high-quality habitats (10.34%), contrasting with the representative songbird species Blackbird (Turdus merula) at 1.38%, which demonstrated adaptability to urban environments. Critical habitats were concentrated in shrub forests, supporting habitat connectivity. Proximity to water bodies was critical for raptors, wading, swimming, and climbers, whereas terrestrial birds and songbirds were more affected by artificial lighting. (3) The “urban and suburban park rings” policy has effectively enhanced habitat quality and connectivity, promoting urban biodiversity resilience. This study improves our understanding of how different bird communities adapt to urbanization in terms of habitats and movement corridors, and provides useful information for formulating urban bird biodiversity conservation strategies. Full article

Natal dispersal is a crucial period for raptors with serious implications for individuals’ survival and population demography. In this study we analyzed data from 18 GPS-tracked golden eagles in order to describe their dispersal ecology in northern Greece, where the species feeds mostly on tortoises. Young eagles in our population dispersed at 176 days post fledging, spent their first year of independence relatively close (40–60 kms) to their natal ranges and exhibited a variable temporary settlement behavior. Overall dispersal range sizes did not differ seasonally, but temporary settlement area range sizes were significantly larger in winter. Three eagles survived to territorial settlement and occupied ranges 20–60 kms from their natal areas. The application and refinement of the Scottish GET dispersal ranging model suggested that eagles used areas that had higher topographical relief and lower canopy cover during their natal dispersal. Habitat heterogeneity seems to also be influential during temporary settlement. Our study is the first to provide both such insights for golden eagles in southern eastern Europe and a method for delineating temporary settlement areas for the species. Our findings can be explained in terms of food and habitat availability. We highlight the importance of conserving heterogeneous open areas of complex topography and applying proactive management measures within temporary settlement areas for our population’s conservation. Full article

Single individuals of the Greater Spotted Eagle (Clanga clanga), Indian Spotted Eagle (Clanga hastata), Tawny Eagle (Aquila rapax), Western Marsh Harrier (Circus aeruginosus), and two Pallid Harriers (Circus macrourus) were deployed with satellite transmitters in 2021 to study their home ranges, habitat associations, movement, and migration patterns. Data were collected for a combined number of 2291 days, providing 84,544 locations. Home ranges were calculated as kernel utilization distributions and expressed as 95% KDE and core areas as 50% KDE. Overall, eagles had larger home ranges (mean ± SD) of 942.70 ± 937.83 km² compared to harriers, 43.84 ± 35.55 km². Among eagles, the Greater Spotted Eagle had the largest home-range size of 2147.03 km² calculated in Kazakhstan, while the female Pallid Harrier had the smallest home range of 5.74 km² in Russia. Daily and monthly distances varied among eagles and harriers. The female Pallid Harrier covered the longest average monthly distance of 8585.43 ± 11,943.39 km, while the shortest monthly distance of 1338.22 ± 716.38 km was traveled by the Indian Spotted Eagle. All tagged birds migrated toward higher latitudes in the Northern hemisphere, except the Indian Spotted Eagle, which migrated to Pakistan. The male Western Marsh Harrier covered the longest migration distance in a shorter span of time, while the female Pallid Harrier took the longest to cover its migration distance. Overall, the daily distance covered during migration varied from 115.09 km traveled by the Indian Spotted Eagle to an overwhelming distance of 2035.85 km covered by the male Western Marsh Harrier. Scrubs, water bodies, croplands, and settlements were important habitat features associated with eagles, while croplands, open scrub, and built-up areas were associated with the female Pallid Harrier. The male Western Marsh Harrier was found to be primarily associated with saltpans and salt-affected areas having emergent vegetation. This study presents new insights into the movement and spatial ecology of long-distance migrant raptors that winter in Western India. We provide preliminary support for the use of the Western Circum–Himalayan Corridor as one of the important corridors of the Central Asian Flyway that warrants much appreciation among the current set of flyway corridors. Full article

Raptors (Accipitriformes, Falconiformes and Strigiformes) are important for ecological niches as bioindicators and an apex predator; however, their global populations have continuously decreased due to human activities, habitat loss and contagious diseases. Avian malaria that may cause the negative impact on raptors’ health may also contribute to the declining of raptor populations. This study reported malaria’s molecular prevalence and genetic diversity in wild-caught and rehabilitated raptors in the Kasetsart University Raptor Rehabilitation Unit. In total, 109 raptors from 18 provinces of Thailand were classified into two groups, which included 78 diurnal raptors (DIRs) in Accipitriformes and 31 nocturnal raptors (NORs) in Strigiformes. Each ethylenediaminetetraacetic (EDTA) blood sample (0.5–1 mL) was tested through haematological analyses and polymerase chain reaction (PCR)-based detection to assess parasites’ health impacts. Amplicons of PCR positive samples were analysed for a nucleotide sequencing and phylogenetic relationships. The overall prevalence of avian malaria was low at 3.67% (4/109) (95% CI: 1.44–9.06%), with a prevalence of 3.86% (3/78) (95% CI: 1.32–10.70%) in DIRs and 3.23% (1/31) (95% CI: 1.32–10.70%) in NORs. Most of the infected samples were from southern Thailand. This suggested that the raptors in humid habitats are more vulnerable to the malarial infection, which was likely associated with vector and parasite abundance. Clinical appearances and haematological examinations demonstrated that raptors could tolerate the infection and only became asymptomatic and subclinically infected. This study is the first report of the infection of avian malaria in Cinerous Vulture, Himalayan Vulture and Barred Eagle Owl in Thailand, providing baseline information in preparedness for the disease diagnostic and further study of avian malaria in some endangered raptor species. Full article

Wild birds are a natural reservoir for zoonotic viruses. To clarify the role of migratory birds in viruses spread in Poyang Lake, we investigated the microbiome of 250 wild bird samples from 19 species in seven orders. The bacterial and viral content abundance and diversity were preliminarily evaluated by Kraken2 and Bracken. After de novo assembly by Megahit and Vamb, viral contigs were identified by CheckV. The reads remapped to viral contigs were quantified using Bowtie2. The bacterial microbiome composition of the samples covers 1526 genera belonging to 175 bacterial orders, while the composition of viruses covers 214 species belonging to 22 viral families. Several taxonomic biomarkers associated with avian carnivory, oral sampling, and raptor migration were identified. Additionally, 17 complete viral genomes belonging to Astroviridae, Caliciviridae, Dicistroviridae, Picornaviridae, and Tombusviridae were characterized, and their phylogenetic relationships were analyzed. This pioneering metagenomic study of migratory birds in Poyang Lake, China illuminates the diverse microbial landscape within these birds. It identifies potential pathogens, and uncovers taxonomic biomarkers relevant to varied bird habitats, feeding habits, ecological classifications, and sample types, underscoring the public health risks associated with wintering migratory birds. Full article

Crocodilians are considered to be “ecosystem engineers” because their modification of habitats provides opportunities for feeding, drinking, breeding, and other vital life activities to a wide variety of other animals. One such habitat modification is the construction of nest mounds during the breeding season by most crocodilian species, including American alligators (Alligator mississippiensis). While many reports exist describing wildlife associated with alligator nests, no studies have quantified faunal associates and their corresponding behaviors while visiting nests. To address this data gap, we used automated game cameras to monitor wildlife and their behaviors at alligator nests during the egg incubation period (June–September) in coastal South Carolina, USA (2016–2021). We documented a total of 81 species (79 vertebrates and 2 invertebrates) at 78 alligator nests representing six taxonomic groups, including 48 birds (59.2%), 9 mammals (11.1%), 19 reptiles (23.4%), 3 amphibians (3.7%), 1 malacostracan (1.2%), and 1 insect (1.2%). Collectively, faunal associates primarily used alligator nests for feeding/foraging (51.8%), traveling (29.3%), and loafing (19.9%) and to a much lesser extent basking, burrowing/shelter, breeding, and nesting. However, trends in alligator nest use varied among faunal associate groups (birds, mammals, reptiles, amphibians, etc.), subgroups (e.g., passerines, raptors, wading birds, and waterfowl), and species. Several novel behaviors by some nest associates were also noted during the study, including the first observations of Virginia oppossum (Didelphis virginiana) opening and predating nests, bobcat (Lynx rufus) consuming alligator hatchlings, and Carolina wren (Thryothorus ludovicianus) feeding on the contents of a recently predated alligator egg. The results of this study indicate that a diverse assemblage of vertebrates (and some invertebrates) use alligator nest sites in coastal South Carolina for a variety of life activities during the egg incubation period, and the proportion of the behaviors exhibited varies among animal groups and species. This study provides a first step for investigations regarding the net impacts of alligator nest-faunal associate interactions and ultimately the greater ecological role of alligators and other crocodilians. Full article

Despite advancements through satellite telemetry, knowledge of the behaviour and ecology of large raptors during natal dispersal is still poor, even though this transience phase is important in understanding the population dynamics and conservation of these keystone species. After this phase, which can take several years, the subsequent rapid transitional event on first territory settlement is less studied. It apparently occurs earlier without competition from existing territory occupants. The time of year when young large raptors settle on a territory has rarely been addressed empirically. Our study of seasonal timing of first settlement used data from 46 golden eagles GPS-tagged as nestlings in Scotland which were tracked to their first territory settlement, as adjudged by a robust algorithmic method. We show that when young golden eagles occupied their first territory, their settlements were uncommon in summer and most common in late winter/spring, but also occurred in autumn into early winter. The significant seasonal pattern was consistent, regardless of the probable prior occupancy status (vacant/occupied) of the settled territory (respectively, the likely absence or presence of defending territorial birds). This showed that seasonal territory settlement was unlikely to be related to any response from territory occupants. It infers further that seasonality in first territory settlement was underpinned by innate behaviours in dispersing eagles. Seasonal distribution of settlement dates was significantly different between sexes, with males more likely to settle in autumn, predominantly in prior vacant territories. We speculate on potential causative drivers behind our results and conclude that more research is clearly needed in this field of study. Full article

Chemical pollution affects the health of marine biota, key functions of the ecosystem, and endangers its biodiversity. The current environmental monitoring and assessment approach is based on chemical and ecological measurements, while the linkage between them, biological effects at the individual level, has been largely neglected. It is currently well acknowledged that the monitoring of chemical concentrations alone is not sufficient to protect populations; it considers only a tiny number of substances, while myriad others are left unnoticed. In addition, the hazards related to contaminant mixtures remain undetected. Biological effects of contaminants can be detected and measured at different levels of biological organization, i.e., from the molecular/biochemical level up to changes in populations and communities. In Baltic Sea monitoring programs, the few observations on the effects of contaminants have, for decades, mostly been made at only the higher biological organization levels, applying reproduction success parameters in top predators such as raptor birds and seals as indicators. However, recording early warning signals of contaminant exposure and effects on the health of individuals at lower biological levels makes it possible to anticipate and prevent damage at the higher levels. Moreover, it is also crucial to monitor effects at lower levels of the marine food web. The so-called biomarkers focus on changes in various biological functions and include parameters related to the detoxification of xenobiotics, oxidative stress, neurotoxicity, geno- and cytotoxicity and reproductive disorders, among others. Research on biomarkers aiming at improving their use in monitoring and assessing the contamination status of marine areas has been intensive during recent decades, although the implementation of the methods to monitoring programmes has been slow. Here, the current state of biological effects monitoring using biomarkers, as well as selected case studies in the Baltic Sea, are presented, followed by recommendations on their application in this sea area. Full article

Estimating turnover in a population provides information on population dynamics, such as dispersal and mortality. Dispersal increases genetic diversity and affects the genetic structure. Golden eagles are monogamous, tend to mate for life, and have strong nest site fidelity, which suggests low turnover rates. Here, we first studied genetic diversity and population structure in the Finnish golden eagle population using 11 microsatellite loci and a fragment of a mitochondrial DNA control region. We found no notable changes in genetic diversity during the 15-year study period and did not discover any population structure. Then, we examined the turnover rate using chick genotypes (N = 935) by estimating relatedness between chicks born in the same territory in different years. The results showed a turnover rate of 23%, which correlated with the breeding success of the previous year. Similarly, in the absence of turnover, the pair changed nest sites within a territory after an unsuccessful breeding. In addition, our dataset also revealed natal dispersal of ten individuals. Natal dispersal distance was 110 km on average (median 98 km); however, the distance seemed to vary depending on geographical location, being greater in Northern Finland than in Southern Finland. Full article