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The composition of the gut microbiome varies due to dietary habits. We investigated influences of diet on the composition of the gut microbiome using the feces of 11 avian species, which consumed grain-, fish- and meat-based diets. We analyzed gut microbiome diversity and composition by next-generation sequencing (NGS) of 16S ribosomal RNA. The grain-diet group had higher gut microbiome diversity than the meat- and fish-diet group. The ratio of Bacteroidetes and Firmicutes phyla was higher in the grain-diet group than in the meat- and fish-diet groups. The grain-diet group had a higher ratio of Veillonellaceae than the meat-diet group and a higher ratio of Eubacteriaceae than the fish-diet habit group. To clarify the influence of diet within the same species, white-tailed eagles (Haliaeetus albicilla, n=6) were divided into two groups, and given only deer meat or fish for approximately one month. The composition of the gut microbiome of individuals in both groups were analyzed by NGS. There were indications of fluctuation in the levels of some bacteria (Lactobacillus, Coriobacteriales, etc.) in each diet group. Moreover, one individual for each group which switched each diet in last week changed to each feature of composition of bacterial flora. The above results show that the composition of the gut microbiome differ depending on diet, even within the same species. [ABSTRACT FROM AUTHOR]

The White-Tailed Eagle (WTE) Haliaeetus albicilla is a top avian predator that has rapidly increased in numbers and range in large parts of Europe in recent decades. In Poland, over the past 30 years, it has recolonized previously abandoned areas. In 1991, the first breeding pair in a large forest complex, the Augustów Forest (Northeast (NE) Poland), was recorded. In 2022, there were 13 breeding pairs. We analyzed changes in the diet composition of WTE in 2000–2023, divided into three periods: 2000–2005, 2009–2017, and 2018–2023. Throughout the 24 years of study, birds were the most frequently recorded food item, accounting for an average of 58% of food items, followed by fish (34%) and mammals (7%). During the study period, the most numerous food items were the Northern Pike Esox lucius, Coot Fulica atra, Common Bream Abramis brama, Mallard Anas platyrhynchos, and storks Ciconia sp. These species together accounted for 52% of food items. We recorded a long-term increasing share of Northern Pike, storks, and Great Crested Grebe Podiceps cristatus. Opposite changes, with declining frequency, were found for Coots and ducks. The share of the Coot, ducks, and Great Crested Grebe, as well as the total share of food connected with lakes in the WTE's diet, increased along the growing area of lakes in the territory of the WTE. The proportion of fish in the food did not show a relationship with the increase in the area of lakes, while the most frequently eaten fish species changed. Observed changes in food composition appear related to the settlement of the habitat-diverse areas by individual breeding pairs and changes the availability of main food categories. [ABSTRACT FROM AUTHOR]

An observation of an adult bird on the 20th August 2022 along the shore of Bozalan (Bakardere) Reservoir near Verinsko village (CW Bulgaria) is reported. This is the first species’ record in the last 132 years in that part of the country.

Bottom‐up control is an important regulator of marine mesopredators such as seabirds. The prevalence of top‐down control on these species is however less well understood. In particular, how native predators affect seabird populations has rarely been quantified.Here, we investigate how an increase in white‐tailed eagles in northern Norway, a stronghold for the species, affected a local population of 25,000 pairs of black‐legged kittiwakes, a red‐listed seabird, during a 42‐year period ending with colony extinction. We use a natural experiment of two neighbouring colonies with/without eagle predation to disentangle the effects of eagles from local kittiwake foraging conditions (using size of young herring as a proxy).At the colony where eagle predation occurred, and in contrast to the eagle‐free colony, kittiwake breeding success and population size declined with increased eagle abundance, the latter more strongly under poor foraging conditions. Breeding success increased with improving foraging conditions at both colonies.Simple population modelling shows that although conditions were insufficient to sustain the eagle‐exposed colony, the increased abundance of eagles sped up its extirpation by many years.Policy implications. Our study shows that top‐down effects from avian predators can be significant regulators of seabird populations, challenging their conservation where native, often protected, predators are rising. Such effects, and their possible interaction with other factors, must also be accounted for when using seabird demographic traits as environmental indicators and when developing more flexible and effective management and action plans. [ABSTRACT FROM AUTHOR]

The White-Tailed Eagle (WTE) Haliaeetus albicilla is a top avian predator that has rapidly increased in numbers and range in large parts of Europe in recent decades. In Poland, over the past 30 years, it has recolonized previously abandoned areas. In 1991, the first breeding pair in a large forest complex, the Augustów Forest (Northeast (NE) Poland), was recorded. In 2022, there were 13 breeding pairs. We analyzed changes in the diet composition of WTE in 2000–2023, divided into three periods: 2000–2005, 2009–2017, and 2018–2023. Throughout the 24 years of study, birds were the most frequently recorded food item, accounting for an average of 58% of food items, followed by fish (34%) and mammals (7%). During the study period, the most numerous food items were the Northern Pike Esox lucius, Coot Fulica atra, Common Bream Abramis brama, Mallard Anas platyrhynchos, and storks Ciconia sp. These species together accounted for 52% of food items. We recorded a long-term increasing share of Northern Pike, storks, and Great Crested Grebe Podiceps cristatus. Opposite changes, with declining frequency, were found for Coots and ducks. The share of the Coot, ducks, and Great Crested Grebe, as well as the total share of food connected with lakes in the WTE’s diet, increased along the growing area of lakes in the territory of the WTE. The proportion of fish in the food did not show a relationship with the increase in the area of lakes, while the most frequently eaten fish species changed. Observed changes in food composition appear related to the settlement of the habitat-diverse areas by individual breeding pairs and changes the availability of main food categories.

Some wind farms have implemented automated camera-based monitoring systems, e.g., IdentiFlight to mitigate the impact of wind turbines on protected birds. These systems have promoted the collection of large amounts of unique data that can be used to describe flight behavior in a novel way. The aim of this study was to evaluate how this unique data can be used to create a robust quantitative behavioral analysis, that can be used to identify risk-prone flight behavior and avoidance behavior and thereby used to assess collision risk in the future. This was achieved through a case study at a wind farm on the Swedish island Gotland, where golden eagles (Aquila chrysaetos), white-tailed eagles (Haliaeetus albicilla), and red kites (Milvus milvus), were chosen as the bird species. These three species are generally rare breeds in Europe and have also been shown to be particularly vulnerable to collisions with wind turbines. The results demonstrate that data from the IdentiFlight system can be used to identify risk-prone flight behaviors, e.g., tortuous flight and foraging behavior. Moreover, it was found that these flight behaviors were affected by both weather conditions, but also their distance to the nearest wind turbine. This data can, thus, be used to evaluate collision risk and avoidance behavior. This study presents a promising framework for future research, demonstrating how data from camera-based monitoring systems can be utilized to quantitatively describe risk-prone behavior and thereby assess collision risk and avoidance behavior. [ABSTRACT FROM AUTHOR]

Birds are one of the groups involved in the development of Sarcocystis Lankester (1882), serving either as intermediate or definitive hosts. The white-tailed sea eagle Haliaeetus albicilla (Linnaeus, 1758), red kite Milvus milvus (Linnaeus, 1758) (both Accipitriformes) and common starlings Sturnus vulgaris Linnaeus, 1758 (Passeriformes) were examined to elucidate their participation in the development of Sarcocystis, as well as to determine the specific identity of the parasites based on morphological and especially molecular analyses. In 2020–2021, one white-tailed eagle, one red kite and five common starlings were parasitologically examined for the presence of Sarcocystis using flotation centrifugation coprological method and by wet mounts of intestinal mucosa scrapings and/or muscle samples. Positive samples were processed by light microscopy, histologically and followed molecularly at four genetic markers (18S rRNA, 28S rRNA, ITS1 and cox1). The white-tailed eagle harboured oocysts/sporocysts of S. arctica Gjerde et Schulze, 2014 in the intestinal mucosa, while the intestinal mucosa of the red kite and breasts and leg muscles of one common starling were positive to S. halieti Gjerde, Vikøren et Hamnes, 2018. Sequences from eagle shared 99.6–100% identity with each other and S. arctica in the red fox (V. vulpes Linnaeus, 1758) from the Czech Republic. Sequences from the common starling and red kite shared 100% identity with each other and with S. halieti in the great cormorant (P. carbo [Linnaeus, 1758]) from Lithuania and H. albicilla from Norway. The white-tailed sea eagle might act as definitive host of S. arctica, whereas the common starling and red kite represent intermediate and potential definitive hosts, respectively, for S. halieti.

Abstract Background Whole genomes are commonly assembled into a collection of scaffolds and often lack annotations of autosomes, sex chromosomes, and organelle genomes (i.e., mitochondrial and chloroplast). As these chromosome types differ in effective population size and can have highly disparate evolutionary histories, it is imperative to take this information into account when analysing genomic variation. Here we assessed the accuracy of four methods for identifying the homogametic sex chromosome in a small population using two whole genome sequences (WGS) and 133 RAD sequences of white-tailed eagles (Haliaeetus albicilla): i) difference in read depth per scaffold in a male and a female, ii) heterozygosity per scaffold in a male and a female, iii) mapping to the reference genome of a related species (chicken) with annotated sex chromosomes, and iv) analysis of SNP-loadings from a principal components analysis (PCA), based on the low-depth RADseq data. Results The best performing approach was the reference mapping (method iii), which identified 98.12% of the expected homogametic sex chromosome (Z). Read depth per scaffold (method i) identified 86.41% of the homogametic sex chromosome with few false positives. SNP-loading scores (method iv) identified 78.6% of the Z-chromosome and had a false positive discovery rate of more than 10%. Heterozygosity per scaffold (method ii) did not provide clear results due to a lack of diversity in both the Z and autosomal chromosomes, and potential interference from the heterogametic sex chromosome (W). The evaluation of these methods also revealed 10 Mb of putative PAR and gametologous regions. Conclusion Identification of the homogametic sex chromosome in a small population is best accomplished by reference mapping or examining differences in read depth between sexes.

Background. The white-tailed eagle (Haliaeetus albicilla) is a rare and vulnerable predator of Ulyanovsk region. The article presents original materials on the nesting biology of the species in the winter-spring period in the conditions of the breeding site, collected on the territory of “Sengileevskiye gory” national park. Materials and methods. To collect the material, an autonomous video surveillance system was used, installed over a perennial nest of white-tailed eagles. The observations continued from December 13, 2020 to April 24, 2021. Results. Demonstrative activity at the nest of white-tailed eagles began in the third decade of January. Active nest building began in the first decade of March. During the second decade of March, the birds began to imitate brooding. The male was the most active during the nest building period. The forage diet in the winterspring period consists of 5 species of vertebrates, among which fish predominates. Conclusions. The male plays the key role in initiating reproduction. Demonstrative nesting begins at the height of winter, active nest building in early spring. Imitation of incubation of clutches is most likely a manifestation of the protection of the nesting site under conditions of intraspecific competition.

A two-week-old white-tailed eagle presented with an inability to stand and flex its limbs. Despite hatching naturally and owing to lack of parental attention, the bird was raised indoors by zookeepers with no access to sunlight. Palpation and radiographic examination of the bilateral tibiotarsus and femur bone revealed pronounced deformation and curvature, and bilateral decreased bone densities, respectively. The reduced calcium concentration in the blood was treated with calcium gluconate injections and calcium-supplemented feeds. Chopped mouse tails were fed directly, and whole pink-skinned nude mice were fed weekly. The zookeeper also gently massaged the bird and dressed it with a bandage. Sunlight exposure was provided daily. Saliva containing chicken feed was obtained from the mother. The bird could stand properly after four weeks of treatment, and the blood calcium concentration was restored to normal levels. [ABSTRACT FROM AUTHOR]

This study proposes a new metaheuristic optimization algorithm, namely the white-tailed eagle algorithm (WEA), for global optimization and optimum design of retaining structures. Metaheuristic optimization methods are now broadly implemented to address problems in a variety of scientific domains. These algorithms are typically inspired by the natural behavior of an agent, which can be humans, animals, plants, or any physical agent. However, a specific metaheuristic algorithm (MA) may not be able to find the optimal solution for every situation. As a result, researchers will aim to propose and discover new methods in order to identify the best solutions to a variety of problems. The white-tailed eagle algorithm (WEA) is a simple but effective nature-inspired algorithm inspired by the social life and hunting activity of white-tailed eagles. The WEA's hunting is divided into two phases. In the first phase (exploration), white-tailed eagles seek prey inside the searching region. The eagle goes inside the designated space according to the position of the best eagle to find the optimum hunting position (exploitation). The proposed approach is tested using 13 unimodal and multimodal benchmark test functions, and the results are compared to those obtained by some well-established optimization methods. In addition, the new algorithm automates the optimum design of retaining structures under seismic load, considering two objectives: economic cost and CO2 emissions. The results of the experiments and comparisons reveal that the WEA is a high-performance algorithm that can effectively explore the decision space and outperform almost all comparative algorithms in the majority of the problems. [ABSTRACT FROM AUTHOR]

Using whole mitochondrial DNA sequences from 89 White-tailed Eagles (Haliaeetus albicilla) sampled from Iceland, Greenland, Norway, Denmark and Estonia between 1990 and 2018, we investigate the mitogenomic variation within and between countries. We show that there is a substantial population differentiation between the countries, reflecting similar major phylogeographic patterns obtained previously for the control region of the mitochondria, which suggested two main refugia during the last glacial period. Distinct mitogenomic lineages are observed within countries with divergence times exceeding the end of the last glacial period of the Ice Age. Deviations from neutrality indicate that these lineages have been maintained by natural selection and there is an excess of segregating amino acids in comparison with number of fixations suggesting a large load of deleterious mutations. The maintenance of the distinct mitogenic lineages within countries inflates our estimates of divergence times. [ABSTRACT FROM AUTHOR]

Birds are one of the groups involved in the development of Sarcocystis Lankester (1882), serving either as intermediate or definitive hosts. The white-tailed sea eagle Haliaeetus albicilla (Linnaeus, 1758), red kite Milvus milvus (Linnaeus, 1758) (both Accipitriformes) and common starlings Sturnus vulgaris Linnaeus, 1758 (Passeriformes) were examined to elucidate their participation in the development of Sarcocystis , as well as to determine the specific identity of the parasites based on morphological and especially molecular analyses. In 2020–2021, one white-tailed eagle, one red kite and five common starlings were parasitologically examined for the presence of Sarcocystis using flotation centrifugation coprological method and by wet mounts of intestinal mucosa scrapings and/or muscle samples. Positive samples were processed by light microscopy, histologically and followed molecularly at four genetic markers (18S rRNA, 28S rRNA, ITS1 and cox1). The white-tailed eagle harboured oocysts/sporocysts of S. arctica Gjerde et Schulze, 2014 in the intestinal mucosa, while the intestinal mucosa of the red kite and breasts and leg muscles of one common starling were positive to S. halieti Gjerde, Vikøren et Hamnes, 2018. Sequences from eagle shared 99.6–100% identity with each other and S. arctica in the red fox (V. vulpes Linnaeus, 1758) from the Czech Republic. Sequences from the common starling and red kite shared 100% identity with each other and with S. halieti in the great cormorant (P. carbo [Linnaeus, 1758]) from Lithuania and H. albicilla from Norway. The white-tailed sea eagle might act as definitive host of S. arctica , whereas the common starling and red kite represent intermediate and potential definitive hosts, respectively, for S. halieti. [Display omitted] • The possible complete life cycle of S. arctica is proposed. • The white-tailed sea eagle (Haliaeetus albicilla) might act as definitive host of S. arctica. • Red kite (Milvus milvus) represents a potential definitive host for S. halieti. • Role as intermediate and probably as definitive hosts of genus Milvus for S. halieti is supported and discussed. • The common starling (Sturnus vulgaris) is as new intermediate host for S. halieti. [ABSTRACT FROM AUTHOR]

Background: Whole genomes are commonly assembled into a collection of scaffolds and often lack annotations of autosomes, sex chromosomes, and organelle genomes (i.e., mitochondrial and chloroplast). As these chromosome types differ in effective population size and can have highly disparate evolutionary histories, it is imperative to take this information into account when analysing genomic variation. Here we assessed the accuracy of four methods for identifying the homogametic sex chromosome in a small population using two whole genome sequences (WGS) and 133 RAD sequences of white-tailed eagles (Haliaeetus albicilla): i) difference in read depth per scaffold in a male and a female, ii) heterozygosity per scaffold in a male and a female, iii) mapping to the reference genome of a related species (chicken) with annotated sex chromosomes, and iv) analysis of SNP-loadings from a principal components analysis (PCA), based on the low-depth RADseq data. Results: The best performing approach was the reference mapping (method iii), which identified 98.12% of the expected homogametic sex chromosome (Z). Read depth per scaffold (method i) identified 86.41% of the homogametic sex chromosome with few false positives. SNP-loading scores (method iv) identified 78.6% of the Z-chromosome and had a false positive discovery rate of more than 10%. Heterozygosity per scaffold (method ii) did not provide clear results due to a lack of diversity in both the Z and autosomal chromosomes, and potential interference from the heterogametic sex chromosome (W). The evaluation of these methods also revealed 10 Mb of putative PAR and gametologous regions. Conclusion: Identification of the homogametic sex chromosome in a small population is best accomplished by reference mapping or examining differences in read depth between sexes. [ABSTRACT FROM AUTHOR]

An observation of an adult bird on the 20th August 2022 along the shore of Bozalan (Bakardere) Reservoir near Verinsko village (CW Bulgaria) is reported. This is the first species' record in the last 132 years in that part of the country. [ABSTRACT FROM AUTHOR]

The article presents the discussion on sibling aggression leading to siblicide documented in a wide variety of bird species. Topics include facultative siblicide resulting from competition for limited food resources; and showing asynchronous hatching, altricial development, sexual size dimorphism, spatial and temporal concentration of food, and small brood size.

Some wind farms have implemented automated camera-based monitoring systems, e.g., IdentiFlight to mitigate the impact of wind turbines on protected birds. These systems have promoted the collection of large amounts of unique data that can be used to describe flight behavior in a novel way. The aim of this study was to evaluate how this unique data can be used to create a robust quantitative behavioral analysis, that can be used to identify risk-prone flight behavior and avoidance behavior and thereby used to assess collision risk in the future. This was achieved through a case study at a wind farm on the Swedish island Gotland, where golden eagles (Aquila chrysaetos), white-tailed eagles (Haliaeetus albicilla), and red kites (Milvus milvus), were chosen as the bird species. These three species are generally rare breeds in Europe and have also been shown to be particularly vulnerable to collisions with wind turbines. The results demonstrate that data from the IdentiFlight system can be used to identify risk-prone flight behaviors, e.g., tortuous flight and foraging behavior. Moreover, it was found that these flight behaviors were affected by both weather conditions, but also their distance to the nearest wind turbine. This data can, thus, be used to evaluate collision risk and avoidance behavior. This study presents a promising framework for future research, demonstrating how data from camera-based monitoring systems can be utilized to quantitatively describe risk-prone behavior and thereby assess collision risk and avoidance behavior.

The major histocompatibility complex (MHC) genes code for key immune receptors responsible for recognition of intra- and extracellular pathogens (MHC class I and class II, respectively). It was hypothesized that MHC polymorphism can be maintained via fluctuating selection resulting from between-habitat variation in pathogen regimes. We examined associations between MHC class I and class II genes and habitat structure in an apex avian predator, the white-tailed eagle, Haliaeetus albicilla. We genotyped MHC class I and class II genes in ca. 150 white-tailed eagle chicks from nearly 100 nesting territories distributed across 3 distinct populations in Poland. Habitat structure was quantified at the level of foraging territories and directly at the nest sites. We found strong support for associations of habitat traits with diversity and allelic composition at the MHC class II. Forest area within territory and forest productivity were identified as the major habitat predictors of MHC class II polymorphism, whereas other habitat traits (distance to nearest open water, grassland, and water area within territory or understory presence) showed fewer associations with class II alleles. In contrast, there was little support for associations between MHC class I genes and habitat structure. All significant associations were apparent at the within-population level rather than between populations. Our results suggest that extracellular (rather than intracellular) pathogens may exert much stronger selective pressure on the white-tailed eagle. Associations of habitat structure with MHC class II may reflect fluctuating (balancing) selection, which maintains MHC diversity within populations. [ABSTRACT FROM AUTHOR]

In this work we present some of the data about the nesting ecology of the White-tailed Eagle (Haliaeetus albicilla) collected during 2009-2018 in the Danube Delta Biosphere Reserve and its surroundings. A total of 144 different nests (occupied, unoccupied and destroyed) were recorded in this period. We also recorded 7 breeding pairs (territories) whose nests could not be identified. The preferred tree species for nesting were Salix alba with 63% of all identified nests, 17% were in Populus alba, Populus x canadensis hibrid 15%, 3% in Alnus glutinosa, 1% in Tilia tomentosa and 1% in Quercus robur. The nests were located in the tallest trees available on the site and were placed at heights between 5 and 24 meters. 67% of these were above 13 m of the ground, while 33 % below. The White-tailed Eagle nest site selection may be a response both to tree availability in the foraging habitat as well as food supply.

Seven species of eagle breed in France: Golden Eagle (Aquila chrysaetos), Lesser Spotted Eagle (Aquila pomarina), Bonelli’s Eagle (Aquila fasciata), Booted Eagle (Hieraaetus pennatus), Short-toed Eagle (Circaetus gallicus), Osprey (Pandion haliaetus) and White-tailed Eagle (Haliaeetus albicilla). Populations of all species have increased since the beginning of the 2000s and breeding pairs are estimated at: 2500-3300 in 2012 (Short-toed Eagle), 585-810 in 2012 (Booted Eagle), 450-500 in 2012 (Golden Eagle), 80-90 in 2015 (Osprey),33 in 2016 (Bonelli’s Eagle) and 1 each in 2018 (Lesser spotted Eagle and White-tailed Eagle). These two latter species became new breeding species in 2003 and 2011 respectively. Productivity, expressed as fledgling/pair/year, is estimated to be on average 0.57 (Short-toed Eagle), 1.56 (Osprey), 1.18 (Bonelli’s Eagle), 0.82 (Lesser spotted Eagle), 1.1 (White-tailed Eagle) and from 0.26 (min) to 0.70 (max) (Golden Eagle). The main threats to reproduction relate to decreases in habitat quality (resulting from disturbance, habitat loss and wind farms) and the increase of mortality (from power lines, poaching and poisoning).

The white-tailed eagle (Haliaeetus albicilla) is strictly protected in Poland due to its threat of extinction. This study’s main goal was to assess their exposure to indirect poisoning by anticoagulant rodenticides (AR). This study presents the investigation results of 40 white-tailed eagles’ suspected poisoning cases in the years 2018–2020 in Poland. In all tested liver samples, using a liquid chromatography–mass spectrometry method, at least one of the AR (bromadiolone, brodifacoum, difenacoum, flocoumafen) was detected and confirmed. The other tested AR compounds (chlorophacinone, coumachlor, coumatetralyl, difethialone, diphacinone, warfarin) were not detected. The mean concentration of the sum of rodenticides was 174.4 µg/kg (from 2.5 to 1225.0 µg/kg). In 20 cases, the sum concentration was above 100 µg/kg and in 10 cases it was above 200 µg/kg. Interpretation of cases of AR poisonings should take into account their concentration in the liver, anatomopathological lesions, circumstances of death/finding of the animal, and elimination of other possible causes of poisoning. Based on this study, AR was the direct cause of death in 10% of incidents. Extensive use of rodenticides generates a high risk of poisonings of white-tailed eagles in Poland.

Summary: The prevalent pesticide carbofuran was banned in the European Union (EU) in 2008; however, the extent of its actual elimination from the environment has been little studied. The presence of this pesticide in the livers of the protected raptors the white-tailed eagle (Haliaeetus albicilla) and the common buzzard (Buteo buteo) was monitored in Poland from 2008 to 2019 using liquid chromatography with tandem mass spectrometry analysis and data from government institutions. Carbofuran residues were detected in the liver samples of the analysed raptors throughout the period studied. In total, carbofuran was detected in the livers of 33% of the eagles and 54% of the buzzards; concentrations were in the ranges of 11–699 and 14–1890 μg kg–1 of dry matter, respectively. Effective measures to eliminate banned pesticides from the market more efficiently are required. [ABSTRACT FROM AUTHOR]

Apex predators are characterized by high levels of biomagnifying organohalogenated contaminants (OHCs) which have been found to induce detrimental health effects in wildlife, such as immune system impairment. The leukocyte coping capacity (LCC) assay is a functional real-time measure of an innate immune response essential in pathogen resistance, known as the respiratory burst. The current study suggests the novel use of this tool to test whether OHCs impair the innate immune system of a sentinel top predator, the white-tailed eagle (Haliaeetus albicilla; WTE). The LCC analysis was performed in the field on WTE nestlings (n = 84) from northern Norway over two breeding seasons. Poly- and perfluoroalkyl substances (PFAS) dominated the total OHC load, surpassing the levels of legacy organochlorines. In addition, we detected significant negative correlations between concentrations of all polychlorinated biphenyls, p,p′-dichlorodiphenyldichloroethylene, perfluorohexane sulfonic acid and long-chain perfluorocarboxylic acids and the LCC of WTE nestlings. Based on our current findings reflecting a potential negative effect of both emerging and legacy OHCs on innate immune capacity, we suggest LCC to be a relevant and accessible test expanding the ecotoxicological toolbox to assess sub-lethal effects of OHCs in apex avian wildlife.

This work is aimed at determining the onset of breeding of the White-tailed Eagle and the reasons that affect its breeding phenology in the central part of the Volga–Kama region (Republic of Tatarstan, together with the adjacent areas of the republics of Chuvashia and Udmurtia, as well as Samara and Ulyanovsk oblasts). In the Republic of Tatarstan, the bulk of data were obtained in 2011–2016; in Ulyanovsk and Samara oblasts, in 2012; in the Republic of Chuvashia, in 2013, 2015, 2016; and in Udmurtia, in 2016. An analysis of the onset of breeding was carried out on the basis of photo records of the White-tailed Eagle nests with nestlings primarily at ages of 30–60 days and some younger than 30 days, in 2011–2016. The age of nestlings was determined by the photo tables comparing the degree of development of their plumage. When establishing the date of the first egg laying, the age of the elder (or the only) nestling and the incubation time, which amounts to 37 days, were taken into account. In total, 119 cases of breeding were analyzed. For additional control of calculations concerning the earliest periods of breeding, at the beginning of the breeding season, on February 23, 2015, distant observations of a group of 16 nests were carried out using optical devices along the upper reaches of the Kuibyshev reservoir. More precise data on the dates of egg laying were also obtained using a surveillance camera at an eagle nest in the Volga–Kama Biosphere Nature Reserve. According to the results of calculations, the period of the first egg laying extends from February 22 to April 11 (n = 119). Most of the clutches (70.6%, n = 84) are laid in the period from February 22 to March 15, and the maximum occurs in the first five days of March (26.05%, n = 31). A comparison with previously published data shows that, on average, the eagles start breeding half a month earlier than they did in the 20th century. In our opinion, the shift towards earlier breeding dates is primarily caused by the presence of artificial food supply at local wintering sites and increased species numbers in the Volga–Kama region. The White-tailed Eagle's status in the region partially changed from the migrating breeder to resident breeder. The distances from the breeding territories to the wintering grounds with abundant of forage shortened significantly. The influence of climate warming on the time of egg-laying cannot be excluded either. [ABSTRACT FROM AUTHOR]

Collision risk of soaring birds is partly associated with updrafts to which they are attracted. To identify the risk-enhancing landscape features, a micrositing tool was developed to model orographic and thermal updraft velocities from high-resolution remote sensing data. The tool was applied to the island of Hitra, and validated using GPS-tracked white-tailed eagles (Haliaeetus albicilla). Resource selection functions predicted that eagles preferred ridges with high orographic uplift, especially at flight altitudes within the rotor-swept zone (40–110 m). Flight activity was negatively associated with the widely distributed areas with high thermal uplift at lower flight altitudes (<110 m). Both the existing wind-power plant and planned extension are placed at locations rendering maximum orographic updraft velocities around the minimum sink rate for white-tailed eagles (0.75 m/s) but slightly higher thermal updraft velocities. The tool can contribute to improve micrositing of wind turbines to reduce the environmental impacts, especially for soaring raptors. [ABSTRACT FROM AUTHOR]

In 2006, after centuries of absence, a pair of white-tailed eagles (Haliaeetus albicilla) bred successfully in the Netherlands. Since then, the species has slowly spread across the country. The white-tailed eagle's return is a consequence of its spectacular increase in Northern Europe and Germany, and the westward expansion of the breeding area. At least one bird of the first breeding pair hatched in Schleswig-Holstein, Northern Germany. [ABSTRACT FROM AUTHOR]

The composition of the gut microbiome varies due to dietary habits. We investigated influences of diet on the composition of the gut microbiome using the feces of 11 avian species, which consumed grain-, fish- and meat-based diets. We analyzed gut microbiome diversity and composition by next-generation sequencing (NGS) of 16S ribosomal RNA. The grain-diet group had higher gut microbiome diversity than the meat- and fish-diet group. The ratio of Bacteroidetes and Firmicutes phyla was higher in the grain-diet group than in the meat- and fish-diet groups. The grain-diet group had a higher ratio of Veillonellaceae than the meat-diet group and a higher ratio of Eubacteriaceae than the fish-diet habit group. To clarify the influence of diet within the same species, white-tailed eagles (Haliaeetus albicilla, n=6) were divided into two groups, and given only deer meat or fish for approximately one month. The composition of the gut microbiome of individuals in both groups were analyzed by NGS. There were indications of fluctuation in the levels of some bacteria (Lactobacillus, Coriobacteriales, etc.) in each diet group. Moreover, one individual for each group which switched each diet in last week changed to each feature of composition of bacterial flora. The above results show that the composition of the gut microbiome differ depending on diet, even within the same species.

There is a growing concern about the occurrence of bisphenols and benzophenone UV filters in natural ecosystems, while data are limited regarding their actual occurrence in wildlife species, especially in raptors. In this study, concentrations of bisphenol and benzophenone UV filter analogues were determined in liver tissue samples (n = 38) from white-tailed eagles (Haliaeetus albicilla) that were found dead in Smøla (2006–2018), which is a Norwegian municipality that holds one of the densest breeding populations of white-tailed eagles in Europe. Bisphenol AF (BPAF; a fluorinated analogue) was the most ubiquitous contaminant since it was detected in 32 liver samples at concentrations ranging from 1.08 to 6.68 ng/g wet weight (w.w.), followed by bisphenol A (BPA, mean 10.4 ng/g w.w.), benzophenone-1 (BzP-1, mean 3.24 ng/g w.w.), and 4-hydroxybenzophenone (4-OH-BzP, mean 0.62 ng/g w.w.). The concentrations found in livers suggested that white-tailed eagles potentially accumulate bisphenols and benzophenone UV filters, which raises concern, as these plastic and personal care product-related emerging contaminants can show endocrine-disrupting properties. The high detection frequency of the fluorinated BPAF warrants further attention as other fluorinated compounds have proven to be extremely persistent and potentially harmful to wildlife.

The number of White-tailed Eagles (Haliaeetus albicilla Linnaeus 1758) wintering in the Danube Delta Biosphere Reserve (D. D. B. R.) was investigated in the period 2016 - 2018. In the period between October through March of each year we recorded a total of 312 individuals. Of these, 67% were adult birds, 17% juveniles and 16 % immature. The wintering WtE densities were calculated for the year 2016 as having a value of 0.015 individuals/km², for 2017 to 0.022 i/km² and for 2018 to 0.015 i/km². In 2017 we recorded 132 individuals, out of which more than a half (55%) were recorded in the Şontea - Fortuna Complex, followed by the Gorgova - Uzlina Complex, with 31%. Razim - Sinoe, Dunavăţ - Dranov, Matita - Merhei and Roşu - Puiu Complex each have no more than 6% of the recorded individuals. The WtE densities recorded during the synchronous counting of 2017 were 0.247 i/km² for Şontea - Fortuna, 0.139 i/km² for Gorgova - Uzlina, 0.026 i/km² for Matita - Merhei, 0.016 i/km² for Dunavăţ - Dranov, 0,015 i/km² for Razim - Sinoe and 0,007 i/km² for Roşu - Puiu. The sedentary wintering individuals corroborated with the northern population of individuals wintering in the Danube Delta highlights the importance of Danube Delta ecosystems in the annual movements of the species. [ABSTRACT FROM AUTHOR]

The white-tailed eagle (Haliaeetus albicilla) suffered a severe population decline due to environmental pollutants in the Baltic Sea area ca. 50 years ago but has since been recovering. The main threats for the white-tailed eagle in Finland are now often related to human activities. We examined the human impact on the white-tailed eagle by determining mortality factors of 123 carcasses collected during 2000-2014. Routine necropsy with chemical analyses for lead and mercury were done on all carcasses. We found human-related factors accounting for 60% of the causes of death. The most important of these was lead poisoning (31% of all cases) followed by human-related accidents (e.g. electric power lines and traffic) (24%). The temporal and regional patterns of occurrence of lead poisonings suggested spent lead ammunition as the source. Lead shot was found in the gizzards of some lead-poisoned birds. Scavenging behaviour exposes the white-tailed eagle to lead from spent ammunition. [ABSTRACT FROM AUTHOR]

Altered human presence, which resulted from COVID-19 lockdowns, led to instant and wide-ranging effects on wildlife across the globe. While humans have gradually reappeared in nature after the lockdowns, it has remained unclear how persistent these lockdown effects have been on ecosystems. We have earlier reported an unexpected chain of events linked to the closing of the tourist traffic to an iconic seabird island in the Baltic Sea. When tourists disappeared, the number of white-tailed eagles rose dramatically, which had strong negative effects on breeding common murres. Using data from the first post-lockdown season (2021), when human presence increased, we document a sudden return to pre-lockdown conditions with fewer eagles, lowered disturbance of murres and recovered murre productivity. However, eagle disturbances of murres remained in an isolated part of the island, revealing that the interaction between humans, eagles and seabirds occur at a small geographical scale. This suggests that small-scale mediation of human behavior can be effective in mediating animal behavior and thereby allow for co-existence between seemingly conflicting conservation goals. • Covid-19 lockdown led to fewer tourists on an iconic seabird island. • With fewer tourists, white-tailed eagle numbers rose dramatically. • This had strong effects on breeding seabirds. • Returning tourists led to fewer eagles and recovered seabird productivity. • Strategic management of human presence can mitigate conflicts on small scales. [ABSTRACT FROM AUTHOR]

This article presents data on the diet of the White-Tailed Eagle (Haliaeetus albicilla) collected during breeding seasons of 2006–2015 in the Polesski State Radiation-Ecological Reserve. The data included 127 records of prey remains belonging to 27 species of vertebrates collected in and under the nests. We discovered that the diet of the White-Tailed Eagle mainly consists of vertebrates of three classes: fishes (Pisces) 48.1 %, birds (Aves) 41.7 % and mammals (Mammalia) 10.2 %. At the present, the main prey species in the diet of the White-Tailed Eagle in the breeding season are: Bream (Abramis brama) – 22.0 %, Black Stork (Ciconia nigra) – 12.6 %, Northern Pike (Esox lucius) – 10.2 %, Wild Boar (Sus scrofa) – 7.1 %, White Stork (Ciconia ciconia) – 6.3 %, Mallard (Anas platyrhynchos) – 5.5 % and Eurasian Coot (Fulica atra) – 5.5 %. Together these species makes up 69.2 % or 2/3 of the diet of this raptor. We also established that cannibalism is a character feature of the local population of White-Tailed Eagle, and its proportion is 2.4 %.

Spring migration of the White-Tailed Eagle (Haliaeetus albicilla) within the Omsk region proceeds in a wide zone along the Irtysh river, in a North-North-Westerly direction. In spring and early summer, established breeding pairs are distributed across the nesting sites in all climatic zones of the region from the steppes to the taiga; immature and single individuals inhabit mainly the Northern forest-steppe, the floodplain of the Irtysh river, and the shores of large freshwater lakes. In September-October, migrating individuals stay for long periods in feeding areas, concentrating in the southeastern part of the territory.

Interest in the occurrence of a bird's flight flew into the background the study of the adaptation of the pelvic fins of birds. It fully concerns both the skeletal elements and the muscular system of the femur leg. It should also be noted that the initial studies of this issue have shown extremely specific characteristics of the structural elements of the area of the hip joint. This in turn suggests that studies of the pelvic fins of birds are relevant and almost not studied. A paticulary important aspect of research of this issue is the establishment of valid principles and mechanism for the development of the femur of the thigh, taking into account the specific features of locomotion. In this article biomorphological features of the hip joint muscles of predantory birds (white-tailed eagle, common buzz, golden eagle, small hawk, merlin, winter path, andy condor, rhino owl, white owl, eary owl, tawny owl, barn owl) are outlined. It was established that the representatives of this series of degrees of differentation of muscles of the hip joint area due to the stepping type of the bipolar locomotion, as well as the biomorphological festures of the static, which in turn imposes certain imprints on the degree of development of each individual muscle of the hip joint. Also fix points are detailed, presence or absence of porosity is determined. In addition, in order to determine the degree of muscles and muscle groups development, each muscle was weighed. It was found that the extension of muscles of the hip joint of the white-tailed eagle requires considerably greater effort than bending, and of the golden eagle, big hawk, twist and the buzzard, on the contrary, the balge louding during static and locomotive fulls on the bend. Nightly and daytime predantory birds differ not only in the way of life (night or day), body weight, but also in various manipulations of the limbs, in paticular during hunring for the prey, the force of the extremity during the attack and the method of capture by the claws imposing certain imprints on the development of hip joint bones. [ABSTRACT FROM AUTHOR]

Circadian rhythms result from adaptations to biotic and abiotic environmental conditions that cycle through the day, such as light, temperature, or temporal overlap between interacting species. At high latitudes, close to or beyond the polar circles, uninterrupted midsummer daylight may pose a challenge to the circadian rhythms of otherwise nocturnal species, such as eagle owls Bubo bubo. By non‐invasive field methods, we studied eagle owl activity in light of their interactions with their main prey the water vole Arvicola amphibius, and their competitor the white‐tailed eagle Haliaeetus albicilla during continuous midsummer daylight on open, treeless islands in coastal northern Norway. We evaluated circadian rhythms, temporal overlap, exposure, and spatial distribution. The owls maintained a nocturnal activity pattern, possibly because slightly dimmer light around midnight offered favourable hunting conditions. The eagles were active throughout the 24‐h period as opposed to the strictly diurnal rhythm reported elsewhere, thus increasing temporal overlap and the potential for interference competition between the two avian predators. This may indicate an asymmetry, with the owls facing the highest cost of interference competition. The presence of eagles combined with constant daylight in this open landscape may make the owls vulnerable to interspecific aggression, and contrary to the available literature, eagle owls rarely exposed themselves visually during territorial calls, possibly to avoid detection by eagles. We found indications of spatial segregation between owls and eagles reflecting differences in main prey, possibly in combination with habitat‐mediated avoidance. Eagle owl vocal activity peaked in the evening before a nocturnal peak in visual observations, when owls were active hunting, consistent with the hypothesis of a dusk chorus in nocturnal bird species. The owls may have had to trade‐off between calling and foraging during the few hours around midnight when slightly dimmer light reduced the detection risk while also providing better hunting conditions [ABSTRACT FROM AUTHOR]

Abstract: Environmental pollution is an important driver of biodiversity loss. Yet, to date, the effects of chemical exposure on wildlife populations have been quantified for only a few species, mainly due to a lack of appropriate laboratory data to quantify chemical impacts on vital rates. In this study, we developed a method to quantify the effects of toxicant exposure on wildlife population persistence based on field monitoring data. We established field‐based vital‐rate‐response functions for toxicants, using quantile regression to correct for the influences of confounding factors on the vital rates observed, and combined the response curves with population viability modelling. We then applied the method to quantify the impact of DDE on three bird species: the White‐tailed Eagle, Bald Eagle, and Osprey. Population viability was expressed via five population extinction vulnerability metrics: population growth rate (r1), critical patch size (CPS), minimum viable population size (MVP), probability of population extirpation (PE), and median time to population extirpation (MTE). We found that past DDE exposure concentrations increased population extirpation vulnerabilities of all three bird species. For example, at DDE concentrations of 25 mg/kg wet mass of egg (the maximum historic exposure concentration reported in literature for the Osprey), r1 became small (White‐tailed Eagle and Osprey) or close to zero (Bald Eagle), the CPS increased up to almost the size of Connecticut (White‐tailed Eagle and Osprey) or West Virginia (Bald Eagle), the MVP increased up to approximately 90 (White‐tailed Eagle and Osprey) or 180 breeding pairs (Bald Eagle), the PE increased up to almost certain extirpation (Bald Eagle) or only slightly elevated levels (White‐tailed Eagle and Osprey) and the MTE became within decades (Bald Eagle) or remained longer than a millennium (White‐tailed Eagle and Osprey). Our study provides a method to derive species‐specific field‐based response curves of toxicant exposure, which can be used to assess population extinction vulnerabilities and obtain critical levels of toxicant exposure based on maximum permissible effect levels. This may help conservation managers to better design appropriate habitat restoration and population recovery measures, such as reducing toxicant levels, increasing the area of suitable habitat or reintroducing individuals. [ABSTRACT FROM AUTHOR]

Kin recognition has been shown in some bird species, suggesting that birds might be able to actively avoid inbreeding through mate choice. However, the evidence for such behaviour in wild bird populations is scarce. Intrusions performed by conspecifics could be part of the breeding strategy of a territorial bird species: an intruder might find the opportunity to replace a resident individual and acquire its territory. If intruders seek the opportunity to breed, their relatedness to the opposite-sex resident could influence their nest site intrusions similarly to mate choice. Observations of intrusions also revealed that vagrant juveniles of long-lived raptors repeatedly visit their natal population before maturation. The present study focused on the White-tailed Eagle ( Haliaeetus albicilla): a territorial, long-lived, monogamous raptor species. We investigated whether (1) relatedness is considered in mate choice in this species, based on noninvasively collected DNA samples. (2) We furthermore addressed whether nest site intrusions could be explained by any of the following three nonexclusive hypotheses: (i) finding a mate, (ii) acquiring a good-quality territory, or (iii) visiting the natal area. Our results suggest that White-tailed Eagles avoid kin in mate choice. Although a considerable proportion of the intruders were juveniles, none of them was likely to be offspring of resident pairs of the study population. We found a nonsignificant trend towards lower relatedness than expected from random intrusions in both sexes. The revealed intrusion events suggest a sex bias: males seem to prefer better-quality territories more than females do. [ABSTRACT FROM AUTHOR]

During the research conducted between 2009 and 2017 in the Danube Delta Biosphere Reserve and its surroundings, a total of 74 occupied nests were registered, 61 of which showed successfully completed nesting. A total of 193 chicks resulted, so the mean of the reproductive rate in all the years, was calculated to be 1.2 chicks/nest, a value that fit within the limits of the other averages in literature. From a total of 61 nests where breeding was successfully completed, the average in 2009 was 1.36 chicks/nest, in 2010 - 1.33 chicks/nest, in 2011 it was 1.3 chicks/nest, in 2012 - 1 chick/nest, in 2013 - 1.17 chicks/nest, in 2014 - 1.15 chicks/nest, in 2015 - 1.08 chicks/nest, in 2016 - 1.12 chicks/nest, and in 2017 the mean was 1.35 chicks/nest. Out of 61 nests where breeding was successfully completed from 2009 to 2017, 29 nests were used (and breeding was successfully completed) once, 8 nests were used twice, 7 three times, 4 four times, 5 five times, 4 six times, 3 were used seven times, and only 1 nest was used eight times. [ABSTRACT FROM AUTHOR]

We investigated the effects of parasite removal on various blood clinical-chemical variables (BCCVs). BCCVs are indicators of health, reflecting, e.g., homeostasis of liver, kidney function, and bone metabolism. The study was conducted in Norway on chicks of two predatory birds: White-tailed Eagle ( Haliaeetus albicilla (L., 1758)) and Northern Goshawk ( Accipiter gentilis (L., 1758)). Chicks were treated against both endoparasites (internal parasites) and ectoparasites (external parasites). We treated against ectoparasites by spraying nests with pyrethrins. Within nests, chicks were randomly treated with either an anti-helminthic medication (fenbendazole) or sterile water (controls). Treatment against either ectoparasites or endoparasites led to higher levels of the bone and liver enzyme alkaline phosphatase. Bilirubin levels were lower when treated against ectoparasites, whereas bile acids were higher. Anti-endoparasite treatment led to higher creatinine levels. In Northern Goshawks, treating against endoparasites led to higher urea levels and lower potassium levels. Treatment against ectoparasites increased uric acid and urea levels and reduced bilirubin levels and protein:creatinine ratios. In conclusion, anti-parasite treatments led to changes in several BCCVs, suggesting differences in nutrient absorption and physiological state of chicks that are possibly related to the costs of parasitism, but maybe also to the parasite treatment itself. [ABSTRACT FROM AUTHOR]

A two-week-old white-tailed eagle presented with an inability to stand and flex its limbs. Despite hatching naturally and owing to lack of parental attention, the bird was raised indoors by zookeepers with no access to sunlight. Palpation and radiographic examination of the bilateral tibiotarsus and femur bone revealed pronounced deformation and curvature, and bilateral decreased bone densities, respectively. The reduced calcium concentration in the blood was treated with calcium gluconate injections and calcium-supplemented feeds. Chopped mouse tails were fed directly, and whole pink-skinned nude mice were fed weekly. The zookeeper also gently massaged the bird and dressed it with a bandage. Sunlight exposure was provided daily. Saliva containing chicken feed was obtained from the mother. The bird could stand properly after four weeks of treatment, and the blood calcium concentration was restored to normal levels.

Movement and space use are important components of animal interactions with the environment. However, for hard-to-monitor raptor species, there are substantial gaps in our understanding of these key determinants. We used noninvasive genetic tools to evaluate the details of space use over a 3-yr period by White-tailed Eagles ( Haliaeetus albicilla) at the Naurzum Zapovednik in northern Kazakhstan. We genotyped, at 10 microsatellite markers and one mitochondrial marker, 859 eagle feathers and assigned naturally shed feathers to individuals. We identified 124 White-tailed Eagles, including both members of 5-10 pairs per year, and were able to monitor birds across years. Distances between eagle nests and hunting perches were always greater than nearest neighbor distances, eagles never used the closest available hunting perch, and hunting perches were always shared with other eagles. When eagles switched nests between years, the nests they chose were almost always well outside the space that theory predicted they defended the prior year. Our data are inconsistent with classical territorial and colonial models of resource use; they more closely resemble semi-colonial behavior. It is unlikely that standard methods of animal tracking (e.g., marking and telemetry), would have provided a similarly cost-effective mechanism to gain these insights into spatial and temporal aspects of eagle behavior. When combined with existing information on space use of other local species, these data suggest that partitioning of spatial resources among White-tailed Eagles and other eagles at the Zapovednik may be facilitated by the alternative strategies of space use they employ. [ABSTRACT FROM AUTHOR]

The presence of poorly sited wind farms raises concerns for wildlife, including birds of prey. Therefore, there is a need to extend the knowledge of the potential human-wildlife conflicts associated with wind energy. Here, we report on the movements and habitat use of post-fledging satellite-tagged white-tailed eagles in Finland, where wind-energy development is expected to increase in the near future. In particular, we examine the probability of a fledgling approaching a hypothetical turbine that is placed at different distances from the nest. We found that this probability is high at short distances but considerably decreases with increasing distances to the nest. A utilisation-availability analysis showed that the coast was the preferred habitat. We argue that avoiding construction between active nests and the shoreline, as well as adopting the currently 2-km buffer zone for turbine deployment, can avoid or minimise potential impacts on post-fledging white-tailed eagles. [ABSTRACT FROM AUTHOR]