Large Raptors Research Articles

Population monitoring and conservation implications of intra- and interspecific nest occupation rates in swallows.

With the exception of a few groups of birds, such as large raptors and colonial seabirds, direct counts of nests cannot be conducted over very large areas for most of the abundant and widely distributed species, and thus indirect methods are used to estimate their relative abundances and population sizes. However, many species of the Family Hirundinidae (swallows and martins) build their mud nests in discrete, predictable and accessible sites, which are reused across years. Therefore, the direct count of active nests could constitute a reliable method for estimating breeding population sizes and their changes at large spatial and temporal scales. We illustrate the feasibility of this monitoring approach through a single year survey of >2700 nests of three coexisting Old-World species, the barn swallow (Hirundo rustica), the red-rumped swallow (Cecropis daurica), and the crag martin (Ptyonoprogne rupestris), distributed across Portugal and Spain. Our results revealed changes in the use of nesting substrates and increases in interspecific nest usurpation rates over recent decades. While 56% of the nests of C. daurica were located in rocks five decades ago, almost 100% are nowadays located in anthropogenic substrates such as bridges, road culverts, and abandoned buildings, which could have favored the range expansion of this species. Nest occupation rates were surprisingly low (12% in C. daurica, 21% in H. rustica, and 37% in P. rupestris), and the proportion of abandoned nesting sites was very high (65% in C. daurica, 50% in H. rustica, and 27% in P. rupestris). Abandonment rates reflect the population decline reported for H. rustica. Notably, the usurpation of nests of C. daurica by house sparrows Passer domesticus, which is the main cause of breeding failure, has increased from 2.4% in 1976-1979 to 34.7% of the nests nowadays. The long-term monitoring of nests may constitute a reliable and affordable method, with the help of citizen science, for assessing changes in breeding population sizes and conservation threats of these and other mud-nest building hirundines worldwide.

Survival, Nest Site Affiliation and Post-Fledging Movements of Danish White-Tailed Eagles (Haliaeetus albicilla)

The early life movement patterns of long-lived, large raptors, such as the white-tailed eagle (Haliaeetus albicilla), remain largely unexplored. In this study, we have tracked 22 individuals of white-tailed eagles hatched in Denmark to investigate key parameters, including survival rates, causes of death, nest site fidelity, geographical distribution, and dispersal behaviors. Our analyses are based on approximately 340,000 GPS/GSM telemetry positions from the 22 individuals. We found that survival rates were lower in the first year of life, especially among females, but increased in subsequent years. The primary causes of death were wind turbine collisions and avian influenza. Movement analyses revealed that juvenile eagles frequented nest sites in August and September, with females showing earlier exploratory flights and dispersal. Both males and females spent most of their first calendar year near their nest sites. In the second calendar year, a significant proportion of their time was spent at well-known white-tailed eagle resting areas in Denmark, as well as visiting neighboring countries. Notably, one individual set a new distance record for a Danish GPS-tagged white-tailed eagle, venturing at least 1750 km away from its nest site to visit Sweden, Finland, Russia, and Norway. Our results, indicating that juvenile white-tailed eagles continue to utilize nest sites into September, suggest an extension of the recommended time period for nest protection zones provided by BirdLife Denmark (DOF).

Seasonal Variation in First Territory Settlement of Dispersing Golden Eagles: An Innate Behaviour?

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.

Approach Distances of Scottish Golden Eagles Aquila chrysaetos to Wind Turbines According to Blade Motion Status, Wind Speed, and Preferred Habitat

Understanding drivers underlying birds’ responses to operational wind turbines is essential for robust wind farm proposal assessments, especially for large raptors with life history traits engendering sensitivity to impacts from two potential adverse effects: fatality through collision with rotating turbine blades and functional habitat loss through avoidance of turbines. The balance between these two potential effects represents opposing extremes on a continuum and is influenced by several factors. Collisions have an obvious impact on survival, but the impacts of avoidance may be more insidious and potentially more significant for a population. It is reasonable to conclude that collisions are less likely when blades are motionless. Consequently, turbine shutdown systems (TSSs, “shutdown on demand” or “curtailment”), instigated as raptors approach operational turbines, may provide mitigation against collisions. By contrast, if avoidance is most likely, this could be independent of blade motion, and TSSs/curtailment would provide no mitigation against habitat loss. For birds tending to wariness of turbines, therefore, it is important to understand if it is conditional on blade motion. Scottish golden eagles show a strong propensity to avoid (be wary of) turbines, subject largely to the suitability of habitat at and surrounding turbine locations. A previous Scottish study found that approach distances to turbines by non-territorial eagles were unaffected by blade motion but were closer at higher wind speed. Here, we analyse movement data from a GPS-tagged territorial eagle and non-territorial eagles responding to the motion status (and wind speed) of turbines at another Scottish wind farm. Eagles’ approach distances to turbines were only weakly affected by blade motion but were closer at higher wind speed. We again found that habitat suitability in and around turbine locations was strongly influential on eagles’ approach distance to turbines. Our confirmation that blade motion had little effect on Scottish golden eagles’ wariness of turbines suggests that for eagles that are prone to avoid turbines, their wariness is a response to turbines per se, and not blades’ movement. In our study system, and others where avoidance is the predominant response, curtailment of turbines’ operation on birds’ close approaches, or making turbine blades more obvious, should, therefore, have little material influence on functional habitat loss impacts. If true, this has important implications for wind farm designs and any proposed mitigation.

African savanna raptors show evidence of widespread population collapse and a growing dependence on protected areas.

The conversion of natural habitats to farmland is a major cause of biodiversity loss and poses the greatest extinction risk to birds worldwide. Tropical raptors are of particular concern, being relatively slow-breeding apex predators and scavengers, whose disappearance can trigger extensive cascading effects. Many of Africa's raptors are at considerable risk from habitat conversion, prey-base depletion and persecution, driven principally by human population expansion. Here we describe multiregional trends among 42 African raptor species, 88% of which have declined over a ca. 20-40-yr period, with 69% exceeding the International Union for Conservation of Nature criteria classifying species at risk of extinction. Large raptors had experienced significantly steeper declines than smaller species, and this disparity was more pronounced on unprotected land. Declines were greater in West Africa than elsewhere, and more than twice as severe outside of protected areas (PAs) than within. Worryingly, species suffering the steepest declines had become significantly more dependent on PAs, demonstrating the importance of expanding conservation areas to cover 30% of land by 2030-a key target agreed at the UN Convention on Biological Diversity COP15. Our findings also highlight the significance of a recent African-led proposal to strengthen PA management-initiatives considered fundamental to safeguarding global biodiversity, ecosystem functioning and climate resilience.

Pleistocene raptors from cave deposits of South Australia, with a description of a new species of Dynatoaetus (Accipitridae: Aves): morphology, systematics and palaeoecological implications

The Pleistocene fossil record of Australian raptors (Accipitridae: eagles, hawks and Old World vultures) is very poorly understood with only three distinct extinct species confirmed until now. The small Necrastur alacer remains unstudied; however recent research has established Cryptogyps lacertosus as a valid species that, along with the very large Dynatoaetus gaffae, has potential affinities with the Aegypiinae–Circaetinae clade. These, along with a single large living inland raptor, the Wedge-tailed Eagle Aquila audax, suggest that Australia had an impoverished diversity of large raptors compared to other similar continental regions. However, fossil material similar in size to A. audax from multiple Pleistocene cave deposits raises the possibility of further taxa and is here assessed. A partial skeleton from Green Waterhole/Fossil Cave in the Tantanoola District of South Australia is referred to Cryptogyps lacertosus on the basis of similar size to bones of this species and that the associated coracoid is identical to that found with a tarsometatarsus that was previously referred to this species, coming from Leaena’s Breath Cave on the Nullarbor Plain, Western Australia. This partial skeleton allowed additional material from the Old Collections, Wellington Caves, and Walli Caves in New South Wales to be referred to this species. A second species, more robust than A. audax, is identified from material from Victoria Fossil Cave at Naracoorte. Phylogenetic analyses determined this species to be the sister taxon of the much larger Dynatoaetus gaffae recently described from several Australian sites, and so we name it as Dynatoaetus pachyosteus sp. nov. Further fragmentary remains attributable to either A. audax, C. lacertosus or D. pachyosteus are recorded from sites in the Wellington Caves complex, NSW. This study increases the known diversity of raptors in Pleistocene Australia, consistent with the presence of the more diverse megafaunal prey that existed at the time. Ellen K. Mather [ math0083@flinders.edu.au ], College of Science and Engineering, Flinders University, GPO 2100, Adelaide, SA 5001, Australia; Michael S. Y. Lee [ Mike.Lee@samuseum.sa.gov.au ], Earth Sciences Section, South Australian Museum, North Terrace, Adelaide 5000, Australia (College of Science and Engineering, Flinders University, GPO 2100, Adelaide, SA 5001, Australia); Diana A. Fusco [ diana.fusco@flinders.edu.au ], College of Science and Engineering, Flinders University, GPO 2100, Adelaide, SA 5001, Australia; John Hellstrom [ j.hellstrom@unimelb.edu.au ], Faculty of Science, School of Geography, Earth and Atmospheric Sciences, University of Melbourne, Grattan Street, Parkville, Melbourne, 3010, Australia; Trevor H. Worthy [ trevor.worthy@flinders.edu.au ], College of Science and Engineering, Flinders University, GPO 2100, Adelaide, SA 5001, Australia.

Long-term female bias in sex ratios across life stages of Harpy Eagle, a large raptor exhibiting reverse sexual size dimorphism.

The primary (PSR), secondary (SSR) and adult (ASR) sex ratios of sexually reproducing organisms influence their life histories. Species exhibiting reversed sexual size dimorphism (RSD) may imply a higher cost of female production or lower female survival, thus generating biases in PSR, SSR and/or ASR towards males. The Harpy Eagle is the world's largest eagle exhibiting RSD. This species is found in the Neotropical region and is currently threatened with extinction. We used molecular markers to determine the sex of 309 Harpy Eagles spanning different life stages-eaglets, subadults and adults-from 1904 to 2021 within the Amazon Rainforest and Atlantic Forest. Sex ratios for all life stages revealed a female-biased deviation across all periods and regions. Our results suggest that the population bias towards females is an evolutionary ecological pattern of this species, and SSR and ASR likely emerged from the PSR. This natural bias towards females may be compensated by an earlier sexual maturation age of males, implying a longer reproductive lifespan and a higher proportion of sexually active males. A better understanding of the Harpy Eagle's life history can contribute to understanding sex-role evolution and enable more appropriate conservation strategies for the species.

Responses of GPS-Tagged Territorial Golden Eagles Aquila chrysaetos to Wind Turbines in Scotland

Research on potentially adverse effects of wind farms is an expanding field of study and often focuses on large raptors, such as golden eagles, largely because of their life history traits and extensive habitat requirements. These features render them sensitive to either fatality (collision with turbine blades) or functional habitat loss (avoidance through wariness of turbines). Simplistically, avoidance is antagonistic to collision; although, the two processes are not necessarily mutually exclusive in risk. A bird that does not enter a wind farm or avoids flying close to turbines cannot collide with a blade and be killed. In the USA, collision fatality is implicated as the typical adverse effect. In Scotland, avoidance of functional habitat loss appears more likely, but this depends in part on the habitat suitability of turbine locations. Previous Scottish studies have largely concentrated on the responses of GPS-tagged non-territorial golden eagles during dispersal. Several arguments predict that territorial eagles may have lower avoidance (be less wary) of turbines than non-territorial birds. Hence, we contrasted the responses of GPS-tagged non-territorial (intruding) and territorial eagles to the same turbines at 11 operational Scottish wind farms. We show that territorial eagles rarely approached turbines, but, as in previous Scottish studies of non-territorial birds, the spatial extent of avoidance depended on the habitat suitability of both turbine locations and their wider surroundings. Unexpectedly, we found that territorial eagles were apparently as wary as intruding non-territorial conspecifics of the same turbines. Our results show that regardless of age or territorial status, Scottish golden eagles largely avoided wind turbine locations, but this avoidance was conditional, in part, on where those turbines were located. Responses to turbines were also strongly dependent on birds’ identities and different wind farms. We speculate on how widespread our findings of avoidance of turbines by golden eagles are elsewhere in Europe, where there appear to be no published studies showing the level of collision fatalities documented in the USA.

Smaller Australian raptors have greater urban tolerance

Urbanisation is occurring around the world at a rapid rate and is generally associated with negative impacts on biodiversity at local, regional, and global scales. Examining the behavioural response profiles of wildlife to urbanisation helps differentiate between species that do or do not show adaptive responses to changing landscapes and hence are more or less likely to persist in such environments. Species-specific responses to urbanisation are poorly understood in the Southern Hemisphere compared to the Northern Hemisphere, where most of the published literature is focussed. This is also true for raptors, despite their high diversity and comparably high conservation concern in the Southern Hemisphere, and their critical role within ecosystems as bioindicators of environmental health. Here, we explore this knowledge gap using community science data sourced from eBird to investigate the urban tolerance of 24 Australian raptor species at a continental scale. We integrated eBird data with a global continuous measure of urbanisation, artificial light at night (ALAN), to derive an urban tolerance index, ranking species from positive to negative responses according to their tolerance of urban environments. We then gathered trait data from the published literature to assess whether certain traits (body mass, nest substrate, habitat type, feeding guild, and migratory status) were associated with urban tolerance. Body size was negatively associated with urban tolerance, as smaller raptors had greater urban tolerance than larger raptors. Out of the 24 species analysed, 13 species showed tolerance profiles for urban environments (positive response), and 11 species showed avoidance profiles for urban environments (negative response). The results of this study provide impetus to conserve native habitat and improve urban conditions for larger-bodied raptor species to conserve Australian raptor diversity in an increasingly urbanised world.

Sex difference in natal dispersal distances of Golden Eagles Aquila chrysaetos in Scotland

Natal dispersal distance (NDD) is critical in understanding and defining populations and their conservation. It is defined as the linear distance between the natal location and first reproductive (‘effective NDD’) or potential reproductive (‘gross NDD’) location. It is a measure of gene flow and the functional connectivity across generations between individuals breeding in the same or different geographies. NDD is difficult to record in large raptors. GPS‐satellite telemetry has facilitated its recording. Previous Scottish studies showed that gross and effective NDD were apparently equivalent, and an algorithm based on telemetric data could identify the territory settlement timing and location of birds originally tagged as nestlings. We analysed natal dispersal data from 39 Golden Eagles GPS‐tagged in Scotland to estimate NDD. Raw median estimates were 29.8 km for males (n = 22) and 58.6 km for females (n = 17), 38.1 km averaged across sexes. Males had significantly shorter NDD, as theoretically predicted. Our NDD estimates were shorter but not grossly dissimilar to those from the USA, where sex differences in NDD had not been confirmed. Respective sample sizes may underly the latter contrast in confirmation. We also showed that in the absence of data from sexed birds, NDD estimates can be different. Natal dispersal duration was not related to NDD, suggesting that time to prospect a territory opportunity was not associated with the selected territory's distance from the natal site. The previous status of the subsequent settled territory (occupied or vacant) was also not related to NDD. We conclude that sex differences in NDD are important in application to population demography and conservation. Although we found no support for two other potential drivers of NDD (natal dispersal duration and previous territory status), identifying additional influences on NDD is in its infancy in large raptors and deserves more study.

Historical changes in mortality patterns of diurnal and nocturnal raptors in the Czech Republic, Central Europe: 1913–2017

Raptors are apex predators and essential environmental indicators of ecosystem changes, with anthropogenic mortality heavily influencing their population trends. However, mortality factors can change over time, potentially diverting attention from the underlying drivers of raptor declines. Therefore, a broader perspective beyond studying contemporary mortality patterns for individual species is necessary to prioritize conservation efforts across raptor species. Our study analyzed data from six databases spanning 1913–2017 for the recoveries of 24,443 dead birds, including 24 diurnal and nocturnal raptor species in the Czech Republic. Our results showed that direct persecution historically dominated raptor mortality, but contemporary patterns are shaped by different sources of anthropogenic mortality. Mortality due to vehicle collisions, electrocution or collision at powerlines, and other anthropogenic sources gradually increased from 1913 until 2000 but began to decline in the last two decades. After 2000, vehicle collisions caused higher mortality rates than mortality linked to powerlines and other anthropogenic causes. Natural mortality was lower than average anthropogenic mortality during 1913–1990 but prevailed over anthropogenic mortality after 2000. Species-specific variation in raptor mortality causes was also detected. Direct persecution was the most common mortality factor for diurnal species with higher human-wildlife conflict. Powerline mortality affected mainly farmland and larger raptors, while vehicle collisions were the most significant mortality factor for most owl species and other anthropogenic mortality for barn owls Tyto alba. Raptor conservation efforts should prioritize reducing direct persecution, but coordinated actions to mitigate vehicle collision mortality are also necessary for nocturnal raptors.

Substantial Variation in Prospecting Behaviour of Young Golden Eagles Aquila chrysaetos Defies Expectations from Potential Predictors

Natal dispersal of large raptors is poorly understood, despite being a crucial transitional life-cycle phase affecting gene flow and population dynamics. A research-gap rarely examined concerns how young dispersing raptors strategize movements towards first settlement on a prospective breeding territory. First territory settlement is a critical decision for a lifetime and can take several years. With such importance, large raptors should theoretically devote considerable effort to acquire accurate information during prospection. Nevertheless, when discovery of territorial opportunities may be difficult, but easier in vacant territories, we posit two extremes in strategizing prospection behaviours: (1) “Quick, grab it when available with limited reconnaissance,” as opposed to (2) “Slow, waiting game with frequent reconnaissance”. We analysed pre-settlement data from 37 GPS-tagged nestling golden eagles, later recorded as having settled on their first territory. The number of eagles’ unique daily visits to their later settled territories was a measure of prospection intensity. We documented substantial variation in prior visits, between less than 10 to several hundred. Analyses considered several potential predictors. We expected a positive association between number of prospecting visits and natal dispersal duration, since with more time to gather information there should be more visits. We also expected fewer prospecting visits in prior vacant territories. Neither of these expectations were supported. There was a non-significant tendency for more prospection visits by males. Our study provides novel information on a seldom-studied behaviour in a large raptor. It illustrates substantial variation in prospecting behaviour, but expectations of potential drivers behind this variation were not confirmed, urging further study.

Long-term concentration of tropical forest nutrient hotspots is generated by a central-place apex predator

Apex predators typically affect the distribution of key soil and vegetation nutrients through the heterogeneous deposition of prey carcasses and excreta, leading to a nutrient concentration in a hotspot. The exact role of central-place foragers, such as tropical raptors, in nutrient deposition and cycling, is not yet known. We investigated whether harpy eagles (Harpia harpyja) in Amazonian Forests—a typically low soil fertility ecosystem—affect soil nutrient profiles and the phytochemistry around their nest-trees through cumulative deposition of prey carcasses and excreta. Nest-trees occurred at densities of 1.5–5.0/100 km2, and each nest received ~ 102.3 kg of undressed carcasses each year. Effects of nests were surprisingly negative over local soil nutrient profiles, with soils underneath nest-trees showing reductions in nutrients compared with controls. Conversely, canopy tree leaves around nests showed significant 99%, 154% and 50% increases in nitrogen, phosphorus and potassium, respectively. Harpy eagles have experienced a 41% decline in their range, and many raptor species are becoming locally extirpated. These are general examples of disruption in biogeochemical cycles and nutrient heterogeneity caused by population declines in a central-place apex predator. This form of carrion deposition is by no means an exception since several large raptors have similar habits.

Ecological drivers of breeding periodicity in four forest neotropical eagles

We explore the potential factors that affect clutch initiation in four Neotropical large raptors (Harpy eagle—HE, Crested eagle—CE, Ornate hawk-eagle—OHE, and Black hawk-eagle—BHE) by analyzing 414 clutch events mostly obtained from captive individuals. Differences in how clutch initiation is associated with changes in photoperiod were found between HE and both hawk-eagles, and between CE and BHE. Changes in temperature at the time of clutch initiation only differed between HE and OHE, whereas changes in precipitation varied between BHE and all other species. Principal Component Analysis of these environmental cues showed that ellipses in the dataset of each species overlap, but only ellipses from CE and OHE had the same variation trends. This means that although these species live under similar ecological conditions, they exhibit three different patterns of response to environmental cues. Apparently, these patterns are not associated with phylogenetic relatedness because species belonging to the same clade do not show the same response pattern. Diet diversity analysis revealed that HE has the least varied diet, and CE and OHE the most varied diet. The fact that species who fit the same reproductive timing response to environmental cues show similar diets leads us to hypothesize that breeding in these eagles was most likely shaped by food availability.

Grassland Alterations Do Not Affect Breeding Success, but Can Explain Dietary Shifts of a Generalist Raptor Species

Habitat alteration is a widespread threat severely affecting large raptors because of their low density and the huge area they inhabit. In this study, we assessed whether human-driven habitat alterations mediated dietary shifts of apex predators, focusing on the Eastern imperial eagle (Aquila heliaca). Following a bottom-up conception (before–after), we evaluated the effect of grassland change on the eagle’s dietary shift and breeding success. Land use patterns underwent a significant transformation over the study period, creating a large decrease in grasslands. The territories lost an average of 25.79% of their grasslands. Habitat alteration mediated dietary shifts, but had no reproductive consequences for eagles. Eagles became 1.90 times more likely to predate on northern white-breasted hedgehog and 1.62 times more likely to forage on white stork in the period after grassland alteration. The frequency of tortoises also increased, and they were 4.04 times more likely to be predated on in the years after transformation. Conversely, brown hare was 0.51 times less likely to be consumed in the grassland loss period, while this likelihood was 0.54 times lower for rodents and 0.64 times lower for the European souslik. Doves, meanwhile, were 2.73 times more likely to be predated on in the years following grassland destruction. We found that the presence and biomass of songbirds correlated negatively with the breeding success of eagles, and biomass supply from European souslik was negatively associated with breeding success, while the white stork’s presence and biomass resulted positively in more progeny. Diet diversity did not have an effect on the eagle’s reproduction. The responses of these eagles may vary across territories, depending on how they rank their prey, as the territory effect was a powerful factor shaping dietary shifts for this top predator. Our results offer new evidence of the link between habitat alteration, dietary shifts, and reproductive success, contributing to our understanding of the enigmatic mechanism through which an apex predator successfully adapts to large-scale land use pattern transformation by increasing dietary specialization. We recommend restoration of habitat complexity, including preservation of field margins, grassland patches with scattered small shrub formations, and grassland margins between medium-sized arable lands, promotion of measures for traditional grassland management through gradual grazing, and a ban on the use of shredders.

Prey resources are equally important as climatic conditions for predicting the distribution of a broad‐ranged apex predator

AbstractAimA current biogeographic paradigm states that climate regulates species distributions at continental scales and that biotic interactions are undetectable at coarse‐grain extents. However, advances in spatial modelling show that incorporating food resource distributions are important for improving model predictions at large distribution scales. This is particularly relevant to understand the factors limiting the distribution of widespread apex predators whose diets are likely to vary across their range.LocationNeotropical Central and South America.MethodsThe harpy eagle (Harpia harpyja) is a large raptor, whose diet is largely comprised of arboreal mammals, all with broad distributions across Neotropical lowland forest. Here, we used a hierarchical modelling approach to determine the relative importance of abiotic factors and prey resource distribution on harpy eagle range limits. Our hierarchical approach consisted of the following modelling sequence of explanatory variables: (a) abiotic covariates, (b) prey resource distributions predicted by an equivalent modelling for each prey, (c) the combination of (a) and (b), and (d) as in (c) but with prey resources considered as a single prediction equivalent to prey species richness.ResultsIncorporating prey distributions improved model predictions but using solely biotic covariates still resulted in a high‐performing model. In the Abiotic model, Climatic Moisture Index (CMI) was the most important predictor, contributing 76% to model prediction. Three‐toed sloth (Bradypus spp.) was the most important prey resource, contributing 64% in a combined Abiotic‐Biotic model, followed by CMI contributing 30%. Harpy eagle distribution had high environmental overlap across all individual prey distributions, with highest coincidence through Central America, eastern Colombia, and across the Guiana Shield into northern Amazonia.Main ConclusionsWith strong reliance on prey distributions across its range, harpy eagle conservation programmes must therefore consider its most important food resources as a key element in the protection of this threatened raptor.

Kleptoparasitism from condors to eagles mediated by an exotic prey

The presence of alien invasive species can enhance competitive interactions between native species. A common type of direct competition is kleptoparasitism, i.e., the theft of food. This foraging strategy is closely linked to scavenging and can represent a central source of food for some populations and species. Here, we describe novel observations of an obligate scavenger, the Andean condor (Vultur gryphus), stealing invasive European hares (Lepus europaeus) hunted by a large raptor, the Black-chested Buzzard eagle (Geranoaetus melanoleucus), in southern Argentina. We re-analyzed data on food habits of sympatric, obligate scavengers to show that Andean condors consume more hare than two smaller vultures. Our observations suggest that the prevalence of European hare in the diet of Andean condors is partially due to opportunistic kleptoparasitism of the Black-chested Buzzard eagle. We propose that condors kleptoparasite eagles regularly, with cascading consequences for the population dynamics of condors, eagles, and hares. Our observation illustrates how novel food resources generated by invasive species can lead to new context-dependent competitive interactions between obligate scavengers and apex predators.

Крупные хищные птицы в заповеднике «Нургуш», Кировская область, Россия

Крупные хищные птицы в заповеднике «Нургуш», Кировская область, Россия

Многолетняя динамика численности крупных ищных птиц на ключевой орнитологической территории «Камско-Бакалдинские болота» (Нижегородская область, Россия)

Identification of breeding territories and long-term population monitoring has been carried out in the Important Bird Areas (IBA) with a global importance “Kamsko-Bakaldinskiye marshes” since 1980. Five large bird species were studied here: Osprey (Pandion haliaetus), Short-Toed Eagle (Circaetus gallicus), Greater Spotted Eagle (Aquila [Clanga] clanga), Golden Eagle (Aquila chrysaetos), White-Tailed Eagle (Haliaeetus albicilla). In this report we will summarize the results. IBA covers the northern (Zavolzhsky) part of the Lyskovsky and Vorotynsky districts of the Nizhny Novgorod region, as well as the adjacent areas of Borsky, Semenovsky, and Voskresensky districts. Its total area is 3156.0 km2. The largest massif of upland, transitional, and lowland bogs in the Volga River basin is preserved here in its natural state. A significant part of IBA area (2265 km2) is listed as Ramsar wetland of international importance. Kamsko-Bakaldinskiye marshes has undergone significant transformation over the past 50 years. Until the 1980s, intensive logging was carried out here with an excess areas were organized by 1994, covering 54% of IBA area and leading to a decrease in logging volumes. In the 1980s drainage and peat extraction amounted to 1% of an area. Disastrous fires of 1972 and 2010 spread through about 50% of an area. The number of rare raptor species was positively influenced by the implementation of a unique project to install 62 nesting platforms in 1998–2014. Multidirectional vectors – the destruction of habitats and their conservation, combined with compensatory biotechnical measures, superimposed on the general population trends of large raptors in the center of the European part of Russia. As a result, the population dynamics of different species in Kamsko-Bakaldinskiye marshes differs significantly. The population dynamic for four out of five studied species shows a clear positive trend. Thus, the number of Osprey and White-Tailed Eagle has increased by three and six times, respectively. A project that included nesting platform installation had a significant impact on Osprey population. White-Tailed Eagle depended on it to a lesser extent, however, throughout an entire observation period, there was a general positive trend in the abundance of the species in the European part of Russia. The negative impact of catastrophic fires in 2010 on Osprey and White-Tailed Eagle was insignificant. Abundance of Short-Toed Eagle and Greater Spotted Eagle in 2000–2014 wasseverely underestimated. After 2014, additional data were collected, which allowed us to determine the abundance and distribution of these species in studied area, as well as to identify a positive population trend. In 2000–2014, actual Short-Toed Eagle abundance was twice as high as estimates made in the period. Subsequently, a favorable factor for Short-Toed Eagle was the large burnt area left by fires, which the birds used as new hunting grounds. A twofold increase in Short-Toed Eagle population happened in 2011–2023. The difference in estimates of Greater Spotted Eagle abundance in 2014 and 2018 is mainly due to the results of additional research efforts. Breeding territories have been identified in previously poorly studied floodplain habitats. In addition, the number of Greater Spotted Eagle increased slightly after the fires of 2010 destroyed most of its breeding territories in Kamsko-Bakaldinskiye marshes. The number of Golden Eagle significantly increased in 2000–2010 due to the use of nesting platforms. Then it began to decline due to the long-term depression in Mountain Hare and Grouse populations, as well as catastrophic fires that affected most of breeding territories. Thus, Golden Eagle turned out to be the most vulnerable to pyrogenic changes in their habitat. The number of the species has fallen to the lowest point, almost reaching level of the 1980s. Species’ breeding territories are only preserved in areas unaffected by fires. Golden Eagle’s population decline has had a positive impact on populations of other large raptor species, especially noticeable for Greater Spotted Eagle. The emergence of its breeding territories was noted where Golden Eagle’s breeding territories were lost due to fires. Kamsko-Bakaldinskiye Marshes currently remains the most important refugium for rare large raptor species in Nizhny Novgorod Region, where it is advisable to expand and strengthen protected areas and restore permanent implementation of biotechnical projects.

Степной орел на территории резервата «Бокейорда» и Ащиозекского заказника (Западно-Казахстанская область) в 2022–2023 годы

Степной орел на территории резервата «Бокейорда» и Ащиозекского заказника (Западно-Казахстанская область) в 2022–2023 годы