The great bustard (Otis tarda) is a globally threatened farmland bird with variable population trends across Europe. While many populations are declining, the West-Pannonian population has increased, providing an opportunity to investigate species persistence in intensively cultivated landscapes. We examined seasonal habitat use of this population using Ecological Niche Factor Analysis (ENFA) on a seven-year dataset of systematic observations—the first ENFA application for the West-Pannonian great bustard population. This methodological framework allowed us to identify key ecological factors driving habitat selection, assess interannual consistency, and explore sex-specific differences. Our results indicate that agri-environmental scheme (AES) supported fallows and winter rapeseed are consistently selected and function as critical seasonal resources, whereas other habitat types are used only during certain periods of the season, but remain essential within the agricultural mosaic. Habitat preferences were largely similar between males and females, with minor seasonal differences. By linking habitat selection to measurable land-use features, our study provides a robust, evidence-based framework for guiding conservation management of great bustards. These findings demonstrate how targeted agri-environmental interventions can enhance habitat suitability and persistence of threatened farmland species, offering practical guidance for spatial planning and conservation strategies grounded in empirical habitat-use data.

Designation and management of protected areas (PAs) can mitigate detrimental anthropogenic impacts on biodiversity. Across Europe, an extensive network of PAs exist to protect wildlife and habitats. These sites aim to provide important refugia for species of conservation interest, which include the Red Kite (Milvus milvus; hereafter "kites"). Currently, kites are classified as globally Least Concern but in danger of extinction in parts of their range such as Spain. However, it remains unclear to what extent kite ranges overlap with PAs with fundamental knowledge gaps persisting for the species during winter. Using data for 103 kites tagged with GPS-GSM telemetry loggers over 180 winters between 2013-2022, we modelled proportional overlap between kite winter ranges and both European Natura 2000 sites and Important Bird and Biodiversity Areas (IBAs). We also explored the effects of various demographic, geographic and environmental predictors of PA overlap in tagged kites. Overall, 24.5 ± 28.1% (± SD) of kite winter core areas and 26.6 ± 20.5% of winter home ranges overlapped with European PAs. Kites that wintered in areas with greater agricultural land cover had lower overlap with PAs. Kites that wintered in Iberia (Spain and Portugal) and the Pyrenees (France and into northern Spain) had lower overlap with PAs than conspecifics wintering in Central Europe. Wildlife that rely on traditional agricultural landscapes during winter may thus remain unprotected by existing European PAs. Policymakers should consider the conservation needs of such species when designating new PAs, especially as Spain holds the largest global wintering kite population, and the species is categorised as "In danger of extinction" in the Spanish National Catalogue of Threatened Species. Improving protection of wintering kites in Iberia remains an urgent conservation priority.

Understanding bird avoidance behaviour at wind turbines is essential for accurate collision risk assessment. We provide one of the first empirical analyses of both micro-avoidance (avoidance of rotor-swept airspace) and meso-avoidance (avoidance of the entire turbine) in Red Kites (Milvus milvus), based on high-resolution GPS telemetry integrated with turbine operational data and simulation-based error correction. Red Kites showed consistently high avoidance rates: meso-avoidance averaged ~ 90% and micro-avoidance ~ 80%, resulting in an overall avoidance probability of ~ 98%. Avoidance varied with individual experience-birds with greater prior exposure to turbines showed lower meso-avoidance. Whether this reflects habituation and increased collision risk or improved spatial awareness remains to be investigated. Environmental conditions also modulated avoidance: higher wind speeds and increased cloud cover were associated with stronger avoidance responses. This suggests that under unfavourable weather, Red Kites adopt more cautious flight behaviour that may be associated with lower collision risk. In contrast, turbine-specific features (e.g. tower height or rotor diameter) had no significant effect. These findings indicate that Red Kites flexibly adjust their spatial behaviour in response to turbine exposure and environmental context. By refining species-specific avoidance estimates and identifying mechanisms influencing risk, our findings improve the empirical basis for collision risk assessment in Red Kites and highlight that avoidance behaviour may vary with environmental conditions and turbine experience.

.-There are many raptor rehabilitation centers around the world that receive and care for wild raptors. Wildlife rehabilitation is a labor- and cost-intensive part of addressing animal welfare. Apart from the compassionate aspect of taking responsibility for an injured animal, there remains an open question as to whether doing so contributes to animal conservation. The fates of such animals after their rehabilitation and release have rarely been studied. Long-term post-release monitoring is needed to assess survival and reproduction. Here, we investigate the post-release fates of 22 White-tailed Eagles (Haliaeetus albicilla), including juveniles, immature birds, and adults in Austria, the Czech Republic, Germany, and Slovakia. Using GPS tracking, we monitored the eagles for 2-2639 d (median 1/4 340 d) between 2005 and 2023. The longest-surviving eagle was tracked for more than 7 yr. Release was followed by a short 6-d period of high mortality, followed in turn by a long-term annual adult survival rate of 74.6%. Anthropogenic factors contributed to 70% of the long-term mortality cases. Reason for admission, length of hospital stay, and use of flight aviaries had no statistically significant effect on long-term survival. Five eagles successfully bred and produced a total of 10 fledglings. Traveling as much as 1378 km, the released eagles dispersed throughout central, northern, and eastern Europe. Thus, it can be concluded that successful rehabilitation of White-tailed Eagles resulted in high survival rates; and in five cases, successful reproduction indicated effective reintegration into the wild population.

Most species of migrating birds use a combination of innate vector-based orientation programs and social information to facilitate accurate navigation during their life. A number of various interspecies hybridisations have been reported in birds. The traits of parents are expressed in hybrids in typical ways which are either intermediate, combined or heterotic. Here, we analyse the different migration behaviours of medium-sized raptors, i.e., Red Kites Milvus milvus, Black Kites Milvus migrans, and their hybrids. We chose six well-established parameters to compare the behaviour of Kite hybrids with those of both parental species. When comparing 16 quantified behavioural characteristics between Red Kites and F1 hybrids and between Black Kites and F1 hybrids, significant differences were found in 10 characteristics between Red Kites and F1 hybrids but only one of the 16 characteristics between Black Kites and F1 hybrids. Hence, F1 hybrid individuals showed behaviour much more similar to Black Kites than Red Kites. It implies that the basis of the migratory behaviour of Kites is an innate program with the dominance of genetic determinants supplemented by the use of social learning from individuals of the parent species.

Wind turbines are important for achieving renewable energy goals, but present a considerable threat to wildlife, especially birds and bats. This study reports 41 confirmed collisions of GPS-tracked Red Kites (Milvus milvus) with wind turbines across Europe (2017-2024). We compared environmental and turbine-specific factors during collisions and non-collision movements within 500 m of turbines. Collisions occurred year-round, with the highest mean number of collisions per day during spring and autumn migration. Rotor clearance and diameter were significant predictors of collision risk: turbines with greater clearance exhibited lower probabilities of collision, likely due to reduced overlap with typical Red Kite flight altitudes. Based on our model, a 25.5 m increase in rotor diameter was associated with a fivefold increase in collision probability; mitigating this risk would require increasing rotor clearance by approximately 19.3 m. Variation in collision probability was greater between wind parks than between individual birds. No significant effects were found for cloud cover, precipitation, wind speed, or turbine density within 500 m. Our findings suggest that turbines with rotor diameters <= 90 m and clearances >= 60 m may pose a lower relative threat to Red Kites. Increasing rotor diameters without adjusting height restrictions reduces clearance and increases the risk of collisions. These results highlight the need for turbine designs minimizing overlap with bird flight heights and underscore the importance of legislative adjustments to height restrictions.

ABSTRACT Anthropogenic activities threaten many wildlife populations by increasing mortality rates, making it crucial to identify the locations and causes of mortality to inform conservation actions. Technological advancements, such as GPS satellite tracking, enable precise recording of wildlife movements. High‐resolution data from such devices can facilitate rapid carcass recovery and provide insights into the mortality causes of tagged individuals. Obtaining required information to determine these causes is complex, and standardized approaches can overcome these limitations. In this study, we introduce the LIFE EUROKITE Assessment Protocol (LEAP), a framework for determining the timing, locations, and causes of mortality in GPS‐tagged birds. LEAP is a multifaceted approach that integrates: (1) GPS tracking data, (2) evidence from the mortality location (site investigation), and (3) necropsy results to derive the mortality cause and a corresponding certainty score. We supplement the detailed description of LEAP with case studies assessing its effectiveness. Using 329 deceased GPS‐tagged red kites (Milvus milvus) we compared conditions of the carcasses processed using LEAP with 145 opportunistically collected raptor carcasses. We also show that LEAP improves carcass condition and therefore allows for higher quality necropsy results. Additionally, we assessed how availability among sources of information (tracking, site investigation and necropsy) influences the quality of mortality assessments. Applying LEAP with all data sources provided the highest quality assessments in 64% of cases. Some 35% of cases were of high quality without necropsy, instead drawing evidence only from tracking data and site investigations. Predation related mortality was less prevalent (11%) when relying on necropsy compared to cases without necropsy (36%), while poisoning showed the opposite trend. Furthermore, we provide guidelines and empirical examples of mortality assessments. Our standardized LEAP approach ensures the best use of all available information regarding mortality events in GPS‐tagged birds and advances wildlife mortality research as a valuable tool for conservationists and wildlife managers.

Wind energy development is a key component of climate change mitigation. However, birds collide with wind turbines, and this additional mortality may negatively impact populations. Collision risk could be reduced by informed selection of turbine dimensions, but the effects of turbine dimensions are still unknown for many species.As analyses of mortality data have several limitations, we applied a simulation approach based on flight height distributions of six European raptor species. To obtain accurate flight height data, we used high-frequency GPS tracking (GPS tags deployed on 275 individuals). The effects of ground clearance and rotor diameter of wind turbines on collision risk were studied using the Band collision risk model.Five species had a unimodal flight height distribution, with a mode below 25 m above ground level, while Short-toed Eagle showed a more uniform distribution with a weak mode between 120 and 260 m. The proportion of positions within 32–200 m ranged from 11 % in Marsh Harrier to 54 % in Red Kite.With increasing ground clearance (from 20 to 100 m), collision risk decreased in the species with low mode (−56 to −66 %), but increased in Short-toed Eagle (+38 %). With increasing rotor diameter (from 50 to 160 m) at fixed ground clearance, the collision risk per turbine increased in all species (+151 to +558 %), while the collision risk per MW decreased in the species with low mode (−50 % to −57 %).These results underpin that wind turbine dimensions can have substantial effects on the collision risk of raptors. As the effects varied between species, wind energy planning should consider the composition of the local bird community to optimise wind turbine dimensions. For species with a low mode of flight height, the collision risk for a given total power capacity could be reduced by increasing ground clearance, and using fewer turbines with larger diameter.

The breeding behaviour of raptors is determined by many characteristics, such as courtship and mating patterns, nest building, foraging, territorial defence activities, clutch incubation, and caring for the young. Here, we study the breeding behaviour of the Red Kite (Milvus milvus), a European native bird of prey. From a period between 2018 and 2022, we analysed data for 33 adult Red Kites (14 males and 19 females) during 70 successful breeding episodes in Austria, the Czech Republic, and Slovakia. Using satellite telemetry and in situ observations, we found differences between males and females in the size of the home range, number of nights on the nest, and maximum distances from the nest. We analysed the influence of different factors on movement activity, breeding productivity, and home range size. Females spent significantly more nights on the nest than did males, flew shorter distances from the eyrie, and occupied smaller areas. Red Kites with two or more breeding experiences arrived significantly earlier than did unexperienced Kites in their first breeding attempts. Juveniles departed from the nest sooner than did their parents. Birds with more fledged juveniles occupied smaller home ranges. Our study reveals new knowledge of substantially different breeding behaviours in male and female Central European Red Kites.

Human-induced direct mortality affects huge numbers of birds each year, threatening hundreds of species worldwide. Tracking technologies can be an important tool to investigate temporal and spatial patterns of bird mortality as well as their drivers. We compiled 1704 mortality records from tracking studies across the African-Eurasian flyway for 45 species, including raptors, storks, and cranes, covering the period from 2003 to 2021. Our results show a higher frequency of human-induced causes of mortality than natural causes across taxonomic groups, geographical areas, and age classes. Moreover, we found that the frequency of human-induced mortality remained stable over the study period. From the human-induced mortality events with a known cause (n = 637), three main causes were identified: electrocution (40.5 %), illegal killing (21.7 %), and poisoning (16.3 %). Additionally, combined energy infrastructure-related mortality (i.e., electrocution, power line collision, and wind-farm collision) represented 49 % of all human-induced mortality events. Using a random forest model, the main predictors of human-induced mortality were found to be taxonomic group, geographic location (latitude and longitude), and human footprint index value at the location of mortality. Despite conservation efforts, human drivers of bird mortality in the African-Eurasian flyway do not appear to have declined over the last 15 years for the studied group of species. Results suggest that stronger conservation actions to address these threats across the flyway can reduce their impacts on species. In particular, projected future development of energy infrastructure is a representative example where application of planning, operation, and mitigation measures can enhance bird conservation.

The first successful breeding of eastern imperial eagles (Aquila heliaca) in the Czech Republic, which lies at the north-western edge of its world breeding range, was confirmed in 1998. Here we summarise the dispersal, overwintering and expansion of the Czech population based on observational, ringing and telemetry data. The Czech breeding population had increased to at least 14 breeding pairs and 18 territorial pairs by 2022. Between 2017 and 2021, 19 nestlings were equipped with GPS/GSM devices. Two of the 16 surviving individuals (12.5%) spent their first winter in the Mediterranean (1,460 km and 1,671 km from natal nest), but did not repeat this migration pattern again. The other 14 tracked individuals wintered close to their natal areas. Maximal recorded distances from the natal nest and total area occupied (100% minimal convex polygons) were significantly lower in the first calendar year than the second. Signs of settlement prior to the first nesting attempt were already apparent by the third or fourth calendar year. Excluding exploratory trips during the floater period, final natal dispersals for two of the breeding males were 46 km and 92 km, respectively. Further spreading of the species' Czech breeding range is expected in the future.

Abstract A mature Great Bustard (Otis tarda) female tagged with a satellite transmitter in Dévaványa made four breeding attempts in 2019. A total of seven eggs were laid on the four occasions. None of the breeding attempts were successful, and the bird was killed by a predator, presumably a Red Fox (Vulpes vulpes), during the fourth breeding attempt. The four egg-laying attempts are a new experience in the reproductive biology of the species. The failure of the nestings and the death of the bird itself confirm that the conservation measures of the species, as emphasised in international and national conservation plans – controlling predators and egg predator populations, ensuring undisturbed breeding conditions – are important conservation biology actions serving for the protection of the species.

The Red Kite (Milvus milvus) is a common raptor in suitable areas of Austria, the Czech Republic, and Slovakia during the nonbreeding season. However, the exact number of birds wintering in these countries remains unknown. Through an integrated approach using satellite telemetry, direct field surveys at nocturnal roosts, and citizen science databases, we estimated the wintering population of Red Kites in this area during the winter of 2020/2021. Based on three surveys taking place at the beginning (28 November 2020), middle (9 January 2021), and end (5 February 2021) of winter, respectively, we counted 566, 558, and 536 Red Kites. The observations from online citizen science databases mostly appeared to correspond with the area of communal roost sites. Using our combined approach, the estimates of wintering Red Kites were determined as minimum numbers in the study area. A comparison of historical data (from the second half of the 20th and beginning of the 21st centuries, respectively) and our own results suggests that the wintering population of Red Kites in the study area has increased substantially. This dynamic could be caused by changes in climatic conditions, a shift of the birds' breeding range in Europe, changes in migration behavior and/or food availability, and/or conservation efforts.

The Central European Population of the Eastern Imperial Eagle (Aquila heliaca) is located on its most western global distribution edge. After a strong decline in the last two centuries, the population recovered in the past decades not least due to extensive protection measurements. Conservation and scientific programs on international and national level were implemented in several countries, especially in Hungary, Slovakia, Austria, Czech Republic, and Serbia. In frame of these activities imperial eagle were tagged by satellite transmitter since 2003 in several projects by different organisations of the region. In the current presentation we show preliminary results of an analysis of the natal dispersal movements of the immature birds of this residential population of Eastern Imperial Eagles. Therefore, more than 14 million data points of more than 130 individuals were available and analysed. We defined start of natal dispersal as the point when the young birds left their natal territory (5 km from natal nest) for at least 10 consecutive days. Because of high individual variability, we decided to classify the end of dispersal manually as the time the bird became territorial for the first time. We analysed movement pattern for the whole period of natal dispersal as well as for different life stages/age classes. Therefore we distinguished between breeding (1.2–30.9) and non-breeding season (1.10–30.2) for each year of life of the birds. It turns out that daily travel ranges are higher during the breeding season than outside the breeding season and that activity decreases over the years until the birds start establishing a territory. Furthermore, we estimate utilization distribution (UD) by calculating a dynamic Brownian Bridge Movement Model (dBBMM). Therefor in a first step, a dBBMM was calculated for each single individual. Those individual UDs were summarised up by using days of tracking as weight. The resulting UD gives an overview of distribution and space use of immature Eastern Imperial Eagles. It shows that while wide explorative flights of single birds occur, the majority of the birds stays mainly in Central Europe within the range of the breeding distribution of the population. Additional, there is a connection to the western parts of Greece and the island of Crete. The results help to enhance knowledge about habitat use and identify hotspots for further conservation efforts.

Migration and over-wintering strategy of raptors can be influenced by many factors such as sex, age and experience of birds, habitat variability and food availability. Based on the telemetry data of nine Red Kites (Milvus milvus), we observed in situ their wintering grounds in southern Italy during winter 2019/2020. Red Kites originated from Austria and the Czech Republic arrived to their wintering grounds from 10th September to 5th December 2019 and departed between 9th February and 7th May 2020. Tagged Kites stayed in their wintering grounds from 73 to 207 days (mean 135±46 SD). These birds occupied home range and the core area from 39 to 9,351 km2 (KDE 95%; mean 3,591±3,460 SD) and 6 to 1,998 km2 (KDE 50%; mean 566±483 SD), respectively. We observed a total of 242 Red Kites at nine communal roost sites (min. = 14, max. = 45 individuals) used by tagged Red Kites. Roosts were situated at an average altitude of 630 m above sea level. Agricultural countryside with small or large fields, small or large forest patches, meadows, pastures, sheep or cattle farms surrounded areas around communal roosts of Red Kites.

Understanding intrinsic and extrinsic influences of movement behavior in migratory species, with the potential to recommend management actions for species of conservation concern, requires data from across the species' range. For some raptor species, such as the red kite (Milvus milvus; kite), existing data focus on breeding populations or movements en route to wintering areas without considering movements within the wintering areas. Here, we contribute to filling this knowledge gap by investigating landscape-level associations of kites in their southwestern European winter ranges between 2015 and 2020. We also explore aspects of the migration process in terms of geographical patterns in the location of over-wintering grounds, including time spent and distances traveled within them. We predicted that space use in over-wintering areas would be linked to the proportional amount of open, lowland, or urban land cover they contain at the landscape level. Specifically, we tested whether winter range sizes (95% kernel density estimator [KDE] home ranges and 50% KDE core areas) would be smaller in areas with greater proportional open and urban land cover within kite ranges. Controlling for the effects of age and sex, we compared results in 3 over-wintering regions: the Iberian Peninsula, Italy, and the Pyrenean region of southern France. We tracked 36 kites by global positioning system-global system for mobile communications (GPS-GSM) telemetry over 70 individual winters between 2015 and 2020. Kites wintering in the Pyrenees had larger home ranges and core areas but moved less than those wintering in Italy and the Iberian Peninsula. As predicted, ranges were smaller in areas with greater proportional open and lowland land cover; however, there was no effect of urban areas. Older kites that arrived late to the wintering areas had larger home ranges than those that arrived early or on time. During the study 20 kites died or the transmitter malfunctioned. Six of 13 confirmed deaths were due to anthropogenic activity; 5 kites were poisoned. Our results confirm that land use and elevation are key influences of kite space use in southwestern European over-wintering populations, but additional demographic intrinsic factors also affect ranging parameters. These data indicate that over-winter conservation action for kites, for example supplementary feeding with livestock carrion, should focus on open lowland landscapes throughout the species' winter range.

Calls for urgent action to conserve biodiversity under global change are increasing, and conservation of migratory species in this context poses special challenges. In the last two decades the Convention on the Conservation of Migratory Species of Wild Animals (CMS) has provided a framework for several subsidiary instruments including action plans for migratory bird species, but the effectiveness and transferability of these plans remain unclear. Such laws and policies have been credited with positive outcomes for the conservation of migratory species, but the lack of international coordination and on-ground implementation pose major challenges. While research on migratory populations has received growing attention, considerably less emphasis has been given to integrating ecological information throughout the annual cycle for examining strategies to conserve migratory species at multiple scales in the face of global change. We fill this gap through a case study examining the ecological status and conservation of a migratory raptor and facultative scavenger, the red kite (Milvus milvus), whose current breeding range is limited to Europe and is associated with agricultural landscapes and restricted to the temperate zone. Based on our review, conservation actions have been successful at recovering red kite populations within certain regions. Populations however remain depleted along the southern-most edge of the geographic range where many migratory red kites from northern strongholds overwinter. This led us to a forward-looking and integrated strategy that emphasizes international coordination involving researchers and conservation practitioners to enhance the science-policy-action interface. We identify and explore key issues for conserving the red kite under global change, including enhancing conservation actions within and outside protected areas, recovering depleted populations, accounting for climate change, and transboundary coordination in adaptive conservation and management actions. The integrated conservation strategy is sufficiently general such that it can be adapted to inform conservation of other highly mobile species subject to global change.

In a study of the extent and timing of Red Kite Milvus milvus dispersal movements from Central Europe (Austria, the Czech Republic and Slovakia) using GPS telemetry, we found support for the hypothesis that Red Kite dispersal, including migration behaviour, is dependent on both age and sex. Examination of the tendency to stay in, or return to, a particular area in Red Kites indicated that, while part of the population remained in the natal area, most migrated to overwintering sites across a broad belt of southern European sites stretching from the Iberian Peninsula to the Balkans. Red Kites first bred at 2 years old, i.e. in their 3rd calendar year. Migration routes were significantly longer in females than males, while natal philopatry was significantly higher in males than females. The lengths of single-year migration routes decreased significantly over consecutive years, and breeding philopatry increased significantly in cases where previous breeding was successful.

To develop effective conservation strategies for migratory birds, it is essential to understand the ecology of a species at each biological phase, including its wintering (or non-breeding) season. For the red kite (Milvus milvus), an endangered raptor from the Western Palearctic, its wintering ecology is little known. We tagged 44 red kites using GPS/satellite transmitters to study their non-breeding seasons in Spain. Two spatial strategies were recorded: 34 individuals (77%) spent all their wintering periods in only one area, whilst the remaining individuals (23%) moved between two main areas at least once. This strategy, however, was not consistent over the years. In the latter case, the distance between wintering areas was 311.6 ± 134.7 km, and individuals usually spent equally long periods in each area (96 ± 35 days). No effects of age or sex were found on these area shifts, so they may have been driven by food or habitat resource availability. We also found high interindividual variability in home range sizes. The home ranges of adults were two- to three-times smaller than those of immatures, probably due to a better knowledge of the territory.

Dispersal is a key process affecting the dynamic and genetic structure of populations. To increase our knowledge on first-year dispersal in the white-tailed eagle (WTE), 35 nestlings in the Czech Republic, Hungary, and Austria were equipped with GPS/GSM loggers while on the nest between 2016 and 2019. Twenty-nine individuals surviving until March 31 were used to assess post-fledging areas, first-year dispersal distance and direction, temporary settlement areas, and habitat selection. The first flight from the nest was observed between May 19 and July 8. Start of dispersal from post-fledging areas occurred between July 1 and November 14. Post-fledging areas were significantly larger in males ( p = 0.001, median 1236 km 2 , n = 15) than females (median 139 km 2 , n = 12). Maximal dispersal distance ranged from 93 to 433 km from the native nest (median = 187 km) and did not correlate with Simpson’s Diversity Index computed for habitats in individual 100% minimum convex polygons (MCP). Median sizes of minimum convex polygons were 26,888 km 2 for 100% MCP and 13,376 km 2 for 95% MCP ( n = 29). Median sizes of kernel density estimates (KDE) were 3393 km 2 for 80% KDE and 1137 km 2 for 50% KDE. After start of dispersal, young WTEs returned to the proximity of the parental nest for night roosting sporadically. No sex-specific differences in dispersal distance were recorded. While young individuals from the three subpopulations are likely to occur in the same area during the first year of life, future nesting site identification will enable us to assess real gene flow and the connectivity level among them. As this study has illustrated, future conservation efforts to protect young WTEs will require cross-border cooperation.