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Replacement clutch of greater Spotted Eagle Clanga clanga after clutch loss: the first documented case in Poland
Contrasting patterns of genetic diversity and lack of population structure in the lesser spotted eagleClanga pomarina(Aves: Accipitriformes) across its breeding range
AbstractCharacterizing the genetic diversity and structure of populations is essential for understanding their evolutionary history and planning species conservation. The lesser spotted eagle (Clanga pomarina) is a large migratory raptor with a relatively small breeding range concentrated in Eastern Europe. We evaluated the level of genetic diversity and population structuring by estimating the length diversity of 23 microsatellite markers in 306 individuals and sequencing 473 nucleotides from the mitochondrial pseudo-control region in 265 individuals across the distribution range. The microsatellite data suggested shallow differentiation between geographical regions and moderate genetic diversity across the range; no recent population bottlenecks were detected. Mitochondrial diversity was relatively low; however, high values were recorded at the southern edge of the distribution range. This, in combination with the star-like distribution of mitochondrial haplotypes, suggests the expansion of the European population from a single (Balkan) refugium during the late Pleistocene or early Holocene after the glacial population bottleneck. However, the Caucasian population may have survived in a separate refugium. We conclude that the lack of clear population structuring and ongoing gene flow across Europe support the treatment of the geographically restricted global population of the lesser spotted eagle as a single evolutionary and conservation unit.
Spatial and temporal differences in migration strategies among endangered European Greater Spotted Eagles Clanga clanga
Summary Understanding connectivity between migratory bird breeding and wintering grounds is essential for range-wide planning of conservation activities. We used GPS tracking to explore the migration of 28 ‘Endangered’ Greater Spotted Eagles, Clanga clanga from three remaining European breeding populations towards their wintering range, and to identify population and sex-specific patterns in selection of wintering sites. The tracked eagles wintered in three continents, 46% in Africa (mostly Eastern Sahel), 43% across southern Europe (mostly Greece) and 11% in Asia (the Middle East). Migratory connectivity was weak (rM = 0.16), and the population spread across the wintering range was large (1,917 km). The three studied populations differed in their migration strategy, with northerly, Estonian breeders all wintering in Southern Europe, and Polish and Belarusian breeders divided between Southern Europe and Africa. Migration strategy was different between Belarusian males and females, with males more likely to winter in Africa than Europe, and on average, migrating 2,500 km further south than females. Migration to Africa took longer, but was partly compensated by higher migration speeds. Greater Spotted Eagles wintered in wetland sites throughout their wintering range, with 15 of 29 birds wintering in internationally or nationally protected sites (including 12 Ramsar sites). Nearly a third of European winterers stayed in the same Greek national park, perhaps indicating a limitation of suitable sites in Europe due to wetland loss or degradation. This highlights the importance of protected wetlands to this species, but also shows their vulnerability to future wetland degradation. Only two of 14 wintering sites in Africa were under protection, showing a potential mismatch between protection of females and males in their wintering grounds.
Can apex predators at the periphery of their range be effectively safeguarded? The Greater Spotted Eagle Clanga clanga in Poland
GPS tracking reveals range size and movement patterns in immature eagles (Clanga clanga and C. clanga x pomarina) with delayed maturation
Abstract The immature period is an important stage in the life histories of animals, influencing their subsequent development and future experiences. This stage is particularly pronounced in long-maturing raptors. In this study, we examined individual ranging areas at breeding and wintering grounds of the vulnerable Clanga clanga (Greater Spotted Eagle) and their hybrids with C. pomarina (Lesser Spotted Eagle) from their primary European Union populations in Poland and Estonia. We analyzed GPS tracking data from 26 individuals (including 11 hybrids) tagged between 2008 and 2022. Our results revealed a reduction in individual ranging areas at both breeding and wintering grounds as the birds matured. With increasing age, C. clanga arrived earlier at future breeding sites, likely to synchronize with breeding adults and enhance their ability to compete for territories and mates. As they aged, immature eagles also extended their stay at breeding grounds. Some individuals limited their ranging areas as early as their 4th or 5th calendar year, indicating the onset of site fidelity, whereas others continued wide-ranging movements into their 7th year. Males, in particular, exhibited philopatry and frequently visited nests of established pairs within their natal population prior to their own recruitment as breeders. Immatures were first observed at nests between their 3rd and 7th calendar years, but confirmed breeding typically occurred later, between their 8th and 10th calendar years. Eight individuals (7 males) were found breeding at an average distance of 8.1 ± 7.3 km from their natal nests. No behavioral differences were observed between C. clanga and their hybrids. Our findings illustrate the slow maturation and prolonged preparation for breeding in this species and its hybrids. These results may inform population dynamics modeling and aid in the conservation of these vulnerable species.