The greater spotted eagle (Clanga clanga), also called the spotted eagle, is a large migratory bird of prey in the family Accipitridae.
It is a member of the subfamily Aquilinae, commonly known as "booted eagles".Helbig, A. J., Kocum, A., Seibold, I., & Braun, M. J. (2005). A multi-gene phylogeny of aquiline eagles (Aves: Accipitriformes) reveals extensive paraphyly at the genus level. Molecular phylogenetics and evolution, 35(1), 147-164. It was once classified as a member of the genus Aquila, but has been reclassified to the distinct genus Clanga, along with the two other species of spotted eagle.Helbig, A. J., Seibold, I., Kocum, A., Liebers, D., Irwin, J., Bergmanis, U., Meyburg, B.-U., Scheller, W., Stubbe, M. & Bensch, S. (2005). Genetic differentiation and hybridization between greater and lesser spotted eagles (Accipitriformes: Aquila clanga, A. pomarina). The Journal of Ornithology, 146(3), 226-234.
During breeding season, greater spotted eagles are widely distributed across Eastern Europe, parts of Central Europe, central Russia, central Asia and parts of China, along with other isolated areas. During winter, they migrate, primarily to South Asia, Southeast Asia, the Middle East, the upper Mediterranean Basin, and parts of East Africa. Greater spotted eagles favor wetter habitats than most other booted eagles, preferring riparian zones as well as bogs, lakes, ponds, and other bodies of water surrounded by woodland. They breed primarily on floodplains, especially ones that experience high water levels. During winter and migration, they often seek out similar wetland habitats, but have also been observed in dry upland areas such as savanna plateaus.Naoroji, R., & Schmitt, N. J. (2007). Birds of prey of the Indian subcontinent. Om Books International.
The eagle is an opportunistic forager, especially during the winter. It will readily scavenge a variety of food sources, including carrion, as well as small mammals (principally rodents), frogs, and a variety of smaller birds (especially water birds), and occasionally reptiles and insects. The eagle is primarily an aerial hunter, gliding from concealed perches over marshes or wet fields to catch prey.Karyakin, I. V. (2008). The Greater Spotted Eagle in the Volga region, Ural Mountains and western Siberia. Raptors Conservation, 11, 23-69.
This species builds stick nests in large trees, laying a clutch of one to three eggs. The female of a pair incubates and broods the young while the male hunts and delivers prey. Parents rarely raise more than one fledgling per year.Brown, L. & Amadon, D. (1986) Eagles, Hawks and Falcons of the World. The Wellfleet Press. .Väli, Ü. (2004). The greater spotted eagle Aquila clanga and the lesser spotted eagle A. pomarina: taxonomy, phylogeography and ecology. Tartu University Press. As is common among a few species of raptors, the oldest chick is much larger than its younger siblings, and will often attack and kill the younger siblings.
The greater spotted eagle's range overlaps with the closely related lesser spotted eagle (Clanga pomarina). The two species are known to breed together frequently, forming hybrid offspring, which is detrimental to the population of the rarer greater spotted eagles.Väli, Ü., Dombrovski, V., Treinys, R., Bergmanis, U., Daroczi, S. J., Dravecky, M., Ivanovski, V., Lontkowski, J, Maciorowski, G., Meyburg, B.-U., Mizera, T., Zeitz, R. & Ellegren, H. (2010). Widespread hybridization between the greater spotted eagle Aquila clanga and the lesser spotted eagle Aquila pomarina (Aves: Accipitriformes) in Europe. Biological Journal of the Linnean Society, 100(3), 725-736. The greater spotted eagle is classified as a vulnerable species by the International Union for Conservation of Nature. Its populations are threatened by habitat destruction, collisions with objects, and hybridization with lesser spotted eagles.Väli, Ü. (2015). Monitoring of spotted eagles in Estonia in 1994-2014: Stability of the lesser spotted eagle (Aquila pomarina) and decline of the greater spotted eagle (A. clanga). Slovak Raptor Journal, 9(1), 55.
Taxonomy and etymology
Greater spotted eagles are members of the Aquilinae, or "booted eagles", subfamily, a monophyletic group within the larger Accipitridae family. All booted eagles have feathers covering their legs. Members of this diverse, wide-ranging family may be found on every continent except Antarctica. Thirty-eight species of booted eagle are recognized.Gill, F., Donsker, D., & Rasmussen, P. (Eds.). (2021). IOC world bird list. IOC.
Booted eagles are often grouped with the genera Buteo and Haliaeetus, and other more heavy-set Accipitridae, but they may be more closely related to the slenderer accipitrine hawks than previously believed. The greater spotted eagle's closest living relative is the lesser spotted eagle. They are believed to have diverged from their most recent common ancestor around the middle Pliocene, approximately 3.6 million years ago (mya). This "proto-spotted eagle" probably lived in the general region of modern-day Afghanistan, and split into northern and southern lineages when both glaciers and deserts advanced in Central Asia at the start of the last ice age. The northern lineage subsequently separated into the greater (eastern) and lesser (western) spotted eagle species of today, probably around the Pliocene–Pleistocene boundary, almost 2 mya.
Spotted eagles were classified as part of the genus Aquila, along with several other mostly large, brownish eagles. However, molecular phylogenetic studies using one mitochondrial and two nuclear gene sequences showed that the spotted eagles form a monophyletic group with each other and the long-crested eagle (Lophaetus occipitalis). Studies suggest that the spotted eagles should be grouped with Lophaetus, or that all of these species should be grouped within Aquila.Wink, M., & Sauer-Gürth, H. (2004). Phylogenetic relationships in diurnal raptors based on nucleotide sequences of mitochondrial and nuclear marker genes. Raptors worldwide, 483-498. Furthermore, a close relationship has been found between the spotted eagles and the black eagle (Ictinaetus malaiensis) native to Asia. The spotted eagles, long-crested eagle, and black eagle may comprise a species complex or clade.Lerner, H. R., & Mindell, D. P. (2005). Phylogeny of eagles, Old World vultures, and other Accipitridae based on nuclear and mitochondrial DNA. Molecular phylogenetics and evolution, 37(2), 327-346. The spotted eagles were ultimately reclassified as a distinct genus, Clanga, due to overwhelming genetic evidence and large divergences in morphology and ecology between spotted eagles and their sister taxa.Väli, Ü. (2002). Mitochondrial pseudo‐control region in old world eagles (genus Aquila). Molecular Ecology, 11(10), 2189-2194. The scientific name Clanga may derive from Ancient Greek (), or its root may be the Greek word (a variant form of ) for "a kind of eagle" as mentioned by Aristotle.
Extensive hybridization between the greater spotted eagle and the lesser spotted eagle occurs perhaps because the two species have one of the closest relationships of any closely studied Accipitrid taxa, despite significant genetic differences.Global Raptor Information Network. 2021. Species account: Greater Spotted Eagle Clanga clanga. Downloaded from http://www.globalraptors.org on 18 Oct. 2021 The mitochondrial genetic sequences of these species have more than 3% divergence, about twice what is considered the minimum genetic difference to distinguish two species.Helbig, A. J., Seibold, I., Kocum, A., Liebers, D., Irwin, J., Bergmanis, U., Meyburg, B.-U., Scheller, W., Stubbe, M. & Bensch, S. (2005). Genetic differentiation and hybridization between greater and lesser spotted eagles (Accipitriformes: Aquila clanga, A. pomarina). journal of Ornithology, 146(3), 226-234. A third spotted eagle, the Indian spotted eagle (Clanga hastata), was recognized as a distinct species from the similarly sized lesser spotted eagle in 2006.Lerner, H., Christidis, L., Gamauf, A., Griffiths, C., Haring, E., Huddleston, C.J., Kabra, S., Kocum, A., Krosby, M., Kvaloy, K., Mindell, D., Rasmussen, P., Rov, N., Wadleigh, R., Wink, M. & Gjershaug, J.O. (2017). Phylogeny and new taxonomy of the Booted Eagles (Accipitriformes: Aquilinae). Zootaxa, 4216(4), 301-320.
Description
The greater spotted eagle is rather large and compact. Normally, it is black-brown with a contrasting yellow beak. This species has a short neck with a large and often shaggy-naped head, a strong beak, and a short gape-line with round nostrils. The wings are broad and long, reaching the tail tip. The tail is relatively short and rounded. The overall effect of the broad wings and short tail can give them an almost vulture-like silhouette. The feet are large, and the feathers covering the legs are less compactly arranged than on lesser spotted eagles.
Greater spotted eagles tend to perch in the open. Most perches are on treetops at a forest edge, or more isolated vantage points such as a bush, utility pole, or steep riverbank. It is not uncommon for greater spotted eagles to forage from the ground, or rest there in a somewhat hunched posture.
Adult greater spotted eagles are generally a rather uniform dark to blackish brown, though the coloration may appear purplish and glossy. They may appear more starkly contrasted when freshly moulted.
The upperwing covert feathers are often a shade paler than the rest, though these eagles generally appear uniformly dark with two contrasting features: a pale beak and a narrow white U above the tail, though the latter is usually concealed at rest. The species is sexually dimorphic or even polymorphic. Pale and intermediate phenotypes are rare, although they can be slightly more common in eastern ranges.Lontkowski, J., & Maciorowski, G. (2010). Identification of juvenile greater spotted eagle, lesser spotted eagle and hybrids. Dutch Birding, 32, 384-397.
Pale adults, sometimes referred to as Clanga clanga fulvescens, have bicolored plumage. The tail, flight feathers, and greater wing coverts are all blackish, with the body and the rest of the wing coverts appearing light yellow or pale golden buff, sometimes becoming creamy when aged. The buff colour of the fulvescens phenotype is usually contrasted with diffuse dark coloring around the eyes, on the leading edges of wings, and more rarely and sparsely on the chest.Cramp, S., & Simmons, K. E. L. (1980). Vol. II: Hawks to bustards. Oxford [etc.]: Oxford University Press. Intermediate and other variants are very rare, but include those with a slightly paler body and variable yellowish-brown streaking or mottling on the fore upperwing coverts (which can make them look similar to juvenile lesser spotted eagles), or mottled yellow-brown with a dark-streaked breast and pale-tipped wing coverts (like the juvenile eastern imperial eagle (Aquila heliaca)). These intermediate types may show the typical dark brown to black on the upper body, but in flight display pale mottled grey wing linings, or even normal coloration apart from the contrasting paler underbody.