Greater spotted eagle
| Greater spotted eagle | ||||||||||||
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Greater spotted eagle ( Clanga clanga ) |
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| Clanga clanga | ||||||||||||
| ( Pallas , 1811) |
The greater spotted eagle ( Clanga clanga , Syn .: Aquila clanga ) is a species of bird from the hawk family (Accipitridae). This medium-sized representative of the subfamily Aquilinae occurs in Central Europe only in eastern Poland as a breeding bird, to the east the distribution area extends to the Pacific . The species inhabits near-natural, water-rich forest landscapes and feeds primarily on small to medium-sized mammals and water birds.
Greater spotted eagles migrate from medium to long distances ; the wintering area includes the subtropics and tropics of southern Europe, Asia and Africa. The population of the species is declining, at least in the western part of the range, mainly due to habitat destruction and human persecution, the world population is therefore endangered.
description
Greater spotted eagles belong to the medium-sized representatives of the subfamily of Aquilinae . They reach a body length of 59 to 71 cm and a wingspan of 1.57 to 1.79 m and are therefore considerably larger than a common buzzard . The sexual dimorphism is quite pronounced in terms of size and weight, males reach an average of about 85% of the size of the females. Males weigh 1.7 to 1.9 kg and have a wing length of 477 to 517 mm, females reach a weight of 1.8 to 2.5 kg and a wing length of 507 to 542 mm. As with all representatives of the genus Clanga and the closely related genus Aquila , the tips of the hand wings are strongly fingered and the legs are feathered down to the toes. In flight, the wings appear relatively short and noticeably wide, the tail is clearly rounded at the outer edges.
Overall, adult birds are almost monochrome, very dark brown. The entire trunk, the head as well as the upper and lower wing coverts are dark brown and form a weak contrast to the slightly lighter, monochrome dark brown-gray wing and shock feathers in the flying bird. Only the upper tail-coverts have a faint white border. Very rarely does a light color morph occur, which is often referred to in the literature as the "fulvescens" variety. In this morph, the head and the entire trunk as well as all wing covers are light beige to gold in color. The wings and control feathers are dark brown-gray as in normal colored birds.
The iris is brown, the wax skin and toes are yellow. The base of the beak is gray compared to the otherwise black beak.
In juvenile plumage, the basic color of the plumage is a little darker than that of the adult birds. All upper wing coverts are edged in white, the light tips of the large hand and arm coverts form a bright band on the upper wing that is clearly visible in the flying bird. The inner hand wings , the arm wings and the control springs show a dense, dark transverse banding and are also bordered in white. The iris is brown. The young birds are colored after four years.
Vocalizations
Basically three calls can be distinguished: The courtship call is a hoarse "krüch", which is mostly used in connection with courtship flights. When threatened, for example by large birds of prey flying near the nest, both partners utter a long drawn out "hieh". The contact call, which is also used by young birds when begging, can be rewritten as "kjäck, kjäck".
distribution and habitat
The distribution area covers large parts of the forest zone of the central and eastern Palearctic and extends from the east of Poland and the Baltic States in a band that is broad in the west and increasingly narrowing in the east to the southeast Russian region of Primorye on the Pacific . The exact area of the species is often unclear in the west of the distribution area due to the difficult differentiation from the lesser spotted eagle, in the Asian part of the distribution due to the low settlement by humans and the remote habitats.
In north-south direction, the area extends from the southern areas of the boreal zone (coniferous forest zone) to the northern areas of the steppe zone . The greater spotted eagle lives there in open, moist to wet forests and forest edges with bordering swamps, marshes, moors or wet meadows, as well as floodplains. Overall, the species is very much tied to water-rich forest landscapes that are hardly influenced by humans.
In Germany the species is a very rare guest in the north and east, but is probably overlooked or confused with the spotted eagle due to the difficult identification.
Systematics
Despite the huge distribution area, no subspecies have been described for the greater spotted eagle. The closest relative is the very similar lesser spotted eagle , the sister taxon of this species pair is the Ganges eagle ( Clanga hastata ). This species, which is restricted to the Indian subcontinent , was listed as a subspecies of the lesser spotted eagle until a few years ago, but in 2002 it was delimited as a separate species due to its morphological , anatomical and breeding biological characteristics and behavioral characteristics. Molecular genetic studies have confirmed this species status, according to which the spotted eagle is even more closely related to the greater spotted eagle than to its former subspecies C. hastata .
A further molecular genetic investigation showed that the lesser spotted eagle and the greater spotted eagle are not reproductively completely isolated from each other, although the gene flow apparently only occurs in the direction of the lesser spotted eagle. The results suggest that mixed pairs consist predominantly of female spotted eagles and male spotted eagles and that the hybrid females in turn breed with male spotted eagles. The first assumption agrees with the previous observations of mixed pairs. The second assumption is plausible, as this is the only way to maintain the size difference between the pair partners, because greater spotted eagles are significantly larger than spotted eagles.
In detail, about 8% of the phenotypic spotted eagles examined showed haplotypes of the spotted eagle in the mitochondrial DNA (mtDNA) that was only passed on through the maternal line . Investigations of the cell nucleus DNA showed, however, that the spotted eagle with greater spotted eagle haplotypes in the mtDNA are genetically between the samples of individuals of both species in which the haplotypes of the mtDNA matched the phenotypes. This suggests that these spotted eagles with spotted eagle mtDNA are either direct descendants of a mixed pair of female greater spotted eagles and male spotted eagles (F1 hybrids) or descendants of a female hybrid with a male spotted eagle. The relatively high percentage of spotted eagles with spotted eagle hyplotypes ultimately indicates that at least individual spotted eagles regularly form mixed pairs with spotted eagles far west of the closed distribution area of the species. That this is actually the case was confirmed, among other things, by the discovery of a mixed pair in Mecklenburg-Western Pomerania in 2003; further east, individual mixed pairs have been known since the early 1990s.
Hunting style and diet
Similar to the closely related lesser spotted eagle , the greater spotted eagle often hunts in search flight and on foot, but less often than the lesser spotted eagle from the raised hide. The search flight takes place at low altitude, but also in high circling. When a suitable prey is discovered, the eagle will drop or dive into an attack. Troops of waterfowl are driven apart by repeated swooping flights in order to then purposefully prey on a blown individual.
In the breeding area, the food consists predominantly of small to medium-sized mammals and birds, in addition to which amphibians and reptiles are also frequently captured. Small fish, insects or carrion are less likely to be eaten. In winter, depending on the location of the winter quarters, the main food is very often insects such as locusts and swarming termites as well as carrion or, in wetlands, mainly water birds.
Reproduction
The courtship usually begins immediately after arriving at the breeding site. The male performs persistent wave flights, whereby it moves downwards at the highest point of a "wave" with attached wings, in order to then rise again with the gained momentum to the next wave. There is intensive calling.
The nests are mainly built on deciduous trees in the forest and mostly on the edge of the forest, and mostly self-built. The nest diameter is between 70 and 110 cm. The nests are often used multiple times and can then reach heights of up to 150 cm. The nest hollow is laid out with green branches.
The eggs are rarely laid as early as the end of April, but mostly in the beginning to mid-May. The clutches usually consist of two eggs, rarely just one or three eggs. In Belarus, for example, 1 egg was found once and 2 eggs five times in 6 clutches. The eggs are pale brownish or mottled purple on a white background. Eggs from Belarus measured an average of 65.8 × 52 mm.
The breeding season is 42 to 45 days. In contrast to the lesser spotted eagle , cainism is not mandatory for the greater spotted eagle and two young birds fledge regularly. The nestling period lasts 63 to 67 days; the young birds usually fly out in mid-July to early August.
hikes
Greater spotted eagles migrate from medium to long distances . The wintering area covers a huge area in the subtropics and the tropics of Eurasia and Africa. The species is observed there in many areas, some of which are spatially far apart, in which, however, mostly only single or at most a few dozen individuals overwinter.
In Europe, the species winters in small numbers in southern France ( Camargue ), in the south and north-east of Italy and on the Balkan Peninsula , exceptionally further north, e.g. B. in Switzerland . Further to the east, the species overwinters mainly in western Turkey , in the Middle East and on the Arabian Peninsula , in the north of the Indian subcontinent as well as in Southeast Asia and southern China . After all, the species overwinters, at least in small numbers, in northeast Africa and south of the Sahara . Greater spotted eagles seem to be predominantly broad-fronted migrants ; they are observed rarely and only in small numbers at the classic concentration points of bird migration, for example on the Bosporus .
The breeding areas are reached in the west of the distribution as early as mid-March, further east in April. The move begins at the end of September.
Existence and endangerment
The species is very rare everywhere, at least in Europe. According to the IUCN, the pan-European population was estimated at around 900 breeding pairs in 2004 , the world population at a maximum of 10,000 individuals. So far, however, there are hardly any reliable inventory figures, particularly from the Asian part of Russia. At least in Europe, the population has been declining for decades, with habitat destruction and human persecution as the main causes. The IUCN therefore classifies the world population as "vulnerable" (endangered).
swell
Individual evidence
- ↑ Meyburg, BU, Kirwan, GM Garcia, EFJ (2017). Greater Spotted Eagle (Clanga clanga). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, DA & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (accessed on [1] on January 16, 2017).
- ^ J. Ferguson-Lees, DA Christie: Raptors of the World. Christopher Helm, London, 2001. ISBN 0-7136-8026-1 : p. 730.
- ^ D. Forsman: The Raptors of Europe and the Middle East - A Handbook of Field Identification . T & AD Poyser, London, 1999: pp. 332-347.
- ↑ T. Mebs & D. Schmidt: The birds of prey in Europe, North Africa and the Middle East. Franckh-Kosmos, Stuttgart 2006. ISBN 3-440-09585-1 : p. 178.
- ↑ SJ Parry, WS Clark, V. Prakash: On the taxonomic status of the Indian Spotted Eagle Aquila hastata. Ibis 144, No. 4, 2002: pp. 665-675. doi : 10.1046 / j.1474-919X.2002.00109.x .
- ↑ Ülo Väli: Mitochondrial DNA sequences support species status for the Indian Spotted Eagle Aquila hastata . Bull. BOC 126, Issue 3, 2006: pp. 238–242 ( full text in the Biodiversity Heritage Library (BHL) , accessed April 1, 2013).
- ↑ Andreas J. Helbig, Ingrid Seibold, Annett Kocum, Dorit Liebers, Jessica Irwin, Ugis Bergmanis, Bernd U. Meyburg, Wolfgang Scheller, Michael Stubbe and Staffan Bensch: Genetic differentiation and hybridization between greater and lesser spotted eagles (Accipitriformes: Aquila clanga , A. pomarina) . Journal of Ornithology, Volume 146, Issue 3, 2005: pp. 226-234.
- ^ A b V. Ivanovsky: Notes on the Breeding Biology of Spotted Eagles Aquila clanga and A. pomarina in Byelorussia. In: Meyburg, B.-U. & Chancellor, RD (eds): Eagle Studies. WWGBP, Berlin, London, Paris, 1996 ISBN 3-9801961-1-9 : 297-299.
literature
- J. Ferguson-Lees, DA Christie: Raptors of the World. Christopher Helm, London, 2001. ISBN 0-7136-8026-1
- D. Forsman: The Raptors of Europe and the Middle East - A Handbook of Field Identification . T & AD Poyser, London, 1999. ISBN 0-85661-098-4
- Urs N. Glutz von Blotzheim , Kurt M. Bauer and E. Bezzel: Handbook of the birds of Central Europe. Volume 4th, 2nd edition, AULA-Verlag, Wiesbaden 1989, ISBN 3-89104-460-7 .
Web links
- Clanga clanga in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed October 13 of 2008.
- Videos, photos and sound recordings for Aquila clanga in the Internet Bird Collection
- A greater spotted eagle's nest camera http://www.looduskalender.ee/n/de/node/2350#cam
