Consecration (genus)
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Hen harrier ( Circus cyaneus ) ♀ |
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| Scientific name | ||||||||||||
| Circus | ||||||||||||
| Lacepede , 1799 |
The harriers ( circus ) are a genus of birds of prey from the family of the hawk-like (Accipitridae). Weihen (singular: Weih , from Middle High German wîe ) are medium-sized birds of prey, which are characterized by a slim silhouette and long, wide wings. The range of the genus extends from the subpolar Holarctic to Oceania and South America . Harriers live in open, spacious habitats in which they prey on small rodents and birds in flight . The entire genus Circus is characterized by its graceful courtship flight, in which the male woos the female. In some consecrations, the males polygynously mate with several females at the same time. Almost all species breed in ground nests, with the male providing food for the breeding female and the young.
The genus circus was established by Bernard de Lacépède in 1799 and is relatively young in evolutionary terms. It probably developed between the late Miocene and the Pliocene from a forest-dwelling ancestor who penetrated the grass steppes that were then emerging worldwide. Phylogenetically it stands within the hawks and sparrowhawks ( Accipiter ). Within the consecration, we can roughly distinguish between two groups that have specialized ecologically in steppe or wetland habitats. While around eight types of consecration used to be differentiated, there has recently been a tendency to divide the genus into 15 to 16 recent species. There are also two extinct species from Hawaii and New Zealand .
features
Harriers are medium-sized birds of prey with a body length of 39–61 cm and a wingspan of 90–155 cm. They are characterized primarily by their slim physique, their long and wide wings and long legs. Like many other birds of prey, harriers show a clear sexual dimorphism in which the females of a species are larger and heavier than the males. This difference varies from species to species; it is particularly pronounced in very small species that specialize in songbirds. The species with the greatest dimorphism is the South American white-browed harrier ( C. buffoni ), the females of which are on average 42% heavier than the males. The difference is smallest in the mangrove row with 26%. The males of the smallest living species, the steppe harrier ( C. macrourus ), reach wing lengths of 310–356 mm, their conspecifics from 345–393 mm. The only slightly larger harrier ( C. pygargus ) is 227 to 305 (males) and 254 to 445 g (females) the easiest way. At the other end of the spectrum, the White brewing consecration lie with 370 to 458 (males) and 375 to 484 mm (Female) wing length as the longest and the marsh harrier ( C. approximans ) with 520–740 (males) and 700–1100 g (females) as the heaviest. The extinct Hawaiian forest harrier ( C. dossenus ) was, however, even smaller than all species living today, while the also extinct New Zealand Eyles harrier ( C. teauteensis ) was around four times as heavy as recent marsh harriers. Both extinct species were characterized by their relatively shorter, round wings, which probably set them apart from the rest of the genus.
The plumage drawings of the individual circus species sometimes only differ in nuances, but some species also clearly stand out from the rest of the genus. Depending on the species, there is often a pronounced dimorphism between the sexes in terms of coloration, although in some cases - especially in tropical species - females and males are colored the same. The color spectrum of the consecrations consists mainly of black, white, brown and gray hues. For most species, a basic pattern can be made out, which is composed of a dark brown upper side, an underside dotted from the chest downwards on a lighter background and a radially dotted face mask. It occurs mainly in female ordinations and as youth clothing; In contrast, adult animals and especially males show more variation. A relatively large group of dryland-dwelling species is characterized in the male plumage by a basic pattern with an ash-gray upper side, which is complemented by a differently colored underside.
The face veil , which resembles that of the owls (Strigiformes) and consists of a wreath of stiff feathers around the eyes, is characteristic of the entire genus . It increases the hearing performance of the animals, whose skulls have relatively large ear holes compared to other birds of prey. All circus species have well-developed beak bristles around the beak . All consecrations show a more or less pronounced line drawing on the underside of the body, at least in the youth dress, which is lost in a large part of the species in the adult dress . Dotted ( spotted harrier ) and sparrowhawk drawings ( gray harrier ) are the exception. Wax skin and legs are colored yellow in all species. In adult birds, the iris of the eyes is usually yellow, young birds often still show a brown iris.
In the field, consecrations stand out because of their flight pattern. Often, they fly in search of prey in slow, tumbling Gaukelflug in just a few meters above the vegetation and look while heading for the ground. The wings are set to form a stiff, flat V. Phases of gliding flight are interrupted by wing flapping; shortly before the birds strike, they often shake briefly on the spot. During the courtship season, male consecrations display artful flight maneuvers. In doing so, they rise circling to great heights and there perform parabolic upward and downward swings along a horizontal line, as they are also known from other birds of prey. On the other hand, the daring fall maneuvers, which in some species of harrier follow the horizontal flight and are reminiscent of a falling leaf, are unique. The slim build and proportionally very long wings and tail feathers can be seen especially in flight.
Spreading and migrations
With the exception of Antarctica, consecrations are widespread on all continents and have also reached remote islands such as Hawaii and New Zealand in the course of their development. The hen harrier ( C. cyaneus ) has the largest distribution area , whose breeding areas range from the Iberian Peninsula to Kamchatka . The Reunion consecration ( C. maillardi ), however, has the smallest distribution area of all consecrations, which only covers the 2507 km² island of Reunion . The breeding areas of the Corn Harrier and Hudson Harrier ( C. hudsonius ) reach the Arctic Circle. To the south, the breeding occurrences of the genus in North America and Eurasia extend into the steppe or prairie belts and are largely limited by the deserts and semi-deserts that adjoin them. The gray harrier ( C. cinereus ) occurs as far as Patagonia in the southern hemisphere . With five members of the genus, Eurasia has the greatest diversity of species. The extensive lack of the genus in the subtropics of the northern hemisphere is striking: Neither Central America nor large parts of North Africa and South Asia are used by harriers as breeding areas. The Old World has the greatest biodiversity with around 13 species, six of which are found in Eurasia. Sub-Saharan Africa is home to four, Australia and Oceania two to three species, depending on the species definition. In the New World, only the Hudson consecration occurs in North America, while South America is inhabited by gray and white-browed harriers. Almost all consecrations occur in large parts of their breeding areas and winter quarters sympatric with other species of the genus.
All circus species in the northern hemisphere show migratory behavior. In autumn, the western occurrences of the meadow, corn, marsh harrier and steppe harrier migrate to southern Europe, the Middle East and Africa, while the eastern occurrences of the species overwinter in India and Southeast Asia . East Asian consecrations migrate to southern China, the Thai-Malay Peninsula, Indonesia and the Philippines over the winter . The northern occurrences of the North American Hudson consecration move after the breeding season over the southern USA and Mexico to South America. However, in some species, not all birds migrate south. For example, many more southerly breeding populations of Reed Harrier and Hudson Harrier remain at their location all year round or only pass short distances. The main reason for this is the different food supply in winter. Further south, the hiking trails are less seasonal and geographical. While the white-browed harrier and the marsh harrier move towards the equator in relatively large numbers in winter, black harrier, gray harrier and spotted harrier tend to pass outside of the breeding season.
habitat
Almost all consecrations are birds of prey that specialize in open habitats. The only exceptions are the extinct harriers of Hawaii and New Zealand, which have re-developed into forest dwellers. The genus is roughly divided into two ecological groups: Inhabitants of arid and semi-arid steppe ecotopes with short, sparse vegetation and species adapted to moist habitats that are often overgrown with high reeds. Both habitat categories are characterized by the extensive absence of trees. Most of the harriers prefer flat terrain, but some species such as Réunion or Papuan harrier also use slopes for hunting and breeding.
The breeding areas of the genus Circus range from marshes and lagoons at sea level to altitudes of a few thousand meters in highland dwellers such as black harriers and Papuan harriers. As a rule, hunting areas reach higher than the breeding habitats. The group of wetlands in particular is threatened by the global drainage and agricultural utilization of marshes, vineyards and swamps. But dry habitats such as grasslands , heaths and savannahs are also on the decline in many regions, which poses a threat to the stocks of harrier species there. The two extinct species of consecration disappeared as a result of the repopulation of their island habitats by humans, accompanying neozoa and the clearing of forest habitats.
nutrition
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The diet of harriers consists mainly of small mammals, (especially ground-dwelling) birds and other small vertebrates. The respective proportion in the diet varies from species to species and often also between the sexes. The smaller males and lighter species like the Montagu's Harrier predominantly prey on birds, sometimes even in flight. The heavier females and heavier harriers such as the marsh harrier tend to be larger mammals that can be the size of rabbits.
Systematics and taxonomy
The genus circus was described late compared to other widespread genres. Although Carl von Linné described the marsh harrier as Falco aeruginosus and the meadow harrier as Falco pygargus in the tenth edition of his Systema Naturae from 1758 . But it was not until 1799 that Bernard Germain Lacépède established the consecrations as a separate genre circus . The generic name chosen by him, Latin for "circle" or "ring", was chosen by Lacépède probably in allusion to the courtship flight of birds. The number of consecration species remained in flux for a long time. This was mainly due to the fact that the demarcation between them was controversial and species concepts changed in the course of the 20th century. Erwin Stresemann's treatise on the marsh harrier from 1924 was particularly influential. A total of eight species of marsh harrier were counted up to the 1970s: hen harrier, meadow harrier , steppe harrier, magpie harrier , mohren harrier , spotted harrier , white brow harrier and the marsh harrier , which included all wetland forms. In addition, there was the extinct Eyles consecration , which had been discovered in New Zealand at the end of the 19th century, but was hardly included in the consideration of the genus. Ebel Nieboer, who did his doctorate on the morphological differences of harriers, removed the frog harrier from the marsh harrier complex in 1973 and put the number of species at nine. At the end of the 1980s, Dean Amadon and John Bull raised twelve species by removing the wetland harriers of the Indian Ocean ( maillardi ), East Asia ( spilonotus ) and Australia and Oceania ( approximans ) as separate species from Stresemann's circle of forms. This showed a general trend from the “ lumper ” approach, which tended to group similar species together, to a “splinter” approach, which prefers separate species. Nevertheless, the new species remained controversial for a long time and were summarized in very different combinations in many overview works up to the end of the 20th century. In 1991 Circus dossenus was described from Hawaiian fossil sites. With Robert Simmons 'monograph on the genus from 2000 and James Ferguson-Lees ' and David Christie's extensive Raptors of the World , genus concepts were finally cemented that emphasized genetic, morphological and ecological differences between the various consecrations and further increased the number of species. Simmons separated the Hudson harrier and hen harrier as well as Madagascar and Réunion harrier from each other and established the Papuan harrier as a separate species C. spilothorax ; he came up with a total of 16 recent species. Ferguson-Lees and Christie did not fully agree with Simmons, but incorporated many of his arguments and distinguished 13 types of consecration. The Handbook of the Birds of the World , based on Simmons, currently counts 16 species of consecration. Then there are the two extinct species of New Zealand and Hawaii.
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| Systematics of the genus Circus (simplified) according to Oatley et al. (2015). The consecrations are in the midst of the polyphyletic hawks and sparrowhawks ( Accipiter ). The position of the white-browed consecration is uncertain: alternative analyzes of the same data classify it as the sister of all other consecrations. |
Morphological systematics questioned the orders long time with the cave ordinations ( Polyboroides ) and Sperber consecration ( Geranospiza ) in a common subfamily Circinae whose common feature was especially long legs. However, early DNA analyzes indicated a close relationship to the goshawks and sparrows ( Accipiter ). That was a somewhat surprising finding, because this short-winged and forest-dwelling genus differs greatly from the consecration in terms of appearance and ecology. However, the finding has been confirmed and refined over the years. According to recent analyzes, circus is in the midst of a polyphyletic genus Accipiter and is particularly closely related to a group around the goshawk ( Accipiter gentilis ). The molecular genetic studies suggest that the consecration between the late Miocene and the early Pliocene (6–8 mya ) developed from a hawk-like ancestor when he advanced into the C4 grass steppes , which then spread across the world. The consecrations diversified quickly and populated the same regions often in different radiations , which explains, among other things, why so many species occur together today. In addition to habitat changes, winter migration also seems to have played a role in diversification: Northern species are usually most closely related to species that breed where the former overwinter.
The consecrations are roughly divided into two clades , whereby the position of the white-browed consecration is uncertain. Either it forms the sister group with the Montagu's Harrier and the Marsh Harrier Complex, or it is at the very origin of the Circus family tree, which would have made it the first to separate from the rest of the genus. With the exception of the Montagu's Harrier, all gray dryland species are closely related. The basal position of the spot consecration in this group suggests that it developed in the Pliocene (2.2–5.5 my) in Australia and spread from there. Conversely, the sister group around the Marsh Harrier seems to have its origin in the northern hemisphere. If the white-browed consecration belongs to this clade, it probably also split off in the Pliocene. The relationships in the Marsh Harrier complex underpin both Stresemann's conservative system and the more differentiated representations of recent times: All postulated species can be genetically differentiated from one another, but the differences are often only negligible. The consecration of the Mangrove, Madagascar and Réunion is only between 100,000 and 300,000 years old. Marsh harrier and Papuan harrier are similarly closely related. While geographical distance, morphological differences and different ecologies speak for a separation in the first group, the proximity of the Papuan Harrier and the Marsh Harrier to each other suggests a combination in the same way. Subfossil bone finds from consecration are only known from the Holocene . Nothing is known about the relationship between the extinct forest harrier ( C. dossenus ) from Hawaii and the also extinct Eyles consecration ( C. teauteensis ) from New Zealand. At least for the Eyles consecration, however, a close relationship to the swamp consecration is assumed.
References
literature
- James Ferguson-Lees, David A. Christie: Raptors of the World . Houghton Mifflin, Boston 2001, ISBN 0-618-12762-3 .
- Ebel Nieboer: Geographical and Ecological Differentiation in the Genus Circus . Vrije Universiteit te Amsterdam, Amsterdam 1973.
- Robert E. Simmons: Harriers of the World: Their Behavior and Ecology. Oxford University Press , 2000. ISBN 0-19-854964-4 .
- Erwin Stresemann: The shape of the marsh harrier, Circus aeruginosus . In: Journal of Ornithology . tape 72 , no. 2 , 1924, p. 262-269 , doi : 10.1007 / BF01905633 .
- Storrs L. Olson, Helen F. James: Descriptions of 32 new species of birds from the Hawaiian Islands. Part 1: Non-Passeriformes . In: Ornithological Monographs . tape 45 , 1991, ISBN 0-935868-54-2 .
- TH Worthy, Richard N. Holdaway: The lost world of the moa: prehistoric life of New Zealand . In: Life of the past . Indiana University Press, Bloomington 2002, ISBN 978-0-253-34034-4 .
- Graeme Oatley, Robert E. Simmons, Jérôme Fuchs: A molecular phylogeny of the harriers (Circus, Accipitridae) indicate the role of long distance dispersal and migration in diversification . In: Molecular Phylogenetics and Evolution . tape 85 , 2015, p. 150–160 , doi : 10.1016 / j.ympev.2015.01.013 .
Web links
- JM Thiollay: Hawks, Eagles (Accipitridae) . In: J. del Hoyo, A. Elliott, J. Sargatal, DA Christie, E. de Juana (Eds.): Handbook of the Birds of the World Alive. www.hbw.de, Lynx Edicions, Barcelona.
Individual evidence
- ↑ a b c d Ferguson-Lees & Christie 2001, pp. 493-508.
- ^ A b Olson & James 1991.
- ↑ a b Hume 2017, p. 90.
- ↑ Nieboer 1973, pp. 33-34.
- ↑ a b Ferguson-Lees & Christie 2001, pp. 136-145, 493-508.
- ↑ Simmons 2000, pp. 53-56.
- ↑ Simmons 2000, pp. 39, 59-63.
- ↑ Nieboer 1973, p. 7.
- ↑ Simmons 2000, pp. 30-31.
- ↑ Linnaeus 1758, pp. 89, 91.
- ↑ Lacépède 1799, p. 4.
- ↑ Simmons 2000, p. 59.
- ↑ Simmons 2000, pp. 20-34.
- ↑ Ferguson-Lees & Christie 2001, p. 8.
- ↑ Thiollay 2018. Accessed March 30, 2018th
- ↑ Oatley et al. 2015, p. 153.
- ↑ Simmons 2000, p. 21.
- ↑ Oatley et al. 2015, pp. 154–158.
- ↑ Oatley et al. 2015, pp. 152–159.
- ↑ Worthy & Holdaway 2002, pp. 347-348.