Chroicocephalus
Portrait of a Graukopfmöwe ( Chroicocephalus cirrocephalus )
Chroicocephalus is a genus of gulls, which was after 2005 abgegliedert after a taxonomic reclassification of the family Laridae of the genus Larus. It includes twelve relatively small to medium sized species of gulls. The genus is distributed worldwide, four species are found in the northern hemisphere, the rest have their main range in the southern hemisphere. A species that Graukopfmöwe, occurs both in Africa and in South America.
Characteristic of some species of the genus is the dark in breeding plumage head cap; in some others it is brighter or only hinted at, in some it is missing completely. Also in the genera Leucophaeus and Ichthyaethus there are dark head caps, it was therefore assumed a close relationship between these groups. Genetic studies have shown, however, that this feature is not suitable for the determination of kinship relations. It is a very original feature of the gulls to remain intact in some species, but in others was filed. This happened several times in the course of evolution, and even very closely related species such as the Black-headed Gull and the Hartlaubmöwe may differ in this regard.
The affiliation of a number of characteristics strongly deviating Kappenmöwe ( Chroicocephalus saundersi ) to this genus is disputed. Genetic studies suggest that this taxon belongs in its own genus ( Saundersilarus ). However, this has so far not officially recognized. The two types of Silver Gull ( Chroicocephalus novaehollandiae ) and Rotschnabelmöwe ( Chroicocephalus scopulinus ) were, as earlier the Hartlaubmöwe ( Chroicocephalus hartlaubii ), long regarded as subspecies of a species. Today, in general, all three taxa species status is granted.
Description
The species of the genus Chroicocephalus are relatively small to medium sized, lightly built to moderately strong seagulls. The smallest and easiest way is with a body length of 28-30 cm and a weight of 170-230 g of the Bonapartemöwe, the largest and most powerful with a body length of 44-48 cm and a weight of about 478 g of the Andean Gull.
The beak of the Chroicocephalus species is relatively long, slender to medium-bodied and not very high, laterally flat tip with a relatively long and relatively flat Gonyswinkel. The Gonys is only slightly curved to nearly straight. The nostril is situated drop-shaped and on the basal portion of the beak. The beak is red, brown or black in color. Patches or bandages do not occur, often the tip of the beak is black. The feet and legs are reddish or brown.
Six species of the genus show in breeding plumage, a dark head cap. This saves the back of the head and neck in contrast to the other genera, so this game will remain white. Wherein the cap is Graukopfmöwe gray, indicated at the Hartlaubmöwe as a fine edge. For the other four types missing. The eye is either a bright, yellowish to whitish or brown iris. The narrow, often colored orbital ring falls in many species hardly noticeable. For species with dark head caps usually contrast the white lids.
Mantle, back and wing tops are light gray in all species. The broad white trailing edge, which is typical of the Larus species, is absent; it is at best a bright edge available. This is located on the distal part of the hand wing, starting at the bend of wing, always a white, wedge- shaped field. The distribution of the black primaries pattern varies. In most species, there are black subterminal or Endbinden different expansion. The underside of the hand wing is generally blackish to a large extent. The white tail is cut straight relative. In immature birds he shows a black armband.
Bonapartemöwe
Hartlaubmöwe
Graukopfmöwe
System
External system
A majority of all species of gulls stood long in the genus Larus and although some attempts have been made previously by taxonomic reclassifications of Laridae, found a division into several genera wider recognition only after 2005 extensive genetic findings templates.
Back in 2000, studies of mitochondrial DNA had suggested that it concerns with the existing definition of the genus to a Polyphylum. It turned out that the black-headed gull and related species ( "masked species" ) are not so closely related to the other forms of the genus are as expected. The latter include the herring gull - relatives ( "white headed species" ), the group around the Mediterranean Gull ( " black headed species" ) and some black-headed forms of the new world (such as the Laughing Gull, "hooded species" ). Rather, the species are the black-headed gull at the other end of the kinship group of gulls, while the species that had been made long before in their own genres (eg, the kittiwake, the Sabine's Gull or the Ivory Gull ) between the two groups are, what is represents the cladogram as follows:
Chroicocephalus (among black-headed gull )
Saundersilarus ( Kappenmöwe )
Hydrocoloeus ( dwarf and Rosenmöwe )
Creagrus ( Gull )
Pagophila ( Ivory Gull )
Xema ( Sabine's Gull )
Rissa (among kittiwakes )
Larus ( Herring et al )
Ichthyaethus (among Gull )
Leucophaeus ( inter alia Laughing Gull )
Since not all species were considered in 2000, 2005, a further, much more extensive investigation with DNA samples from all 53 recognized species of gulls at the time took place. Although it may not all phylogenetic characteristics could be clarified, several well -defined groups against each other emerged. This had indeed been partly identified already in the 20th century as subgenera, but it resulted in some surprising findings about the exact composition of these groups. As a result, the authors of the study suggested that some of the established genres in the 19th century, which were only recognized as a subgenus name again and to the existing genus Larus in the genera Chroicocephalus (eg, Black-headed Gull ), Ichthyaethus (z. B. Fischmöwe ) Hydrocoloeus ( Little Gull ) and Leucophaeus (eg Blutschnabelmöwe ) break down, or only the " white -headed species " ( "white headed species" ) to remain in the genus Larus. Some institutions such as the International Ornithological Congress, the American Ornithologists ' Union, the British Ornithologists ' Union and the South American Classification Committee are the already accepted.
Internal system
Back in 1959, said Martin Moynihan the species listed here as a species because of behavioral characteristics and morphology as "Masked Gulls " together. In 2005, the internal relationships of this group were examined genetically more closely. There was on the one hand, the monophyly of this group ( as previously suspected based on other studies) on the other hand, that two taxa of the northern hemisphere - the slender- and Bonapartemöwe - split off relatively early from the rest of the group. The other is a group that occur almost exclusively in the southern hemisphere. An exception is the Black-headed Gull, large parts of the Palaearctic populated but seems to be embedded in kinship nevertheless the group of southern taxa. Perhaps the most closely related brown-headed Black-headed Gull, also represented on the Northern Hemisphere, was missing in the study. The relationships presented in detail as follows ( names have been compared with the study updated):
Hartlaubmöwe ( Chroicocephalus hartlaubi )
Graukopfmöwe, African subspecies ( Chroicocephalus c. Poiocephalus )
Graukopfmöwe, South American subspecies ( Chroicocephalus c. Cirrocephalus )
Black-headed Gull ( Chroicocephalus ridibundus)
Silver Gull ( Chroicocephalus novaehollandiae )
Rotschnabelmöwe ( Chroicocephalus scopulinus )
Maorimöwe ( Chroicocephalus bulleri )
Andean Gull ( Chroicocephalus serranus )
Patagonienmöwe ( Chroicocephalus maculipennis )
Bonapartemöwe ( Chroicocephalus philadelphia )
Slender- ( Chroicocephalus genei )
The authors put this cladogram also to temporal estimates of. After that, Slender-billed and Bonapartemöwe had cleaved prior to about 1.85 million years ago and settled an ancestor of the southern group of South America. Radiation was then continued within a relatively short time. From South America were probably colonized Africa and on the northern hemisphere and the Australian space in time from 0.55 to 0.38 million years ago. Here, an additional radiation took place in the period between 0.24 million and 0.13 million years ago. Before adopted 0.07 million years then a second time from South America Africa was colonized. Here, the African subspecies of Graukopfmöwe arose.
Species
- Slender- ( Chroicocephalus genei )
- Bonapartemöwe ( Chroicocephalus philadelphia )
- Rotschnabelmöwe ( Chroicocephalus scopulinus )
- Silver Gull ( Chroicocephalus novaehollandiae )
- Maorimöwe ( Chroicocephalus bulleri )
- Andean Gull ( Chroicocephalus serranus )
- Braunkopfmöwe ( Chroicocephalus brunnicephalus )
- Patagonienmöwe ( Chroicocephalus maculipennis )
- Black-headed Gull ( Chroicocephalus ridibundus)
- Graukopfmöwe ( Chroicocephalus cirrocephalus )
- Hartlaubmöwe ( Chroicocephalus hartlaubii )
- Kappenmöwe ( Chroicocephalus saundersi )