Gray geese ( Anser anser )
|Wagler , 1831|
The goose birds (Anseriformes) form an order of birds (Aves). The group includes, among other things, the birds known colloquially as geese , ducks and swans , but also, for example, the defensive birds of South America . Goose birds are among the most important groups of birds in the world's wetlands.
Goose birds generally have a plump, firm body with a comparatively small head, which is often attached to a long neck. The beak is wide and flattened apart from the warbirds; At its tip there is often a hardening that is used to pluck off plant material, while at the edges there are small "teeth" made of horn, the lamellae , which help filter out edible particles from the water.
Another characteristic feature are the webbed feet between the three toes pointing forward, which, however , are strongly regressed in the defensive birds and the cleft footed goose ( Anseranas semipalmata ). As the name suggests, they are used to move quickly in the water.
The plumage is waterproof and in many species, especially the males, have a colorful pattern. It is constantly nourished by a water-repellent oil that is secreted by a gland located on the trunk and stimulated by the beak and then distributed over the whole body by brushing the feathers. When moulting , most species lose all feathers at the same time; During this time, the males usually show very inconspicuous plumage, which, in their flightless state, serves to camouflage them from predators. The thermal insulation is guaranteed by a thick layer of down feathers and a layer of fat under the skin.
Most geese birds are excellent fliers; the Bar-headed Goose ( Anser indicus ) is even the highest-flying bird at all. As migratory birds, numerous species cover extensive migrations between their breeding grounds and wintering areas, which can be many thousands of kilometers long.
Habitat and nutrition
Geese birds usually live close to the water, in swamps and moors, the estuaries or the banks of rivers or on coastal waters. Some species spend most of their lives in the open ocean and only return to land to breed.
Most look for their food on or near the surface of the water, others dive for aquatic plants, while geese, swans and defensive birds in particular also feed on grass and herbs on land, among other things. Goose birds regularly swallow small stones that serve as gastroliths in the muscular stomach to break up food.
Although fragmentary fossil finds are known from the Cretaceous , which were sometimes mistaken for goose birds, the oldest undoubtedly goose bird comes from the Paleocene . It is presbyornis , which, according to Livezey's analyzes, is more closely related to ducks than to defensive birds. The fossil bird was initially mistaken for a relative of the avocets or the flamingos , before Harrison and Walker placed it near the geese in 1976.
Only Presbyornis is known from the Paleocene and Eocene . Only in the Oligocene did more fossil geese birds appear, but they seem to have been rare during this period. In the Miocene there was an explosive radiation with the development of the types known today.
The monophyly of goose birds has long been undisputed. That the outwardly deviating warrior birds belong to this group was already suspected in 1863 by William Kitchen Parker on the basis of morphological similarities. Later analyzes confirmed this and showed that the defensive birds are the sister group of all other recent geese birds.
The two ornithologists Storrs Lovejoy Olson and Alan Feduccia took the morphology of the fossil presbytery as an opportunity to suspect a relationship between the geese and the plover-like. Other scientists rejected this theory because it was based on only a single synapomorphism . Further possible relationships were established with the hen birds , the walking birds and the flamingos . A sister group relationship between geese and hen birds currently finds most supporters, the common taxon is called Galloanserae .
There are ten families of goose birds, seven of which are extinct. Of the remaining three, two combined have only four species, and the overwhelming remainder of 169 species are in the duck family.
- Defense birds (Anhimidae)
- Cleft foot geese (Anseranatidae)
- Duck birds (Anatidae) with geese, swans and ducks.
- Presbyornithidae with four fossil species of the Paleocene and Eocene , which belong to the genus Presbyornis . They are the oldest known goose birds.
- Romainvillidae, the only known species is Romainvillia dahlini from the Eocene / Oligocene , goose-sized, morphologically mediated between cistus and whistled geese.
- Cygnopteridae with three species in the genus Cygnopterus from the Oligocene and Miocene ; they were often mistaken for fossil swans, but according to ornithologist Bradley C. Livezey they deserve the rank of a family of their own.
- Brontornithidae with the only known genus Brontornis , a flightless giant bird from the Miocene of South America, which is assigned to the "terror birds" ( Phorusrhacidae ) in many, especially older publications .
- Paranyrocidae with the only known species Paranyroca magna , a swan- sized bird of the Miocene of North America.
- Thunderbirds (Dromornithidae) huge, flightless birds with seven fossil species from the Oligocene to the Pleistocene of Australia.
- Garganornis ballmanni ( Incertae sedis ), a large, terrestrial species from the late Miocene of southern Italy ( Gargano ).
Most of the information in this article has been taken from the sources given under literature; the following sources are also cited:
- Bradley C. Livezey: A phylogenetic analysis of basal Anseriformes, the fossil Presbyornis, and the interordinal relationships of waterfowl. In: Zoological Journal of the Linnean Society 1997, No. 121, pp. 361-428
- CJO Harrison & Walker CA: Birds of the British Upper Eocene . In: Zoological Journal of the Linnean Society 1976, No. 59, pp. 323-351
- Carole Donne-Goussé, Vincent Laudet, Catherine Hänni: A molecular phylogeny of anseriformes based on mitochondrial DNA analysis . In: Molecular Phylogenetics and Evolution 2002, Vol. 23, No. 3, pp. 339-356
- SL Olson & A. Feduccia: Presbyornis and the origin of Anseriformes (Aves: Charadriomorphae) . In: Smithsonian Contributions to Zoology 1980, No. 323, pp. 1-24
- Peter F. Murray: Magnificent Mihirungs: The Colossal Flightless Birds of the Australian Dreamtime. Indiana University Press, 2003, ISBN 0-253-34282-1
- Hanneke JM Meijer. 2014 A Peculiar Anseriform (Aves: Anseriformes) from the Miocene of Gargano (Italy) . CR Palevol. 13 (1); 19-26. DOI: 10.1016 / j.crpv.2013.08.001