Brant Goose
Brent Goose (Branta bernicla bernicla )
The Brent Goose (Branta bernicla ) is a small, gregarious species of the genus Branta (Branta ) of the family Anatidae ( Anatidae ). It is the smallest and darkest of the sea geese, which in addition to the brent goose, the Barnacle Goose, the red-breasted goose and Canada goose. Your breeding area is the Arctic cold desert and arctic tundra of Eurasia and North America. In Germany it is winter visitor on the North Sea coast. The special features of the Brent Goose is one of their close ties to the sea and the coast during migration and wintering.
The German name of the goose refers, as in the wood pigeon on the white neck ring. Occasionally, the goose is also referred to as Rottgans, which is derived from the dull sounding Flugruf.
- 9.1 Notes and references
- 9.2 Literature
- 9.3 External links
Subspecies
The Brent Goose is divided into three subspecies:
- The Dark- brent goose (Branta bernicla bernicla ) is called the nominate form, which was described by Carl Linnaeus first time scientifically. It is dark slate gray and has small white bands on the sides of the neck.
- Schwarzbäuchige the brent goose (Branta bernicla nigricans ) is sometimes referred to as Pacific Brent Goose. Your body plumage has clear blacks and a wide, almost closed white neck ring.
- Hellbäuchige the brent goose (Branta bernicla hrota ) has a lightened, brownish body plumage with narrow white collars.
Appearance
Brent geese are black gray feathered with gray-brown back and black -and-white banded edges. The adult birds have narrow at the neck white crescent spots that are of different size depending on the subspecies. Upper and under tail-coverts, and belly are white. The chest color is either light gray deducted depending on the subspecies of the black front chest or some darker gray and gradually passes into the dark chest plumage. Beak, legs and wings are colored black. The wingspan is 110-120 cm, weight about 1 to 1.5 kilograms. In general, males are about 150 grams heavier than the females.
The chicks are pinnate gray-brown in the dress down at the top, head and neck sides and belly are light gray.
Voice
The Brent Goose is not a very ruffreudige goose. Her voice is often only to hear if she is present in groups or if they move to another place. When anxiety is a deep, dull and nasal " rott, rott, rott " to hear or " rott rorott ". This may also turn out throaty " rronk ". During the flight, she gives a short and hard " ack " or " ek " by itself. In grazing squads hold through constant, silent " bi bi bi" contact with each other. Aggressive Ringelgänse give sibilant sounds.
Dissemination
The Brent Goose breeds in Arctic Eurasia and the Arctic North America. Its distribution area is therefore known as circumpolar Holarctic. As distribution limits the July isotherms of 1 degree Celsius in the north and 7 degrees Celsius in the south considered.
The individual subspecies keep it in the summer in the following regions:
- The Dark- brent goose (Branta bernicla bernicla ) in northern Siberia approximately between the 65th and 80th parallel,
- Schwarzbäuchige the brent goose (Branta bernicla nigricans ) from eastern Siberia east to north-western Canada, about from 160 to 80 longitude and
- Hellbäuchige the brent goose (Branta bernicla hrota ) in the intervening areas of Western Canada, North Greenland, Spitsbergen and Franz Josef Land.
The winter quarters are
- In dunkelbäuchigen Brent Goose (Branta bernicla bernicla ) on the European Atlantic and North Sea coast of southern France until after Jutland and in the British Isles. In Germany you will find brent geese in the winter months regularly and in larger squads in the Wadden Sea to the North Sea. In low levels, they wintered in the Wismar Bay of the Baltic Sea. Inland, the Brent Goose is very rare.
- In schwarzbäuchigen Brent Goose (Branta bernicla nigricans ) on the Pacific coast from British Columbia to Baja California, only sporadically along the coasts of Japan and China, very rare in Europe and
- In hellbäuchigen Brent Goose (Branta bernicla hrota ) on the coast of South East England.
Way of life
The Brent Goose is a migratory bird that runs to the south in winter. If they are on their train, form Ringelgänse not the characteristic V-formation, they fly quickly, but not in formation. The migration routes of Brent geese are not genetically fixed, but are passed on to the various sub- populations. In addition to the train in the winter quarters, there is a so-called Mauserzug the non-breeding animals at certain moulting places, especially on the Taimyr Peninsula. Apart from mating and breeding season live brent geese in large flocks. Usually show Ringelgänse a great partner loyalty, however, they re- mate at loss of a partner.
The breeding begins immediately upon arrival in the breeding areas in June. Brent geese breed in colonies in a coastal arctic tundra. The hellbäuchige race finished her breeding business often on small islands off the coast. Brent geese breed in small colonies and build their nests on dry, higher portions of the tundra. Not infrequently, the colonies are located in the immediate vicinity of raptors and large gulls. However, this binding is not as pronounced as in the emperor goose. Three to five eggs are laid usually. After 24 to 26 days the young hatch, and their growth will only take about 40 days. As soon as the newly hatched chicks are dry, replace the families about on lakes, rivers and estuaries in the brood area. The pair bond loosens during this time. The Ganter but from the families and form independent Mauser squads. The full moult begins with the hatching of the chicks. The swing shift that begins in mid-July in adult birds, lasts until the middle of August. This is the time when the young goose fledge.
Nutrition
Brent geese live on short grass, herb, moss and lichen vegetation and marine plants. The geese are bound with mainly flat coasts of the Wadden Sea in search of food. Your search for food takes place on seagrass, green algae and Quellerflächen. In winter, they also use the grass and Wintersaatflächen of the inland area. At the northern German Wadden Sea farmers feared in the foothills of the coast and on the islets the passage of the Brent Goose, although today they are compensated for the damage caused. So the geese invaded limited tracts of land where they ate the vegetation down in no time to the length of an English lawn, where they preferred the Andel grass of salt marshes.
Stock development
Population trends in total
Having to 1932 large seagrass stocks received by an infestation with the unicellular slime mold Labyrinthula, the population went to the European Winterzuggebieten to about 10 to 25 percent of the population numbers at the beginning of the 20th century. In addition to the loss of wintering food but also contributed to an intensified hunting and improvement works to the wintering grounds to the population decline. To population recovery wore protective measures, which included, among other things, a ban on hunting with. The remaining populations of Brent Geese also put themselves in their diet in order to plant the Salzhaffwiesen. In Western Europe, today the resting places of the Brent Goose be protected in order to optimize by avoiding disturbances to the energy budget of birds.
Development of the various subspecies
- The stock of dunkelbäuchigen Brent Goose (Branta bernicla bernicla ) rose from about 20,000 in 1955 to about 250,000 to 300,000 at the end of the 20th century.
- The stock of schwarzbäuchigen Brent Goose (Branta bernicla nigricans ) fell from several thousand animals for the year 1900 to a few hundred in the second half of the 20th century, but it is the turn of the millennium about 4000 animals.
- The stock of hellbäuchigen Brent Goose (Branta bernicla hrota ) is difficult to quantify. He dropped since 1900 from a total of about 10,000 animals from order then to recover since the middle of the century and in 2003 was again at about 25,000 animals.
The IUCN estimates that the total population of the species at 570,000 animals.
Protection
To almost bring the concept of protection for the Brent Geese to a wider audience, organize in Schleswig-Holstein, inter alia, NABU, protection station Wadden Sea, WWF and the National Park Service jointly Ringelgans days on the North Frisian holms in the National Park Schleswig -Holstein Wadden Sea.