Bean Goose
Bean Goose (Anser fabalis )
The Bean Goose (Anser fabalis ) or Rietgans is one among the field geese (Anser ) associated Genuine Goose ( Anserini ). She sees the pink-footed goose ( Anser brachyrhynchus ) are very similar, but this is now considered a separate species. In the wild they can be at their two-syllable Flugruf recognize a loud trumpeting " kayak, kayak ". The species was first described in 1787 by Dr. John Latham. In Germany it is found from the end of September in large numbers as a winter visitor.
The Bean Goose is mainly in the north of Central Europe a migrant and winter visitor. Partly breeding settlements that may emanate from captivity refugees or injured wild birds, there is since 1993 in the Netherlands.
Name
The German term Bean Goose has become common because you can often see this goose on meadows and cornfields in search of food. The scientific Anser fabalis translates bean goose. Two explanations are possible for this name. For a bean can belong to their diet. For adult geese of this type are located next to the beak root two narrow crescent-shaped or even just small bean-shaped white stripes.
Appearance
The plumage is generally gray-brown, dark brown on the neck and the square head against it. This distinguishes the Bean Goose of the white-fronted goose (Anser albifrons ) and the greylag goose (Anser anser ). Breast and belly are light brown, even down to the tail whitish colored, the wings, however, again dark brown. Both on the flanks and on the outer sides of the wings and tip of the tail can be found in the plumage fine white lines.
The bill provided with serrated side edges at the base and the tip black, the middle is a different width depending on the subspecies orange mark. From the same color are also provided with broad webbed feet. Eye color is dark brown.
The Dunenküken are olive-brown on the body surface. The body sides are greenish yellow, the body underside is whitish. Through the Eye runs a dark stripe. The beak is up to the date on which the young birds fledge, dark gray and has a light pink to cream-colored nail. In contrast, the young animals have a discreet olivbraunes Tarnkleid from Dunenfedern with black stripes in the head region. Feet and beak are mouse gray.
The average size of birds is 65 to 90 cm with a wingspan of 140 to 170 cm; from the appearance of the male resembling the female is usually slightly smaller. Adult animals weigh about 3 to 4 kg. From bean geese ringed one knows that they can be over twenty years old in the wild.
Voice
The Bean Goose is significantly less than ruffreudig about the gray goose or white-fronted goose. The triumph of a pair is accented nasal cackling and trumpeting and sounds like a ga gi gig even boiled bean geese flying by is heard, like gaga or agagag, more rarely, as käjak or Gock geese sounds a typical nasal reputation.
Nutrition
The food of the bean geese is their breeding range from lichens, grasses, herbs and water plants in the fall also from berries such as moss and bog bilberries and beans. Of the latter, is also due to her English name "bean goose " and her Latin epithet fabalis ago (Latin faba bean = ).
In their wintering areas they eat roots, especially couch grass, potatoes and cereal grains, grasses, crop residues also particularly fond of harvested fields (especially high-calorie sugar beet or maize). Bean geese can be found also on cereal crops, where they can cause for exceeding the threshold value of 1500 goose days per hectare feeding damage.
The young birds feed on the other hand, not only of flowers and buds, but also non- vegetarian insects, molluscs, crustaceans and even small fish eggs.
Habitat
Bean geese live in their breeding grounds in pairs either in the taiga middle of pine and birch forests, bogs and forest swamps on reed islands and calm waters or further north in the bush, moss or even lichen tundra, there will usually, but not always, near lakes and river valleys, like in steep inaccessible terrain shore. Breeding pairs are also far away from the waters on extensive gravel fields.
In their wintering areas they live in large colonies and prefer harvested cropland (particularly sugar beet and corn fields), meadows and pastures. They like to sleep on open water, in winter on ice, and walk every day, sometimes more than ten kilometers, between their bedroom and pastures back and forth.
Dissemination
Bean geese are migratory birds that have established regular Zugtraditionen and ever seek the same breeding and wintering areas by family again and again.
The former extend in the tundra and taiga of northern Scandinavia in the west to eastern Siberia and the Sea of Okhotsk in the east.
The wintering areas are extremely diverse: they include in Central Europe, especially southern Sweden, Denmark and the German Baltic coast, the North German Plain to the Lower Rhine between Wesel and Emmerich am Rhein and the Netherlands, isolated parts of the British East Anglia and South-West Scotland, to an alpine near field West Austria and Switzerland to far into France and wide regions of the lowlands of the Danube. In cold winters it attracts them and the Atlantic coast down to Spain and Portugal, rarely even to Morocco.
In the Mediterranean region include the French Riviera and the Italian and Croatian Adriatic coast to their winter habitat, further east the Bulgarian-Romanian coastal regions of the Black Sea.
East Siberian populations overwinter contrast, in Central Asia, particularly Iran, or even further east in the People's Republic of China, Southeast Asia, Korea and Japan.
Reproduction
Bean geese looking in their second or third year of life in the wintering area for a partner with whom they will stay together for life.
They move about around March to the north and meet with the breed in the taiga birds in late April, at the tundra - nesting birds, however, until the mid to late May in their breeding area one that is often covered at this time of snow and ice. The Bean Goose is among the Arctic goose species that return earliest in their breeding areas. In the time remaining until the snow melts, it sometimes comes to mating battles between the males. Copulation takes place after a short prelude, in giving to understand their readiness to mate by immersion of the neck both partners, rather than in the water. To this end, the male mounts the female, which usually sinks while in the water. By common neck stretching and wing flapping the ritual is completed.
The female builds then shrubs and bushes, in the reeds or situated in that marsh nesting on low, dry hills located the nest and feed it with blades of grass, mosses and lichens, and later with his down feathers. These down feathers are brownish gray and have a brighter center. Bean geese attract large only clutches per year.
The storage of two to eight, but usually four to six yellowish eggs begins in the taiga mid-May, in the tundra around mid-June; they are incubated by the female only when the last egg is laid, so that the young hatch in temporal proximity to each other, in the tundra after 25, the taiga after about 28 to 29 days. The male is involved, as with all rights geese not the business of breeding, but guarded females and breeding. In serious danger to both animals duck flat on the floor.
After about one and a half months, the young are fledged, at this time the older animals also have their usually in July and August held Mauser behind. (Non- breeding animals do from June common Mauser coatings, for example for Russia's North Sea island of Novaya Zemlya, where they reside in large numbers. ) The family unit then flies along with other geese in early September back into winter quarters, where the young geese into the next year into staying with their parents. They are ripe brood of two to three years even. The oldest banded wild bird was an age of 29 years.
The Bean Goose mated not only with members of their own species: from hybrids with the white-fronted goose (Anser albifrons ), the Greylag Goose ( Anser anser ), the pink-footed goose ( Anser brachyrhynchus ), snow goose ( Anser caerulescens ) and even belonging to the sea geese Weißwangengans (Branta leucopsis ) is reported.
Endangering
The Bean Goose is not threatened as the third most common wild goose in its entirety, stocks in Europe are estimated at about 200,000 animals. In agriculture, they caused by their consumption of fresh seed cereal regional problems, in Germany it is therefore important as a huntable game birds that can be shot in November and December.
The holdings of the thick -billed bean goose (Anser fabalis serrirostris ) and the Middendorffschen Bean Goose (Anser fabalis middendorffi ), both subspecies of Bean Goose, on the other hand are by hunting and habitat loss as endangered.
Subspecies
We distinguish five subspecies, however, the overlap in the wide areas and therefore can not be clearly differentiated from each other. These five subspecies are often divided into two groups, namely the tundra and the Waldsaatgänse that are now often regarded as separate species.
In Western Europe, two forms occur:
- The stocky looking, counting the Tundrasaatgänsen Anser fabalis rossicus (also referred to as the actual Tundra ) has a relatively short neck and a thick short beak. Their plumage is strikingly dark gray with a brown tinge. There is a striking contrast between the dark brown head and the gray-brown neck. Their wingspan is 140 to 170 centimeters. It breeds in the tundra in northern Russia and northern West Siberia from the rabbit to the Taimyr Peninsula and is the most common subspecies of Bean Goose. She finds herself very numerous in Germany. Your resting populations have increased. It benefited, among others from the flooding of former opencast lignite in northwestern Saxony and Lusatia, because it created a number of new locking waters.
- The langhalsigere, calculated for Waldsaatgans Anser fabalis fabalis has a rather narrow beak, a longer neck and is bigger than the Tundra. She has her breeding area in the taiga of Scandinavia to the Urals. Characteristic of Waldsaatgänse is a clearly defined orange band on the otherwise black bill. The Waldsaatgans is observed every year in small numbers in Germany. In their population declines have been recorded, which also led to a significant reduction in the wintering area. The most important wintering areas for this type lie in Northeast Germany, Sweden and Denmark.
Worldwide three other subspecies of Bean Goose are described below:
- The Johansen - Bean Goose (Anser fabalis johanseni ), which breeds in the taiga and tundra shrub Siberia east of the Ural Mountains to Lake Baikal,
- The Middendorffsche Bean Goose (Anser fabalis middendorffi ), the east of Lake Baikal can be found in the taiga areas and
- The thick -billed bean goose (Anser fabalis serrirostris ), who is staying in the summer in the tundra of northeastern Siberia from the Lena River Delta to the region around the Russian city of Anadyr.
The subspecies johanseni and middendorffi belong to Waldsaatgans, serrirostris for Tundra.
Since forest and Tundrasaatgänse breed in different regions, geographical contact in the breeding areas is limited. The extent to which reproductive barriers exist, has not been elucidated. Differences in the two groups could be maintained only because of the strongly divergent selection pressure in the breeding areas without a reproductive barrier between the two groups exists.