Black-necked Grebe
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Black-necked grebe ( Podiceps nigricollis ) in splendor |
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| Podiceps nigricollis | ||||||||||
| Brehm , 1831 |
The Black-necked Grebe ( Podiceps nigricollis ) is a bird art from the family of grebes (Podicipedidae), which is widespread in Eurasia, North America and Africa. As a breeding bird and partial migrant, it occurs in the entire Central European area . In addition, he is a migrant here and at suitable locations he finds himself as a winter guest.
Unlike most members of the grebe family, it lives socially. It breeds in groups or in colonies that can consist of a few hundred pairs. Characteristic for the species are strong population fluctuations both from year to year and in multi-year intervals.
Appearance
The adult black-necked grebe reaches a height of 30 to 35 centimeters and a weight between 250 and 600 grams. It is therefore smaller than a coot , but larger than a little grebe . Its narrow beak is slightly curved upwards. The forehead is steep and high. There is no noticeable gender dimorphism .
Splendid and simple dress of adult black-necked grebes
In the splendid dress the head, neck, back and front breast are black. The lower part of the chest is white with brown spots, the belly white. The sides of the body are reddish brown. The iris is strikingly red. There is a small hood at the back of the head. The tufts of ears on the head are yellow to bronze in color and do not form a closed triangle, as is the case with the ear diver . The outer hand wings are black-gray, while the inner ones have an admixture of white. The arms are predominantly white, only the innermost are blackish. The under wing is white and the under tail is reddish or smoky gray.
In the transition dress to the plain dress, the red-brown coloration of the body sides is reduced. The throat, front neck and chest are light.
In the plain dress, the top of the body, the back neck and the top of the head are gray-brown. There is a light spot behind the ears, the hood is missing. The underside of the body as well as the sides of the body, the front neck, the sides of the neck and the throat are white. In the wintering areas of Western Europe, adult birds change from plain to magnificent in the period from February to April. In the case of young birds that hatched in the previous year, the change can drag on until May.
Chicks and young birds
Freshly hatched downy young are monotonously black and gray on the back, the belly is light. The head, which is black on the upper side, has two angular light spots. The throat and upper neck are light with single dark spots. The beak is red with a dark band at the level of the nostril and a second in front of the tip of the beak. Young birds are similar to adult birds in simple dress. However, in young birds the light spots on the head sides are more obvious. The front breast is gray in them and the iris is brown, unlike in adults. Downy boys have bare patches of skin on their foreheads, which are very important for maintaining their body temperature. If the boys are very overheated, these areas are well supplied with blood and then glow red. When the boys cool down, however, these areas become pale.,
Behavioral traits
The black-necked grebe is sociable all year round. His reputation is a rising huit . Outside of the breeding season, it likes to spend time near salt lakes and brackish waters . Up to a thousand birds then gather there. Often they also join black-headed gull colonies . Apparently the black-necked grebes benefit from the watchful gulls.
distribution
The distribution area of the black-necked grebe stretches patchy from West Africa and Central Europe to Central Asia. The species is also found isolated in East and South Africa as well as in northern East Asia and North America.
He is a short-haul migrant with scattered walks. In the south of the Central European distribution area it is probably also a resident bird . Its winter quarters are the coastal and inland waters in the south of Great Britain, the Netherlands to Biscay , the Mediterranean area as well as North Africa and the Middle East. Here he can be seen mainly on the lakes of Turkey, Iran and the Caspis region. In Central Europe, it winters mainly on Lake Geneva and Lake Constance.
The migration to the wintering quarters takes place in a south-westerly to south-easterly direction. Non-breeders leave their area as early as summer and the majority of the breeding black-necked grebes also leave the breeding waters before moulting in July to mid-August. Like all grebes, it migrates during the night. During the moulting season, moulting groups of several hundred individuals occur on some waters in the Alpine foothills. The waters in which such accumulations can be observed include Lake Constance, the Ismaninger pond area and the Kochelsee . The black-necked grebes return to the breeding areas from the beginning of April.
habitat
During the breeding season, the black-necked grebe lives in freshwater waters. He prefers nutrient-rich lakes and ponds, which are characterized by dense bank vegetation and have as many submerged plants as possible. Occasionally it breeds on shallow fish ponds or on slowly flowing steppe rivers. Its preferred breeding water has a depth of 40 to 80 centimeters. In the Caucasus, breeding black-necked grebes can still be found at an altitude of 2000 meters. In Kyrgyzstan, their altitude ranges over 3000 meters and in the Altai they occur at 1500 meters above sea level. They overwinter on coasts and on large inland lakes as well as in the lowlands of large rivers and on reservoirs.
food
The diet of the black-necked grebe consists mainly of insects and their larvae as well as small crustaceans and mollusks. Fish play only a subordinate role in the diet of the black-necked grebe. Black-necked grebes find their food mostly diving. The diving duration is usually more than 30 seconds, the diving depth usually less than 2.5 meters, in exceptional cases up to 5.5 meters. Black-necked grebes often stick their heads in water just above their eyes to look for food. Very rarely do they pick up food from the surface of the water or chatter through the surface of the water.
Reproduction
Black-necked grebes reach sexual maturity in their first year of life. In Schleswig-Holstein, annual black-necked grebes make up twenty percent of the breeding population. The pair formation takes place in the wintering areas and during the spring migration. However, partner changes also occur after the start of breeding.
Black-necked grebes are colony breeders. Such colonies can consist of a few nests, but can also contain up to 400 nests.
Courtship
During the migration, black-necked grebes do not show full courtship behavior. A group courtship is characteristic, in which two to four poses and calls alternate per hour. Couples stay together during a breeding season (so-called monogamous seasonal marriage), and occasionally also during the subsequent winter season.
The complete courtship behavior is shown shortly after arrival in the breeding areas. It consists of an aggressive behavior, a courtship on the water and an advertisement for the partner bird on the nest platform. In most cases, black-necked grebes court in groups of two to four pairs. The courtship is usually initiated by a bird that behaves more actively than the other birds and whistles incessantly, which turn into faster trills. This aroused behavior is then transmitted to other birds. They then primarily show aggressive behavior in which they chop at other birds or pursue each other with their heads stretched out.
During courtship on the water, black-necked grebes, like great crested grebes, show what is known as the ghost pose, in which one breeding bird slowly appears before the other. The courtship also includes the presentation of nesting material, the so-called penguin dance, in which the birds raise their upper bodies far out of the water while at the same time violently treading water with their feet, the so-called cat pose, in which the black-necked grebes lift their wings, fluff their shoulder feathers and the Raise the hood, swim in parallel and do a flight run. These courtship poses resemble those of the great crested diver in many ways.
The advertising on the nest platform begins with a mating request on the water in the immediate vicinity of the nest platform. This is followed by a mating request on the nest. Copulation takes place on the nest.
Nest and young birds
Black-necked grebes often build their nests on flooded areas, often near colonies of black-headed, storm, herring or little gulls or terns such as the black, white-winged and common tern. They also build swimming nests which, unlike other grebes, are located between light vegetation above the water. It is characteristic of the species that they start building two to five nests, but only finish one and use it for breeding. Both parent birds are involved in building the nests.
In suitable habitats the distance between individual black-necked grebe nests is very small, defenses are only carried out in an area of around 0.6 meters around the nest. If another black-necked grebe falls below this distance, the owners of the area react by stretching their head forward and opening their beak. The hood is raised and lowered excitedly.
Laying begins in mid-April / early May and continues until June. Replacement and second clutches will be laid by the end of August. The clutches usually contain three to four eggs. Freshly laid rushers are initially matt white. Due to the damp nesting material, they will soon turn green, greenish brown or even dark brown. Eggs are usually laid daily, and the hatching business starts with the second egg. The incubation period is 20 to 22 days. Both parent birds are involved in the brood. The clutch is only left for a very short time. When alarmed by an approaching person, for example, they cover the eggs with nesting material and then go onto the water, where they hide in the vegetation not far. They react to the approach of other grebes or terns with threatening head stretching and hissing noises. The eggs are turned by the breeding parent bird every 20 to 40 minutes. During the hatching period, black-necked grebes rise from the nest every 10 to 15 seconds.
The chicks hatch about a day apart. As soon as their downy dress is dry, they climb onto the back of the adult birds. They usually spend their first eight days there and are fed there too. The young birds are independent when they are 21 days old.
Negative influencing factors
Open nests are destroyed by carrion crows and marsh harriers. For this reason, the breeding success is lower in waters where black-necked grebes are repeatedly disturbed by humans and therefore leave their nests. However, nests are also destroyed by waves or the parent birds give up their brood because the water level has dropped sharply during incubation.
Duration
Current inventory
The breeding population in Europe is between 53,000 and 96,000 breeding pairs. About 75 percent live in the European southwest of Russia and the Ukraine. Between 7,100 and 10,000 breeding pairs breed in Central Europe. The Central European distribution focus is in Germany and Poland. The Lanker See in Schleswig-Holstein is home to the largest colony in Central Europe with around 250 breeding pairs. In the Czech Republic, where there used to be numerous black-necked grebes, stocks have declined sharply. The population is significantly larger in North America, where around 1.5 million breeding pairs occur.
Significant local fluctuations in the population are typical of the black-necked grebe. One of the factors contributing to mass reproduction is the tendency to breed in colonies. In years with too high or too low a water level or a migration to more attractive breeding sites, there can be local drastic drops in established breeding sites. The resettlement of black-necked grebes is particularly common in colonies of black-headed gulls and common terns .
Disturbances in the breeding areas as well as in the important moulting areas, for example through heavy leisure activities, can have a significant impact. Intensive fish farming means considerable food competition for this species. In some regions there is also a dependency on black-headed gull colonies. Where these colonies collapse, black-necked grebes often also migrate.
Inventory development
In Central Europe there was a wave of propagation between the end of the 19th century and around 1930, during which many regions were repopulated. These stocks have declined again in the last few decades, instead there has been an increase in stocks and an expansion of the area in Northern and Western Europe. In the formerly important breeding areas in Central Europe in the Czech Republic, Poland, Austria and Hungary, however, there was in some cases a sharp decline in the population. The stocks in the Czech Republic fell by eighty percent in the 1980s and 1990s. In Austria only between twenty and sixty breeding pairs breed. In Germany the stocks increased in some cases very strongly. The main areas of distribution are Schleswig-Holstein and Mecklenburg-Western Pomerania, where embankments have led to new floodplains that offer this species a suitable habitat. The stocks have also increased in Baden-Württemberg and on Lake Constance. The same applies to some regions in Bavaria and Brandenburg as well as in southern Poland. In Hessen, where the population had expired at the beginning of the 1960s, there has been a resettlement since the 1980s. In the Netherlands, where the population was less than 70 breeding pairs in the 1970s, the population has recovered to between 300 and 500 breeding pairs.
Inventory forecast
The black-necked grebe is one of the species that will be particularly hard hit by climate change. A research team that, on behalf of the British Environmental Protection Agency and the Royal Society for the Protection of Birds, examined the future distribution of European breeding birds on the basis of climate models, assumes that the distribution area of the black-necked grebe will change significantly by the end of the 21st century . According to this forecast, the distribution area will decrease by about eighty percent. The distribution area will concentrate on the Baltic States . The range also includes the Atlantic coast of Norway and southern Sweden. It is predicted that the black-necked grebe still belongs to the breeding population of Central Europe , but the distribution area is then much more patchy.
supporting documents
literature
- Hans-Günther Bauer, Einhard Bezzel and Wolfgang Fiedler (eds.): The compendium of birds in Central Europe: Everything about biology, endangerment and protection. Volume 1: Nonpasseriformes - non-sparrow birds. Aula-Verlag Wiebelsheim, Wiesbaden 2005, ISBN 3-89104-647-2 .
- Einhard Bezzel: birds. BLV Verlagsgesellschaft, Munich 1996, ISBN 3-405-14736-0
- VD Il'ičev & VE Flint (eds.): Handbook of birds of the Soviet Union - Volume 1: History of exploration, Gaviiformes, Podicipediformes, Procellariiformes . Aula Verlag, Wiesbaden 1985, ISBN 3-89104-414-3
Web links
- Podiceps nigricollis in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed January 31 of 2009.
- Videos, photos and sound recordings on Podiceps nigricollis in the Internet Bird Collection
- Entry at the Swiss Ornithological Institute
- Black-necked grebe's feathers
Individual evidence
- ↑ Il'ičev & Flint: Handbook of Birds of the Soviet Union - Volume 1: History of exploration, Gaviiformes, Podicipediformes, Procellariiformes . 1985, p. 248
- ↑ a b c Il'ičev & Flint: Handbook of the birds of the Soviet Union - Volume 1 : History of exploration, Gaviiformes, Podicipediformes, Procellariiformes . 1985, p. 254
- ↑ Il'ičev & Flint: Handbook of Birds of the Soviet Union - Volume 1: History of exploration, Gaviiformes, Podicipediformes, Procellariiformes . 1985, p. 250
- ↑ Il'ičev & Flint: Handbook of Birds of the Soviet Union - Volume 1: History of exploration, Gaviiformes, Podicipediformes, Procellariiformes . 1985, p. 253
- ↑ a b c d Il'ičev & Flint: Handbook of the birds of the Soviet Union - Volume 1: History of exploration, Gaviiformes, Podicipediformes, Procellariiformes . 1985, p. 251
- ↑ a b Bauer et al., P. 194
- ↑ Il'ičev & Flint: Handbook of Birds of the Soviet Union - Volume 1: History of exploration, Gaviiformes, Podicipediformes, Procellariiformes . 1985, p. 252 and p. 253
- ↑ Il'ičev & Flint: Handbook of Birds of the Soviet Union - Volume 1: History of exploration, Gaviiformes, Podicipediformes, Procellariiformes . 1985, p. 251 and p. 252
- ↑ Il'ičev & Flint: Handbook of Birds of the Soviet Union - Volume 1: History of exploration, Gaviiformes, Podicipediformes, Procellariiformes . 1985, p. 254
- ↑ https://schleswig-holstein.nabu.de/imperia/md/content/schleswigholstein/schutzgebiete/6.pdf
- ↑ Bauer et al., P. 192
- ↑ a b c d Bauer et al., P. 193
- ^ Brian Huntley, Rhys E. Green, Yvonne C. Collingham, Stephen G. Willis: A Climatic Atlas of European Breeding Birds , Durham University, The RSPB and Lynx Editions, Barcelona 2007, ISBN 978-84-96553-14-9 , P. 40