Glasses die
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Glass Duck ( Cepphus carbo ) |
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| Systematics | ||||||||||
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| Cepphus carbo | ||||||||||
| Pallas , 1811 |
The Brillenteiste ( Cepphus carbo ) is a Pacific species from the cauliflower family. It was first scientifically described by Peter Simon Pallas in 1811 , but is still one of the least researched species of alkenbirds today. It is very similar to the other two species of the genus Cepphus - the black guillemot and the pigeon guillotine , but the spectacle guillemot is significantly larger and does not show any white wing spots. Its range only overlaps with that of the pigeon duck on the Kuril Islands , and in large areas of its range it is the only species of the genus. The name of the species is the white eye spot, with which the iris contrasts strongly in all clothes . No subspecies are described.
Appearance
Most people with glasses reach an average body weight of 650 grams. The wing length is a little more than 20 centimeters.
The splendid dress of adult spectacle players is uniformly sooty gray-brown. A white spot around the eyes on the side of the head stands out from this. A thin whitish line runs from the eyes to the neck. Smaller white spots can be found at the base of the beak. The slightly lighter color of the chin gradually merges into the dark gray-brown throat. The beak is a little stronger than that of the black and pigeon duck, the upper and lower beak are almost the same size and taper to a point. The inside of the beak, legs, feet and webbed feet are bright coral red.
In the plain dress , the underside of the body and parts of the head are white with pale, dark spots. The parting, the forehead and the face remain dark, the white eye spot is a little more indistinct, but the chin spot is also recognizable in the plain dress. The upper side of the body, on the other hand, remains uniformly dark brown, the feathers in the neck, however, occasionally have lighter seams. The feet, the inside of the beak, the legs and the webbed feet are pale red to pink.
Fledglings are similar to the adult birds in the plain dress, but show more brownish gray on the underside of the body. Their feet are brownish pink and the beak is relatively short with a pale tip. The nestlings have a gray-blackish downy dress.
Distribution area
The distribution area of the Brillenteiste is the north west coast of the Pacific. The main areas of distribution include the Sea of Okhotsk and the north-western coast of the Kamchatka Peninsula . Breeding colonies can also be found on Sakhalin and the Kuril Islands as well as occasionally on the west coast of the Sea of Japan up to the border with North Korea . In Japan, most of the birds breed in the north of Hokkaidō . There were also breeding colonies on the coast of North Korea in the first half of the 20th century, but the current population is not known. The wintering areas are in the southern regions of the breeding area.
The ice cream occurs in coastal waters, which have a surface temperature between 2 and 20 degrees Celsius in summer and a surface temperature between 0 and 15 degrees Celsius in winter. Similar to the pigeon dew, the pigeon dew is mostly found in the shallower coastal waters. Breeding colonies can be found near protected bays.
food
The food and acquisition of food for the glasses of the bar have not yet been very well researched. However, they mainly eat creatures that are on the bottom of the water. They find their food near the coast at water depths between ten and twenty meters. They move only a few kilometers away from the breeding colony in search of food.
Small fish, octopus and crabs were found in the stomachs of three Japanese glasses-makers shot in the 1950s. But invertebrates also belong to their diet. Young birds are fed small fish such as sand eels and anchovies .
Reproduction
Breeding colonies are found on rocky islands and headlands without predatory mammals . Rock crevices are used to create the nests. The nests are created either just above the flushing edge or up to 120 meters from the coastline. Individual nests are occasionally found on cliffs 100 meters above sea level. Brillenteisten are colony breeders, whereby the colonies are often not very large. Most consist of only 20 to 40 pairs, but on larger islands individual colonies can contain 700 pairs. There are several colonies on the Shantar Islands that even have more than 1,000 breeding pairs. The nests are not very close together. Usually one breeding pair is found per 100 square meters. The eggs are placed directly in a shallow trough on the bottom of the nesting chamber. The depth of the nesting chamber varies between 20 centimeters and 1.5 meters.
In the south of the Sea of Japan, brilliant-eyed fish return near their breeding colonies at the beginning of April, and egg-laying begins in early May and lasts until early June. Most chicks hatch between June 10th and 20th and fly out in July and early August. In the Sea of Okhotsk, eggs begin to lay between a month and six weeks later.
The clutch of the glasses consists of two eggs. This is an unusually large clutch for alkenbirds, but is probably due to the fact that the feeding grounds near the breeding colonies allow two nestlings to be raised, as is the case with the pigeon duck. Breeding birds have two lateral breeding spots, the breeding season averages 27 days. So far, no information is available on the share of the male or female parent bird in the breeding business. The nestling period is five to six weeks. The young birds weigh around 36 grams and an average of 466 grams at the time of their excursion.
Predators and life expectancy
So far, no information is available about the breeding success and life expectancy of the Brillenteisten. Both young birds survive in about 45 percent of the nests by the time they fled. Regionally, a very high mortality rate among newly fledged nestlings was found.
The predatory mammals that also kill adult birds in the breeding colonies include the red fox and various species of marten . The birds that beat the spectacled include the Kamchatka and Japanese gulls , eagle owls , probably also giant sea eagles , as well as sea eagles , the peregrine falcon and the big-billed crow . The latter mainly eats eggs and chicks.
Duration
The Russian population is not known, but estimates at the beginning of the 1990s were between 50,000 and 400,000 breeding pairs. BirdLife International currently indicates the population at 140,000 to 148,000 individuals. The largest colonies are believed to be on the Shantar Islands, where there were several colonies in the early 1990s that comprised a total of 5,000 to 8,000 breeding pairs. In Japan, the goggle has become a rare breeding bird that only occurs occasionally. The reasons for the decline are the birds drowning in fishing nets and disturbances in the breeding grounds.
supporting documents
literature
- Anthony J. Gaston, Ian L. Jones: The Auks (= Bird Families of the World. Vol. 4 (recte 5)). Oxford University Press, Oxford et al. 1998, ISBN 0-19-854032-9 .
- Richard Sale: A Complete Guide to Arctic Wildlife. Christopher Helm, London 2006, ISBN 0-7136-7039-8 .
Single receipts
- ^ Sale, p. 269
- ↑ Gaston et al., P. 187
- ↑ Gaston et al., P. 187
- ↑ Gaston et al., P. 189
- ↑ Gaston et al., P. 190
- ↑ Gaston et al., P. 190
- ↑ Gaston et al., P. 190
- ↑ Gaston et al., P. 190
- ↑ Gaston et al., P. 191
- ↑ BirdLife Factsheet , accessed October 10, 2010
- ↑ Gaston et al., P. 187
Web link
- Cepphus carbo inthe IUCN 2013 Red List of Threatened Species . Listed by: BirdLife International, 2012. Retrieved January 14, 2014.