Cepphus
| Cepphus | ||||||||
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Pigeon duck ( Cepphus columba ) |
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| Systematics | ||||||||
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| Scientific name | ||||||||
| Cepphus | ||||||||
| Pallas , 1769 |
Cepphus is a genus of the alken family. This genus includes three species, one of which, the black guillemot , occurs circumpolar and isa regular guest birdon central European coasts, among others. The two other species, the pigeon dew and the so far little researched spectacled dew, are limited in their distribution to the Pacific.
Several subspecies are distinguished for black duck and pigeon duck. In contrast, the Brillenteiste is a monotypical species. All species are currently classified by the IUCN as not endangered ( least concern ).
Appearance
Pigeon and black guillemot are roughly equally heavy birds and weigh on average between 400 and 500 grams. The glasses bar is a little heavier and weighs approx. 650 grams. In all clothes the beak is black, the upper and lower beak are almost symmetrical and have a slim, pointed shape. All three species have a striking coral-red beak inside.
All three species have a predominantly black-brown to black plumage in their splendid plumage. The most brownish plumage has the goggles. The pigeon and black guillemot have conspicuous white wing spots, but the goggle guillotine lacks these wing spots. In contrast, the goggle bar has white eye spots, which gave this species its name. All three species have bright red legs, feet, and webbed feet.
In the plain dress , all three types have a more or less large proportion of whitish to pale brownish feathers. This change is least pronounced in the case of glasses, which have a dark body surface even in a simple dress. The underside of the body, on the other hand, is bright and the chin and throat are also clearly lightened. The top of the head, on the other hand, remains dark, so that the eye-catching eye spot is retained, even if it is not as pronounced as in the magnificent dress. In the case of Gryll and Tabenteiste, the proportion of white in the plain dress is considerably greater. For example, the head is complete and the coat is mostly whitish.
Young birds that have just fledged each resemble the adult birds in their simple dress, but the brown component in the plumage is more pronounced.
distribution
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 northwest coast of the Kamchatka . Breeding colonies can also be found on Sakhalin and the Kuril Islands as well as a few 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. Basically, it also breeds in warmer waters than the other two species.
The black guillemot is a breeding bird on the coasts of the North Pacific including the Bering Strait and Arctic North America, the Arctic archipelagos of Eurasia and northwestern Europe to the south of Ireland and Sweden. The occurrences in Europe are in Iceland , the Faroe Islands , Ireland , in Norway on the island Runde and Scotland as well as on smaller islands off the coast of England. In North America you can meet them from Maine northwards and in small numbers in Alaska . In the Pacific, the breeding areas overlap with those of the pigeon duck. Winter hibernation takes place in ice-free marine areas that are usually not far from their breeding areas.
The pigeon duck breeds in smaller colonies on rocky islands and cliffs of the northern Pacific. The occurrences extend from Kamchatka to North America and there along the coast from Alaska to California . In winter, Alaska's pigeon ducks migrate to ice-free sea zones in the south.
food
The diet of the Cepphus species consists mainly of fish and, to a lesser extent, of crustaceans. The food acquisition usually takes place in shallow waters near the coast. The individual dives of the black guillemot lasted an average of 73 seconds, with an average pause of 27.5 seconds between the individual dives. The daily food requirement for black guillemots held in captivity is 80 to 240 grams of fish.
Reproduction
All three species prefer to breed in loose colonies. In the case of black guillemots, the nest spacing is between one and twenty meters, whereas in the case of glasses there is one nest for every 100 square meters. In all three species, very large colonies are rather rare, which may be related to the specific requirements of the nesting site. Most of the breeding colonies of the pigeon deer consist of no more than twenty to forty pairs, while the colonies of the pigeon deer consist of a dozen to 100 pairs. Even with the black guillemot, the colonies usually consist of no more than a few hundred pairs. In the Canadian Arctic, where rugged cliffs of the species offer many suitable locations, single colonies can number as many as 10,000 pairs. All three species are cave breeders who prefer to use crevices as nesting sites. Pigeon ducks also dig nesting caves or use caves under tree roots or the abandoned burrows of other seabirds or rabbits. The more unusual nesting sites for the pigeon duck include small caves under ship docks, bridges and shipwrecks. Nests have also been found in buildings that are no longer in use.
The Cepphus species differ from most alken birds, among other things, in their clutch size. Since their feeding grounds are close to their breeding colonies, they are able to raise two nestlings and lay two eggs accordingly. Otherwise, this is only the case with the genus Synthliboramphus , with Endomychura clutches of one and two clutches are about equally common. The eggs are laid directly on the ground. Both parent birds are involved in the brood. The young birds fledge after 33 to 38 days.
Systematics
It is not uncommon for the species of the genus Cepphus to be grouped together with the guillemots ( Uria ). From these, however, they distinguish numerous morphological and other features, such as deviating moulting behavior and the way of life. The morphological differences exist, for example, in the shape of the beak, which has a shorter gony and largely featherless nostrils. The barrel is laterally compressed and the foot smaller, the head plumage less plush-like. The species of the genus Cepphus are not very specialized in comparison to other alks. Various morphological and ethological features associate them with the seagulls. They are the only alks with well-developed, functional appendixes.
species
The following species belong to the genus Cepphus :
- Black guillemot ( Cephus grylle )
- Pigeon Duck ( Cephus columba )
- Spectacled guillemot ( Cephus carbo )
supporting documents
literature
- Anthony J. Gaston and Ian L. Jones: The Auks . Oxford University Press, Oxford 1998, ISBN 0-19-854032-9
- Urs N. Glutz von Blotzheim , KM Bauer : Handbook of the birds of Central Europe . Volume 8 / II: Charadriiformes. 3rd part: snipe, gull and alken birds. AULA-Verlag 1999, ISBN 3-923527-00-4 .
Single receipts
- ↑ BirdLife Factsheet , accessed October 10, 2010
- ↑ Gaston et al., Pp. 169, 179 and 187
- ↑ Gaston et al., P. 187
- ↑ 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 , p. 571
- ↑ Gaston et al., P. 175
- ↑ Gaston et al., P. 184
- ↑ a b Glutz v. Blotzheim, p. 1058, p. literature
