Guillemots

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Guillemots
Guillemot between two thick-billed mummies

Guillemot between two thick-billed mummies

Systematics
Class : Birds (aves)
Order : Plover-like (Charadriiformes)
Family : Alkenbirds (Alcidae)
Genre : Guillemots
Scientific name
Uria
Brisson , 1760

The guillemots ( Uria ) are a two species comprehensive bird genus that belongs to the alkenvogel (Alcidae).

The guillemots are sea birds that are widespread in the northern hemisphere. They only stay on the coasts during the breeding season.

Appearance

Both species, the guillemot ( Uria aalge ) and the thick-billed mum ( Uria lomvia ), are 38–46 cm tall and weigh about 1 kg. After the giant aalk ( Pinguinus impennis ), which became extinct in the middle of the 19th century , they are the largest alken birds.

Guillemots are colored black on top and white on the underside. In the winter plumage, the white color extends to the throat, which is black in the breeding plumage. The beak is colored uniformly black. There is a color variant of the guillemot, the ringlet, with a white eye ring, from which a curved white stripe runs a little down the neck.

distribution

The breeding area of ​​the guillemot extends over the coasts of the North Atlantic and North Pacific as well as the adjacent Arctic coast. The distribution area extends south in the Atlantic area to the British Isles and Portugal , in the Pacific to Korea , northern Japan and California . The guillemot also breeds on Heligoland , where it lives on the so-called " Lummenfelsen ".

Thick-billed mums breed further north in the arctic waters; their southernmost occurrences are in Iceland , Newfoundland , Sakhalin , the Kuril Islands and the Aleutian Islands in Alaskas .

Reproduction

Breeding colony on the steep coast of Northern Ireland

Guillemots breed in colonies on rock ledges and cliffs on inaccessible cliffs. The female only lays one egg directly on the rock bed. During incubation, the eggs lie on the adult birds' webs. The pear-shaped, individually drawn eggs are 8.1 x 5 cm in size. Because of its shape, the guillemot rolls poorly, which is advantageous on the often narrow ledges.

Still in their down dress, the flightless, three-week-old guillemot chicks dare to jump into the sea up to 40 meters below them. There they are fed by their parents (usually the father) until they are able to fly.

This unusual behavior has developed because the adults are quite heavy and have relatively small wings. So they cannot transport a lot of food for the young birds in flight. As soon as the young birds get bigger and need more food than their parents can fly in, the so-called lumbar jump occurs. This behavior adjustment thus compensates for the physical disadvantage that results from the relatively poor flight ability of the adults for the rearing of the young.

The jump can be seen, for example, in summer on Heligoland.

species

Tribal history

Morphological as well as genetic examinations revealed a close relationship between the guillemots ( Uria ) and the genus Alca , the only living representative of which is the razorbill . While there are numerous fossil finds of the genus Alca in the Atlantic, only two fossil records of guillemots are known, namely Uria affinis from the Pleistocene of Maine and Uria ausonii from the Pliocene of Italy. (The latter species, however, is assigned to the genus Alca by some authors .) Furthermore, there are only two other fossil Uria finds, namely: Uria brodkorbi and Uria paleohesperis from the Miocene and the Miocene / Pleistocene border of California. According to Truth, the geographical distribution of these finds leads to the hypothesis that the genus Uria developed in the Pacific and spread across the Arctic Sea into the Atlantic between the early Pliocene and the Pleistocene. Olsen and Rasmussen attribute Uria's absence in the Atlantic up to the late Pleistocene to a competitive situation with Alca . Uria representatives could only then gain a foothold in the Atlantic when corresponding niches emerged.

literature

  • VL Friesen, AJ Baker, JF Piatt: Phylogenetic Relationships Within the Alcidae (Charadriiformes: Aves) Inferred from Total Molecular Evidence. In: Molecular Biology and Evolution. Vol. 13, No. 2, 1996, ISSN  0737-4038 , pp. 359-367, full text (PDF; 1.25 MB) .
  • Peter Harrison. Seabirds. An Identification Guide. Revised edition, reprinted. Christopher Helm, London 1988, ISBN 0-7470-1410-8 .
  • Hermann Heinzel , Richard Fitter, John Parslow: Parey's bird book. All birds of Europe, North Africa and the Middle East. 5th edition, unchanged reprint of the 4th edition. Paul Parey. Hamburg et al. 1988, ISBN 3-490-22018-8 .
  • Josep del Hoyo , Andrew Elliott, Jordi Sargatal (eds.): Handbook of Birds of the World. Volume 3: Hoatzin to Auks. Lynx Ediciones, Barcelona 1996, ISBN 84-87334-20-2 .
  • Jiří Mlíkovský, Johanna Kovar: A new species of alken (Aves: Alcidae) from the Upper Oligocene of Austria. In: Annals of the Natural History Museum Vienna. A, Vol. 88, 1987, pp. 131-147, full text (PDF; 4.87 MB) .
  • Elizabeth A. Schreiber, Joanna Burger (Eds.): Biology of Marine Birds. CRC Press, Boca Raton FL 2001, ISBN 0-8493-9882-7 .
  • JG Strauch Jr .: The phylogeny of the Alcidae. In The Auk . Vol. 102, No. 3, 1985, pp. 520-539, full text (PDF; 1.32 MB) .

Individual evidence

  1. ↑ Distribution map of the guillemot
  2. ↑ Distribution map of the thick-billed mum
  3. ↑ Strauch, 1985
  4. ↑ Friesen u. a., 1996
  5. ↑ Mlíkovský and Kovar, 1987.
  6. ↑ Kenneth I. Warheit: The Seabird Fossil Record and the Role of Paleontology in Understanding Seabird Community Structure. In: Elizabeth A. Schreiber, Joanna Burger (Eds.): Biology of Marine Birds. CRC Press, Boca Raton FL 2001, ISBN 0-8493-9882-7 , pp. 17-56.
  7. ↑ Storrs L. Olson , Pamela C. Rasmussen : Miocene and Pliocene Birds from the Lee Creek Mine, North Carolina. In: Smithsonian Contributions to Paleobiology. Vol. 90, 2001, ISSN  0081-0266 , pp. 233-365, online .

Web links

Commons : Uria aalge  - album with pictures, videos and audio files
Commons : Uria lomvia  - album with pictures, videos and audio files