Razorbill

Taxobox
name = Razorbill


image_width = 210px
image_caption = At Westfjords peninsula, Iceland
status = LC
status_system = iucn3.1
regnum = Animalia
phylum = Chordata
classis = Aves
ordo = Charadriiformes
subordo = Lari
familia = Alcidae
genus = "Alca"
genus_authority = Linnaeus, 1758
species = "A. torda"
binomial = "Alca torda"
binomial_authority = Linnaeus, 1758

The Razorbill, "Alca torda", is a large auk, 38-43 cm in length, with a 60-69 cm wingspan. It is the only living member of the genus "Alca".

Adult birds are black on their upperparts and white on the breast and belly. The thick black bill has a blunt end. The tail is pointed and longer than that of a Murre. In winter, the black face becomes white.

Their breeding habitat is islands, rocky shores and cliffs on northern Atlantic coasts, in eastern North America as far south as Maine, and in western Europe from northwestern Russia to northern France. North American birds migrate offshore and south, ranging from the Grand Banks of Newfoundland to New England. Eurasian birds also winter at sea, with some moving south as far as the western Mediterranean.

These birds forage for food by swimming underwater. They mainly eat fish, like sandeels, herring and capelin, also some crustaceans and marine worms. Razorbills usually nest in large colonies and lay their eggs on bare rock or ground. Each partner will forage, then come home to take over with caring for the egg or young. They may well fly more than 100 km out to sea to feed when during egg incubation, but when provisioning the young, they forage closer to the nesting grounds, some dozen kilometers away, and often in shallower waterLilliendahl "et al." (2003)] .

Though the Razorbill's average lifespan is roughly 13 years, a bird ringed in the UK in 1967 has survived for at least 41 years—a record for the species. [cite web |url=http://www.independent.co.uk/environment/nature/seabird-born-in-summer-of-love-still-breeding-in-wales-863919.html |title=Seabird Born in Summer of Love Still Breeding in Wales |accessdate=2008-07-10 |publisher=The (London) Independent |date=2008-07-10 |author=McCarthy, Michael]

Well-known Razorbill colonies include:
* Heligoland, Germany (54°10' N) - near southern limit in Europe, a few pairs only
* Staple Island, Outer Farne Islands, UK (55°38' N) - breeding season May to mid-July.
* Runde, Norway (62°24' N) - 3,000 pairs
* Látrabjarg, Iceland (65°30' N) - 230,000 pairs, about 40% of the global population (mid-1990s estimate). Breeding season June - July.
* Grímsey, Iceland (66°33' N)

Evolution and prehistoric species

While the Razorbill is the only living species, the genus "Alca" had a much higher diversity in the Pliocene. A number of fossil forms have been found:

* "Alca "antiqua" (Late Miocene/Early Pliocene of Lee Creek Mine, USA)Verify source|date=January 2008
* "Alca" sp. (Late Miocene/Early Pliocene of Lee Creek Mine, USA) - possibly "A. stewarti"
* "Alca stewarti" (Kattendijk Sands Early Pliocene of Belgium)
* "Alca ausonia" (Yorktown Early Pliocene of Lee Creek Mine, USA - Middle Pliocene of Italy)
* "Alca" sp. (Puerto de Mazarrón Pliocene of El Alamillo, Spain) - may be "A. antiqua" or "A. ausonia"

As far as is known, the genus "Alca" seems to have evolved in the western North Atlantic or the present-day Caribbean like most other Alcini. Its ancestors would have reached these waters through the still-open Isthmus of Panama during the Miocene [Bédard (1985)] .

Footnotes

References

* (1985): Evolution and characteristics of the Atlantic Alcidae. "In:" aut|Nettleship, David N. & Birkhead, Tim R. (eds.), "The Atlantic Alcidae": 6-19. Academic Press, London. ISBN 0-12-515671-5
*|year=2004|id=49289|title=Alca torda|downloaded=11 May 2006 Database entry includes justification for why this species is of least concern
* (2003): Can surveillance radar be used to monitor the foraging distribution of colonially breeding alcids? [English with Spanish abstract] "Condor" 105(1): 145–150. DOI: 10.1650/0010-5422(2003)105 [145:CSRBUT] 2.0.CO;2 [http://www.bioone.org/perlserv/?request=get-abstract&doi=10.1650%2F0010-5422(2003)105%5B145%3ACSRBUT%5D2.0.CO%3B2 HTML abstract]