Sabine's gull

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Sabine's gull
Adult in Iceland

Least Concern  (IUCN 3.1)[1]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Charadriiformes
Family: Laridae
Genus: Xema
Leach, 1819
Species:
X. sabini
Binomial name
Xema sabini
(Sabine, 1819)
Sabine islands, near Melville Bay, west coast of Greenland
Range
  Breeding
  Migration
  Non-breeding

Sabine's gull (

prey
.

Taxonomy

Sabine's gull was

binomial name Larus sabini. Sabine based his description on specimens that had been collected by his brother Captain Edward Sabine who had accompanied Captain John Ross's on a voyage to look for the Northwest Passage. The birds were found breeding on low-lying islands off the west coast of Greenland in July 1818.[2] Sabine's gull is now the only species placed in the genus Xema that was introduced in 1819 by the zoologist William Leach in an appendix to Ross's account of the voyage.[3][4] The genus name Xema appears to be an invented name without meaning.[5]

Sabine's gull is usually treated as comprising a

Galapagos. On the basis of this the two species were often thought to be each other's closest relatives, a hypothesis ruled out by a number of behaviour and ecological differences. Mitochondrial DNA studies confirmed that they are not closely related, and the closest relative of Sabine's gull is now thought to be the ivory gull, another Arctic species. The two species are thought to have separated around 2 million years ago, longer ago than most groups of gull species.[8]

Geographical variation is slight; birds from

Chukotskiy Peninsula of Russia, and X. s. woznesenskii (Portenko, 1939) is found from the Gulf of Anadyr to Alaska.[9]

Description

Adult flying in Iceland
Sabine's gull flying at the fjord Trygghamna in Spitsbergen

Sabine's gull is a small gull, 27 to 33 cm (10+1⁄2–13 in) in length and weighing 135 to 225 g (4+3⁄4–7+15⁄16 oz). The wings are long, thin and pointed with a span of between 81 and 87 cm (32–34+1⁄2 in). The bill, which is black with a yellow tip, is around 2.5 cm (1 in) long.

This species is easy to identify through its striking wing pattern. The adult has a pale grey back and wing coverts, black primary flight feathers and white secondaries. The white tail is forked. The male's hood darkens during breeding season. Young birds have a similar tricoloured wing pattern, but the grey is replaced by brown, and the tail has a black terminal band. Juveniles take two years to attain full adult plumage. Sabine's gulls have an unusual molt pattern for gulls. Fledged birds retain their juvenile plumage through the autumn and do not start molting into their first winter plumage until they have reached their wintering grounds. Adults have their complete molt in the spring prior to the spring migration, and have a partial molt in the autumn after returning to the wintering area, a reversal of the usual pattern for gulls.[10] They have a very high-pitched and squeaking call.[6]

Distribution and habitat

Sabine's gulls breed in the Arctic, as they maintain a circumpolar distribution across northernmost North America and Eurasia. They migrate south to slightly warmer locations, typically in autumn, with most of the western North American population wintering at-sea in the Pacific Ocean. The birds will also head to islets and outcrops off of the South American west coast (such as the Galápagos Islands), where a consistent food supply is nourished by the cold waters of the Humboldt Current. Along their migration route, Sabine's gulls make stops along the US West Coast, and the pacific coasts of México and Central America; they have been observed in San Diego, California[11] and along the Pacific coast of Baja California and Baja California Sur, México.

By comparison, Greenlandic and eastern American Sabine's gulls usually cross the

Eastern Seaboard, or even further east along coastal Western Europe, typically following autumn storms.[12][13] Sabine's gull is recorded often enough inland, in North America, Europe, and even Siberia, that it has been said to exhibit "cross-continental migration" in addition to migration at sea.[8]

Sabine's gull eggs

Diet and feeding

The diet and feeding preferences of Sabine's gull varies by season and habitat. In the breeding season, the gulls pursue a range of freshwater and terrestrial prey on the

Syrphidae),[8] molluscs, insects, arachnids, water bugs, various invertebrate larvae, crustaceans, fish, as well as nestling birds or unhatched eggs. Young chicks and eggs, while generally consumed opportunistically, may include waterfowl, black turnstones and lapland longspurs
, as well as other gulls, including Sabine's gulls.

References

  1. doi:10.2305/IUCN.UK.2020-3.RLTS.T22694479A157413905.en
    . Retrieved 19 November 2021.
  2. doi:10.1111/j.1095-8339.1817.tb00244.x
    .
  3. ^ Leach, William Elford (1819). Ross, John (ed.). A Voyage of Discovery made under the orders of the Admiralty in her Majesty's ships Isabella and Alexander, for the purpose of exploring Baffin's Bay, and enquiring into the probability of a North-West passage. London: John Murray. Appendix II, p. 57.
  4. ^
    Rasmussen, Pamela, eds. (July 2021). "Noddies, gulls, terns, skimmers, skuas, auks"
    . IOC World Bird List Version 11.2. International Ornithologists' Union. Retrieved 1 December 2021.
  5. ISBN 978-1-4081-2501-4
    .
  6. ^
    ISBN 978-0198540991
    .
  7. ISBN 0-85661-091-7
    .
  8. ^
    doi:10.2173/bna.593
    . Retrieved 6 January 2011.
  9. ISBN 978-84-87334-20-7
    .
  10. S2CID 53364581
    .
  11. ^ "Observations iNaturalist Sabine's gull San Diego, CA". iNaturalist. Retrieved 26 February 2024.
  12. ISBN 84-87334-20-2
    .
  13. ISBN 0-394-41405-5
    .

External links

Wikimedia Commons has media related to Xema sabini.
Wikispecies has information related to Xema sabini.
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