Superregnum: Eukaryota
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Cladus: Craniata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Cladus: Reptiliomorpha
Cladus: Amniota
Classis: Reptilia
Cladus: Eureptilia
Cladus: Romeriida
Subclassis: Diapsida
Cladus: Sauria
Infraclassis: Archosauromorpha
Cladus: Crurotarsi
Divisio: Archosauria
Subsectio: Ornithodira
Subtaxon: Dinosauromorpha
Cladus: Dinosauria
Ordo: Saurischia
Cladus: Eusaurischia
Cladus: Theropoda
Cladus: Neotheropoda
Infraclassis: Aves
Cladus: Euavialae
Cladus: Avebrevicauda
Cladus: Pygostylia
Cladus: Ornithothoraces
Cladus: Euornithes
Cladus: Ornithuromorpha
Cladus: Ornithurae
Cladus: Carinatae
Parvclassis: Neornithes
Cohors: Neognathae
Ordo: Charadriiformes
Subordo: Lari
Familia: Laridae
Subfamilia: Larinae
Genus: Larus
Species: Larus atlanticus
Name
Larus atlanticus Olrog, 1958
Synonymy
Larus belcheri atlanticus (protonym)
References
Acta Zoologica Lilloana 15: 8
Vernacular names
brezhoneg: Gouelan Olrog
català: Gavià menjacrancs
čeština: Racek argentinský
Cymraeg: Gwylan gynffonddu'r Môr Iwerydd
Deutsch: Olrogmöwe
English: Olrog's Gull
Esperanto: Argentina mevo
español: Gaviota cangrejera
فارسی: کاکایی اطلسی
suomi: Rapulokki
français: Goéland d'Olrog
italiano: Gabbiano di Olrog
日本語: オルローグカモメ
Nederlands: Olrogs meeuw
Diné bizaad: Tónteel tsídii binághah diłhiłígíí
português: Gaivota-de-rabo-preto
svenska: Olrogtrut
தமிழ்: அத்திலாந்திக்குக் கடற்பறவை
Tiếng Việt: Mòng biển Olrog
Olrog's gull (Larus atlanticus) is a species of gull found along the Atlantic coast of southern Brazil, Uruguay, and northern Argentina. It was formerly considered a subspecies of the very similar L. belcheri. It is a large gull with a black back and wings, white head and underparts, a black band in the otherwise white tail, and a yellow bill with a red and black tip. Nonbreeding adults have a blackish head and a white eye ring. The species is named after Swedish-Argentine biologist Claes C. Olrog.[2][3] It has a rather restricted breeding range and is threatened by habitat loss, and the IUCN has rated it as being "near threatened".
Description
Olrog's gull is a large gull with a white head, neck, rump, breast, and belly. The back and wings are black except for a white trailing edge to the wings. The tail is white with a broad black band at the back. The beak is yellow with a black band and red tip. The eyes are brown with a red orbital ring and the legs and feet are dull yellow. The length of this gull is 50 to 60 cm (20 to 24 in) and it has a wingspan of 130 to 140 cm (51 to 55 in). Males are a little larger than females. Juveniles have black heads and brownish plumage.[4]
Distribution
South Brazil
Olrog's gull is native to the Atlantic coast of Argentina, Uruguay, and southern Brazil. It breeds at a very limited number of colonies between 38.49° and 45.11°S, about two-thirds of which are in the estuary of the Bahia Blanca River. It nests on the ground just above high-water mark, on low islands and islets. At other times, it is to be seen on rocky coasts, harbours, beaches, coastal lagoons, brackish water, and estuaries.[5]
Behavior
During the breeding season, Olrog's gull feeds largely on crabs, which are picked up from the exposed shore or the seabed while walking or swimming, or dipping under the surface of shallow water. This particular diet gives the gull its name in its native range: gaviota cangrejera, or crab-eater gull.
At other times of year, it supplements its crab diet with bivalve molluscs and polychaete worms. Other prey items include insects, gastropod molluscs, fish, and fish waste, and the birds sometimes visit sewage outlets and refuse dumps.[6]
Breeding starts in September and October. Olrog's gull is monogamous and nests in dense colonies. The nest is on rock, sand, or shingle and is usually lined with vegetation, but sometimes with seaweed, feathers, shells or bones. Two or three olive-brown eggs with brown splotches are laid and the incubation period is about 30 days. Fledging takes place between November and January according to the location of the colony.[6]
References
BirdLife International (2018). "Larus atlanticus". IUCN Red List of Threatened Species. 2018: e.T22694286A132538305. doi:10.2305/IUCN.UK.2018-2.RLTS.T22694286A132538305.en. Retrieved 11 November 2021.
Handford, P. (April 1987). "In Memoriam: Claes Christian Olrog, 1912-1985". The Auk. 104 (2): 319–320. doi:10.1093/auk/104.2.319. JSTOR 4087042.
Beolens, Bo; Watkins, Michael; Grayson, Michael (2009-09-28). The Eponym Dictionary of Mammals. Baltimore: The Johns Hopkins University Press. pp. 592 (see p. 298). ISBN 978-0-8018-9304-9. OCLC 270129903.
"Larus atlanticus". NeoTropical Birds. The Cornell Lab of Ornithology. Retrieved 2013-12-13.
"Species factsheet: Larus atlanticus". BirdLife International. Retrieved 2013-12-13.
"Larus atlanticus". NeoTropical Birds. The Cornell Lab of Ornithology. Retrieved 2013-12-13.
José Fernando Pacheco; Joaquim Olinto Branco & Vitor de Queiroz Piacentini (2009). "Olrog's Gull Larus atlanticus in Santa Catarina, Brazil: northernmost occurrence and first state record". Cotinga. 31: 80–81.
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