The grey-headed gull (''Chroicocephalus cirrocephalus''), also known as the grey-hooded gull, is a small species of
gull
Gulls, or colloquially seagulls, are seabirds of the subfamily Larinae. They are most closely related to terns and skimmers, distantly related to auks, and even more distantly related to waders. Until the 21st century, most gulls were placed ...
which breeds patchily in South America and Africa south of the
Sahara
The Sahara (, ) is a desert spanning across North Africa. With an area of , it is the largest hot desert in the world and the list of deserts by area, third-largest desert overall, smaller only than the deserts of Antarctica and the northern Ar ...
. It is not truly
migratory, but is dispersive, becoming more widespread in winter. This species has occurred as a rare vagrant to the United States, Italy, and Spain. As is the case with many gulls, it had traditionally been placed in the genus ''
Larus
''Larus'' is a large genus of gulls with worldwide distribution (by far the greatest species diversity is in the Northern Hemisphere).
Many of its species are abundant and well-known birds in their ranges. Until about 2005–2007, most gulls ...
''. Recent evidence suggests the South American and African populations may represent two separate
cryptic species
In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...
.
Description
The grey-headed gull is slightly larger than the
black-headed gull at 42 cm length. The summer adult has a pale grey head, a grey body, slightly darker in tone than in black-headed gull, and red bill and legs. The black tips to the primary wing feathers have conspicuous white "mirrors". The underwing is dark grey with black wingtips. The grey hood is lost in winter, leaving just two dark smudges around and behind the eye. The eye is dark in immatures, but has a white iris in adults. The sexes are similar. It takes two years to reach maturity; first year birds have a black terminal tail band, and more dark areas in the wings. In flight, the wings are broader than those of black-headed gull. It is a noisy species, especially at colonies. The call is a raucous
crow
A crow is a bird of the genus ''Corvus'', or more broadly, a synonym for all of ''Corvus''. The word "crow" is used as part of the common name of many species. The related term "raven" is not linked scientifically to any certain trait but is rathe ...
-like ''caw, caw''.
It is locally abundant, breeding in large colonies in reedbeds and marshes; it lays two or three eggs in a nest, which can be on the ground or floating. Like most gulls, it is highly gregarious in winter, both when feeding and in evening roosts. Although it is predominantly coastal or estuarine, it is not a pelagic species, and is rarely seen at sea far from land. Flocks numbering hundreds or thousands can form when the feeding conditions are appropriate.
Taxonomy
Currently, two
subspecies
In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...
are accepted:
*''C. c. cirrocephalus''
( Vieillot, 1818) – South America
*''C. c. poiocephalus''
( Swainson, 1837) – Africa
They are scarcely distinguishable, with the South American subspecies slightly larger and paler-backed than the African subspecies, and with a marginally larger white spot ("mirror") on the two outer primaries.
[ Recent genetic evidence however suggests however that they may represent two separate species, as the African subspecies ''C. c. poiocephalus'' may be more closely related to the (also African) ]Hartlaub's gull
Hartlaub's gull (''Chroicocephalus hartlaubii'') is a small gull in the genus ''Chroicocephalus''. It was formerly (as with other related gulls) placed in the genus ''Larus'' until genetic research demonstrated that the old broad view of that gen ...
''C. hartlaubii'', than it is to the nominate South American ''C. c. cirrocephalus''; if verified, this would require the splitting of the African taxon as a separate species to avoid paraphyly
Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...
. This has however not yet (as of 2024) been adopted by the IOC World Bird List.
Chroicocephalus cirrocephalus, Mejía, Peru 1.jpg, ''C. c. cirrocephalus'' in non-breeding plumage, Mejía, Peru
Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...
Chroicocephalus cirrocephalus, Laguna del Cisne, Canelones, Uruguay 1.jpg, ''C. c. cirrocephalus'' in flight in breeding plumage, Uruguay
Uruguay, officially the Oriental Republic of Uruguay, is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast, while bordering the Río de la Plata to the south and the A ...
Grey-headed Gull (Chroicocephalus cirrocephalus poiocephalus), Cape Vidal, South Africa.jpg, ''C. c. poiocephalus'' at Cape Vidal, South Africa
South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...
Chroicocephalus cirrocephalus.jpg, ''C. c. poiocephalus'' in breeding plumage, Bakau, Gambia
The Gambia, officially the Republic of The Gambia, is a country in West Africa. Geographically, The Gambia is the List of African countries by area, smallest country in continental Africa; it is surrounded by Senegal on all sides except for ...
Grey-headed Gulls, Lake Elementeita, Kenya (Chroicocephalus cirrocephalus).jpg, ''C. c. poiocephalus'' flock, Lake Elementaita, Kenya
Kenya, officially the Republic of Kenya, is a country located in East Africa. With an estimated population of more than 52.4 million as of mid-2024, Kenya is the 27th-most-populous country in the world and the 7th most populous in Africa. ...
Chroicocephalus cirrocephalus MHNT.ZOO.2010.11.125.16.jpg, Eggs of ''C. c. poiocephalus'' from Banc d'Arguin, Mauritania - MHNT
References
* ''Seabirds'' by Harrison,
* ''Birds of The Gambia'' by Barlow, Wacher and Disley,
* Pons J.M., Hassanin, A., and Crochet P.A.(2005). ''Phylogenetic relationships within the Laridae (Charadriiformes: Aves) inferred from mitochondrial markers.'' Molecular Phylogenetics and Evolution 37(3):686-699
External links
Species text in The Atlas of Southern African Birds
{{Taxonbar, from=Q652348
grey-headed gull
Birds of South America
Birds of Sub-Saharan Africa
grey-headed gull
Taxa named by Louis Pierre Vieillot