Grey-headed Gull

The grey-headed gull (''Chroicocephalus cirrocephalus''), also known as the grey-hooded gull, is a small species of gull which breeds patchily in South America and Africa south of the Sahara. 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''. Recent evidence suggests the South American and African populations may represent two separate cryptic species.

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-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 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 ''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. 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
Chroicocephalus cirrocephalus, Laguna del Cisne, Canelones, Uruguay 1.jpg, ''C. c. cirrocephalus'' in flight in breeding plumage, Uruguay
Grey-headed Gull (Chroicocephalus cirrocephalus poiocephalus), Cape Vidal, South Africa.jpg, ''C. c. poiocephalus'' at Cape Vidal, South Africa
Chroicocephalus cirrocephalus.jpg, ''C. c. poiocephalus'' in breeding plumage, Bakau, Gambia
Grey-headed Gulls, Lake Elementeita, Kenya (Chroicocephalus cirrocephalus).jpg, ''C. c. poiocephalus'' flock, Lake Elementaita, Kenya
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