Chroicocephalus

Chroicocephalus
Black-headed gull (Chroicocephalus ridibundus)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Charadriiformes
Family:	Laridae
Genus:	Chroicocephalus Eyton, 1836
Type species
Larus capistratus[1] = Larus ridibundus Temminck, 1820
Species
See list

Chroicocephalus is a genus of medium to relatively small gulls which were included in the genus Larus until genetic evidence published in 2005 showed that Larus as then constituted was paraphyletic.^[2] Ten species are currently accepted.^[3] An eleventh, Saunders's gull, was included until a 2022 study demonstrated that it did not belong in Chroicocephalus; it is now treated in its own genus Saundersilarus.^[4] The genus name Chroicocephalus is from Ancient Greek khroizo, "to colour", and kephale, "head".^[5]

The species range from 28 cm up to 48 cm long, with Bonaparte's gull being the smallest, and Andean gull the largest. In all species, the body and tail are white, and the upperwing pale grey; the wingtips have distinct grey, white, and black patterns important for identification. Several have distinctively brown, pale grey, or blackish-grey coloured heads in the breeding season, but some also have the head pure white like the rest of the body. The eyes are dark in some species, or with a distinctive white iris in others; the legs and bills are bright to very dark red.^[6]

Representatives of this genus are found in regions/subregions all over the world, except for Antarctica; the species are often parapatric, but with two species together in New Zealand, the Mediterranean region, parts of southern Africa, and parts of South America. Exceptionally, three species (black-headed, brown-headed, and slender-billed gulls) can occur together in parts of southwest Asia.^[6]