''Sternula'' is a genus of small white

tern Terns are seabirds in the family Laridae, subfamily Sterninae, that have a worldwide distribution and are normally found near the sea, rivers, or wetlands. Terns are treated in eleven genera in a subgroup of the family Laridae, which also ...

s, with a global distribution along sheltered sandy coasts and large rivers. The seven species are all closely related, with similar plumage and size, all are between 22–28 cm long and 39–63 g weight. All are pale grey above, and white or very pale grey below; in all the outer primaries are darker grey (to nearly blackish), but the number of primaries that are dark varies slightly between the species. Most have a distinctive head pattern in the breeding season, with a black crown and eyeline, and a white forehead; one (fairy tern) differs in lacking the black eye line, and one (Damara tern) has a fully black crown with no white forehead in the breeding season. The legs and bill are mostly yellow (with or without a black tip) in the breeding season, but black in Damara tern. In all species the winter plumage has a more extensive white forehead, the bill is black, and the legs darker red-brown to blackish. Although the genus was first described in 1822 by

Friedrich Boie Friedrich Boie (4 June 1789 – 3 March 1870) was a German entomologist, herpetologist, ornithologist, and lawyer.Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). ''The Eponym Dictionary of Reptiles''. Baltimore: Johns Hopkins Universi ...

, the species in the genus were generally retained within the larger genus ''

Sterna ''Sterna'' is a genus of terns in the bird family Laridae. The genus used to encompass most "white" terns indiscriminately, but mtDNA sequence comparisons have determined that this arrangement was paraphyletic. It is now restricted to the typi ...

'', the genus that holds most terns, until a study in 2005 showed that this treatment was

paraphyletic 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 ...

, with these seven species less closely related to typical ''Sterna'' terns, than several other terns long treated in other genera like ''

Chlidonias The name marsh tern refers to terns of the genus ''Chlidonias'', which typically breed in freshwater marshes, rather than coastal locations. Taxonomy The genus ''Chlidonias'' was introduced in 1822 by the French polymath Constantine Samuel Rafi ...

'' and '' Larosterna''.Bridge, E. S.; Jones, A. W. & Baker, A. J. (2005)
A phylogenetic framework for the terns (Sternini) inferred from mtDNA sequences: implications for taxonomy and plumage evolution
. ''Molecular Phylogenetics and Evolution'' 35: 459–469. ''Sternula'' diverged early from other terns about 16 million years ago, with only the very different noddies (''Anous'' and ''Gygis''), and the 'brown-backed' ''

Onychoprion ''Onychoprion'' is a genus of four species of terns in the family Laridae. The genus name is from Ancient Greek , "claw" or "nail", and , "saw". As a group, they have been variously called "brown-winged terns" or "brown-backed terns", though onl ...

'' terns diverging earlier. Despite the early origin of the genus, the current diversity within the genus is much more recent, with the species having a common ancestor around 4 million years ago. Saunders's and least terns were both formerly considered to be subspecies of little tern. The genus name is a diminutive of ''

'', "tern".

Species

Seven species are accepted by the

IOC World Bird List ''Birds of the World: Recommended English Names'' is a paperback book written by Frank Gill and Minturn Wright on behalf of the International Ornithologists' Union. The book is an attempt to produce a standardized set of English names for all bi ...

References

{{Authority control Bird genera Taxa named by Friedrich Boie