The spectacled tern ( Onychoprion lunatus), also known as the grey-backed tern, is a seabird in the family Laridae.
Description
A close relative of the
Bridled tern and
(with which it is sometimes confused), the spectacled tern is less common than the other members of its
genus and it has been studied less. The three species, along with the
Aleutian tern were recently split into a new genus
Onychoprion from
Sterna (Bridge
et al., 2005). They resemble the sooty tern but with a grey back instead of a black one. Their breast and underparts are white, and they have a black eye line from the bill to the back of the head.
Distribution and habitat
The spectacled tern breeds on islands of the
tropical Pacific Ocean. At the northern end of its distribution it nests in the Northwestern Hawaiian Islands (with the largest population being
Lisianski Island) and two small islets off
Oahu, in the east as far as the
Tuamotu Islands, with other
seabird colony in the
Society Islands, the
Line Islands,
Phoenix Islands,
Mariana Islands and
American Samoa. There are unconfirmed reports of breeding as far south as
Fiji, and as far east as
Easter Island. Little is known about the populations outside of Hawaii. Outside of the breeding season the species is partly
bird migration, with birds from the Hawaiian Islands flying south. It is thought that birds in other parts of the Pacific are also migratory, and will disperse as far as Papua New Guinea, the Philippines, and
Easter Island.
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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. PDF fulltext
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Mostello, C. S.; Palaia, N. A. & Clapp, B. (2000). Gray-backed Tern ( Sterna lunata). In: Poole, A. & Gill, F. (eds.): The Birds of North America 525. The Birds of North America, Inc., Philadelphia, PA.
