The white tern or common white tern (''Gygis alba'') is a small

seabird Seabirds (also known as marine birds) are birds that are adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same enviro ...

found across the

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

oceans of the world. It is sometimes known as the fairy tern, although this name is potentially confusing as it is also the common name of '' Sternula nereis''. Other names for the species include angel tern and white noddy in English, and manu-o-Kū in Hawaiian. The little white tern ('' Gygis microrhyncha''), previously considered a subspecies of the white tern (''Gygis alba microrhyncha''), is now recognised as a separate species.

Taxonomy

The white tern was first formally described by the Swedish naturalist

Anders Sparrman Anders Sparrman (27 February 1748, Tensta, Uppland – 9 August 1820) was a Swedish naturalist, abolitionist and an apostle of Carl Linnaeus. Biography left, Miniature of Sparrman at the time of his travels with James Cook. By unknown artis ...

in 1786 under the binomial name ''Sterna alba''. The genus ''Gygis'' was introduced by the German zoologist

Johann Georg Wagler Johann Georg Wagler (28 March 1800 – 23 August 1832) was a German herpetologist and ornithologist. Wagler was assistant to Johann Baptist von Spix, and gave lectures in zoology at the Ludwig Maximilian University of Munich after it was moved ...

in 1832. The name ''Gygis'' is from the

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...

for a mythical bird and the specific is Latin for "white".

Molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

studies have shown that the white tern is more closely related to the noddies than it is to the other terns. This implies that "white noddy" would be a more appropriate English name. The white tern has the following recognized

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

: *''G. a. alba'', ( Sparrman, 1786): tropical islands of the south

Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...

including

Fernando de Noronha Fernando de Noronha () is an archipelago in the Atlantic Ocean, part of the State of Pernambuco, Brazil, and located off the Brazilian coast. It consists of 21 islands and islets, extending over an area of . Only the eponymous main island is inha ...

, Trinidade, Martin Vas Rocks, Ascension and

St. Helena Saint Helena () is a British overseas territory located in the South Atlantic Ocean. It is a remote volcanic tropical island west of the coast of south-western Africa, and east of Rio de Janeiro in South America. It is one of three constit ...

islands *''G. a. candida'', (

Gmelin Gmelin may refer to: * Gmelin's test, a chemical test * Gmelin database, a German handbook/encyclopedia of inorganic compounds initiated by Leopold Gmelin People * Carl Christian Gmelin (1762–1837), German botanist, author of ''Flora Badensis ...

, 1789):

Seychelles Seychelles (, ; ), officially the Republic of Seychelles (french: link=no, République des Seychelles; Creole: ''La Repiblik Sesel''), is an archipelagic state consisting of 115 islands in the Indian Ocean. Its capital and largest city, V ...

Mascarene Islands The Mascarene Islands (, ) or Mascarenes or Mascarenhas Archipelago is a group of islands in the Indian Ocean east of Madagascar consisting of the islands belonging to the Republic of Mauritius as well as the French department of Réunion. Thei ...

to central

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

including southern

Maldives Maldives (, ; dv, ދިވެހިރާއްޖެ, translit=Dhivehi Raajje, ), officially the Republic of Maldives ( dv, ދިވެހިރާއްޖޭގެ ޖުމްހޫރިއްޔާ, translit=Dhivehi Raajjeyge Jumhooriyyaa, label=none, ), is an archipelag ...

excluding range of ''G. a. leucopes'' and ''Gygis microrhyncha'' *''G. a. leucopes'', Holyoak & Thibault, 1976:

Pitcairn Islands The Pitcairn Islands (; Pitkern: '), officially the Pitcairn, Henderson, Ducie and Oeno Islands, is a group of four volcanic islands in the southern Pacific Ocean that form the sole British Overseas Territory in the Pacific Ocean. The four isl ...

Some authors have postulated that there may be three species of ''Gygis:'' ''Gygis alba'', in the Atlantic Ocean, and ''Gygis candida'' and ''Gygis microrhyncha'', both in the Pacific.

Description

The white tern has a wingspan of . It has white plumage and a long black bill.Niethammer, K. R., and L. B. Patrick-Castilaw. 1998. White Tern (''Gygis alba''). in ''The Birds of North America'', No. 371 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA. Nesting on

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and sec ...

islands, usually on trees with small branches but also on rocky ledges and on man-made structures, the white tern feeds on small

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

which it catches by plunge diving.

Giant tortoises Giant tortoises are any of various large land tortoises Giant tortoise or giant tortoises may also refer to: * Galápagos giant tortoise, ''Chelonoidis nigra'' are a complex of the largest living species of tortoise. :: Pinta giant tortoise or ...

have been observed to hunt the bird on Fregate Island in the

Distribution and habitat

The white tern ranges widely across the Pacific Ocean from the coasts of Chile and Colombia to New Zealand and along the eastern and southern coasts of Asia from China to India, South Maldives, the islands of the Indian Ocean, and the coast of South Africa. Rarely it is also found in Japan, Madagascar, Mexico, and on some islands in the Atlantic Ocean. It is a

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...

and

epipelagic The photic zone, euphotic zone, epipelagic zone, or sunlight zone is the uppermost layer of a body of water that receives sunlight, allowing phytoplankton to perform photosynthesis. It undergoes a series of physical, chemical, and biological proc ...

bird, living along the coast and moving into wooded areas during the breeding season. File:Fairy or White Tern hatchling.jpg, Fairy or white tern baby, Midway Island File:WhiteTernSeychelles.jpg, White tern parents near their chick, in

Cousin Island Cousin Island is a small () granitic island of the Seychelles, lying west of Praslin. It is a nature reserve protected under Seychelles law as a Special Reserve. It is managed by Nature Seychelles, a national nonprofit organization and Partner of ...

. Gygis alba MHNT.ZOO.2010.11.131.11.jpg, ''Gygis alba'' - MHNT

Behavior

This species is notable for laying its

egg An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the a ...

on bare thin branches in a small fork or depression without a

nest A nest is a structure built for certain animals to hold eggs or young. Although nests are most closely associated with birds, members of all classes of vertebrates and some invertebrates construct nests. They may be composed of organic materia ...

. This behaviour is unusual for terns, which generally nest on the ground, and even the related tree-nesting

black noddy The black noddy or white-capped noddy (''Anous minutus'') is a seabird from the family Laridae. It is a medium-sized species of tern with black plumage and a white cap. It closely resembles the lesser noddy (''Anous tenuirostris'') with which it w ...

constructs a nest. It is thought that the reason for the absence of nests is the reduction in nest

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

s, which in some colonial seabirds can cause the abandonment of an entire colony. In spite of these benefits there are costs associated with tree nesting, as the eggs and chicks are vulnerable to becoming dislodged by heavy winds. For this reason the white tern is also quick to relay should it lose the egg. The newly hatched chicks have well developed feet with which to hang on to their precarious nesting site. It is a long-lived bird, having been recorded living for 42 years.

Relationship with humans

This is one of the most useful of all the landfinding birds used by Pacific navigators. They generally roam no more than 45 km from their home island, to which they usually return at nightfall. Polynesians also caught these birds for food or to keep as pets. The white tern, ''manu-o-Kū'', was named

Honolulu Honolulu (; ) is the capital and largest city of the U.S. state of Hawaii, which is in the Pacific Ocean. It is an unincorporated county seat of the consolidated City and County of Honolulu, situated along the southeast coast of the island ...

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...

's official bird on April 2, 2007. New Zealand's

Department of Conservation An environmental ministry is a national or subnational government agency politically responsible for the environment and/or natural resources. Various other names are commonly used to identify such agencies, such as Ministry of the Environment ...

classifies the white tern as Nationally Critical, with populations having been largely decimated by the introduction of feral cats and rats on

Raoul Island Raoul Island (''Sunday Island'') is the largest and northernmost of the main Kermadec Islands, south south-west of 'Ata Island of Tonga and north north-east of New Zealand's North Island. It has been the source of vigorous volcanic activity ...

, the terns' only breeding site in the country. As of 2016, the white tern population in New Zealand was reported to be increasing following the eradication of introduced predators in 2002. Globally, the white tern has a large range that is home to several large colonies, and both recognised species are listed as Least Concern by the IUCN Red List.

References

External links

White tern videos, photos & sounds
on the Internet Bird Collection {{Authority control

white tern The white tern or common white tern (''Gygis alba'') is a small seabird found across the tropical oceans of the world. It is sometimes known as the fairy tern, although this name is potentially confusing as it is also the common name of '' Sternu ...

Birds of Norfolk Island Birds of the Atlantic Ocean Birds of the Indian Ocean Birds of the Pacific Ocean

Taxa named by Anders Sparrman

Pantropical fauna