Cốc biển

Cốc biển
Fregata magnificens
Phân loại khoa học
Giới (regnum)	Animalia
Ngành (phylum)	Chordata
Lớp (class)	Aves
Bộ (ordo)	Suliformes
Họ (familia)	Fregatidae Degland & Gerbe, 1867
Chi (genus)	Fregata Lacépède, 1799
Range map
5 loài
Fregata magnificens Fregata aquila Fregata andrewsi Fregata minor Fregata ariel

Cốc biển là một chi chim biển duy nhất trong họ cùng tên Fregatidae. Có 5 loài trong chi này. Chúng có đôi cánh, đuôi, và mỏ dài và con đực có túi bướu cổ màu đỏ, nó được bơm căng lên vào mùa sinh sản để thu hút con cái.

Phân loại học

Từ nguyên

Họ Frigate được nhà tự nhiên học người anh Eleazar Albin sử dụng năm 1738 trong quyển A Natural History of the Birds. Quyển sách cũng minh họa chim trống red gular pouch. Nó có nguồn gốc do những người đi biển Pháp đặt tên là la frégate—một loại tàu frigate. Thuật ngữ này đã được nhà tự nhiên học người Pháp Jean-Baptiste du Tertre đề cập tới khi mô tả loài chim này năm 1667.

Christopher Columbus encountered frigatebirds when passing the Cape Verde Islands on his first voyage across the Atlantic in 1492. In his journal entry for 29 September he used the word rabiforçado, modern Spanish rabihorcado or forktail. In the Caribbean frigatebirds were called Man-of-War birds by English mariners. This name was used by the English explorer William Dampier in his book An Account of a New Voyage Around the World published in 1697:

The Man-of-War (as it is called by the English) is about the bigness of a Kite, and in shape like it, but black; and the neck is red. It lives on Fish yet never lights on the water, but soars aloft like a Kite, and when it sees its prey, it flys down head foremost to the Waters edge, very swiftly takes its prey out of the Sea with his Bill, and immediately mounts again as swiftly; never touching the Water with his Bill. His Wings are very long; his feet are like other Land-fowl, and he builds on Trees, where he finds any; but where they are wanting on the ground.

Classification

Frigatebirds were grouped with cormorants, and sulids (gannets and boobies) as well as pelicans in the genus Pelecanus by Linnaeus in 1758 in the tenth edition of his Systema Naturae. He described the distinguishing characteristics as a straight bill hooked at the tip, linear nostrils, a bare face, and fully webbed feet. The genus Fregata was defined by French naturalist Bernard Germain de Lacépède in 1799. Louis Jean Pierre Vieillot described the genus name Tachypetes in 1816 for the great frigatebird. The genus name Atagen had been coined by German naturalist Paul Möhring in 1752, though this has no validity as it predates the official beginning of Linnaean taxonomy.

In 1874, English zoologist Alfred Henry Garrod published a study where he had examined various groups of birds and recorded which muscles of a selected group of five they possessed or lacked. Noting that the muscle patterns were different among the steganopodes (classical Pelecaniformes), he resolved that there were divergent lineages in the group that should be in separate families, including frigatebirds in their own family Fregatidae. Urless N. Lanham observed in 1947 that frigatebirds bore some skeletal characteristics more in common with Procellariiformes than Pelecaniformes, though concluded they still belonged in the latter group (as suborder Fregatae), albeit as an early offshoot. Martyn Kennedy and colleagues derived a cladogram based on behavioural characteristics of the traditional Pelecaniformes, calculating the frigatebirds to be more divergent than pelicans from a core group of gannets, darters and cormorants, and tropicbirds the most distant lineage. The classification of this group as the traditional Pelecaniformes, united by feet that are totipalmate (with all four toes linked by webbing) and the presence of a gular pouch, persisted until the early 1990s. The DNA-DNA hybridization studies of Charles Sibley and Jon Edward Ahlquist placed the frigatebirds in a lineage with penguins, loons, petrels and albatrosses. Subsequent genetic studies place the frigatebirds as a sister group to the group Suloidea, which comprises the gannets and boobies, cormorants and darters. Microscopic analysis of eggshell structure by Konstantin Mikhailov in 1995 found that the eggshells of frigatebirds resembled those of other Pelecaniformes in having a covering of thick microglobular material over the crystalline shells.

Molecular studies have consistently shown that pelicans, the namesake family of the Pelecaniformes, are actually more closely related to herons, ibises and spoonbills, the hamerkop and the shoebill than to the remaining members. In recognition of this, the order comprising the frigatebirds and Suloidea was renamed Suliformes in 2010.

In 1994 the family name Fregatidae, cited as described in 1867 by French naturalists Côme-Damien Degland and Zéphirin Gerbe, was conserved under Article 40(b) of the International Code of Zoological Nomenclature in preference to the 1840 description Tachypetidae by Johann Friedrich von Brandt. This was because the genus names Atagen and Tachypetes had been synonymised with Fregata before 1961, resulting in the aligning of family and genus names.

Fossil record

Fossil of Eocene species Limnofregata azygosternon

The Eocene frigatebird genus Limnofregata comprises birds whose fossil remains were recovered from prehistoric freshwater environments, unlike the marine preferences of their modern-day relatives. They had shorter less-hooked bills and longer legs, and longer slit-like nasal openings. Three species have been described from fossil deposits in the western United States, two—L. azygosternon and L. hasegawai—from the Green River Formation (48–52 million years old) and one—L. hutchisoni—from the Wasatch Formation (between 53 and 55 million years of age). Fossil material indistinguishable from living species dating to the Pleistocene and Holocene has been recovered from Ascension Island (for F. aquila), Saint Helena Island, both in the southern Atlantic Ocean, and also from various islands in the Pacific Ocean (for F. minor and F. ariel).

A cladistic study of the skeletal and bone morphology of the classical Pelecaniformes and relatives found that the frigatebirds formed a clade with Limnofregata. Birds of the two genera have 15 cervical vertebrae, unlike almost all other Ciconiiformes, Suliformes and Pelecaniformes, which have 17. The age of Limnofregata indicates that these lineages had separated by the Eocene.

Living species and infrageneric classification

Frigatebird phylogeny

Great frigatebird (Fregata minor)     Christmas frigatebird (Fregata andrewsi)         Magnificent frigatebird (Fregata magnificens)     Ascension frigatebird (Fregata aquila)         Lesser frigatebird (Fregata ariel)

The type species of the genus is the Ascension frigatebird (Fregata aquila). For many years, the consensus was to recognise only two species of frigatebird, with larger birds as F. aquila and smaller as F. ariel. In 1914 the Australian ornithologist Gregory Mathews delineated five species, which remain valid. Analysis of ribosomal and mitochondrial DNA indicated that the five species had diverged from a common ancestor only recently—as little as 1.5 million years ago. There are two species pairs, the great and Christmas Island frigatebirds, and the magnificent and Ascension frigatebirds, while the fifth species, the lesser frigatebird, is an early offshoot of the common ancestor of the other four species. Three subspecies of the lesser and five subspecies of the great frigatebird are recognised.

Living species of frigatebirds
Common and binomial names	Image	Description	Range
Magnificent frigatebird (Fregata magnificens) Mathews, 1914		With a body length of 89–114 cm (35–45 in), it is the largest species and has the longest bill. The adult male is all-black with a scarlet throat pouch that is inflated like a balloon in the breeding season. Although the feathers are black, the scapular feathers have a purple sheen, in contrast to the male great frigatebird's green sheen. The female is brownish-black, but has a white breast and lower neck sides, a brown band on the wings, and a blueish-grey eye-ring.	Widespread in the tropical Atlantic, it breeds in colonies in trees in Florida, the Caribbean and Cape Verde Islands, as well as along the Pacific coast of the Americas from Mexico to Ecuador, including the Galápagos Islands.
Ascension frigatebird (Fregata aquila) (Linnaeus, 1758)		Apart from its smaller size, the adult male is very similar to the magnificent frigate bird. The female is brownish black with a rusty brown mantle and chest, and normally lacks any white patches present on the front of female birds of other species. The occasional female observed with a white belly may be breeding before obtaining the full adult plumage.	It is found on Boatswain Bird Island just off Ascension Island in the tropical Atlantic Ocean, having not bred on the main island since the 1800s.
Christmas frigatebird (Fregata andrewsi) Mathews, 1914		The adult male is the only frigatebird species with white on its belly – an egg shaped patch. It is larger with a longer bill than the related great frigatebird. Its upperparts are black with green metallic gloss on the mantle and scapulars. The female has dark upperparts with brown wing bars, a black head with white belly and white collar (sometimes incomplete) around its neck.	Breeds only on Christmas Island in the eastern Indian Ocean.
Great frigatebird (Fregata minor) (Gmelin, 1789)		The adult male has black upperparts with green metallic gloss on the mantle and scapulars. It is completely black underneath with subtle brown barring on the axillaries. The upperparts of the female are dark with lighter brown wing bars. Its head is black with a mottled throat and belly. White collar around neck.	Found in tropical Indian and Pacific oceans, as well as one colony—Trindade and Martim Vaz—in the south Atlantic, generally where the water is warmer than 22 °C (72 °F), and breeding on islands and atolls with sufficient vegetation to nest in.
Lesser frigatebird (Fregata ariel) (G.R.Gray, 1845)		With a body length of around 75 cm (30 in), it is the smallest species. The adult male has black upperparts with greenish to purple metallic gloss on the mantle and scapulars, and is black underneath except for bold white axillary spurs. The upperparts of the female are dark with lighter wing bars. The head is black with white belly and white collar around neck.	Tropical and subtropical waters across the Indian and Pacific Oceans. Atlantic race trinitatis was limited to Trindade, off Eastern Brazil but may now be extinct.

Các loài

• Chi Fregata
  • Fregata magnificens
  • Fregata aquila
  • Fregata andrewsi
  • Fregata minor
  • Fregata ariel

Tài liệu

• Harrison, Peter (1988). Seabirds: An Identification Guide. London: Christopher Helm. ISBN 0-7470-1410-8

Liên kết ngoài

• Frigatebird videos on the Internet Bird Collection