Great frigatebird

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Great frigatebird
Male greater frigate bird displaying.jpg
Adult male, displaying, with inflated gular sac
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Suliformes
Family: Fregatidae
Genus: Fregata
Species:
F. minor
Binomial name
Fregata minor
(Gmelin, 1789)
Great frigatebird (Fregata minor) distribution map HBW.svg
Range map
Synonyms

Pelecanus minorGmelin 1789
Tachypetes palmerstoni

The great frigatebird (Fregata minor) is a large seabird in the frigatebird family. There are major nesting populations in the tropical Pacific Ocean, such as Hawaii and the Galápagos Islands; in the Indian Ocean, colonies can be found in the Seychelles (on Aldabra and Aride Islands) and Mauritius, and there is a tiny population in the South Atlantic, mostly on and around St. Helena and Boatswain Bird Island (Ascension Island).

The great frigatebird is a large and lightly built seabird up to 105 cm long with predominantly black plumage. The species exhibits sexual dimorphism; the female is larger than the adult male and has a white throat and breast, and the male's scapular feathers have a purple-green sheen. In the breeding season, the male is able to distend his striking red gular sac. The species feeds on fish taken in flight from the ocean's surface (mostly flying fish), and indulges in kleptoparasitism less frequently than other frigatebirds. They feed in pelagic waters within 80 km (50 mi) of their breeding colony or roosting areas.

Taxonomy

The great frigatebird was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae . He placed it in the genus Pelecanus and coined the binomial name Pelecanus minor. [2] Gmelin based his description on the "lesser frigate pelican" that had been described in 1785 by the English ornithologist John Latham in his book A General Synopsis of Birds. [3] [4] Latham, in turn, largely based his account on the "man of war bird" that had been described and illustrated by the English naturalist George Edwards in 1760. [5] The great frigatebird is now one of five closely related species of frigatebird that make up their own genus ( Fregata ) and family (Fregatidae). Its closest relative, within the group, is the Christmas Island frigatebird (Fregata andrewsi). [6] [7] Due to the rules of taxonomy, the species name of minor has been retained. This has led to the discrepancy of minor (Latin for "smaller") in contrast with its common name. [8]

A Late Pleistocene fossilised wing phalanx and proximal end of humerus (indistinguishable from the extant great frigatebird) were recovered from Ulupau Head on Oahu. [9]

Subspecies

Five subspecies are usually recognised: [7]

Description

Male, showing feathers on gular sac Male Galapagos greater frigate bird.jpg
Male, showing feathers on gular sac

The great frigatebird measures 85 to 105 cm (33 to 41 in) in length and has a wingspan of 205–230 cm (81–91 in). [10] Male great frigatebirds are smaller than females, but the extent of the variation varies geographically. [11] The male birds weigh 1,000–1,450 g (2.20–3.20 lb) while the heavier female birds weigh 1,215–1,590 g (2.679–3.505 lb). [12]

Chick, Genovesa Island, Ecuador Great Frigatebird, chick.jpg
Chick, Genovesa Island, Ecuador

Frigatebirds have long narrow pointed wings and a long narrow deeply forked tail. They have the highest ratio of wing area to body mass and the lowest wing loading of any bird. This has been hypothesized to enable the birds to use marine thermals created by small differences between tropical air and water temperatures. The plumage of males is black with scapular feathers that have a green iridescence when they refract sunlight. Females are black with a white throat and breast and have a red eye ring. Juveniles are black with a rust-tinged white face, head, and throat.

Distribution and habitat

The great frigatebird has a wide distribution throughout the world's tropical seas. Hawaii is the northernmost extent of their range in the Pacific Ocean, with around 10,000 pairs nesting mostly in the Northwestern Hawaiian Islands. In the Central and South Pacific, colonies are found on most island groups from Wake Island to the Galápagos to New Caledonia with a few pairs nesting on Australian possessions in the Coral Sea. Colonies are also found on numerous Indian Ocean islands, the most well-known include the Seychelles islands of Aldabra and Aride, Christmas Island, the Maldives and Mauritius. The Atlantic population is very small, restricted to Ascension Island, St. Helena, and the Brazilian islands of Trindade and Martin Vaz.

Great frigatebirds undertake regular migrations across their range, both regular trips and more infrequent widespread dispersals. Birds marked with wing tags on Tern Island in the French Frigate Shoals were found to regularly travel to Johnston Atoll (873 km), one was reported in Quezon City in the Philippines. [13] One male great frigatebird relocated from Europa Island in the Mozambique Channel to the Maldives 4400 km away for four months, where it fed on rich fishing grounds. [14] Despite their extended range, birds also exhibit philopatry, breeding in their natal colony even if they travel to other colonies. [15]

Behaviour

Feeding

An immature great frigatebird performing a surface snatch on a sooty tern chick dropped by another bird Frigatebird snatch.JPG
An immature great frigatebird performing a surface snatch on a sooty tern chick dropped by another bird

The great frigatebird forages in pelagic waters within 80 km (50 mi) of the breeding colony or roosting areas. Flying fish from the family Exocoetidae are the most common item in the diet of the great frigatebird; other fish species and squid may be eaten as well. Prey is snatched while in flight, either from just below the surface or from the air in the case of flying fish flushed from the water. Great frigatebirds will make use of schools of predatory tuna or pods of dolphins that push schooling fish to the surface. [16] Like all frigatebirds they will not alight on the water surface and are usually incapable of taking off should they accidentally do so. They are often seen foraging in large, mixed-species flocks, especially flocking with sooty terns and wedge-tailed shearwaters. [17]

Great frigatebirds will also hunt seabird chicks at their breeding colonies, taking mostly the chicks of sooty terns, spectacled terns, brown noddies, black noddies and even from other great frigatebirds. [17] Studies show that only females (adults and juveniles) hunt in this fashion, and only a few individuals account for most of the kills. [18] Great frigatebirds will also feed opportunistically in coastal areas on turtle hatchlings and fish scraps from commercial fishing operations. [17]

Great frigatebirds will attempt kleptoparasitism, chasing other nesting seabirds (boobies, tropicbirds and gadfly petrels [17] in particular) in order to make them regurgitate their food. This behaviour is not thought to play a significant part of the diet of the species, and is instead a supplement to food obtained by hunting. A study of great frigatebirds stealing from masked boobies estimated that the frigatebirds could at most obtain 40% of the food they needed, and on average obtained only 5%. [19]

Breeding

Male collecting twigs for the nest Male greater frigate bird building nest.jpg
Male collecting twigs for the nest
Breeding pair Greater frigatebird breeding pair.jpg
Breeding pair
Chick begging from female parent Great Frigatebird chick begging.JPG
Chick begging from female parent
Fregata minor - MHNT Fregata minor MHNT.ZOO.2010.11.2.17.jpg
Fregata minor - MHNT

Great frigatebirds are seasonally monogamous, with a breeding season that can take two years from mating to the end of parental care. The species is colonial, nesting in bushes and trees (and on the ground in the absence of vegetation) in colonies of up to several thousand pairs. Nesting bushes are often shared with other species, especially red-footed boobies and other species of frigatebirds.

Both sexes have a patch of skin at the throat that is the gular sac; in male great frigatebirds this skin is red and can be inflated to attract a mate. Groups of males sit in bushes and trees and force air into their sac, causing it to inflate over a period of 20 minutes into a startling red balloon. As females fly overhead the males waggle their heads from side to side, shake their wings and call. Females will observe many groups of males before forming a pair bond. Having formed a bond the pair will sometimes select the display site, or may seek another site, to form a nesting site; once a nesting site has been established both sexes will defend their territory (the area surrounding the nest that can be reached from the nest) from other frigatebirds.

Pair bond formation and nest-building can be completed in a couple of days by some pairs and can take a couple of weeks (up to four) for other pairs. Males collect loose nesting material (twigs, vines, flotsam) from around the colony and off the ocean surface and return to the nesting site where the female builds the nest. Nesting material may be stolen from other seabird species (in the case of black noddies the entire nest may be stolen) either snatched off the nesting site or stolen from other birds themselves foraging for nesting material. Great frigatebird nests are large platforms of loosely woven twigs that quickly become encrusted with guano. There is little attempt to maintain the nests during the breeding season and nests may disintegrate before the end of the season.

A single dull chalky-white egg measuring 68 mm × 48 mm (2.7 in × 1.9 in) is laid during each breeding season. [20] If the egg is lost the pair bond breaks; females may acquire a new mate and lay again in that year. Both parents incubate the egg in shifts that last between 3–6 days; the length of shift varies by location, although female shifts are longer than those of males. Incubation can be energetically demanding, birds have been recorded losing between 20 and 33% of their body mass during a shift.

Incubation lasts for around 55 days. Great frigatebird chicks begin calling a few days before hatching and rub their egg tooth against the shell. The altricial chicks are naked and helpless, and lie prone for several days after hatching. Chicks are brooded for two weeks after hatching after which they are covered in white down, and guarded by a parent for another fortnight after that. Chicks are given numerous meals a day after hatching, once older they are fed every one to two days. Feeding is by regurgitation, the chick sticks its head inside the adults mouth.

Parental care is prolonged in great frigatebirds. Fledging occurs after four to six months, the timing dependent on oceanic conditions and food availability. [10] After fledging chicks continue to receive parental care for between 150 and 428 days; frigatebirds have the longest period of post-fledging parental care of any bird. The length of this care depends on oceanic conditions, in bad years (particularly El Niño years) the period of care is longer. The diet of these juvenile birds is provided in part by food they obtained for themselves and in part from their parents. Young fledglings will also engage in play; with one bird picking up a stick and being chased by one or more other fledglings. After the chick drops the stick the chaser attempts to catch the stick before it hits the water, after which the game starts again. This play is thought to be important in developing the aerial skills needed to fish.

Great frigatebirds take many years to reach sexual maturity and only breed once they have acquired the full adult plumage. This is attained by female birds when they are eight to nine years of age and for male birds when they are 10 to 11 years of age. [21] The average lifespan is unknown but is assumed to be relatively long. As part of a study conducted in 2002 on Tern Island in Hawaii, 35 ringed great frigatebirds were recaptured. Of these 10 were 37 years or older and one was at least 44 years old. [22]

Status

Because of the large overall total population and extended range the species is classified by the International Union for Conservation of Nature as being of Least Concern. [1]

In the South Atlantic, great frigatebirds (subspecies F. m. nicolli) once bred on both Saint Helena and Trindade. The Saint Helena population disappeared in ancient times and is only known from subfossil remains, estimated to be a few hundred years old. [23] The Trindade archipelago is part of a Brazilian military area and the human population consists only of a few Brazilian Navy personnel, limiting easy access for ornithologists. Once abundant, it has disappeared as a breeding bird from the main island of Trindade, [24] but small numbers remain elsewhere in this archipelago. [23] [25] [26] The main island was once covered in forest but after this was destroyed, overgrazing by the introduced goats prevented any recovery. A series of eradication programs in the second half of the 20th century eliminated all the introduced vertebrates other than house mice. Feral cats that had seriously depleted ground nesting birds were finally eradicated in 1998. [24] In Brazil, the only country where F. m. nicolli survives, the great frigatebird is considered critically endangered. [26]

Related Research Articles

<span class="mw-page-title-main">Seabird</span> Birds that have adapted to life within the marine environment

Seabirds 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 environmental problems and feeding niches have resulted in similar adaptations. The first seabirds evolved in the Cretaceous period, and modern seabird families emerged in the Paleogene.

<span class="mw-page-title-main">Frigatebird</span> Family of seabirds (Fregatidae)

Frigatebirds are a family of seabirds called Fregatidae which are found across all tropical and subtropical oceans. The five extant species are classified in a single genus, Fregata. All have predominantly black plumage, long, deeply forked tails and long hooked bills. Females have white underbellies and males have a distinctive red gular pouch, which they inflate during the breeding season to attract females. Their wings are long and pointed and can span up to 2.3 metres (7.5 ft), the largest wing area to body weight ratio of any bird.

<span class="mw-page-title-main">Ascension frigatebird</span> Species of bird

The Ascension frigatebird is a seabird of the frigatebird family Fregatidae which breeds on Boatswain Bird Island and Ascension Island in the tropical Atlantic Ocean.

<span class="mw-page-title-main">Christmas frigatebird</span> Species of bird

The Christmas frigatebird, or Christmas Island frigatebird, is a seabird of the frigatebird family Fregatidae which is an endemic breeder to Christmas Island in the Indian Ocean.

<span class="mw-page-title-main">Red-billed tropicbird</span> Species of seabird of tropical oceans

The red-billed tropicbird is a tropicbird, one of three closely related species of seabird of tropical oceans. Superficially resembling a tern in appearance, it has mostly white plumage with some black markings on the wings and back, a black mask and, as its common name suggests, a red bill. Most adults have tail streamers that are about two times their body length, with those in males being generally longer than those in females. The red-billed tropicbird itself has three subspecies recognized, including the nominate. The subspecies mesonauta is distinguished from the nominate by the rosy tinge of its fresh plumage, and the subspecies indicus can be differentiated by its smaller size, more restricted mask, and more orange bill. This species ranges across the tropical Atlantic, eastern Pacific, and Indian Oceans. The nominate is found in the southern Atlantic Ocean, the subspecies indicus in the waters off of the Middle East and in the Indian Ocean, and the subspecies mesonauta in the eastern portions of both the Atlantic and the Pacific Oceans and in the Caribbean. It was one of the many species described by Carl Linnaeus in his 1758 10th edition of Systema Naturae.

<span class="mw-page-title-main">Sooty tern</span> Species of bird

The sooty tern is a seabird in the family Laridae. It is a bird of the tropical oceans, returning to land only to breed on islands throughout the equatorial zone.

<span class="mw-page-title-main">White tern</span> Species of bird

The white tern or common white tern 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 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, previously considered a subspecies of the white tern, is now recognised as a separate species.

<span class="mw-page-title-main">Masked booby</span> Species of bird

The masked booby, also called the masked gannet or the blue-faced booby, is a large seabird of the booby and gannet family, Sulidae. First described by the French naturalist René-Primevère Lesson in 1831, the masked booby is one of six species of booby in the genus Sula. It has a typical sulid body shape, with a long pointed yellowish bill, long neck, aerodynamic body, long slender wings and pointed tail. The adult is bright white with black wings, a black tail and a dark face mask; at 75–85 cm (30–33 in) long, it is the largest species of booby. The sexes have similar plumage. This species ranges across tropical oceans, except in the eastern Atlantic and eastern Pacific. In the latter, it is replaced by the Nazca booby, which was formerly regarded as a subspecies of masked booby.

<span class="mw-page-title-main">Galápagos petrel</span> Species of bird

The Galápagos petrel is one of the six endemic seabirds of the Galápagos. Its scientific name derives from Ancient Greek: Pterodroma originates from pteron and dromos, meaning "wing" and "runner", and phaeopygia comes from phaios and pugios, meaning "dusky" and "rump". Members of Pterodroma genus are also called the gadfly petrels because their erratic twisting and turning in flight resemble that of gadflies.

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<span class="mw-page-title-main">Lesser frigatebird</span> Species of bird

The lesser frigatebird is a seabird of the frigatebird family Fregatidae. At around 75 cm (30 in) in length, it is the smallest species of frigatebird. It occurs over tropical and subtropical waters across the Indian and Pacific Oceans as well as off the Atlantic coast of Brazil.

<span class="mw-page-title-main">Brown noddy</span> Species of bird

The brown noddy or common noddy is a seabird in the family Laridae. The largest of the noddies, it can be told from the closely related black noddy by its larger size and plumage, which is dark brown rather than black. The brown noddy is a tropical seabird with a worldwide distribution, ranging from Hawaii to the Tuamotu Archipelago and Australia in the Pacific Ocean, from the Red Sea to the Seychelles and Australia in the Indian Ocean and in the Caribbean to Tristan da Cunha in the Atlantic Ocean. The brown noddy is colonial, usually nesting on elevated situations on cliffs or in short trees or shrubs. It only occasionally nests on the ground. A single egg is laid by the female of a pair each breeding season. In India, the brown noddy is protected in the PM Sayeed Marine Birds Conservation Reserve.

<span class="mw-page-title-main">Antarctic tern</span> Species of bird

The Antarctic tern is a seabird in the family Laridae. It ranges throughout the southern oceans and is found on small islands around Antarctica as well as on the shores of the mainland. Its diet consists primarily of small fish and crustaceans. It is very similar in appearance to the closely related Arctic tern, but it is stockier, and it is in its breeding plumage in the southern summer, when the Arctic tern has shed old feathers to get its non-breeding plumage. The Antarctic tern does not migrate like the Arctic tern does, but it can still be found on a very large range. This tern species is actually more closely related to the South American tern.

<span class="mw-page-title-main">Bird colony</span> Large congregation of birds at a particular location

A bird colony is a large congregation of individuals of one or more species of bird that nest or roost in proximity at a particular location. Many kinds of birds are known to congregate in groups of varying size; a congregation of nesting birds is called a breeding colony. Colonial nesting birds include seabirds such as auks and albatrosses; wetland species such as herons; and a few passerines such as weaverbirds, certain blackbirds, and some swallows. A group of birds congregating for rest is called a communal roost. Evidence of colonial nesting has been found in non-neornithine birds (Enantiornithes), in sediments from the Late Cretaceous (Maastrichtian) of Romania.

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References

  1. 1 2 BirdLife International (2020). "Fregata minor". IUCN Red List of Threatened Species . 2020: e.T22697733A163770613. doi: 10.2305/IUCN.UK.2020-3.RLTS.T22697733A163770613.en . Retrieved 12 November 2021.
  2. 1 2 3 Gmelin, Johann Friedrich (1789). Systema naturae per regna tria naturae : secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis (in Latin). Vol. 1, Part 2 (13th ed.). Lipsiae [Leipzig]: Georg. Emanuel. Beer. p. 572.
  3. ↑ Latham, John (1785). A General Synopsis of Birds. Vol. 3, Part 2. London: Printed for Leigh and Sotheby. pp. 590–591.
  4. ↑ Mayr, Ernst; Cottrell, G. William, eds. (1979). Check-List of Birds of the World. Vol. 1 (2nd ed.). Cambridge, Massachusetts: Museum of Comparative Zoology. p. 161.
  5. ↑ Edwards, George (1760). Gleanings of Natural History, Exhibiting Figures of Quadrupeds, Birds, Insects, Plants &c. Vol. 2. London: Printed for the author. Plate 309.
  6. ↑ Kennedy, Martyn; Spencer, Hamish G (2004). "Phylogenies of the frigatebirds (Fregatidae) and tropicbirds (Phaethonidae), two divergent groups of the traditional order Pelecaniformes, inferred from mitochondrial DNA sequences". Molecular Phylogenetics and Evolution. 31 (1): 31–38. doi:10.1016/j.ympev.2003.07.007. PMID   15019606.
  7. 1 2 Gill, Frank; Donsker, David; Rasmussen, Pamela, eds. (August 2022). "Storks, frigatebirds, boobies, darters, cormorants". IOC World Bird List Version 12.2. International Ornithologists' Union. Retrieved 19 November 2022.
  8. 1 2 3 4 Mathews, GM (1914). "On the species and subspecies of the genus Fregata". Australian Avian Record. 2 (6): 120 (117–121).
  9. ↑ James, Helen F. (1987). "A late Pleistocene avifauna from the island of Oahu, Hawaiian Islands" (PDF). Documents des laboratories de Géologie, Lyon. 99: 221–30.
  10. 1 2 Metz, VG; Schreiber, EA (2002). "Great Frigatebird (Fregata minor)". In Poole, A; Gill, F (eds.). The Birds of North America. Vol. 681. Philadelphia PA: The Birds of North America.
  11. ↑ Schreiber, E; Schreiber, R (1988). "Great Frigatebird size dimorphism on two central Pacific atolls". Condor. 90 (1): 90–99. doi:10.2307/1368437. JSTOR   1368437.
  12. ↑ Orta, J; Kirwan, GM; Garcia, EFJ; Boesman, P (2020). "Great Frigatebird (Fregata minor)". In del Hoyo, J; Elliott, A; Sargatal, J; Christie, DA; de Juana, E (eds.). Handbook of the Birds of the World Alive. Lynx Edicions. doi:10.2173/bow.grefri.01. S2CID   216406285 . Retrieved 30 November 2014.(subscription required)
  13. ↑ Dearborn, D; Anders, A; Schreiber, E; Adams, R; Muellers, U (2003). "Inter island movements and population differentiation in a pelagic seabird". Molecular Ecology. 12 (10): 2835–2843. doi:10.1046/j.1365-294X.2003.01931.x. PMID   12969485. S2CID   18679093.
  14. ↑ Weimerskirch, Henri; Le Corre, Matthieu; Marsac, Francis; Barbraud, Christophe; Tostain, Olivier; Chastel, Olivier (2006). "Postbreeding Movements of Frigatebirds Tracked with Satellite Telemetry". The Condor. 108 (1): 220–25. doi: 10.1650/0010-5422(2006)108[0220:PMOFTW]2.0.CO;2 .
  15. ↑ Harrison C. (1990). Seabirds of Hawaii: natural history and conservation. Cornell Univ. Press, Ithaca, NY. ISBN   0-8014-2449-6
  16. ↑ Au, DWK; Pitman, RL (1986). "Seabird interactions with dolphins and tuna in the Eastern Tropical Pacific" (PDF). Condor. 88 (3): 304–317. doi:10.2307/1368877. JSTOR   1368877.
  17. 1 2 3 4 "Fregata minor (Great frigatebird)".
  18. ↑ Megyesi, JL; Griffin, CR (1996). "Brown Noddy chick predation by Great Frigatebirds in the northwestern Hawaiian islands". Condor. 98 (2): 322–327. doi: 10.2307/1369150 . JSTOR   1369150.
  19. ↑ Vickery, J; Brooke, M (1994). "The kleptoparasitic interactions between Great Frigatebirds and Masked Boobies on Henderson Island, South Pacific". Condor. 96 (2): 331–340. doi:10.2307/1369318. JSTOR   1369318.
  20. ↑ Beruldsen, Gordon (2003). Australian Birds: Their Nests and Eggs. Kenmore Hills, Qld: self. pp. 186–87. ISBN   0-646-42798-9.
  21. ↑ Valle, Arlos A; de Vries, Tjitte; Hernández, Cecilia (2006). "Plumage and sexual maturation in the Great frigatebird Fregata minor in the Galapagos Islands" (PDF). Marine Ornithology. 34: 51–59.
  22. ↑ Juola, Frans A; Haussmann, Mark F; Dearborn, Donald C; Vleck, Carol M (2006). "Telomere shortening in a long-lived marine bird: cross-sectional analysis and test of an aging tool". Auk. 123 (3): 775–783. doi: 10.1642/0004-8038(2006)123[775:TSIALM]2.0.CO;2 .
  23. 1 2 Olson, Storrs L. (2017). "Species rank for the critically endangered Atlantic Lesser Frigatebird (Fregata trinitatis)". Wilson Journal of Ornithology. 129 (4): 661–674. doi:10.1676/1559-4491-129.4.661. S2CID   91072996.
  24. 1 2 Alves, RJV; da Silva, NG; Aguirre-Muñoz, A (2011). "Return of endemic plant populations on Trindade Island, Brazil, with comments on the fauna" (PDF). In Veitch, CR; Clout, MN; Towns, DR (eds.). Island invasives: eradication and management : proceedings of the International Conference on Island Invasives. Gland, Switzerland: IUCN. pp. 259–263. OCLC   770307954.
  25. ↑ Olson, Storrs L. (1981). "Natural history of vertebrates on the Brazilian islands of the mid South Atlantic". National Geography Society Research Reports. 13: 481–492. hdl:10088/12766.
  26. 1 2 Efe, Márcio Amorim (2008). "Fregata minor (Gmelin, 1789)" (PDF). Livro vermelho da fauna brasileira ameaçada de extinção Volume 2 (in Portuguese). Brasília: Ministério do Meio Ambiente. pp. 412–413. ISBN   978-85-7738-102-9.

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