Great frigatebird

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Great frigatebird
Adult male, displaying, with inflated gular sac

Least Concern  (IUCN 3.1)[1]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Suliformes
Family: Fregatidae
Genus: Fregata
Species:
F. minor
Binomial name
Fregata minor
(Gmelin, 1789)
Range map
Synonyms

Pelecanus minor Gmelin 1789
Tachypetes palmerstoni

The great frigatebird (Fregata minor) is a large

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

breeding colony
or roosting areas.

Taxonomy

The great frigatebird was

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

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

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.

Trindade and Martin Vaz
.

Great frigatebirds undertake regular

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

The great frigatebird forages in

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
Breeding pair
begging
from female parent
MHNT

Great frigatebirds are seasonally

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.

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.

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

Least Concern.[1]

In the South Atlantic, great frigatebirds (subspecies F. m. nicolli) once bred on both

critically endangered.[26]

Gallery

  • Male in flight, Galápagos Islands
    Male in flight, Galápagos Islands
  • Juvenile male in flight
    Juvenile male in flight
  • Female in flight
    Female in flight
  • Another female in flight
    Another female in flight
  • Male, Galápagos Islands
    Male, Galápagos Islands
  • Female, Galápagos Islands
    Female, Galápagos Islands

References

  1. ^
    doi:10.2305/IUCN.UK.2020-3.RLTS.T22697733A163770613.en
    . Retrieved 12 November 2021.
  2. ^ a b c 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. PMID 15019606
    .
  7. ^
    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. ^ a b c d 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. ^ a b 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. JSTOR 1368437
    .
  12. S2CID 216406285
    . Retrieved 30 November 2014.(subscription required)
  13. S2CID 18679093
    .
  14. doi:10.1650/0010-5422(2006)108[0220:PMOFTW]2.0.CO;2
    .
  15. ISBN 0-8014-2449-6
  16. JSTOR 1368877
    .
  17. ^ a b c d "Fregata minor (Great frigatebird)".
  18. JSTOR 1369150
    .
  19. JSTOR 1369318
    .
  20. 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. doi:10.1642/0004-8038(2006)123[775:TSIALM]2.0.CO;2
    .
  23. ^
    S2CID 91072996
    .
  24. ^
    OCLC 770307954. Archived from the original
    (PDF) on 2016-03-05. Retrieved 2014-12-11.
  25. hdl:10088/12766
    .
  26. ^
    ISBN 978-85-7738-102-9. Archived from the original
    (PDF) on 2014-12-11. Retrieved 2014-12-11.

Further reading

External links

Wikispecies has information related to Fregata minor.
Wikimedia Commons has media related to Fregata minor.
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