Great frigate bird
| Great frigate bird | ||||||||||
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Brooding frigate bird ( Fregata minor ), male with inflated throat pouch |
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| Scientific name | ||||||||||
| Fregata minor | ||||||||||
| ( JF Gmelin , 1789) |
The banded frigate bird ( Fregata minor ) is a large bird from the family of the frigate birds (Fregatidae). They are very large, black or black and white seabirds that are larger than most other seabirds found in tropical waters. Only the rare white-bellied frigate bird is bigger.
The IUCN classifies the white frigate bird as not endangered ( least concern ).
Appearance
The banded frigatebird reaches a body length of 86 to 100 cm and a wingspan of up to 229 cm. Banded frigate birds weigh between one and two kilograms. There is a sexual dimorphism so that the sexes can also be differentiated when observing the field.
The adult male is predominantly black with a greenish tinge on the upper side and has a brown band across the middle elytra. On the underside, the plumage is brownish-black. The bright red throat pouch that it wears under its long, slender beak is striking. This throat pouch is something extraordinary: 85 percent of its color comes from the pigment astaxanthin , a carotenoid that is nowhere else in the bird world in such high concentration.
The upper side of the female is similarly colored. It also has a brown neck ring on the back of the neck. On the throat and fore neck, the plumage is greyish and the lower neck, chest and sides are white.
The banded frigate bird can only be confused with the rare white-bellied frigate bird and the ariel frigate bird . The ariel frigate bird is lighter in all plumage than the banded frigate bird, it is also smaller. The white-bellied frigate bird is slightly larger than the banded frigate bird, it differs from it by the white spot on the belly. The banded frigate bird, however, is completely black on the underside of the body.
Distribution area
Great frigate birds are widespread in the tropical Pacific . They are usually found in places where the surface temperature of the water is more than 22 degrees Celsius. Banded frigate birds are found on the Galápagos Islands and breed in the South Atlantic on Trindade and Martim Vaz . They are regularly observed on the north coast of Australia, in New Zealand and the south coast of Australia stray visitors occasionally occur. They are revered as national animals in the island republic of Nauru .
In general, they use islands in the tropical Pacific as breeding grounds, which are made up of trees and bushes.
nutrition
The banded frigate mainly eats flying fish and cephalopods. He catches his food during the flight. Flying fish are caught in flight, as are squids of the Ommastrephidae family, also known as "flying squids". Otherwise, Northern Frigatebirds look for fish or cephalopods that swim so close to the surface that the Northern Frigate Bird does not have to dive in with more than its beak or head to catch them. Only very rarely does he touch the water with his body or even dive into it. Even on windless days, it is able to take off from the water surface and continue its flight. Banded frigate birds are also brood predators. Eggs and young birds are also mainly captured from the air.
Banded frigate birds are presumably dependent on the following of predatory fish and schools of dolphins in their hunting . Many fish try to escape these predators by either swimming to the surface of the water or by making long leaps above the surface of the water. Banded frigate birds are also kleptoparasites that steal food especially from gannets . However, they only acquire a small part of their diet from this behavior. Kleptoparasitism only plays a major role in times when food is generally rare. As a rule, they look for food individually, but where food is available in large quantities, several great frigate birds can congregate. Often other seabirds such as the masked booby , wedge-tailed petrel , red-footed booby and black tern can also be observed there.
Reproduction
Banded frigate birds are monogamous breeding birds that mate anew in each reproductive period. They probably breed for the first time when they are four to five years old. Both parent birds are involved in rearing the young birds. The brood care lasts a very long time. Fledglings are provided with food by their parent birds between six and fourteen months after they have fled. A breeding pair that has successfully raised a young bird does not breed again until the second year.
Banded frigate birds are colony breeders. Breeding colonies can range from two to 3000 nests. In large breeding colonies, sub-colonies of around 20 nests each develop. The nests are between 60 centimeters and 1.4 meters apart. After the pair bond, a partner bird always remains on the nest.
The breeding season varies depending on the geographic distribution of the frigate birds. Banded frigate birds begin courtship on Christmas Island from the end of January. The eggs are laid between March and June. The nest is built on bushes and trees, often directly in the flat crown. Banded frigate birds very rarely build their nests directly on the ground. The nest is built from twigs, twigs and leaves. Most of the nesting material is collected by the male and used by the female. Occasionally the males steal nesting material from boobies or other frigate birds. Nest building begins with courtship and is erected within ten days, and tied frigate birds carry out repairs until the young birds fly out. The clutch consists of only one egg. The newly hatched chick is hovered by both parent birds for the first two weeks and guarded by one of the parent birds for another two weeks. The parent birds break away in an interval of one to two days. Young birds are initially fed three to four times a day after hatching. When they have grown somewhat, they are fed only once a day or even every other day. Both parent birds are equally involved in the care of the young bird. The nestling time varies depending on the location. On Aldabra , the average nestling time is 169 days.
The reproductive success varies depending on the location. On the Galápagos Islands, only 39 frigate birds fledged from 206 eggs. On Aldabra, however, the breeding success was significantly higher at 51 percent. Here, 57 young birds fledged from 111 eggs. On the Galapagos Islands, the high intra-species nesting site competition is causing numerous nesting losses. Rushes also successfully hunt young birds here.
Danger
On Christmas Island , 48 hectares of forest were cleared, which previously served as a breeding ground for this species. The other breeding sites on this island, which is politically part of Australia, are protected. Causes of death on Christmas Island include deaths from power lines and entanglement in tow lines used in fishing. Breeding birds are generally very sensitive to interference from humans.
Banded frigate birds were or still are part of the diet of the indigenous population on some of their breeding islands. The islands on which this was or is the case include Christmas Island, Mauritius and the Cocos Keeling Islands .
literature
- PJ Higgins (Ed.): Handbook of Australian, New Zealand & Antarctic Birds. Volume 1, Ratites to Ducks, Oxford University Press, Oxford 1990, ISBN 0-19-553068-3
Web links
- Fregata minor in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed on December 18 of 2008.
- Videos, photos and sound recordings of Fregata minor in the Internet Bird Collection
Individual evidence
- ↑ FA Juola, K. McGraw, DC Dearborn: Carotenoids and throat pouch coloration in the great frigatebird (Fregata minor). Comparative biochemistry and physiology. Part B, Biochemistry & Molecular Biology; Vol. 149 (2); Pp. 370-377, 2008
- ^ Higgins, p. 914
- ^ Higgins, p. 914
- ^ Higgins, p. 915
- ^ Higgins, p. 916
- ^ Higgins, p. 918
- ^ Higgins, p. 918
- ^ Higgins, p. 918
- ^ Higgins, p. 914
- ^ Higgins, p. 914