Frigatebirds
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There are five species in the family Fregatidae, the frigatebirds. They are very closely related, and are all in the single genus Fregata. Frigatebirds attack other sea birds, hence the name. They are also sometimes called Man of War birds or Pirate birds. Since they are related to the pelicans, the term "frigate pelican" is also a name applied to them.
Description:
Frigatebirds are large, with iridescent black feathers (the females have a white underbelly), with long wings (male wingspan can reach 2.3 metres) and deeply-forked tails. The males have inflatable red-coloured throat pouches, which they inflate to attract females during the mating season.
As members of pelecaniformes, frigatebirds have the key characteristics of all four toes being connected by the web, a gular sac (also called gular skin), and a furcula that is fused to the breastbone. Although there is definitely a web on the frigatebird foot, the webbing is reduced and part of each toe is free. Frigatebirds produce very little oil and therefore do not land in the ocean. The gular sac is used as part of a courtship display and is, perhaps, the most striking frigatebird feature.
Frigatebirds are found over tropical oceans and ride warm updrafts. Therefore, they can often be spotted riding weather fronts and can signal changing weather patterns.
These birds do not swim and cannot walk well, and cannot take off from a flat surface. Having the largest wingspan to body weight ratio of any bird, they are essentially aerial, able to stay aloft for more than a week, landing only to roost or breed on trees or cliffs.
Breeding / Nesting:
They lay one or two white eggs. Both parents take turns feeding for the first three months but then only by the mother for another eight months. It takes so long to rear a chick that frigatebirds cannot breed every year. It is typical to see juveniles as big as their parents waiting to be fed. When they sit waiting for endless hours in the hot sun, they assume an energy-efficient posture in which their head hangs down, and they sit so still that they seem dead. But when the parent returns, they will wake up, bob their head, and scream until the parent opens its mouth. The starving juvenile plunges its head down the parent's throat and feeds at last.
Feeding:
Their feeding habits are pelagic. Frigatebirds often rob other seabirds of their catch, using their speed and manoeuvrability to outrun their victims. However, they are perfectly capable of catching fish, baby turtles and similar prey, snatching them up from flight.
Distribution and identifying characteristics differ among frigatebird species, and thus are addressed in species-specific articles.
Species
- Genus Fregata
- Magnificent Frigatebird or Man O'War, Fregata magnificens.
- Ascension Frigatebird, Fregata aquila: Breeds only on the tiny Boatswainbird Island near Ascension Island in the tropical Atlantic Ocean. It formerly bred on the larger island, but was exterminated by introduced cats, Brown Rats, and human persecution. It breeds on the rocky slopes of Boatswainbird. There may be of the order of 10,000 birds. As with other frigatebirds its movements when not breeding are little known because of identification problems within this difficult group, but it occurs off west Africa. A frigatebird found moribund in 1953 in Tiree, Scotland was identified at the time as Magnificent Frigatebird but was re-examined in 2002 and found to be an Ascension Frigatebird. It feeds on fish and similar surface prey such as small turtles.
- Christmas Island Frigatebird, Fregata andrewsi. : Endemic to the Christmas Islands in the Indian Ocean. Like other frigatebirds, this species does not walk or swim, but is a very aerial bird which obtains its food by picking up live prey items from beaches or the water surface, and the aerial piracy of other birds. It is estimated that the population of this species will decline by 80 percent in the next 30 years due to predation of the young by the introduced yellow crazy ants species (Anoplolepis gracilipes), which have devastated the wildlife of the island, and have also killed 10–20 million Christmas Island red crabs. The adult male of this species is easily identified, since it is all black except for a white belly patch. Other plumages resemble those of the smaller Lesser Frigatebird, but have whiter bellies and longer white underwing spurs.
- Great Frigatebird, Fregata minor.
- Lesser Frigatebird, Fregata ariel.
References / Sources: USGS ... Wikipedia.org
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