Frigatebirds can soar for weeks and rarely wet their feathers
Frigatebirds—family Fregatidae, five living species in genus Fregata—patrol all tropical and subtropical oceans with black plumage, forked tails, and hooked bills. Males inflate a red gular pouch; females show white undersides. They may soar for weeks, hunting by day and roosting on trees or cliffs by night.
Their bones are so air-filled that the skeleton makes up only 5 percent of body weight, while flight muscles and feathers each account for about a quarter. Their preen glands make very little oil, so the plumage would soak through if they sat on the sea, and their long wings would make taking off again very hard. They therefore snatch prey from the surface without landing, as the English explorer William Dampier described when he called them Man-of-War birds, and they also rob other seabirds.
The name comes from French sailors’ la frégate, a fast warship; Eleazar Albin used Frigate Bird in 1738 alongside a picture of the red-pouched male. Columbus passed them near Cape Verde on 29 September 1492 and wrote down rabiforçado, forktail.
Linnaeus put them in Pelecanus in 1758 with pelicans, cormorants and gannets. In 1874 Alfred Henry Garrod’s muscle studies showed that group held divergent lineages, and molecular work later tied pelicans to herons and ibises instead, so in 2010 frigatebirds and their gannet-cormorant relatives became the order Suliformes. The family name Fregatidae was formally conserved in 1994.
For years only two species were recognised until Gregory Mathews described five in 1914, all still valid. The magnificent frigatebird reaches 114 centimetres and the lesser about 71. Eocene Limnofregata from freshwater deposits in the western United States had shorter, straighter bills and longer legs, and like modern frigatebirds had 15 neck vertebrae instead of the 17 of most relatives.
Source: Frigatebird
