The frigatebirds are a family, Fregatidae, of seabirds. There are five species in the single genus Fregata. 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. They have long wings, tails, and bills and the males have a red gular pouch that is inflated during the breeding season to attract a mate.
Frigatebirds are pelagic piscivores that obtain most of their food on the wing. A small amount of their diet is obtained by robbing other seabirds, a behaviour that has given the family its name, and by snatching seabird chicks. Frigatebirds are seasonally monogamous, and nest colonially. A rough nest is constructed in low trees or on the ground on remote islands. A single egg is laid each breeding season. The duration of parental care in frigatebirds is the longest of any bird.
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 called "gular pouches", which they inflate to attract females during the mating season.
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.