This large (90-100cm) frigatebird has a deeply forked tail, long narrow wings and a large coral pink (adult female) or moderate dark grey (male) bill. The male is mostly black, with a white belly, and a large inflatable red throat sac. The female has a white belly and breast, with the white extending to the shoulders. It is larger than both the Great Frigatebird F. minor (86-93 cm) and Lesser Frigatebird F. ariel (76 cm), both of which have females with a greyish bill (although the Lesser can have a coral pink bill) and males with either no black (Great) or small white spurs at the junction of the wings and flanks (Lesser). Younger birds have a orange head and neck, and can be very difficult to distinguish from other species, although the white belly patch is hexagonal, as opposed to oval (Great) or with long spurs (Lesser).