The purplish black magnificent frigate-bird, Fregata magnificens, 40 in. (100 cm) long, is found from the Bahamas and Baja California S to Brazil and Ecuador; the great frigate-bird, F. minor, is found in the Indian Ocean. Other species, e.g., the Ascension and Christmas Island frigate-birds, are named for their habitats. The lesser frigate-bird, the smallest (32 in./80 cm) of the family, is found in the South Pacific and on the islands off Brazil and Madagascar.

Frigate-birds are classified in the phylum Chordata, subphylum Vertebrata, class Aves, order Pelecaniformes, family Fregatidae.