Distribution

Breeding Range

Figure 1 . In the e. Pacific, from Isla Santa Margarita off sw. Baja California, Mexico (20,000 pairs; Moreno and Carmona 1988); on Isla San Benedicto and possibly Isla Socorro in the Revillagigedos Is., in mangroves along the coast of Sinaloa, Mexico, at Bahia del Pabellon (10,000–20,000 pairs) and Bahia Santa Maria (18,000 pairs; Everett and Anderson 1991); small numbers of breeding attempts at San Luis I., Cholluda I., and Alcatraz I. in n. Gulf of Mexico (Everett and Anderson 1991); on Tres Marias Is. off Nayarit; Pearl Is. off w. Panama, south to Gulf of Guayaquil and coast of mainland Ecuador (Murphy 1936) and west to the Galápagos Is. (Am. Ornithol. Union 1998).

In the Atlantic, breeds in extreme s. Florida on Dry Tortugas (only current U.S. breeding site; Stevenson and Anderson 1994); islands off coasts of Yucatán Peninsula (Cayos Arcas at Alacran Reef and possibly others), Belize, Honduras, and Panama; the Bahamas, Cuba, Jamaica, Cayman Is. (Little Cayman I., 300–500 pairs; EAS), Navassa I. east of Haiti, Hispaniola, islands off the coast of Puerto Rico, the Virgin Is., Barbuda, Guadeloupe, and the Grenadines; Bonaire, Little Tobago, Curaçao, and other islands off the coasts of Venezuela, Colombia, and French Guiana.

There is a gap in breeding distribution along the north coast of Brazil east to Sela Gineda I. in the Fernando de Noronha archipelago (300 pairs; Oren 1984). No colonies are known between there and s. Bahia State, where 300 pairs breed on Redonda I. in the Abrolhos archipelago (Coelho 1981) and Santa Barbara I. (60 pairs; Antas 1991). In Redonda State there are colonies off Macaé, on Cabo Frio I. (Sick 1993), and on the Cagarras/Redonda Is. (2,000 nests; Antas 1991); off Sáo Paulo State there is a colony at Alcatraz I., off Santos (Sick 1993). Between these and the southernmost colony, Moleques do Sul I. (150 nests; Bege and Pauli 1988), 700 pairs breed on Currais I., Parana State (Scherer Neto 1986).

Nonbreeding Range

In Pacific, north exceptionally to Alaska, regularly to central California, south to n. Peru; through Gulf of California inland to Salton Sea, CA, and s. Arizona; throughout Gulf of Mexico and Caribbean to Bermuda (rarely), and along Atlantic Coast from N. Carolina (exceptionally to Newfoundland) south to n. Argentina; also in e. Atlantic around Cape Verde Is. (Am. Ornithol. Union 1998). Roosts coastally in Florida from Cedar Key and Cape Kennedy south. During severe storms, small flocks may be driven inland (Fellers 1988). Seen more commonly along Gulf Coast from Apr through Aug (Harrington et al. 1972). Often seen outside of range during storms and in El Niño events. Said to ride on front of storms, which results in their being taken off course (del Hoyo et al. 1992). Occasionally may follow large river inland. Pattern of occurrences in w. North America analyzed by Mlodinow (1998) as follows: individuals from Gulf of Mexico occur regularly on Texas coast Apr–Oct, as vagrants as far west as New Mexico, mainly mid-Aug to late Oct; individuals from e. Pacific and Gulf of California, Mexico, stray regularly to coastal-central California and occasionally into Arizona, from Jun to Sep but especially Jul to early Aug. Accidental in many states (Alaska, Colorado, Minnesota, Wisconsin) and Canadian provinces (Ontario, Quebec, Newfoundland; Am. Ornithol. Union 1998).

In e. Atlantic, as far east as Cape Verde Is. (16°N, 24´ W; Hazevoet 1994); possibly also Bissagos Is. (Mayr and Cottrell 1979). Seen occasionally along w. African coast and west coast of Europe (Great Britain, Netherlands, Denmark; Mayr and Cottrell 1979).

Extirpated from several historic breeding sites in the Caribbean owing to human disturbance and development: 4 sites in Puerto Rico (J. Saliva pers. comm.), 2 islands in U.S. Virgin Is. (EAS), Anegada in British Virgin Is. (EAS), Sombrero I. off Anguilla I. (J. Pierce pers. comm.), and possibly in Grenadines, Guadeloupe, Haiti, Swan I. (Honduras), Navassa I. (van Halewyn and Norton 1984). Extirpated from Marquesas Key, FL, and coastal Texas (Aransas Co.; Am. Ornithol. Union 1998). Formerly widely distributed in Cape Verde Is.; by 1994 confined to 2 small islets with <10 pairs in total (Hazevoet 1994). Introduced mammalian predators and continuing human disturbance are causing further declines in populations (see Conservation and management, below).

Small frigatebird (Limnofregata azygosternon) from lower Eocene in Green River formation, Wyoming; bill shorter and less hooked, hind limbs less reduced, wing shorter than current Fregata; shares some characteristics with tropicbirds (Phaethon) and some with boobies (Sula) that Fregata does not (Olson 1977). Fossil frigatebird from St. Helena I., s. Atlantic Ocean, determined most likely to be Great, not Magnificent, by heavier bill and stouter humeri (Olson 1975).