Magnificent Frigatebird

Fregata magnificens

(c) John Cassady
  • FREGATIDAE
  • Frigatebirds
  • Pelecaniformes
  • Fragata Magnífica
  • Frégate superbe
Introduction

In 1738, the English naturalist Eleazar Albin linked the Magnificent Frigatebird's common name to the frigate, a sleek ship often used for piracy. Soaring over coastal waters, this relative of pelicans and cormorants has a reputation for stealing food from other seabirds. The Magnificent Frigatebird's long, swallow-like tail enables it to make sharp turns, and its long, broad wings lift the bird with little effort. The Magnificent Frigatebird is most at home in the air. Its short legs cannot walk, and its feathers absorb water, so it rarely rests on the ocean.

Appearance Description
On average, this long, sleek, and powerful flyer measures 40 inches long with a 90-inch wingspan, and weighs 3.3 pounds. A deeply forked tail and a long, hooked bill make the bird appear even longer. Females can be as much as 23% larger than males. Magnificent Frigatebirds are most often observed in flight. Adult males are black with greenish shading over the back and a bright red throat sac that is usually deflated. Females are black overall with a whitish bar in the upper wings and a white vest across the chest. Young Magnificent Frigatebirds are also black, but with a white head, chest, and belly.
Range Map
Courtesy Kenn Kaufman
Range Distribution
In the United States, the Magnificent Frigatebird breeds only on the Dry Tortugas, off the tip of the Florida Keys. Breeding also occurs at many scattered sites throughout the Caribbean and south to coastal Brazil, and in the Pacific from Ecuador north to Baja California. The majority of Magnificent Frigatebirds nest on the Mexican coast at three colonies. The non-breeding range extends further to sea from the Pacific coast of Ecuador north to central California. In the Atlantic, non-breeding frigatebirds frequent the southern coasts of Florida southward through the Gulf of Mexico, the Caribbean, and coastal South America to southern Brazil.
Habitat
These birds breed on islands near warm waters with shrubby plants like barna (Crataeva tapia) and mangroves (particularly red mangroves), upon which they build their nests. Nesting adults forage over both shallow and deep water. When not breeding, the Magnificent Frigatebird frequents coastal waters, lagoons, deep ocean waters, and woody islands, but rarely roosts on the water.
Feeding
Like a soaring hawk, the Magnificent Frigatebird patrols the sky looking down at the surface for food, then swooping or gliding down to the water to snap up flying fish and squid. Because its feathers soak up water, the birds dive only briefly in pursuit of prey or a drink. Sometimes working in groups, frigatebirds steal food from other seabirds, like boobies, gulls, and terns, by chasing them until the food is dropped or regurgitated. A skillful flyer, the frigatebird then nabs the item from the air before it hits the water. The diet is supplemented by fishery waste, immature seabirds, young turtles, and small crabs.
Reproduction
Unique features of the Magnificent Frigatebird's breeding include plumage differences between sexes; a year-long breeding cycle; and male group displays. From September to April, colonies form around groups of displaying males perched atop shrubby plants. As females wheel above, males bend backwards, open their fluttering wings, inflate their bright red throat sacks, and drum the sacks with clattering bills. When a female perches near a male, other males join the display. A monogamous pair bonds with ceremonies like head shaking, bill sparring, and neck crossing.

Males gather or steal sticks, which females arrange into a loose, fairly flat nest, built where the pair bonded. Some nests are covered with grasses or vines. The female lays only one smooth white egg, which is incubated by the pair for about eight weeks. Blind, helpless, and naked, the chick develops very slowly and takes pre-digested food from both parents. The male departs after about a month, and the young frigatebird is fed by the female for another 13 months. Fledging occurs in about five months. The frigatebird's long breeding cycle and habit of stealing food are probably adaptations to the low productivity of tropical waters.
Migration
Because the breeding cycle lasts about a year for Magnificent Frigatebird females, they are probably non-migratory. Immature frigatebirds and post-breeding males have been observed far from their breeding grounds, as indicated by leg bands, but no migration pattern has yet been described.
  • 210,000
  • 210,000
Population Status Trends
Across its range, the Magnificent Frigatebird is declining. Many formerly strong colonies in the Caribbean have disappeared since the 1930s in Aruba, southwestern Puerto Rico, mainland Jamaica, and the U. S. Virgin Islands. Other colonies are feared lost, and still others in St. Elizabeth, Anguilla, Barbados, and the Cape Verde Islands have dwindled to a few dozen pairs or less. The U. S. Fish and Wildlife Service considers this unique seabird a "species of conservation concern," while Partners in Flight label it a "species of high concern," due to its decreasing population and threats to its breeding habitat.
Conservation Issues
Threats to the Magnificent Frigatebird in the United States mirror those throughout its range, consisting mainly of breeding habitat destruction. This bird requires mangroves and other woody scrub for nesting, but expanding agriculture, shrimp farms, and tourism have devastated these coastal forests. Mangroves are being lost at a rate of 1.7% per year in the Caribbean, and petroleum spills and heavy metals hinder reforestation. On many Caribbean islands, exotic herbivores like goats also destroy coastal woodlands. Additionally, farmers and tourists bring cats, dogs, and rats that prey on frigatebirds eggs and young.

In the United States, the Magnificent Frigatebird breeding colony in Dry Tortugas, Florida relocated from the Marquesas Atoll in Florida's Key West National Wildlife Refuge, apparently in response to increasing harassment by recreational boats and small planes. In 1988, breeding was confirmed on the Dry Tortugas with nine nesting pairs. Counts in the late 1990s and early 2000s recorded 50 to 100 pairs at this colony. The Southeastern Waterbird Conservation Plan calls for protecting the Dry Tortugas' colony from invasive predators and intense tourism. It also recommends that the Marquesas Atoll colony be re-established. The small success of the Magnificent Frigatebird in Dry Tortugas demonstrates the potential recovery of a declining species, when it is protected from human intrusion and provided with natural habitat.
What You Can Do
When visiting southern Florida, look for the Magnificent Frigatebird along the coast. The Ding Darling National Wildlife Refuge, on Sanibel Island, Florida, hosts a wildlife festival every second weekend in October.

Buy seafood products and take vacations that do not contribute to the destruction of the mangrove forests that the Magnificent Frigatebirds need for breeding. Shrimp farming and tourism are large contributors to the destruction of mangrove forests.

Respect the Magnificent Frigatebird's nesting colonies, especially in the Dry Tortugas, by not flying over them or approaching them by boat. 

Find out about actions you can take including Audubon programs and activities.
More Information
Learn more about this species and other birds through these resources.
Natural History References
Diamond, A. W., and E. A. Schreiber. 2002. Magnificent Frigatebird (Fregata magnificens). In The Birds of North America, No. 601 (A. Poole and F. Gill, Eds.). The Birds of North America, Inc., Philadelphia, PA.

Sibley, David Allen. The Sibley Guide to Birds. Alfred A. Knopf, New York. 2000.
Conservation Status References
Albin, Eleazar. A natural history of birds. 1731–38.

Diamond, A. W., and E. A. Schreiber. 2002. Magnificent Frigatebird (Fregata magnificens). In The Birds of North America, No. 601 (A. Poole and F. Gill, Eds.). The Birds of North America, Inc., Philadelphia, PA.

Doyle, Thomas W., Thomas C. Michot, Richard H. Day, and Christopher J. Wells. "Recent colonization of mangrove and frigatebird populations in the Dry Tortugas, Florida." Park Science 21:1 (Fall/Winter 2001).

Sibley, David Allen. The Sibley Guide to Birds. Alfred A. Knopf, New York. 2000.

The Southeastern Waterbird Conservation Plan. Compiled by William C. Hunter, Walker Golder, Stefani Melvin, and Jennifer Wheeler. United States Fish and Wildlife Service. September, 2006. Accessed 7 May, 2007.