Brown BoobySula leucogaster

adult male
Robert L. Pitman/VIREO
adult female
Rick and Nora Bowers/VIREO
adult female
Rick and Nora Bowers/VIREO
juvenile
John Cancalosi/VIREO
adult male
Robert L. Pitman/VIREO
adult female
Doug Wechsler/VIREO

Description

Tropical seas around the world are home to this large, long-winged, strong-flying seabird. In North America it is seen most often near the Dry Tortugas, Florida, where it perches in trees or on navigational markers. It may have nested on the Florida Keys in the past, but the only United States nesting sites today are in Hawaii.

Habitat

Tropical oceans. Widespread at sea, including very far from land, over warm waters in tropics and subtropics. Also often found close to shore, especially around islands, sometimes foraging in very shallow or muddy waters. Nests on rocky or sandy islands.

Feeding Diet

Mostly fish. In North American waters, diet includes flying fish and mullet, also squid and shrimp.

Feeding Behavior

Forages mostly by plunging headfirst into water from flight, usually diving at angle and from fairly low above surface. Sometimes hovers before diving, dives from perch, swoops low to take items from surface, or seizes items while swimming. May pursue flying fish in the air. Also steals food from other birds.

Nesting

Probably first breeds at age of 4 years, and may mate for life. Courtship displays by members of pair include bill-touching, bowing, throwing head back with bill pointing skyward. Nests in large or small colonies, sometimes isolated pairs, on tropical or subtropical islands. Nest: Site is on ground or cliff. Nest is shallow depression, sometimes sparsely lined, sometimes with large mound of twigs, grass, and debris, built by both sexes. Eggs: 1-2, rarely 3. Whitish to pale blue-green, becoming nest-stained brown. Incubation is by both sexes, 40-47 days. Young: Both parents feed young, by regurgitation. When 2 eggs laid, 2nd young to hatch rarely survives. Period from hatching to first flight varies, depending on food supply, 84-119 days. Juvenile returns to nest site and begs to be fed for many weeks after first flight, often 20 weeks or more.

Eggs

1-2, rarely 3. Whitish to pale blue-green, becoming nest-stained brown. Incubation is by both sexes, 40-47 days. Young: Both parents feed young, by regurgitation. When 2 eggs laid, 2nd young to hatch rarely survives. Period from hatching to first flight varies, depending on food supply, 84-119 days. Juvenile returns to nest site and begs to be fed for many weeks after first flight, often 20 weeks or more.

Young

Both parents feed young, by regurgitation. When 2 eggs laid, 2nd young to hatch rarely survives. Period from hatching to first flight varies, depending on food supply, 84-119 days. Juvenile returns to nest site and begs to be fed for many weeks after first flight, often 20 weeks or more.

Conservation

Vulnerable to disturbance on islands where it breeds, but survival probably ensured by wide range and large number of nesting sites.

Range

Present year-round in most parts of range, with only local wandering at sea. Birds from western Mexico sometimes stray north into interior of American southwest (especially Salton Sea, Colorado River).

Listen

social calls

Similar Species

adult

Northern Gannet

One of the largest seabirds of the North Atlantic, the gannet is spectacular as it plunges into the sea in pursuit of fish. With a spear-like bill and spiky tail, it looks "pointed at both ends." Nesting colonies are on northern sea cliffs; one at Bonaventure Island, Quebec, has become a famous tourist destination. In winter off southern coastlines, the gleaming white adults may be outnumbered by brown and patchy immatures; it takes four years for gannets to attain full adult plumage.

adult

Masked Booby

Widespread in tropical oceans, this large, long-winged seabird occurs regularly off our southern Atlantic and Gulf coasts; it is also common in Hawaii, mainly in the northwestern chain. Known as a visitor to the Dry Tortugas, Florida, for many years, the Masked Booby did not actually begin to nest there until the 1980s.

adult male and female

Blue-footed Booby

Often shown in documentaries about the Gal

adult, brown morph

Red-footed Booby

Found in tropical seas around the world, this long-winged seabird is only a very rare visitor to North America. Most records are from Florida, especially around the islands of the Dry Tortugas, but the species has also been found off the California coast.

Vireo

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