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Brown Booby

Sula leucogaster ORDER: SULIFORMES FAMILY: SULIDAE

IUCN Conservation Status: Least Concern

A widespread seabird of tropical waters, the Brown Booby ranges as far north as the Gulf of California, and rarely to both coasts of the United States. Like other boobies, it feeds with spectacular plunges into the sea.

At a GlanceHelp

Measurements
Both Sexes
Length
25.2–33.5 in
64–85 cm
Wingspan
52–61 in
132–155 cm
Weight
33.5–63.5 oz
950–1800 g
Other Names
  • White-bellied Booby
  • Fou brun (French)
  • Boba prieta, Bubi chaleco (Spanish)

Cool Facts

  • The Brown Booby is the only ground-nesting booby that regularly builds a substantial nest.
  • Like all boobies and pelicans, the Brown Booby's feet are "totipalmate," having webbing connecting all four toes.
  • Brown Booby nests sometimes contain the bodies of dead Sooty Tern chicks.
  • Male and female Brown Boobies generally look alike in plumage color, except in populations found along the Pacific Coast of Mexico and Central and South America. There the females look like those in other populations, but the males have light gray to white heads.
  • The oldest recorded Brown Booby was a 26 year old male.

Habitat


Ocean

Nests on islands, covering a wide range of vegetation types, geologic features, and weather patterns. Found at sea in nonbreeding season.

Food


Fish

Squid and fish, especially flying fish.

Nesting

Nesting Facts
Clutch Size
1–3 eggs
Egg Description
Pale bluish or greenish, with white outer layer.
Condition at Hatching
Blind and helpless.
Nest Description

Mound of branches, bones, grass, human-generated trash, or other items. Placed on flat ground, usually in full sunshine. Nests in colonies.

Nest Placement

Ground

Behavior


Aerial Dive

Plunge-dives from various heights up to 15 m (50 feet). Folds wings next to body at beginning of dive, then thrusts wings straight out over back, touching in the middle, just before breaking the surface. Dive may reach just below surface, or to as much as 2 m (6 feet) deep. Commonly feeds in areas where large predatory fish such as tuna drive smaller fish to the surface. Also follows fishing vessels.

Conservation

status via IUCN

Least Concern

Brown Booby populations are declining. The Waterbird Conservation for the Americas estimates a population of 280,000-300,000 breeders, rates the species a 14 out of 20 on the Continental Concern score, and considers it a Species of High Concern. Brown Booby are on the 2014 State of the Birds Watch List, which lists bird species that are at risk of becoming threatened or endangered without conservation action. Brown Booby no longer breeds on many tropical islands where predators have been introduced. Human population growth and development of islands have caused severe population declines over the past century in the Caribbean.

Credits

Range Map Help

Brown Booby Range Map
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bird image Blue-winged Warbler by Brian Sullivan

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