Brown Booby

Sula leucogaster




Boobies and Gannets (Sulidae)

Code 4


Code 6



Egg Color:

White to pale blue green, nest stained.

Number of Eggs:

1 - 3

Incubation Days:

40 - 47

Egg Incubator:

Both sexes

Nest Location:

On ground.

Nest Material:

Lined with grass, twigs, and debris.





Brown Booby: Large seabird, dark brown with bright white underwing coverts, belly and vent. Long bill; large feet are yellow, green-yellow or gray. Wings are long, narrow and pointed. Sexes are similar; females slightly larger. Coloration is brighter leading up to breeding season and fades after. Coloration demonstrates geographic variation. Juvenile has gray bill and brown plumage overall with mottled underwing, belly and vent; iris is gray, bill is gray to blue-gray with a small brown tip, legs are cream, flesh or light orange.

Range and Habitat

Brown Booby: May be found worldwide in tropical seas; summer visitor to the Gulf coast and Caribbean Sea; may occur casually farther north along the Atlantic coast; occasionally seen in southern California’s Salton Sea; may also occur accidentally along Pacific coast. Pelagic, breeds on coastal islands.

Breeding and Nesting

Brown Booby: Breeding pairs may remain together for many years, continually reusing the same nesting site. Nests comprise a shallow depression on the ground lined with marine flotsam, feathers and vegetation. One to three white to pale blue-green eggs with a chalky coating are laid in the nest. Incubation ranges from 40 to 47 days and is carried out by both parents.

Foraging and Feeding

Brown Booby: These birds sometimes feed solitarily but are most often found in feeding flocks with other species. They eat parrotfish, mullets, flatfish, halfbeaks, flying fish and other fish. They forage by plunge diving above the ocean surface or making shallow dives at a low angle to the water, skimming the surface to catch fish that leap clear of the surf, depending on the depth of food.


Brown Booby: On breeding grounds emits harsh honking, brays, and hoarse, hissing whistles; usually silent at sea.

Similar Species

Brown Booby: Red-footed Booby dark morph is brown overall with brown underwings and red feet.

The ventral part of the bird, or the area between the flanks on each side and the crissum and breast. Flight muscles are located between the belly and the breast.
Birds do not have two separate cavities for excrement and reproduction like humans do. In birds, there is one single entrance/exit that suits both functions called the vent, cloaca or anus.
The pelagic is a type of bird whose habitat is on the open ocean rather than in a coastal region or on inland bodies of water (lakes, rivers). An example of a pelagic bird is the blacklegged kittiwake.
Parts of a Standing bird X
Head Feathers and Markings X
Parts of a Flying bird X