Sula sula (Linnaeus, 1766)

Taxonomy and Classification

The red-footed booby, with the scientific name Sula sula (Linnaeus, 1766), is the smallest member of the booby and gannet family.

Size Measurements

It reaches approximately 70 cm (28 in) in length, with a maximum wingspan of 152 cm (60 in).

Average Weight

An average weight of 837 g (1.845 lb) was recorded from a sample of 490 adult individuals collected from Christmas Island.

Distinctive Physical Features

This species is identifiable by its red legs, and pink-and-blue bill and throat pouch.

Plumage Morphs

It has multiple distinct plumage morphs.

White Morph Plumage

For the white morph, most plumage is white, with the head often developing a yellowish tinge, and black flight feathers.

Black-Tailed White Morph Plumage

The black-tailed white morph is similar to the white morph but has a black tail, and can be easily confused with the Nazca booby and masked booby.

Brown Morph Plumage

The brown morph is entirely brown overall.

White-Tailed Brown Morph Plumage

The white-tailed brown morph matches the brown morph in overall appearance, but has a white belly, rump, and tail.

White-Headed White-Tailed Brown Morph Plumage

The white-headed and white-tailed brown morph has mostly white body, tail, and head, with brown wings and back.

Morph Breeding and Geographic Dominance

Different morphs of this species commonly breed with one another, but one or two morphs are dominant in most regions; for example, most red-footed boobies in the Galápagos Islands belong to the brown morph, though the white morph also occurs there.

Adult Sexual Dimorphism

Males and females have similar appearances.

Juvenile and Chick Appearance

Juveniles are brownish with darker wings and pale pinkish legs, while newly hatched chicks are covered in dense white down.

Global Distribution Range

The red-footed booby is widely distributed across the tropics of the Atlantic, Pacific, and Indian Oceans.

Atlantic Ocean Distribution

In the Atlantic Ocean, it mainly occurs around the Caribbean islands.

Pacific Ocean Distribution

In the Pacific Ocean, populations live in the Galápagos Islands (mostly on Genovesa and San Cristobal) and in Hawaii on the island of Kauai.

Indian Ocean Distribution

In the Indian Ocean, it occurs on Aldabra, the Seychelles, Rodrigues, the Maldives, the Chagos Archipelago, the Cocos (Keeling) Islands, and Christmas Island.

Extirpation Locations and Causes

This species has been extirpated from many islands due to the combined effects of introduced predators and human hunting; this includes the Glorioso Islands, Assumption Island, Tikopia, Henderson Island, the Marquesas Islands, the Society Islands, and Desecheo Island.

Vagrant Occurrence Locations

It occurs as a vagrant in Sri Lanka, New Zealand, and the United Kingdom.

North American Vagrant Records Trend

Vagrant records of the red-footed booby have also become more frequent in the United States and Canada in recent years.