The Four Keys to ID
- Size & Shape
A solid, slim seabird with very long, slender wings, long, pointed tail, long, pointed bill, and large webbed feet.
Relative Size
Larger than a White-tailed Tropicbird, smaller than a Masked Booby.
goose-sized or larger
Measurements
- Both Sexes
- Length: 27.2-31.1 in (69-79 cm)
- Weight: 30.0-38.8 oz (850-1100 g)
- Wingspan: 59.8 in (152 cm)
© Shawn Billerman / Macaulay Library
- Color Pattern
Adults are highly variable: they can be white with black flight feathers, entirely brown with paler brown heads, or brown with white tails. Galapagos white-morph adults have black tails, not white. Adults have pale bluish bills and both rosy and blue facial skin. Juveniles are sooty brown, similar to young Brown Boobies, with grayish bills and bluish facial skin. Subadult is tan with darker brown wings, dull pinkish bill, and bluish facial skin.
© Marilyn Henry / Macaulay Library - Behavior
Forages by flying above the ocean and scanning for prey, dropping swiftly in a plunge-dive or shallow-angle dive once prey is spotted. They often catch flying fish in the air.
- Habitat
Open tropical oceans around the world, often congregating at upwelling sites or around feeding schools of predatory fish. Nests mostly in trees, sometimes on the ground on tropical islands.
© John Cahill xikanel.com / Macaulay Library
Regional Differences
Ornithologists recognize three subspecies: sula of the Caribbean and Atlantic, websteri in the tropical eastern Pacific Ocean, and rubripes in the remainder of the species’ wide range. All subspecies show multiple color morphs. However, websteri in the Galapagos is the only one with a black-tailed white morph.