Masked Booby

The Masked Booby is the largest and most striking of the white-bodied boobies, with clean white plumage set off by crisp black flight feathers and tail, and a distinctive dark facial "mask" of bare skin surrounding the eyes and bill base that gives the species its name. The heavy yellow bill and pale eyes complete a bold, high-contrast look that is unmistakable at close range.

Breeding on remote, often predator-free tropical islands, Masked Boobies form colonies alongside other seabirds and can be approached quite closely, showing little fear of humans in the absence of historical predation pressure.

Key field marks

• Large size, largest of the booby species
• White body with black flight feathers and black tail
• Dark facial skin forming a mask around the bill and eyes
• Heavy, straight yellow bill

Similar species

• Nazca Booby is extremely similar and was once considered the same species; it is best distinguished by its orange-pink (not yellow) bill.
• Cape and Australasian Gannets are similar in overall pattern but occur outside the tropics and have golden-buff heads rather than a distinct dark mask.
• Juveniles are mottled brown-and-white with a dusky head, gradually acquiring the adult mask and clean white body over a few years.

Masked Boobies nest on remote tropical and subtropical islands across the Atlantic, Pacific, and Indian Oceans, favoring flat, open ground on isolated cays and atolls far from mainland predators. They are highly pelagic outside the breeding season, ranging widely over open ocean far from any land.

Colonies are often shared with other seabirds, including frigatebirds and other booby species, on islands that provide the isolation these ground-nesting birds require for successful breeding.

Behavior

Masked Boobies are powerful plunge-divers, dropping from considerable heights to spear fast-swimming prey like flying fish, and they can also pursue prey in shallow underwater chases.

Voice

At the colony, birds give deep honking and hissing calls during territorial and courtship displays; they are largely silent while at sea.

Feeding

Flying fish and squid form the bulk of the diet, typically captured through steep plunge-dives well offshore.

Nesting and breeding

A simple ground scrape serves as the nest, and while two eggs are typically laid, the older, stronger chick usually kills its younger sibling shortly after hatching, a behavior known as obligate siblicide.