Nazca Booby

The Nazca Booby is a large, white-bodied booby of the eastern tropical Pacific, most familiar to visitors of the Galápagos Islands, where it is one of the most conspicuous breeding seabirds. It was formerly classified as a subspecies of the Masked Booby but is now recognized as a full species based on differences in appearance, voice, and genetics.

Adults are crisp white with black flight feathers and tail, similar to the Masked Booby, but the standout feature is the bright orange to salmon-pink bill, which contrasts with the dark facial skin and gives the species its most reliable field mark.

Key field marks

• Large white body with black flight feathers and tail
• Bright orange-pink bill (versus yellow in Masked Booby)
• Dark facial skin around the eyes
• Robust, heavy build similar to Masked Booby

Similar species

• Masked Booby is nearly identical in pattern but has a yellow bill rather than orange-pink, and the two species' ranges overlap only marginally.
• Blue-footed Booby shares Galápagos habitat but has brown upperparts and blue feet, quite different from the white-and-black Nazca Booby.
• Juveniles are mottled brown, gradually whitening with age, and can be confused with young Masked Boobies where ranges meet.

Nazca Boobies breed primarily in the Galápagos Islands, with additional colonies on other eastern tropical Pacific islands such as Malpelo and the Revillagigedo Islands off Mexico. They favor open, rocky or sparsely vegetated ground on islands with cliff edges suitable for their reliance on wind for takeoff.

Outside the breeding season, birds forage over the nutrient-rich waters of the eastern tropical Pacific, closely tied to the productive currents that support the Galápagos marine ecosystem.

Behavior

Like other boobies, Nazca Boobies are agile plunge-divers, often foraging over schools of fish pushed to the surface by predatory fish or dolphins, and are frequently seen soaring on updrafts along cliff faces.

Voice

Birds give deep, trumpeting honks and whistles at the colony during courtship and territorial disputes; the calls differ subtly from those of the Masked Booby, supporting their status as separate species.

Feeding

Sardines, flying fish, and squid are the primary prey, captured through steep dives from considerable height.

Nesting and breeding

Two eggs are typically laid in a ground scrape, but as in the Masked Booby, the first chick to hatch nearly always kills its younger sibling, a well-documented case of obligate siblicide that has made Nazca Boobies an important study species for evolutionary biologists.