Nazca BoobySula grantiOù et quand les observer

The Nazca booby is a large tropical seabird of the eastern Pacific, with important breeding colonies in the Galapagos. Its crisp white body, dark flight feathers and warm-toned bill create a striking appearance on rocky islands. Once treated as a form of masked booby, it is now recognized as a separate species. It nests on open ground and spends much of its life at sea, returning to colonies for courtship and breeding.

Size

75-89 cm body length

Weight

1.3-2.3 kg

Lifespan

Not reliably established

Status

Least Concern

Pairs display with bill pointing, head movements and exchanged nesting material, usually at a simple scrape on bare ground. A clutch often contains two eggs, but normally only one chick survives because the older chick expels its sibling. Adults commute between colonies and offshore feeding areas. Birds at nests may appear tolerant, yet approaching visitors can interrupt incubation, expose chicks or trigger defensive responses, especially along crowded colony edges. The older, larger chick typically outcompetes or actively kills its younger sibling, a phenomenon known as obligate siblicide. This ensures the survival of the strongest chick, maximizing parental investment in one offspring. Adults often perform elaborate sky-pointing displays during courtship, emphasizing their long, pointed wings.

• Nazca booby was formerly classified within the masked booby.
• Its second egg usually functions as insurance if the first egg fails.
• Adults have pinkish-orange bills, whereas young birds have darker bills and browner plumage.
• Males typically whistle, while females give harsher honking calls.

Galapagos colonies may be observable throughout the year, but nesting schedules differ between islands and years. Local colony information is more useful than a single archipelago-wide breeding calendar. In Mexico, access to remote offshore islands, rather than season alone, limits coastal observation opportunities. In the Galapagos, many Nazca boobies begin courtship and nesting activities after the hot, rainy season, generally starting around June. Peak breeding activity can be seen during the cool, dry season from July to December across the archipelago. Mexico's breeding populations often show similar seasonal patterns, influenced by local upwelling events.

Nazca boobies breed on dry tropical islands, using rocky ledges, open slopes and sparsely vegetated ground. At sea they range over productive eastern Pacific waters. Their colonies are concentrated rather than evenly distributed, so many apparently suitable islands lack breeding birds. They are predominantly pelagic, spending much of their lives at sea, often far from land. While they breed on islands, they forage widely across vast expanses of the eastern Pacific Ocean. This wide-ranging foraging behavior means they are frequently observed from vessels on open ocean passages.

Fish dominate the diet, especially schooling species such as flying fish and sardine-like fishes, with squid also taken. Adults capture prey at sea and carry food back internally to feed chicks. Feeding opportunities shift with currents, prey availability and ocean temperature. Nazca boobies are plunge-divers, dramatically entering the water from heights of 10 to 30 meters to catch fish. Their diet can also include anchovies and mackerel, reflecting their opportunistic foraging strategy. They typically hunt during daylight hours, often joining other seabird species in feeding frenzies.

Common name

Nazca Booby

Scientific name

Sula granti

Animal group

Birds

Size

75-89 cm body length

Weight

1.3-2.3 kg

Lifespan

Not reliably established

Status

Least Concern

Identification

The orange to pinkish-orange adult bill distinguishes Nazca booby from the usually yellow-billed masked booby, while dark feet separate it from blue-footed booby. Juvenile Nazca boobies are brown on their upperparts with a white belly, gradually molting into adult plumage over several years. Their large size and pointed bill also help distinguish them from other seabirds in their range. The black facial mask surrounding their eyes is a key characteristic, even at a distance.