Birds · Suliformes · Sulidae

Masked Booby

Sula dactylatra

Least Concern

The species is abundant and widely distributed; it faces no significant short-term risk. See full glossary

The masked booby is the largest of the boobies, white with black flight feathers and tail and a dark facial mask around the yellow bill. It breeds on tropical oceanic islands worldwide and fishes by plunging from a great height. Like the Nazca booby, from which it was split as a separate species, it lays two eggs and always loses one to obligate siblicide by the elder chick.

Weight

1.2 kg – 2.2 kg

Size

74 cm – 91 cm

Lifespan

25 years

Diet

Carnivore

Feeds mainly on other animals.

Activity

Diurnal

Active mainly during the day.

Social structure

Colony

Lives in large concentrations, often for breeding reasons.

Sighting difficulty

Easy

OceanIslandsCarnivore Diurnal Colonial Bird Ocean Islands

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Fun facts

It lays two eggs several days apart and the elder chick always pushes the younger out of the nest within the first few days: the second egg works as insurance in case the first fails, and in more than ninety per cent of cases that insurance dies.
It plunges from more than twenty metres and enters the water at high speed: air sacs beneath the skin cushion the impact and its nostrils are closed off internally.
It breeds on remote islands throughout the tropical oceans, and the populations are so isolated that several are being studied as possible separate species.

Life cycle & biology

Skeleton type: Vertebrate - internal bony skeleton (bird)
Habitat & environment: Tropical oceanic waters of every ocean; it breeds on predator-free islands and atolls
Sexual maturity: 4 years
Gestation / incubation: 43 days
Litter / clutch size: 1.5 (average)

Sources consulted: https://es.wikipedia.org/wiki/Sula_dactylatra