Photo: Hanne & Jens Eriksen/Vireo

Masked Booby

Sula dactylatra

Widespread in tropical oceans, this large, long-winged seabird occurs regularly off our southern Atlantic and Gulf coasts; it is also common in Hawaii, mainly in the northwestern chain. Known as a visitor to the Dry Tortugas, Florida, for many years, the Masked Booby did not actually begin to nest there until the 1980s.
Conservation status Total population difficult to assess because colonies are numerous and widely scattered, but these factors probably also ensure its survival. No evidence of widespread decline.
Family Boobies and Gannets
Habitat Tropical seas. Forages over warm waters, shallow or deep, sometimes hundreds of miles from land. Nests on islands, mainly low flat islands with little or no vegetation. In Florida, has nested on a small sandy island barely above high-water level.
Widespread in tropical oceans, this large, long-winged seabird occurs regularly off our southern Atlantic and Gulf coasts; it is also common in Hawaii, mainly in the northwestern chain. Known as a visitor to the Dry Tortugas, Florida, for many years, the Masked Booby did not actually begin to nest there until the 1980s.
Photo Gallery
  • adult
  • immature (probably 2nd yr)
  • juvenile
  • adult
Feeding Behavior

Forages by plunging into water from flight (from as high as 90 feet above the sea), striking water headfirst and catching prey within a few feet of the surface. May rest on water, watching for fish below and watching other seabirds in vicinity; when it spots prey, it takes flight and begins plunge-diving, and other birds hurry to join in feeding.


Eggs

1-2. Pale blue to chalky white, becoming nest-stained. Both sexes incubate, placing eggs under webs of feet; incubation period 38-49 days. When 2 eggs are laid, 2nd young to hatch is attacked and ejected from nest by its older sibling and does not survive. Young: Both parents feed young, by regurgitation. Age at first flight 109-151 days. Young return to nest site and continue to be fed by parents for 30-60 days after able to fly.


Young

Both parents feed young, by regurgitation. Age at first flight 109-151 days. Young return to nest site and continue to be fed by parents for 30-60 days after able to fly.

Diet

Mostly fish. Eats a variety of fish, with flying fish often predominating; also some squid.


Nesting

Usually first breeds at age of 4 years. Breeds in colonies. Courtship displays of male include stretching neck and pointing bill skyward. Paired birds present each other with pebbles or feathers, parade slowly forward with prominent display of feet. Nest: Site is on ground, often near edge of slope or cliff for ease of takeoff. Nest is a shallow depression surrounded by slight rim of pebbles, debris.

Illustration © David Allen Sibley.
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Text © Kenn Kaufman, adapted from
Lives of North American Birds

Migration

No regular migration, but wide dispersal at sea. Birds in Pacific have been known to visit sites more than 1000 miles from breeding colony. Apparently present all year off southeastern United States, perhaps more common in warmer months.

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Migration

No regular migration, but wide dispersal at sea. Birds in Pacific have been known to visit sites more than 1000 miles from breeding colony. Apparently present all year off southeastern United States, perhaps more common in warmer months.

Songs and Calls
Usually silent; a variety of hissing and quacking notes on breeding grounds.
Audio © Lang Elliott, Bob McGuire, Kevin Colver, Martyn Stewart and others.
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