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Masked Booby

Sula dactylatra ORDER: SULIFORMES FAMILY: SULIDAE

IUCN Conservation Status: Least Concern

A large seabird of tropical oceans, the Masked Booby is only a rare visitor to North America. It has attempted to breed in the Dry Tortugas in Florida, but it is most frequently encountered at sea in the Gulf of Mexico or off the southern Atlantic states.

Funky Nests
Birds of North America Online

At a GlanceHelp

Measurements
Both Sexes
Length
29.1–33.9 in
74–86 cm
Wingspan
63 in
160 cm
Weight
45.9–82.9 oz
1300–2350 g
Other Names
  • Blue-faced Booby, White Booby
  • Fou Masqué (French)
  • Piquero enmascarado (Spanish)

Cool Facts

  • The population of Masked Boobies breeding along the Pacific Coast of northern South America, including the Galapagos, was recently recognized as a separate species, the Nazca Booby. The Nazca Booby has an orange, not yellow, bill and is smaller with a significantly shorter, shallower bill. Whereas the Masked Booby usually nests on low, flat areas, the Nazca Booby uses cliffs and steep slopes.
  • Although the Masked Booby regularly lays two eggs, it never raises two young. The first egg is laid four to nine days before the second, and the older chick always ejects the second from the nest. The parents do not protect or feed the ejected chick, and it is quickly scavenged by a host of associated crabs, landbirds, and frigatebirds.

Habitat


Ocean

Nests on small tropical islands, especially ones that are flat and without forests. Spends rest of time at sea.

Food


Fish

Fish and squid.

Nesting

Nesting Facts
Clutch Size
1–2 eggs
Egg Description
Light blue.
Condition at Hatching
Nearly helpless, with sparse white down.
Nest Description

Slight depression on ground, surrounded by circle of pebbles or other debris, often near a breezy cliff edge or other take-off feature

Nest Placement

Ground

Behavior


Aerial Dive

Plunge-dives from various heights up to 30 meters (100 feet) into schools of fish.

Conservation

status via IUCN

Least Concern

At least some mortality from tangling in fishing gear, but this problem is not known to be significant. Probably has frequent interactions with purse-seining tuna fisheries, as the fisheries often use Masked Boobies and other seabirds to locate tuna schools, but no data exist.

Credits

    1. Anderson, D. J. 1993. Masked Booby (Sula dactylatra). In The Birds of North America, No. 73 (A. Poole and F. Gill, Eds.). Philadelphia: The Academy of Natural Sciences; Washington, D.C.: The American Ornithologists' Union.
    2. Pitman, R. L., and J. R. Jehl, Jr. 1998. Geographic variation and the reassessment of species limits in the "Masked" Boobies of the eastern Pacific Ocean. Wilson Bulletin 110: 155-170.

Range Map Help

Masked Booby Range Map
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