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
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
- 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.
- 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.