Feeding Behavior

Forages mostly by plunging headfirst into water from flight, usually diving at angle and from fairly low above surface. Sometimes hovers before diving, dives from perch, swoops low to take items from surface, or seizes items while swimming. May pursue flying fish in the air. Also steals food from other birds.

Eggs

1-2, rarely 3. Whitish to pale blue-green, becoming nest-stained brown. Incubation is by both sexes, 40-47 days. Young: Both parents feed young, by regurgitation. When 2 eggs laid, 2nd young to hatch rarely survives. Period from hatching to first flight varies, depending on food supply, 84-119 days. Juvenile returns to nest site and begs to be fed for many weeks after first flight, often 20 weeks or more.

Young

Both parents feed young, by regurgitation. When 2 eggs laid, 2nd young to hatch rarely survives. Period from hatching to first flight varies, depending on food supply, 84-119 days. Juvenile returns to nest site and begs to be fed for many weeks after first flight, often 20 weeks or more.

Diet

Mostly fish. In North American waters, diet includes flying fish and mullet, also squid and shrimp.

Nesting

Probably first breeds at age of 4 years, and may mate for life. Courtship displays by members of pair include bill-touching, bowing, throwing head back with bill pointing skyward. Nests in large or small colonies, sometimes isolated pairs, on tropical or subtropical islands. Nest: Site is on ground or cliff. Nest is shallow depression, sometimes sparsely lined, sometimes with large mound of twigs, grass, and debris, built by both sexes.