Feeding Behavior

Forages mostly by hovering or skimming low over water and taking items from surface; also will sit on water to feed. Probably forages mostly at dusk and at night.

Eggs

One. White or with faint reddish-brown dots. Incubation is by both sexes, averages about 45 days. Young: probably both parents feed young, by regurgitation. Young leaves nest and goes to sea on average about 84 days after hatching.

Young

probably both parents feed young, by regurgitation. Young leaves nest and goes to sea on average about 84 days after hatching.

Diet

Probably mostly crustaceans and small fish. Diet is not well known. Includes small fish, and crustaceans such as euphausiids. Once reported to feed heavily on the larval stage of spiny lobster off southern California.

Nesting

Breeds in colonies on offshore islands. Active at colonies only at night, arriving there just after dark and departing before first light. Some adults may visit colony every month of year. At Farallon Islands off central California, nesting is not synchronized; egg-laying may occur any time late April to mid-July, rarely to September. Before eggs are laid, both members of pair may spend time in nest chambers, giving trilling and twittering songs. Nest: site is in natural cavity or crevice under rock piles, under driftwood, or in old burrow of other species; usually no nest lining added.