Midway Population

Approximately 51,493 nesting pairs nest on Sand Island (Moore 1998). Since rat eradication efforts on Eastern and Spit Islands were initiated in 1994, some nesting activity (6-10 nests) has been observed on these two islands since 1996. With the eradication of rats on Midway's islands, nesting birds have rapidly expanded into new areas. Only breeds in the Northwestern Hawaiian Islands or the Bonin and Volcano Islands of Japan.

Feeding Habits

Feed alone or in small groups, primarily at night. Feed on small fish and squid probably by dipping or surface-feeding. Occasionally associate with feeding Wedge-tailed Shearwaters, Sooty Terns, and Great Frigatebirds.

Breeding

Strictly nocturnal over breeding grounds. Monogamous. Return to same burrow every year. Adults arrive in August and spend the fall months courting, establishing pair bonds, excavating burrows, and nest building.

Bonin Petrels nest in burrows that can be as long as three meters and one meter deep, usually in sandy areas. A single, white egg is laid in the nesting chamber at the end of the burrow. No relaying will take place if the egg is lost. Incubation duty is shared by both adults and lasts about 49 days.

Chicks begin to hatch in early March. Parents feed chicks by regurgitating concentrated stomach oil (similar to Albatross). Parents average one feeding every two nights. Fledging occurs approximately 82 days after hatching. By the end of June, adults and chicks have departed the nesting colonies.