Bonin Petrel

Overview

The Bonin petrel or nunulu (Pterodroma hypoleuca) is a small gadfly petrel found in the northwest Pacific Ocean. It belongs to the family Procellariidae and is characterized by secretive habits and remote breeding colonies, which has limited scientific study of its biology.

Identification

• Approximately 30 cm long with a wingspan of around 67 cm.
• White head with a black cap and face markings that often create a scaled appearance.
• Pale grey upperparts with darker primaries and wing coverts forming an "M" mark across the back; white underwing with dark edging.
• Short, hooked black bill and pink legs with dark patches.

Habitat

Breeds in dense colonies on islands in the Northwestern Hawaiian Islands and on the Volcano and Bonin Islands south of Japan. The population is concentrated in the northwest Pacific Ocean, with the vast majority breeding in the Hawaiian archipelago. After the breeding season, birds migrate northwards to the seas off Honshū and Sanriku in Japan.

Diet

Possesses a fish-dominated diet consisting primarily of lantern fish and hatchetfish, along with some squid. These prey are midwater residents that migrate to the surface at night, leading to the assumption that Bonin petrels are nocturnal feeders that seize prey at the surface while resting or in flight.

Did you know?

Fossil remains found on Kauai, Oahu and Molokai imply that Bonin petrels were a food source for Polynesian settlers before being extirpated from the main Hawaiian Islands by humans. The species has a high hatching success rate of up to 90% in the absence of introduced predators, though rats have devastated populations on some islands.