General

Bonin Petrel: A small petrel with gray upperparts; sides of neck are also gray; underparts white, dark gray around eye, upperwings and on leading and trailing edges of underwings. White forehead and foreface that reaches to the anterior superciliary area, then becomes black-gray with white scaling on forecrown; rest of crown and face, just before eye to ear coverts dark gray; dark brown iris. Sexes are similar. Juveniles have pale gray fringes that give a slightly scaly appearance to upperpart feathers, especially on the mantle and scapulars.

Breeding and Nesting

Bonin Petrel: These petrels are monogamous, and strictly nocturnal in their breeding grounds. They return to same burrow every year. One egg is laid in a 1 to 3 three meter long burrow dug into the sand. No relaying will take place if the egg is lost. Incubation duty is shared by both adults, and lasts about 50 days. Fledging occurs approximately 82 days after hatching.

Foraging and Feeding

Bonin Petrel: They forage offshore in surface waters. They consume fish that inhabit deep waters by day, and fish near the surface at night. They feed mostly at night by sitting on the water while seizing prey or dipping while in flight. They grasp the fish with their short bill when they are caught at the surface. High levels of rhodopsin in their eyes are believed to aid in nocturnal foraging.

Vocalization

Bonin Petrel: Harsh, grating high pitched sounds and clucks, "kukuer"; also emit a high-pitched "tititi" or "kikkikkik." Other calls include "kikooer," "kukuer" and a low pitched "churr" that occasionally sounds like a continuous growl.

Similar Species

Bonin Petrel: The wings of Juan Fernandez Petrel are longer and have more white below, Newell's Shearwater has more uniform, darker upperparts.