Wedge-tailed Shearwater

Puffinus pacificus / ‘Ua‘u kani

‘Ua‘u kani are dark brown to brownish-gray above with white underparts except dark wing margins and undertail-coverts. They have a wedge-shaped tail and a slender, slate-grey hooked bill. Legs and feet are flesh colored. Loud groans, moans, and wails resulted in island residents giving them the name "moaning bird." Vocalizations occur primarily at night in breeding colonies.

‘Ua‘u kani nest in colonies, occupying natural crevices or burrows dug with its bill and feet.

‘Ua‘u kani feed during the day singly or in multi-species flocks. 

They are monogamous. Strictly nocturnal over breeding colony. Their courtship ritual begins shortly after arrival in early March at which time they will establish territories and dig burrows in preparation for egg-laying in June. A pair will sit head to head, often near their burrow entrance, vocalizing two-part wailing duets. Returning to the same nest site or area each year, ‘ua‘u kani nest in shallow burrows, 1-2 meters in length. ‘Ua‘u kani are very synchronous nesters – all lay 1 egg within a 3-week period.

A single, large, white egg is laid in a nesting chamber at the end of burrow. Egg-laying begins around the second week of June and continues throughout the month. No relaying will occur if an egg is lost. Incubation period averages 53 days with both parents alternating shifts on the egg, with each shift lasting as long as 12 days.

Chicks hatch during late-July through late August. Parents feed regurgitated squid and stomach oil to chicks. Feeding takes place every 24 hours. Fledging occurs in approximately 110 days.

Facts About Wedge-tailed Shearwater

Feed during the day singly or in multi-species flocks. Consumes larval forms of goat fish, mackerel scad, and flying squid driven to the surface by schools of predatory fish, such as skipjack tuna.

Life Span
10-11 years

Length: 41-46 cm (16-18 in); wingspan: 97-104 cm (38-41 in)