Thin-billed Prion

The thin-billed prion is a small prion whose unusually narrow bill separates it from the otherwise similar Antarctic and Salvin’s prions. Blue-grey upperparts carry a black M and the white tail has a black tip; the bill is only about 9.3–12.5 mm wide. Antarctic prion has a broader, brighter-blue bill.

It breeds on southern Atlantic and Indian Ocean islands and visits New Zealand waters as a migrant, often after winter storms. It takes small crustaceans, fish and squid by surface-seizing and shallow diving, using a finer bill than filter-feeding broad-billed prions.

Thin-billed prion is a Migrant under the NZ Threat Classification. Introduced predators threaten some overseas colonies. New Zealand records are mainly offshore or storm-wrecked birds; species-level identification usually requires close examination.