The broad-billed prion (Pachyptila vittata ) is a small pelagic seabird in the shearwater and petrel family, Procellariidae. It is the largest prion, with grey upperparts plumage, and white underparts. The sexes are alike. It ranges from the southeast Atlantic to New Zealand mainly near the Antarctic Convergence. In the south Atlantic it breeds on Tristan da Cunha and Gough Island; in the south Pacific it breeds on islands off the south coast of South Island, New Zealand and on the Chatham Islands. It has many other names that have been used such as blue-billed dove-petrel, broad-billed dove-petrel, long-billed prion, common prion, icebird, and whalebird.
The broad-billed prion has the usual prion colours: blue-grey upperparts, white underparts, and the ever present dark "M" across its back and wings. It has a grey crown, a dark eye stripe, and a black-tipped tail. Its heavy bill is iron-grey but can appear blackish from a distance. The head pattern is more distinct and the tail band is less extensive than that of the similar fairy prion. It has a broad flat bill with comb-like fringes called lamellae. This is a large prion measuring 25 to 30 cm (9.8 to 11.8 in) long, with a wingspan of 57 to 66 cm (22 to 26 in) and weighing on average 160 to 235 g (5.6 to 8.3 oz).
This species is found throughout oceans and coastal areas in the Southern Hemisphere. Its colonies is found on Gough Island, Tristan da Cunha, South Island, Chatham Islands, on the subantarctic Antipodes Islands, and other islands off the coast of New Zealand.
They are social birds; however their courtship displays happen at night or in their burrows. When they need to defend their nests they are very aggressive with calling, posturing, and neck-biting.
They are gregarious, and eat crustaceans (copepods), squid, and fish. They utilize a technique called hydroplaning, where the bird flies with its bill in the water, skimming water in, and then filtering the food. They also surface-seize. This prion doesn't follow fishing boats regularly.
Breeding begins on the coastal slopes, lava fields, or cliffs of the breeding islands in July or August, as they lay their single egg in a burrow type nest. The clutch is a single white egg which is approximately 50.0 mm × 36.8 mm (1.97 in × 1.45 in). Both parents incubate the egg for 50 days, and then spend another 50 days raising the chick. The main predators are skuas, although on some islands, cats and rats have reduced this prion's numbers drastically. Colonies disperse from December onwards, although some adults remain in the vicinity of the breeding islands and may visit their burrows in winter.
