Broad-billed prion

Taxonomy

Georg Forster, a German naturalist who accompanied James Cook on his second voyage, described the broad-billed prion in 1777 in his book A Voyage Round the World. Forster placed it in the genus Procellaria, coined by Carl Linnaeus, and gave it the binomial name Procellaria vittata. It now belongs to the genus Pachyptila, introduced in 1811 by Johann Karl Wilhelm Illiger; the genus name combines Ancient Greek words meaning 'dense' or 'thick' and 'feather' or 'plumage'.

The specific epithet vittata comes from Latin for 'banded'. The common name 'prion' derives from Ancient Greek for 'a saw', referring to the serrated bill edges. Members of Pachyptila, together with the blue petrel, form the prions, which are part of the family Procellariidae and order Procellariiformes. Like other Procellariiformes, they have nasal passages called naricorns attached to the upper bill, with nostrils on top.

Their bills are split into seven to nine horny plates. They produce stomach oil from wax esters and triglycerides, stored in the proventriculus, which can be sprayed as defence or used as food for chicks and adults during long flights. A salt gland above the nasal passage helps desalinate their bodies by excreting a high saline solution from the nose.

Description

This prion displays the typical blue-grey upperparts, white underparts, and a 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, and the head pattern is more distinct than that of the fairy prion. The bill possesses the best-developed lamellae among prions, enabling it to feed on tiny animals.

Behaviour

Broad-billed prions are social birds, with courtship displays occurring at night or inside burrows. They defend nests aggressively through calling, posturing, and neck-biting. They are gregarious and feed on crustaceans such as copepods, squid, and fish, using hydroplaning—flying with the bill in the water to skim and filter food—as well as surface-seizing. They do not regularly follow fishing boats.

Breeding begins in July or August on coastal slopes, lava fields, or cliffs of breeding islands, where a single white egg is laid in a burrow. Both parents incubate for 50 days and then raise the chick for another 50 days. Skuas are the main predators, though cats and rats have drastically reduced numbers on some islands. Colonies disperse from December onward, though some adults remain near breeding islands and may visit burrows in winter.

Did You Know?

• The broad-billed prion is also known as the blue-billed dove-petrel, broad-billed dove-petrel, long-billed prion, common prion, icebird, and whalebird.
• The species is found in oceans and coastal areas of the Southern Hemisphere, including the subantarctic Antipodes Islands.