Broad-billed Prion

Identificazione

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. Its bill has the best developed lamellae of all the prions, allowing it to feed on tiny animals. 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).

Tassonomia

The broad-billed prion was described in 1777 by the German naturalist Georg Forster in his book A Voyage Round the World. He had accompanied James Cook on Cook's second voyage to the Pacific. He included a brief description: "the blue petrel, so called from its having a blueish-grey colour, and a band of blackish feathers across the whole wing." Forster placed the broad-billed prion in the genus Procellaria that had been erected for the petrels by Carl Linnaeus in 1758 and coined the binomial name Procellaria vittata. The broad-billed prion is now placed in the genus Pachyptila that was introduced in 1811 by the German zoologist Johann Karl Wilhelm Illiger. The genus name combines the Ancient Greek pakhus meaning "dense" or "thick" with ptilon meaning "feather" or "plumage". The specific epithet vittata is from the Latin vittatus meaning "banded". The word "prion" comes from the Ancient Greek priōn meaning "a saw", which is in reference to the serrated edges of the bill.<p>Members of the genus Pachyptila, together with the blue petrel, make up the prions. They in turn are members of the family Procellariidae, and the order Procellariiformes. The prions are small and typically eat just zooplankton; however as a member of the Procellariiformes, they share certain identifying features. First, they have nasal passages that attach to the upper bill called naricorns. Although the nostrils on the prion are on top of the upper bill. The bills of Procellariiformes are also unique in that they are split into between seven and nine horny plates. They produce a stomach oil made up of wax esters and triglycerides that is stored in the proventriculus. This can be sprayed out of their mouths as a defence against predators and as an energy rich food source for chicks and for the adults during their long flights. Finally, they also have a salt gland that is situated above the nasal passage and helps desalinate their bodies, due to the high amount of ocean water that they imbibe. It excretes a high saline solution from their nose.

Nome scientifico

Pachyptila vittata

Autorità

(Forster, G, 1777)

Ordine

Procellariformi

Famiglia

Procellaridi

Genere

Pachyptila

Areale e habitat

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.

Areale riproduttivo

SO : islets off South I. and outlying is. groups of New Zealand, and Nightingale, Inaccessible, and Gough (Tristan da Cunha group, sc Atlantic Ocean)

Areale non riproduttivo

to s African, tropical Indian Ocean and s Australasian waters

Migrazione

Specie stanziale

Comportamento

Comportamento migratorio: Specie stanziale.

Conservazione

Tendenza della popolazione: in diminuzione.

Tendenza della popolazione

in diminuzione