The Slender-billed Prion is a member of the Pachyptila genus and along with the Blue Petrel make up the prions. They are then members of the Procellariiformes order, and 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 7 and 9 horny plates. They produce a stomach oil made up of wax esters and triglycerides that is stored in the proventriculus. This is used against predators as well 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.
Pachyptila, the word, comes from the Greek words pakhus and ptilon. Pakhus means thick or stout and ptilon means a feather. Also from the Greek language, Prion comes from the word pri?n meaning a saw, which is in reference to its serrated edges of its bill.
Like all prions, they are blue-grey above and white below with a dark "M" on their back to their wingtips. They have a white eyebrow and a dark line extending from below the eye almost to the neck. Their tail is wedge-shaped and grey with a black tip, their bill is blue-grey, and their feet are pale blue.
They are annual breeders and will lay one egg. Both parents will then incubate the egg and care for the young until they fledge.
Like all prions, the Slender-billed eat zooplankton, by filtering it through their bill.
Range and habitat
The Slender-billed Prion spends all of his non-breeding time over ocean water in the southern oceans. When breeding, they will do so on the Crozet Islands, the Kerguelen Islands, the Falkland islands and Noir Island off the coast of southern Chile.
This species has a very large range and their estimated population is 7,000,000, allowing the IUCN to classify them as Least Concern.