The Medium-billed Prion is a member of the Pachyptila genus, which along with the Blue Petrel, make up the prions.
The nominate subspecies, breeds on Prince Edward Island and the Crozet Islands whilst the rare macgillivray breeds on St. Paul Island and Amsterdam Island in the southern Indian Ocean.
Breeding starts in October in huge colonies up to and above one million individuals strong. A single egg is laid in November or early December, which is incubated for around 50 days. It nests in burrows, usually on islands, inland on highland plateaux or on slopes with grass or shrubs. It can also be found in caves or crevices. Both parents share the incubation duties and feed the chick once it is hatched. The chicks are attended nocturnally in order to avoid predation by skuas. They fledge around 60 days after hatching.
This marine species normally occurs offshore, and can be found in areas of upwelling outside the breeding season. Its diet is comprised mostly of crustaceans, especially krill, but also fish and squid, all of which it catches either by hydroplaning, surface-seizing or filtering.
At sea they range from South Africa eastwards to New Zealand. They are wrecked regularly across New Zealand during winter.
The prions are small petrels and together with the blue petrel, they form one of the four groups within the Procellariidae (also referred to as the prions), along with the gadfly petrels, shearwaters and fulmarine petrels.
— Greytown, 2011
Other common names: —
medium-billed prion, Lesser broad-billed prion
27 cm., 170 g., sexes alike, blue-grey head and back, a white throat and belly, a black M-shaped mark across their wings, and a broad black tip to their tail, blue bill, legs blue, bill wider that antarctic or fairy prions.
Where to find: —
salvini regularly reaches NZ in the winter. macgillivrayhas not been recorded in NZ.
Illustration description: —
Illustrations of Ornithology, 1826-43, Sir William Jardine and Prideaux John Selby.
Heather, B., & Robertson, H., Field Guide to the Birds of New Zealand, 2000.
Readers Digest Complete Book of NZ Birds, 1985.
Olliver, W.R.B., New Zealand Birds, 1955.
Page date & version: —
Monday, 2 June 2014; ver2009v1