All species › Tubenoses › Petrels and shearwaters › Common Diving Petrel
Common Diving Petrel | Pelecanoides urinatrix
Alkstormvogeltje | Potoyunco Común
The Common Diving Petrel is a tiny, stocky seabird that whirrs low over the waves on stubby wings and plunges straight through them. In the region it breeds in large numbers on the Prince Edward Islands; it reaches the mainland only very rarely.
Voice
Silent at sea. At the colonies a plaintive, mewing koo-wah-ah at night, from burrows and when flying in.
Recording: Johannes Fischer — CC BY-NC-SA 4.0 · converted to mono · xeno-canto
Identification
About 22 cm, a small, bullet-shaped bird with a short neck, short narrow wings and a very short tail, more like a tiny auk than a petrel. The upperparts are glossy black, the underparts white with a greyish wash on the sides of the neck and breast. The underwing is grey. The short, broad bill is black, the legs bright blue. The sexes are alike. It flies in a straight line low over the water with a buzzing, auk-like wingbeat, vanishes suddenly into a wave and emerges elsewhere already flying.
Confusion species
The very similar South Georgia Diving Petrel (Pelecanoides georgicus) also breeds on the Prince Edward Islands; it is whiter under the wing, has a dark line on the rear of the leg and a different shape to the bill plates, and is almost impossible to separate in the field. Storm petrels such as Wilson's Storm Petrel (Oceanites oceanicus) flutter above the water instead of diving into it and have a white rump. Prions are blue-grey with a dark M across the wings.
Habitat
Cold subantarctic sea, mainly close to the breeding islands and over the continental shelf. It dives using its wings to depths of tens of metres after krill, copepods and small fish. It breeds in self-dug burrows in peaty, vegetated slopes and among boulders, often near the shore.
Where the bird is most at home, classified by the vegetation units of southern Africa.
Range and movements
In the region a numerous breeder on Marion and Prince Edward, where it is present all year. Off the South African mainland only a handful of beached or exhausted birds have been recorded. Beyond the region it breeds on almost all subantarctic islands around the southern oceans, from the Falklands and South Georgia to the Crozet and Kerguelen islands, and along the coasts of southern Australia and New Zealand.
How and when to look
In practice a sighting is reserved for visitors to the Prince Edward Islands or crew on supply voyages. Watch for small black-and-white birds that flush from the bow of the ship and disappear into a wave in mid-flight. A bird off the Cape must be documented with photographs and preferably a specimen.
Conservation status
Not threatened. The world population numbers millions of pairs. Introduced cats and mice have seriously damaged colonies on some islands; on Marion the eradication of cats has helped, but the house mouse still threatens chicks in the burrow.
Scientific name
Pelecanoides urinatrix | (Gmelin, 1789)
Gmelin described the species in 1789 as Procellaria urinatrix; because it was later moved to another genus, the author and year stand in brackets. The genus Pelecanoides was introduced in 1799 by De Lacépède. Pelecanoides means 'pelican-like', from the Greek pelekan, 'pelican', and -oidēs, 'resembling' — for the expandable throat pouch in which these birds carry food to their young. urinatrix is Latin for 'female diver', from urinari, 'to dive' — for the way this bird hunts underwater and even flies straight through waves. The specimen the first description was based on came from Queen Charlotte Sound, New Zealand.