Common Diving Petrel

The common diving petrel (Pelecanoides urinatrix), also known as the smaller diving-petrel or simply the diving-petrel, is a diving petrel, one of four very similar auk-like small petrels of the southern oceans. It is native to South Africa and islands of the southern Indian Ocean, islands and islets off New Zealand and south-eastern Australian islands.

The German naturalist Johann Friedrich Gmelin described the common diving petrel in 1789. Its specific name urinatrix is derived from the Latin urinator "diver". Alternate common names include: Falkland/Berard's diving petrel (berard); Kerguelen/Subantarctic diving petrel (exsul); Tristan diving petrel (remaining subspecies), Puffinure plongeur (in French), Lummensturmvogel (in German), and Potoyunco comĂșn (in Spanish).

There are six subspecies, which vary in body measurements, particularly bill size:
  • P. u. urinatrix (J. F. Gmelin, 1789) Australia, North Island (New Zealand)
  • P. u. chathamensis Murphy & Harper, 1916 Stewart Island, Snares Islands, Chatham Islands (New Zealand)
  • P. u. exsul Salvin, 1896 South Georgia, subantarctic islands of the Indian Ocean, Auckland Islands, Antipodes Island, Campbell Island
  • P. u. dacunhae Nicoll, 1906 Tristan da Cunha and Gough Island
  • P. u. berard (Gaimard, 1823) Falkland Islands
  • P. u. coppingeri Mathews, 1912 uncertain, probably southern Chile

The common diving petrel is a small, plump petrel, 200 to 250 mm (7.9–9.8 in) in length and weighing around 86 to 186 g (3.0–6.6 oz). The plumage is black above and dull white below and it has a large black bill. The wings have thin white strips. The face and neck can be more brown than black. The legs are blue. Unless seen very close, it is almost indistinguishable from the South Georgia diving petrel. The common petrel has brown inner web primary feathers, whereas the South Georgia petrel has light inner web feathering. Common petrels have smaller and narrower bills than the South Georgia petrel. Another difference is that the South Georgia diving petrel has a posterior black line down the tarsi. There are also slight size differences.

The common diving petrel is found between latitudes 35 and 55 degrees south, mostly around islands. While the population is decreasing, it is not believed to be rapid enough to be of concern. While 1.5 m (4.9 ft) nests are usually built on vegetated slopes, they are occasionally built on flatland.

The common diving petrel feeds on the continental shelf during the breeding season, its movements during the non-breeding season are poorly known and whether it disperses more widely is not known. Like other members of their family they catch prey by wing-propelled diving, and are capable of diving to 60 m (200 ft). The diet of this species is dominated by crustaceans. They are known to forage at night on vertically migrating plankton. Feeding is mostly done in the ocean near the shore, but sometimes in the deeper pelagic zone during non-breeding season, which is only 2 months of the year. The mating habits are not well documented, although pairs form monogamous relationships. Breeding colonies are large and there is about one nest per 1 square metre (11 sq ft). The nest is a burrow around 50 cm long with a chamber at the bottom which may or may not be lined with dried grass. Females lay a single white egg, which measures 38 x 29 mm, and is incubated for 53–55 days. The young are brooded for 10–15 days and fledgling occurs at 45–59 days. Both parents take care of the young, which are grey-grown when hatched. The life expectancy is 6.5 years.