South Georgia Diving-petrel
Encyclopedia
The South Georgia Diving Petrel or Georgian Diving-petrel (Pelecanoides georgicus) is a diving-petrel, one of four very similar auk
-like small petrel
s of the southern oceans. It is native to south Atlantic and islands of the southern Indian Ocean
, islands and islets off New Zealand
and south-eastern Australian islands.
Robert Cushman Murphy
and his partner Harper described the South Georgia Diving Petrel in 1916. Its specific name georgicus is derived from the name of the islands were on when they identified the species: South Georgia. Alternate common names include: Puffinure de Géorgie du Sud (in French), Breitschnabel Lummensturmvogel (in German), and Potoyunco de Georgia (in Spanish).
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 Common 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.
islands. It breeds on South Georgia in the south Atlantic and on the Prince Edward Islands
, Crozet Islands
, Kerguelen Islands
and Heard Island and McDonald Islands
in the southern Indian Ocean. In New Zealand
, it breeds on Codfish Island
and formerly bred on the Auckland Islands
. It disperses to surrounding seas and vagrants have been recorded in the Falkland Islands
and Australia
. While 1.5 m (4.9 ft) nests are usually built on vegetated slopes, they are occasionally built on flatland.
ic crustacean
s, particularly krill
, but will also feed on small fish and young cephalopod
s. Breeding season is October–February. The female lays one egg that is incubated for 44–52 days. Fledging occurs in 43–60 days. Threats to the South Georgia Diving Petrel include skua
s, cats, rats, and weka
. They are extinct on Auckland Island
because
Hooker's Sea Lion
s destroyed their nests. South Georgia Diving Petrels are noted for their diving capabilities. "The most proficient divers of the order Procellariformes are likely to be the diving petrels in the family Pelecanoididae." Dive depths for the South Georgia Diving Petrel have been recorded to 48.6 m (159.4 ft), with most in the range of 20.4 to 24.4 m (66.9 to 80.1 ft).
Auk
An auk is a bird of the family Alcidae in the order Charadriiformes. Auks are superficially similar to penguins due to their black-and-white colours, their upright posture and some of their habits...
-like small petrel
Petrel
Petrels are tube-nosed seabirds in the bird order Procellariiformes. The common name does not indicate relationship beyond that point, as "petrels" occur in three of the four families within that group...
s of the southern oceans. It is native to south Atlantic and islands of the southern Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
, islands and islets off New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
and south-eastern Australian islands.
Taxonomy and systematics
The American ornithologistOrnithology
Ornithology is a branch of zoology that concerns the study of birds. Several aspects of ornithology differ from related disciplines, due partly to the high visibility and the aesthetic appeal of birds...
Robert Cushman Murphy
Robert Cushman Murphy
Robert Cushman Murphy was an American ornithologist and former Lamont curator of birds for the American Museum of Natural History....
and his partner Harper described the South Georgia Diving Petrel in 1916. Its specific name georgicus is derived from the name of the islands were on when they identified the species: South Georgia. Alternate common names include: Puffinure de Géorgie du Sud (in French), Breitschnabel Lummensturmvogel (in German), and Potoyunco de Georgia (in Spanish).
Description
The South Georgia Diving Petrel is a small, plump petrel, 180 to 220 mm (7.1 to 8.7 in) in length and weighing around 90 to 150 g (3.2 to 5.3 oz). The plumagePlumage
Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...
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 Common Diving Petrel
Common Diving Petrel
The Common Diving Petrel , 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...
. 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.
Distribution and habitat
It nests in colonies on SubantarcticSubantarctic
The Subantarctic is a region in the southern hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46° – 60° south of the Equator. The subantarctic region includes many islands in the southern parts of the Indian Ocean, Atlantic Ocean and...
islands. It breeds on South Georgia in the south Atlantic and on the Prince Edward Islands
Prince Edward Islands
The Prince Edward Islands are two small islands in the sub-antarctic Indian Ocean that are part of South Africa. The islands, named Marion Island and Prince Edward Island, are located at ....
, Crozet Islands
Crozet Islands
The Crozet Islands are a sub-antarctic archipelago of small islands in the southern Indian Ocean. They form one of the five administrative districts of the French Southern and Antarctic Lands.-Geography:...
, Kerguelen Islands
Kerguelen Islands
The Kerguelen Islands , also known as the Desolation Islands, are a group of islands in the southern Indian Ocean constituting the emerged part of the otherwise submerged Kerguelen Plateau. The islands, along with Adélie Land, the Crozet Islands and the Amsterdam and Saint Paul Islands are part of...
and Heard Island and McDonald Islands
Heard Island and McDonald Islands
The Heard Island and McDonald Islands are an Australian external territory and volcanic group of barren Antarctic islands, about two-thirds of the way from Madagascar to Antarctica. The group's overall size is in area and it has of coastline...
in the southern Indian Ocean. In New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
, it breeds on Codfish Island
Codfish Island
Codfish Island or Whenua Hou is a small island located to the west of Stewart Island/Rakiura in southern New Zealand. It reaches a height of close to the south coast. Following the eradication of possums and weka, it is a predator-free bird sanctuary and the focus of Kakapo recovery efforts...
and formerly bred on the Auckland Islands
Auckland Islands
The Auckland Islands are an archipelago of the New Zealand Sub-Antarctic Islands and include Auckland Island, Adams Island, Enderby Island, Disappointment Island, Ewing Island, Rose Island, Dundas Island and Green Island, with a combined area of...
. It disperses to surrounding seas and vagrants have been recorded in the Falkland Islands
Falkland Islands
The Falkland Islands are an archipelago in the South Atlantic Ocean, located about from the coast of mainland South America. The archipelago consists of East Falkland, West Falkland and 776 lesser islands. The capital, Stanley, is on East Falkland...
and Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
. While 1.5 m (4.9 ft) nests are usually built on vegetated slopes, they are occasionally built on flatland.
Behaviour
The South Georgia Diving Petrel feeds primarily on planktonPlankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
ic crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s, particularly krill
Krill
Krill is the common name given to the order Euphausiacea of shrimp-like marine crustaceans. Also known as euphausiids, these small invertebrates are found in all oceans of the world...
, but will also feed on small fish and young cephalopod
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...
s. Breeding season is October–February. The female lays one egg that is incubated for 44–52 days. Fledging occurs in 43–60 days. Threats to the South Georgia Diving Petrel include skua
Skua
The skuas are a group of seabirds with about seven species forming the family Stercorariidae and the genus Stercorarius. The three smaller skuas are called jaegers in North America....
s, cats, rats, and weka
Weka
The Weka or woodhen is a flightless bird species of the rail family. It is endemic to New Zealand, where four subspecies are recognized. Weka are sturdy brown birds, about the size of a chicken. As omnivores, they feed mainly on invertebrates and fruit...
. They are extinct on Auckland Island
Auckland Island
Auckland Island is the main island of the Auckland Islands, an uninhabited archipelago in the south Pacific Ocean belonging to New Zealand. It is inscribed in the together with the other subantarctic New Zealand islands in the region as follows: 877-004 Auckland Isls, New Zealand S50.29 E165.52...
because
Hooker's Sea Lion
New Zealand Sea Lion
The New Zealand Sea Lion also known as Hooker's Sea Lion or Whakahao in Māori is a species of sea lion that breeds around the coast of New Zealand's South Island and Stewart Island/Rakiura to some extent, and to a greater extent around the New Zealand Sub-Antarctic Islands, especially the Auckland...
s destroyed their nests. South Georgia Diving Petrels are noted for their diving capabilities. "The most proficient divers of the order Procellariformes are likely to be the diving petrels in the family Pelecanoididae." Dive depths for the South Georgia Diving Petrel have been recorded to 48.6 m (159.4 ft), with most in the range of 20.4 to 24.4 m (66.9 to 80.1 ft).