The Antarctic Realm
The Antarctic Realm, as here defined, includes the continent of Antarctica as well as a number of extremely isolated sub-Antarctic islands in the southern Atlantic, Pacific, Indian, and Southern oceans.
Species and subspecies
The southern elephant seal (Mirounga leonina) is the largest extant sea mammal that is not a cetacean. The species has a nearly circumpolar distribution in the Southern Ocean, with the majority of haul-out sites located on sub-Antarctic and Antarctic islands but also along the coasts of southern Argentina, Chile, and Antarctica. Vagrants are frequently found much further north, and colonies once existed on Tasmania, Saint Helena, and the Juan Fernández Islands. During the nineteenth century it was nearly exterminated by large-scale seal hunting, but with that at an end it had recovered to a sizeable population by the 1950s. However, since then an unexplained decline in the subpopulations of the southern Indian and Pacific oceans has occurred. Overall, the animals are not considered to be threatened at present, although the scarcity of suitable breeding sites in Antarctica makes them potentially vulnerable to human interference on islands and in coastal areas.
The emperor penguin (Aptenodytes forsteri) is the tallest and heaviest of all living penguins. The species has a circumpolar range with approximately 54 breeding colonies dotted around the entire coast of Antarctica, the largest of which occur in the Ross Sea and Weddell Sea. Individual vagrants have been recorded on Heard Island, South Georgia, and occasionally in New Zealand. Populations have been decreasing everywhere in recent years owing to the effects of climate change and the resulting loss of sea ice, as well as declining food availability, disease, and disturbance of breeding areas by humans. These threats are projected to increase significantly in the future.
The Macaroni penguin (Eudyptes chrysolophus) remains widespread from the southern tip of South America south to the Antarctic Peninsula and east almost as far as Australia, where it breeds in at least 55 localities mainly on isolated sub-Antarctic islands. Indeed, with a total population of around 18 million the species is thought to be the most numerous of all penguins, but it has nevertheless suffered significant declines since the 1970s due perhaps to changing climatic conditions and competition for food from increasing numbers of fur seals.
The wandering albatross (Diomedea exulans) is one of the largest birds in the world and possesses the longest wingspan. The species has a circumpolar distribution within which individuals spend most of their lives in flight and are incredibly far-ranging, some having been known to circumnavigate the entire Southern Ocean three times in a single year, a distance of more than 120,000 km. Breeding takes place on South Georgia, Macquarie Island, and in the Prince Edward, Crozet, and Kerguelen islands. Populations have declined since the late twentieth century, mainly due to the effects of longline fisheries and pollution.
The white-chinned petrel (Procellaria aequinoctialis) is a type of seabird that ranges across the Southern Ocean as far north as southern Australia, Peru and Namibia and south to the edge of the Antarctic pack-ice. While still common the species has suffered very high rates of incidental mortality due to fisheries by-catch, and is further threatened by habitat degradation and chick predation by invasive species in its scattered, sub-Antarctic breeding colonies.
Two subspecies of southern pintail (Anas eatoni), a type of dabbling duck, are confined to island groups of the southern Indian Ocean, where they are threatened by feral cats. They will be discussed below.
Antarctica is Earth’s southernmost continent and is situated almost entirely south of the Antarctic Circle, surrounded by the Southern Ocean. Roughly twice the size of Australia, it consists of a large island or perhaps two; parts of it may even consist of vast hidden archipelagos. Several island groups surround the continent. About 98 per cent of it is covered by an immense ice sheet that averages 1.9 km in thickness, extending to all but the northernmost reaches of the Antarctic Peninsula. Ice-free areas are mostly bare rock and are located chiefly along the low coasts and offshore islands. In terms of climate it is an ice desert. It is, on average, the coldest, driest, and windiest continent, and has the highest average elevation. The sparse vegetation is chiefly lichens, mosses, and algae. Vertebrates, all marine and all taking their food from the sea, are comprised of seals and a small number of birds, notably penguins and petrels. However, the bird species are often tremendously numerous. Some of the largest bird colonies in the world are found on the sub-Antarctic islands off Antarctica. The present lifelessness of Antarctica has not always been the case. Owing to continental drift, for long periods in its history the climate was temperate, allowing forests of deciduous and coniferous trees to grow along certain coasts, for instance, on the Antarctic Peninsula, and presumably also in the interior. Numerous reptile and amphibian fossils have been discovered in recent decades, along with coal formed by an ancient flora from a period when Antarctica was in its present location.
Isolated Sub-Antarctic Islands
Several remote island groups are located within the cold waters of the southern Atlantic, Pacific, and Indian oceans, where they are home to a number of endemic bird species.
Fihol’s southern rockhopper penguin (Eudyptes chrysocome fiholi) breeds on sub-Antarctic islands of the southern Indian and southern Pacific oceans, after which the birds disperse widely and remain at sea, travelling up to 5000 km during this time.
The Indian yellow-nosed albatross (Thalassarche carteri) ranges at sea from South Africa to just east of New Zealand, breeding on a number of islands in the southern Indian Ocean.
The grey-headed albatross (T. chrysostoma) has a circumpolar distribution, nesting on isolated islands in the Southern Ocean as well as in the southern Atlantic and southern Indian Ocean. Both have suffered significant declines due to commercial longline fisheries by-catch and disease within their nesting colonies.
The sooty albatross (Phoebetria fusca) ranges at sea across the Southern Ocean from South America to Australia, breeding on sub-Antarctic islands in the southern Atlantic and Indian oceans. The species has declined considerably since the late twentieth century due mainly to commercial longline fisheries by-catch, as well as introduced predators and disease within their nesting colonies.
The Kerguelen Islands
The Kerguelen Islands (Îles Kerguelen in French; also known as the Desolation Islands) are located in the southern Indian Ocean about 450 km north-west of the uninhabited Heard and McDonald Islands, more than 3300 km away from the nearest populated location. The main island, Grande Terre, is surrounded by a further 300 smaller islands and islets.
The Kerguelen pintail (Anas eatoni eatoni) occurs only in coastal areas of the Kerguelen Islands, where it is believed to be declining. During the 1950s and 1960s it was introduced to Amsterdam Island, but has not been seen there since 1970 and is assumed to have been extirpated.
The Crozet Islands
The Crozet Islands (Îles Crozet in French) are a sub-Antarctic archipelago of six small islands in the southern Indian Ocean. They are located roughly halfway between Madagascar and Antarctica.
The Crozet shag (Leucocarbo melanogenis) is a type of marine cormorant that breeds only on the Crozet Islands and on Prince Edward and Marion Islands, the latter being two small sub-Antarctic islands located south-west of South Africa.
The Crozet pintail (Anas eatoni drygalskyi) is confined to the Crozet Islands, where in the early 1980s the total population was estimated at between 600 and 700 pairs.
Heard and McDonald Islands
More properly known as the Territory of Heard Island and McDonald Islands (as administered by Australia), this volcanic island group is located about two-thirds of the way from Madagascar to Antarctica and about 4100 km south-west of Perth. Uninhabited and barren, they are among the most remote places on Earth. Heard Island is by far the largest in the group. Bleak, mountainous, and largely covered by ice, it is dominated by Mawson Peak, a 2745-m-high active volcano.
The Heard shag (Leucocarbo nivalis) is a type of marine cormorant that breeds only on Heard Island. The total population is thought to be around 1000 breeding pairs.
Amsterdam and Saint Paul Islands
The Amsterdam and Saint Paul Islands are located in the southern Indian Ocean.
Amsterdam Island (Île Amsterdam in French) is a potentially active volcanic island that last erupted in 1792.
The Amsterdam albatross (Diomedea amsterdamensis) has long been one of the world’s rarest birds. While it ranges from the coast of eastern South Africa to the south of Western Australia, the species breeds only on the Plateau des Tourbières on Amsterdam Island. The total population is currently estimated at around 170.
The Amsterdam wigeon (Mereca marecula), also known as the Amsterdam duck, was a species of waterfowl endemic to small freshwater pools and lakes on Amsterdam Island. This flightless species is known only from bones first discovered in the 1950s and described as being ‘no more than a few hundred years old’. It is thought to have been driven to extinction by visiting whalers and the rats they brought with them soon after.
Saint Paul Island
Saint Paul Island (Île Saint-Paul in French) is located about 85 km south-west of Amsterdam Island. A report of ‘a small brown duck, not much larger than a thrush’ from English explorer John Barrow’s 1793 visit to Saint Paul Island presumably refers to a species related to, although different from, the Amsterdam wigeon (Mereca marecula).
South Georgia Island
South Georgia Island (Isla San Pedro in Spanish) is a sub-Antarctic island located in the southern Atlantic Ocean north of the Antarctic Peninsula and directly east of Cape Horn. Introduced rats were long the main threat to the endemic bird species, but have now been eradicated.
The South Georgia shag (Leucocarbo georgianus) is a type of marine cormorant that breeds only on South Georgia and nearby Shag Rocks.
The South Georgia yellow-billed pintail (Anas georgica georgica) is a type of duck confined to South Georgia, where the total population is thought to number between 1000 and 1500 pairs.
The South Georgia pipit (Anthus antarcticus) is a sparrowlike bird confined to South Georgia, where it was long threatened by introduced rats and mice until their eradication.
Anthropogenic effects on the flora and fauna
Antarctica has no indigenous human population and there is no evidence that it was seen by humans until the nineteenth century. However, belief in the existence of a Terra Australis – a vast polar continent in the far south of the globe to ‘balance’ the northern lands of Europe, Asia and North Africa – had prevailed since the days of Ptolemy in the first century ad. Even in the late seventeenth century, after explorers had found that South America and Australia were not part of the fabled southern continent, geographers continued to believe that one, much larger than its actual size, did indeed exist. In 1675 English merchant Anthony de la Roché accidentally discovered South Georgia Island, the first-ever of land south of the Antarctic Convergence. In 1739 Jean Bouvet de Lozier discovered what is now Bouvet Island. In 1772 Yves-Joseph de Kerguelen-Trémarec discovered the Kerguelen Islands. During 1773–75 the English explorer James Cook finally disproved the existence of ‘Terra Australis Incognita’. He also discovered the South Sandwich Islands and proclaimed the existence of Antarctica ‘probable’, even going so far as to speculate in his journal about whether he had actually discovered a part of it two years earlier. While this is doubtful, his ships HMS Resolution and Adventure did cross the Antarctic Circle on at least three occasions, and came within about 120 km of the coast before retreating in the face of field ice in January 1773. The first confirmed sighting would not take place until the First Russian Antarctic Expedition of 1820, led by Fabian Gottlieb von Bellingshausen and Mikhail Lazarev, reached a point within 32 km of what is now Queen Maud’s Land and recorded the sight of an ice shelf. In 1820 Edward Bransfield also sighted the Antarctic Peninsula, in the process discovering the northernmost islands of the South Shetlands. In 1821 sealers Nathaniel Palmer and George Powell discovered the South Orkney Islands. In 1823 sealer James Weddell sailed into what is now known as the Weddell Sea. In 1831–32 John Biscoe discovered Enderby Land. In 1839 the Wilkes Expedition sailed from Sydney, Australia into the Southern Ocean and reported the discovery ‘of an Antarctic continent west of the Balleny Islands’ on 25 January 1840. This part of the continent is still called Wilkes Land. Also in 1840, crewmen from the expedition of Jules Durmont d’Urville disembarked on a rocky islet about 4 km from Cape Géodésie, on the coast of Adélie Land, where they took samples and erected the French flag. The next expedition to arrive was that of James Clark Ross, who passed through what is now known as the Ross Sea and discovered Ross Island in 1841. In the process he sailed along a huge wall of ice that was later named the Ross Ice Shelf. Mount Erebus and Mount Terror are named after two of his ships. While the first claimed landing on the continent, by the American sealer John Davis, may have taken place as early as 1821, the first confirmed landing was by the American, Mercator Cooper, in East Antarctica on 26 January 1853. Exploration of the mainland intensified during the early twentieth century. In 1902–04, the Englishman Robert Falcon Scott traced the length of the Ross Ice Shelf, discovered the Edward VII Peninsula, crossed the Transantarctic Mountains, and discovered the Antarctic Plateau, penetrating nearly 240 km into it. He would also be the first to see the dry valleys of the Antarctic. The expedition of the Norwegian explorer Roald Amundsen became the first to reach the geographic South Pole on 14 December 1911. Scott and his team reached the Pole just over a month later, all perishing on the return journey.
Thus, Antarctica is the only great landmass that has had no human settlement until the twentieth century. The latter are now present only on a limited basis, in limited naval, tourism, and research stations resembling science-fiction Martian colonies. It is also true that humans have not yet had much of an effect on animal life there, apart from pollution and the effects of global climate change. Because the Antarctic ecosystem is rather simple and therefore very sensitive to disturbance, it is fortunate that its vegetation and fauna is protected by a conservation agreement signed in 1964 by 12 nations (Argentina, Australia, Belgium, Chile, France, Great Britain, Japan, New Zealand, Norway, South Africa, the United States, and the former USSR) engaged in research in Antarctica. The agreement covers harmful interference, the introduction of non-indigenous species, parasites, and diseases, and so forth. Antarctica is thus the first continent in the world where man has tried by treaty to prevent disastrous interference with animal populations. Antarctica is also the only continental area where not a single species has been wiped out since humans arrived there.
In recent historical time (i.e. since ad 1500), the Antarctic Realm has lost at least 1 species of vertebrate (a bird). In addition, there are 13 species/3 subspecies of birds currently threatened with extinction (that is to say, either Critically Endangered, Endangered, or Vulnerable according to the IUCN Red List, as well as certain forms either listed as Data Deficient or Not Assessed but which are clearly at some risk of extinction).