Scientists have long wondered how a wolf-like predator could have evolved on the isolated Falkland Islands independent of any related species. One theory was that its ancestors had drifted over on the ice from Patagonia. A second theory was that it was the sole survivor of well-populated pre-glacial forests on the island. The Warrah resembled the coyote and was possibly descended from the South American culpeo, a canid used as hunting dogs by Yaghan people of Tierra del Fuego. Darwin called it Canis antarcticus, putting it in the same genus as the domestic dog, wolf and coyote. Its coat was extremely dense. Its back and sides were reddish-brown or yellowish with a sprinkling of black. It had a broad skull with small ears; the frontal bones of its skull gave it a slightly bulbous look (like a golden retriever!). The warrah was 4 - 5 ft long (1.25 - 1.60 metres) with a large wolfish head, but its legs were shorter than those of a wolf and it stood only 24 inches (60 cm) at the shoulder. Although wolf-like it was neither a wolf nor a fox. It was said to bark just like a domestic dog. The warrah was only predator on the Falkland Islands and apart from a small mouse it was the only land mammal on the islands.

There are complete specimens of the Warrah (Falklands Islands Fox, Antarctic Wolf) in the Royal Belgian Institute of Natural Sciences, Brussels and Swedish Museum of Natural History, Stockholm. There are a further 9 specimens in museums around the world. A live Warrah was taken to London Zoo, England in 1868, but survived only a few years.

The Warrah was discovered by Captain Strong and the crew of the Welfare in 1692. In 1880, zoologist Thomas Huxley concluded from skull comparisons that it was related to coyote. Later studies indicated it was closer to a fox rather than a wolf. In 1914, Oldfield Thomas moved it into the genus Dusicyon, with the culpeo (photo below) and South American foxes. Its exact taxonomy is still debated - DNA studies of remains are inconclusive. Its current scientific name is Dusicyon australis, meaning foolish dog of the south, alluding to its lack of fear of man. As the only predator on the island it had nothing to fear.

The first description of the Warrah was recorded by Richard Simson, a sailor on the Welfare in 1689-90. He wrote "We saw foxes twice as big as in England, we caught a young one alive, which we kept on board for some months." The ship was later in battle against the French and the warrah leapt overboard.

Midshipman John Byron of The Wager, which was wrecked in the Straits of Magellan in 1741, took refuge on the Falkland Islands with other crew members. Byron wrote that warrahs were as big as middle-sized mastiffs: "four creatures of great fierceness resembling wolves, ran up to their bellies in the water to attack the people in the boat". The frightened sailors put off to sea again. Later the men made camp and set fire to "to the tussock to get rid of them [...] the country was ablaze as far as the eye could reach for several days, and we could see them running in great numbers." Byron saw a warrah came running towards him and shot it. His crew killed five of them. "They were always called wolves by the ship’s company, but except for their size, and the shape of the tail, I think they bore a greater resemblance to a fox. They are as big as a mastiff and their fangs are remarkably long and sharp."

In 1764, Dom Pernetty wrote in his "History of a Voyage to the Malouin Islands": "... officers of M de Bougainville’s suite were, so to speak, attacked by a sort of wild dog; this is, perhaps, the only savage animal and quadruped which exists on the Malouin (Falkland) Islands." Pernetty observed "perhaps, too, this animal is not actually fierce, and only came to present itself and approach us, because it had never seen men. The birds did not fly from us: they approached us as if they had been tame." This tameness and curiosity was also reported by later observers.

De Bougainville wrote of the Warrah in "Voyage Round the World": "The wolf-fox, so called, because it digs itself an earth and because its tail is longer and more fully furnished with hair than that of a wolf, lives in the dunes of the sea-shore. It follows the game and plans its trails intelligently, always by the shortest route from one bay to another; on our first landing we quite believed that they were the paths of human inhabitants. It would appear that this animal starves for part of the year, so meagre and thin is it. It is the size of a dog, and also barks like one, but weakly."

When Spanish settlers introduced cattle to the islands in the early 1700's, the Warrah was killed in large numbers. Surprisingly tame, they could be lured to humans with meat and then stabbed to death. Later, sheep farmers laid poison baits. The Warrah probably didn't offer any real threat to livestock and probably ate penguins and other ground-nesting birds, their eggs, sea creatures (some scavenged) and vegetation.

In 1813, Charles Barnard, captain of American sealer Young Nanina, was marooned and starving on Weddell island. "[...] in search of something to eat, and luckily procured some seal’s flesh, two foxes and three geese. I ate some of their [warrah] flesh, but it is so very strong that nothing but the sauce of extreme hunger could force it down." In March 1833 and March 1834, Darwin visited the islands in the Beagle and noted: "The only quadruped native to the island is a large wolf-like fox which is common to both East and West Falkland. I have no doubt it is a peculiar species, and confined to this archipelago; because many sealers, gauchos and Indians who have visited these islands, all maintain that no such animal is found in any part of South America [...] within a very few years after these islands shall have become regularly settled, in all probability this fox will be classed with the dodo". He noted that warrahs on West Falkland were smaller, redder and darker, with finer fur than those on East Falkland. While on the islands he collected three skin specimens, two of which were later presented to the London Zoological Society.

In "Zoology of the Voyage of the Beagle" Darwin observed "Their habits remain nearly the same to the present day, although their numbers have been greatly decreased by the singular facility with which they are destroyed. I was assured by several of the Spanish countrymen, who are employed in hunting the cattle which they run wild on these islands, that they have repeatedly killed them by means of a knife held in one hand and a piece of meat to tempt them to approach in the other [...] The number of these animals during the past fifty years must have been greatly reduced; already they are entirely banished from that half of East Falkland which lies east of the head of San Salvador Bay and Berkeley Sound; and it cannot, I think, be doubted, that as these islands are now being colonized, before the paper is decayed on which this animal has been figured, it will be ranked among those species which have perished from the earth."

Soon after Darwin left the Falkland Islands, the colonial government set a bounty on the animals to protect settlers' sheep although the warrah probably didn't pose a significant threat. Shepherds claimed high sheep killings, including claims that the warrah sucked the blood of sheep. In 1839 the American Fur Company sent a vessel to the islands for warrah skins. In 1839 Colonel Hamilton-Smith wrote in "The Dog Tribe": "Falkland Island Aquara Dog" after observing "the fur stores of Mr G. Astor in New York, a large collection of peltry which came from the Falkland Islands, where, according to reports that gentleman had received, his hunters had nearly extirpated the species".

In 1844 Bartholomew Sulivan, second lieutenant on Beagle voyage, wrote to Darwin: "It is quite incorrect what we were told respecting the difference in the Foxes of the two Islands. They are the same both in size and colour. We have never been able to detect any difference." Oldfield Thomas measured skulls of the East and West Falkland animals and reached opposite conclusion though said "no certainty is possible", called them Dusicyon darwini of East Falkland and Dusicyon australis of West Falkland.

In 1868, London Zoological Register recorded that keeper Adolphe LeComte had brought back one Antarctic Wolf. It had survived the voyage to England and was kept for several years in the London Zoo. Along with three small birds it was a survivor from a huge collection of animals sent on the Fawn, joining the mail steamer at Montevideo. Other creatures (sea lions, foxes, penguins, geese, wolves, starlings and finches) all perished through careless handling and shipping. In December 1870 the zoo got another "Antarctic Wolf", the surviving half of a pair sent by Mr Byng, the acting colonial secretary of the Falklands. Byng wrote "as Mr Darwin prophesied would probably be the case, the animal, formerly so common, has now become almost extinct on the Falklands, the depredations it commits upon the Sheep having rendered its extirpation necessary." The last warrah was killed at Shallow Bay, in the Hill Cove Canyon, West Falkland, 1876.

In Harmsworth Natural History (1910, main authors R Lydekker, Sir H Johnston & Prof JR Ainsworth-Davis) it is described on p441 under the heading “Antarctic Wolf”: “Seeing that no true wolf is found in continental South America, it is strange to meet with a small species, apparently nearly allied to the coyote, inhabiting the Falkland Islands. The Antarctic wolf (Canis antarcticus) is rather smaller than the larger examples of the coyote, and has shorter fur and a less bushy tail. The general colour is yellowish mingled with black, the individual hairs being yellow at the base, with black tips; the fur of the under parts is whitish. White is also the colour of the fur on the lips, chin, and throat, as well as on the inner margins of the ears. The most characteristic colouring, however, is that of the tail, in which the first two-fifths are of the same hue as the body, the next two-fifths black, and the remainder white. The Antarctic wolf was discovered by Pernety during his voyage in 1763 and 1764, and Darwin, who saw them during, the voyage of the Beagle, writes, “As far as I am aware, there is no other instance in any part of the world of so small a mass of broken land, distant from a continent, possessing so large an aboriginal quadruped peculiar to itself.” These wolves did not associate in packs, were largely diurnal, and usually silent, except during the breeding season; they burrow in the ground, and prey on geese and penguins. This interesting species is now apparently extinct, and unfortunately only a small number of specimens are preserved in the museums of Europe.