The hapless fox from the Chiloé Archipelago wasn't the only canid remarked upon by Charles Darwin in the popular write-up of his world tour. Amongst the others was the Falklands fox, which Darwin writes about in chapter 9 of The Voyage of the Beagle:
The only quadruped native to the island; is a large wolf- like fox (Canis antarcticus), 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.
Molina, from a similarity in habits, thought that this was the same with his "culpeu"; but I have seen both, and they are quite distinct. These wolves are well known from Byron's account of their tameness and curiosity, which the sailors, who ran into the water to avoid them, mistook for fierceness. To this day their manners remain the same. They have been observed to enter a tent, and actually pull some meat from beneath the head of a sleeping seaman. The Gauchos also have frequently in the evening killed them, by holding out a piece of meat in one hand, and in the other a knife ready to stick them. 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. Their numbers have rapidly decreased; they are already banished from that half of the island which lies to the eastward of the neck of land between St. Salvador Bay and Berkeley Sound. Within a very few years after these islands shall have become regularly settled, in all probability this fox will be classed with the dodo, as an animal which has perished from the face of the earth.
How the Falklands fox (also known as the Falklands wolf or warrah) got to the Falkland Islands, which lie 480km from the South American mainland, is still something of a mystery. Recent genetic analyses show that the animal's closest living relative is the maned wolf of South America. But these analyses also indicate that the two canids' lineages diverged over 6 million years ago—and canids do not appear in the South American fossil record until 2.5 million years ago. From this we can infer that, if absolute genetic dating is to be trusted (concerning which, I personally entertain some doubts), the two lineages most likely evolved in North America. We should expect, therefore, to find more recent ancestors of the Falklands fox in the South American fossil record. One possible candidate for such an ancestor is Dusicyon avus from Patagonia, which went extinct 6,000 to 8,000 years ago.
It is believed that the ancestors of the Falklands fox must have crossed over to the islands during the last ice age (which ended 11,500 years ago), when the lower sea-level probably caused a land-bridge between the Falkland Islands and the South American mainland. Darwin's view was that they might have crossed to the Falkland Islands on icebergs (see below). Another, very unlikely suggestion is that the fox is descended from domesticated foxes transported to the islands by the Yaghan people of Tierra del Fuego, who used culpeos as hunting dogs. But there is no archaeological evidence that any humans visited the Falkland Islands before the British first arrived there, and, as Darwin himself pointed out (see above) culpeos are quite distinct from Falkland foxes.
En route home to Blighty aboard HMS Beagle in 1835, Darwin wrote up some Ornithological and Animal Notes from the voyage, in which he included some observations about the Falklands fox:
Out of the four specimens brought home in the Beagle, three will be seen to be darker coloured, they come from the East Isd. The fourth is smaller & rusty coloured, & is from the West Isd. — Mr Lowe, who has been acquainted with these Islands for twenty years, & who is an accurate observer of Nature, asserts that this difference between the Foxes of the two Isds is invariable & constant. He says he has long since observed it. — An accurate comparison of these specimens will be interesting. I have omitted to add that the difference was corroborated by the officers of the Adventure. —
So, perhaps the Falkland fox was actually two species living on the two main Falkland Islands. If so, it would have made another wonderful example of closely related species living on adjacent islands, as was to be the case with Darwin's more famous examples of the Galápagos mockingbirds, tortoises and finches. Indeed, Darwin wrote about the Falkland fox again in passing in his ornithological notes, in an extremely famous passage about the Galápagos mockingbirds, in which he first questioned the stability of species:
… I have specimens [of Galápagos mockingbirds] from four of the larger Islands; the two above enumerated, and (3349: female. Albermarle Isd.) & (3350: male: James Isd). — The specimens from Chatham & Albermarle Isd appear to be the same; but the other two are different. In each Isld. each kind is exclusively found: habits of all are indistinguishable. When I recollect, the fact that the form of the body, shape of scales & general size, the Spaniards can at once pronounce, from which Island any Tortoise may have been brought. When I see these Islands in sight of each other, & possessed of but a scanty stock of animals, tenanted by these birds, but slightly differing in structure & filling the same place in Nature, I must suspect they are only varieties.
The only fact of a similar kind of which I am aware, is the constant | asserted difference — between the wolf-like Fox of East & West Falkland Islds.
— If there is the slightest foundation for these remarks the zoology of Archipelagoes — will be well worth examining; for such facts would undermine the stability of Species.
But, by the time Darwin came to edit The Zoology of the Voyage of H.M.S. Beagle, he was no longer of the opinion that the Falklands fox comprised two distinct species, commenting:
… Mr. Gray, of the British Museum, had the kindness to compare in my presence the specimens deposited there by Captain Fitzroy, but he could not detect any essential difference between them.
Had Darwin been more convinced that the Falklands fox comprised two species, he might well have given it/them more prominence in On the Origin of Species. As it was, however, the poor creature only earns a passing mention:
… as yet I have not found a single instance, free from doubt, of a terrestrial mammal (excluding domesticated animals kept by the natives) inhabiting an island situated above 300 miles from a continent or great continental island; and many islands situated at a much less distance are equally barren. The Falkland Islands, which are inhabited by a wolf-like fox, come nearest to an exception; but this group cannot be considered as oceanic, as it lies on a bank connected with the mainland; moreover, icebergs formerly brought boulders to its western shores, and they may have formerly transported foxes, as so frequently now happens in the arctic regions.
Nowadays, the Falkland fox is known by the scientific name Dusicyon australis, meaning literally foolish dog of the south—a reference to the animal's absence of fear of humans.
Perhaps it was this lack of fear which was the beast's undoing. For Darwin's prophesy turned out to be tragically accurate: the once-common species was hunted by American fur traders in the 1830s, and was later persecuted by Scottish settlers wishing to protect their sheep.
It is believed that the last individual Falkland fox was killed at Shallow Bay, West Falkland in 1876.
Further reading: Alas, poor warrah… New Scientist (20-Dec-2003) [subscribers only link]