Tasmanian Tigers Killed By Climate Change in Australia Before Going Extinct

A thylacine, aka the Tasmanian wolf or Tasmanian tiger, in captivity, circa 1930. These animals are thought to be extinct, since the last known wild thylacine was shot in 1930 and the last captive one died in 1936. Photo by Topical Press Agency/Hulton Archive/Getty Images

Little is known about the thylacine, aka the Tasmanian tiger or Tasmanian wolf. Humans killed them off of Tasmania so quickly that the animals went extinct before we could properly conserve them. But research published Thursday at the University of Adelaide may help answer one of the questions about this mysterious creature: How did it go extinct on the mainland of Australia?

The thylacine, native to Western Australia and Tasmania (the island off the southern coast of the Australian mainland), looked like a dog, hunted like a dog and had a skeleton almost identical to that of a dog. But it was a marsupial, with a pouch and all, making it more closely related to wombats and kangaroos. Yet it had a striped back, hence the "tiger" name.

Most scientists consider the thylacine to be extinct, with the last recorded animal having died after being left out in the cold at a zoo (RIP Benjamin). Occasionally, there are claimed sightings of live thylacines. Australian scientists have even attempted to clone the animal from dead specimens. But the Tasmanian tiger is probably extinct, or at least extremely rare.

Thylacines went extinct on the Australian mainland 3,200 years ago, but they hung on and were thriving in Tasmania before European colonists arrived. Colonists believed that the marsupial carnivores were eating their sheep, so they put a bounty on their heads. Between 1888 and 1909, the government awarded more than 2,000 bounties for dead thylacines, killed indiscriminately by hunters. Since then, the thylacine has become one of the most iconic animals of human-driven extinction, along with the passenger pigeon, quagga, and dodo.

But the question remains: How did all the mainland thylacines die off so quickly? Fossil collections prove that they lived in Australia, and for many years the origin of their demise was a matter of speculation.

Did dingoes do them in? Dingoes, being similar morphologically to Tasmanian wolves, occupy a similar niche, hunting similar prey, and biologists have theorized that they could have competed.

Did aboriginal hunting techniques kill them off? Another theory holds that as aboriginal populations expanded, perhaps they could have wiped out these animals.

Researchers at the University of Adelaide now suggest a different culprit: climate change. By studying the DNA from 51 museum specimens and sub-fossil remains, scientists found that Tasmanian tigers had similar genetic diversity on both the mainland and Tasmania. They also both suffered a major population nosedive around the same time as a climate event associated with an El Niño-Southern Oscillation (ENSO), a weather phenomenon that occurs in the equatorial Pacific.

Australia is known to have more severe effects from El Niño, so the population in Tasmania, where rainfall was likely higher, could have recovered, while the effect on the Australian population was more fatal. The drought-like conditions that ENSO created could have left the animals without the water they needed to survive.

It's possible that all three factors or more drove the thylacine to extinction on the mainland of Australia. But without this event, we might still have these bizarre marsupials alive to study today.