Old Droppings, New Zoology

An Australian zoologist is studying preserved animal droppings to try and find out whether the extinct Tasmanian Tiger might have roamed the wild long after it was believed to have died out, according to news from the University of Adelaide.

The Tasmanian Tiger, also known as the thylacine, was found throughout Tasmania before the 19th Century and was once the world's largest meat-eating marsupial. The animal was about the size of a big dog, with stripes, a heavy tail and large head. It had once lived on the Australian mainland as well, but is believed to have disappeared there some 2,000 years ago when humans created growing competition.

In Tasmania, the thylacine's numbers declined after European settlers arrived in 1803. Many were killed after being blamed for attacks on sheep, prompting the government to pay a bounty to farmers and hunters. However, disease, habitat loss and competition from settler-introduced wild dogs are also believed to have contributed to the Tasmanian Tiger's demise.

By the 1920s, thylacine sightings in Tasmania were rare. However, one Tasmanian Tiger remained alive in captivity at Hobart Zoo until it died in 1936.

Now, however, University of Adelaide zoologist Jeremy Austin, who works for the Australian Centre for Ancient DNA, is seeking to discover whether thylacine might have still survived in the wild beyond the 1930s. The key to his detective work: DNA extracted from animal droppings, also known as scats, collected in the late 1950s and '60s and since preserved at the Tasmanian Museum and Art Gallery.

"The scats were found by Eric Guiler, Australia's last real thylacine expert, who said he thought it more probable they came from the Tasmanian Tiger rather than a dog, Tasmanian Devil or quoll (another carnivorous marsupial)," Austin said. "If we find thylacine DNA from the 1950s scats, it will be significant. The last Tasmanian Tiger killed in the wild was in 1918, so there's a 20-year gap between a wild sighting and one in captivity. It's a long shot that they were still around in the 1950s, but we can't rule it out at this stage."

Austin is also studying DNA taken from ancient bones found in Australia to determine whether the Tasmanian Tiger and Tasmanian Devil were different species from the ones that once lived on the mainland.

"The DNA may be able to reveal they were different species to the Tasmanian animals, although it's unlikely," Austin said. "It's only been 10,000 years since Bass Strait flooded and Tasmania was separated from the mainland. That's not a long period of time in evolutionary terms. The main reason people think they may have been different species is that the Tasmanian Tiger was much bigger than its mainland cousins. That's not surprising given the climate, because the colder the environment, the larger the animal."

The University of Adelaide, "Tasmanian Tiger Extinction Mystery." URL: (http://adelaide.edu/news/news19761.html)

Wikipedia, "Thylacine." URL: (http://en.wikipedia.org/wiki/Tasmanian_Tiger#Extinction)