Wednesday, 29 August 2012

Dr Eric Guiler on the Thylacine

Thylacine ( Thylacinus cyanocephaplus )

The thylacine (also known as the Tasmanian tiger or Tasmanian wolf) formerly ranged over all of mainland Australian as well as Tasmania. Fossil remains have even been found in New Guinea. Some 3000 years ago, thylacines vanished from mainland Australia and their distribution was confined to the island of Tasmania where they occurred throughout the State.

The thylacine is the shape and size of a big dog, the largest one being measured at 9"6" (290 cm) from the nose to the tip of the long tail, (but see also this interesting web resource). Their colour varied from light sandy fawn to a darkish brown with dark stripes over the rump and back. The number of stripes varied between 13 and 21. The stripes extended onto the tail and one reached down the outside of the thigh. The belly was a creamy colour. The tail was not like that of a dog but more an extension of the body like that of a kangaroo; the tail did not have a long hairy brush.

We know surprisingly little about the the biology of the thylacine. It was formerly found in the open forest and coastal scrub habitats. It did not live in thick rain forests. At no time, since European settlement, was it a common species. The capture of a specimen always aroused local interest. There is evidence that thylacines were most abundant around 1890-1902. Thylacines bred once per annum, probably in December, and up to 4 young were carried in the pouch of the female which opened backwards. By July-August the young were too big for the pouch and were left in a sheltered place while the female hunted for food. Later the young followed the mother while she hunted.

Thylacines were not pack hunters. Single animals ran down their prey by persistent chase rather than by speed. They required a large home range, about 40 sq km being the minimum area, although 80 sq km would be more appropriate in most habitats. They stayed in their home range but, as far as is known, they were not territorial. Their food consisted of wallabies and smaller animals. It is believed that thylacines ate only fresh killed meat and never returned to a kill. This was important because it means that they could not be poisoned by baiting carcasses.

But why were thylacines killed? When the European settlers arrived in 1802 they brought sheep with them and the flocks provided a source of easily accessible food for thylacines. Many sheep were killed from about 1830 and thylacines were blamed. However, most of the deaths were probably caused by wild dogs, aborigines and vagabonds. The Government introduced a bounty scheme from 1888-1908, paying £1 (=$2) for an adult and 10 shillings (=$1) for pups. Over 2,200 were killed, as well as many upon which no bounty was claimed.

The bounty scheme, combined with habitat alteration, disturbance to the home range and a possible disease, drastically reduced the numbers of thylacines until around 1920 there were only a few left. The last thylacine to be shot in the wild was in 1932 and the last to die in captivity was in 1936. Interestingly, all the photographs of live thylacines are of captive animals; there are no photographs of the animals in the wild. There are no substantiated accounts of thylacines wilfully attacking a human. They would bite to defend themselves when cornered, or trying to escape. They seem to avoid human contact as much as possible.

Reports of alleged thylacine sightings have been received over the past 60 or so years but none have been unambigously substantiated by positive field evidence. The number of reports has diminished over the last 5-10 years and it must be concluded that, unfortunately, the thylacine is now extinct.

Prepared by Dr Eric Guiler, 
Honorary Research Associate 
School of Zoology, University of Tasmania

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