The odds of the Tasmanian tiger still existing are about one in 1.6 trillion according to scientists.
While there are occasional claims of sightings of the animal, competition with dingoes drove the species to extinction on the mainland of Australia almost 2000 years ago.
Not to be confused with the Tasmanian devil, the Tasmanian tiger or thylacine once occupied most of Australia with a small isolated population persisting on the island of Tasmania until it was colonised by the British in the 19th century.
However, despite the fact the animal is classified as extinct, the idea that a few might be clinging on in remote areas has continued to make headlines over the years.
Most recently, it was reported that researchers in North Queensland are launching a new study on Tasmanian tigers, following a series of reported sightings in Cape York.
James Cook University scientists Professor Bill Laurance and Dr Sandra Abell plan to use more than 50 camera traps to survey areas where Tassie tigers have reportedly been seen – namely the remote Cape York peninsula at the northern tip of mainland Australia.
But mathematical modelling by Colin Carlson at the University of California, and his colleagues, suggest the probability of Tasmanian tigers being alive in 2017 is virtually zero.
His team collected data on confirmed and unconfirmed sightings from 1900 onwards to model the likelihood of thylacines being extinct at different points in time.
Their least optimistic scenario considered only the confirmed sightings, whereas the most optimistic factored in the unconfirmed sightings.
The team’s most optimistic estimate predicts that thylacines could have clung on in the wild only until the late 1950s.
The probability that they are still alive in 2017 is 1 in 1.6 trillion, the modelling suggests.
Based purely on recorded sightings, the research may be less applicable to far-flung wildernesses like Cape York, Brendan Wintle at the University of Melbourne in Victoria, Australia said.
His research team has developed an alternative model that includes data about previous searches in remote regions, as well as aspects of the animal’s biology and behaviour such as its nocturnal nature, which makes sighting less likely, and its size.
However, even this model concludes that the latest possible extinction date for Tasmanian tigers is 1983.
Believed to be the last Tasmanian Tiger was thought to have died in Hobart zoo in Tasmania, Australia in 1936.