Tasmanian tiger might have survived to 1980s or later
Researchers have shed new light on the extinction of the Thylacine, or Tasmanian tiger, one of the most iconic and mysterious animals of the 20th century.
Photograph above is of the last captive Thylacine, taken on 19th December 1933 at the Hobart Zoo by zoologist David Fleay (image courtesy David Fleay trustees).
In a study published recently in the journal Science of the Total Environment, an international research team (from Australia, France, and Czech Republic) led by professor Barry Brook from the University of Tasmania used a comprehensive database of 1,237 observational records from Tasmania, dating from 1910 onwards, to map the species' decline and eventual extinction.
“We found that the Thylacine's distribution shrank rapidly after a period when bounties were provided for animal skins across Tasmania (1888-1909), and that the most likely location of the last surviving subpopulation was in the south-western region,” Professor Brook said.
The team also estimated the most likely extinction date for the species, using uncertainty modelling and sensitivity analysis. “The results showed that extinction likely occurred within four decades after the last capture, so around the 1940s to 1970s. But we found, through further analysis, that extinction might have been as recent as the late 1980s to early 2000s, with a very small chance that it still persists in the remote south-western wilderness areas.”
Spatial extirpation pattern for the Thylacine in Tasmania. Colored contour maps of the inferred year of local extirpation were generated by fitting a re-sampled extinction-date estimator. MTE - mean time of extinction; UCI - upper confidence interval. The circles in each plot show individual sightings, sized by rated quality.
Professor Brook said this study provided the most comprehensive and rigorous analysis of the Thylacine's extinction to date. “We used a novel approach to map the geographical pattern of its decline across Tasmania, and to estimate its extinction date after taking account of the many uncertainties. Our findings not only shed new light on the fate of this iconic species, but also demonstrate a useful method for conservation prioritisation and search efforts for other rare species of uncertain status."
"A sad implication of our study is that the extinction of the Thylacine was not inevitable", says Ivan Jarić, one of the authors of the study and researcher at the Biology Centre of the Czech Academy of Sciences, underlining the importance of the findings. "There has probably been a considerable window of opportunity after the death of the last known individual, spanning several decades, when it was still feasible to introduce adequate measures to prevent its extinction".
Co-author Dr Stephen Sleightholme from the International Thylacine Specimen Database said the Thylacine was one of the most fascinating and enigmatic animals of modern times. “It has captivated the public's imagination for decades and inspired many efforts to prove its ongoing existence. Our study shows that there is still much to learn about its history and ecology.”
Simulated extinction dates for the Thylacine in Tasmania. a) Probability-density distribution of the inferred last true sighting record, based on probabilistic re-sampling of all 1237 specimens and observations from 1910 to 2019. b) The inferred cumulative probability of persistence at a given calendar year, as derived from the distribution shown in a.
For more detailed information check the article, published in Science of the Total Environment:
Brook, B.W., Sleightholme, S.R., Campbell, C.R., Jarić, I. and Buettel, J.C. (2023). Resolving when (and where) the Thylacine went extinct. Science of the Total Environment 877, 162878.