No one writes an obituary for the last of a species that dies alone in the wild. So, knowing precisely when to confirm an extinction comes down to a mix of clever investigation, math, and lots of guesswork.
On September 7, 1936, a thylacine (Cynocephalus thylacinus) held captive in a small Hobart zoo has become the last Tasmanian tiger ever seen breathing.
Officially, at least. Reports of ‘marsupial wolf’ sightings in the rugged island wilderness continued well beyond the 1930s, gradually fading to whispers as the world finally came to terms with the iconic Australian creature was really gone for good.
Based on the suspected lack of verifiable sightings, including tracks and remains, the International Union for Conservation of Nature has closed the chapter on Tasmanian tigers in 1986.
Now, a new investigation of a likely timeline for the thylacine’s last days has been published, confirming that the species was most likely extinct before that date.
Led by scientists from the University of Tasmania, a team of researchers assembled an exhaustive collection of 1,237 sighting reports and developed a new method to calculate the distribution of post-prime recalcitrants, finding that the last individuals had disappeared. in the 1970s.
This is, at least, based on the reports that are most likely to be reliable. There’s a world of difference between an experienced trapper’s word written in the 1960s and Uncle Frank’s clear whispers of the striped dog he swore he saw on his roof last year.
Categorizing the stories on a reliability spectrum provides a bit more leeway in conclusions, allowing for the possibility that small populations persist well into the 1990s, years after authorities declared them extinct.
If we stretch the believability to the breaking point, there’s a slim, if not extremely unlikely, chance that a handful of thylacines could still lurk in the remote southwest of the state at this time.
The island state of Australia was already a haven for the Tasmanian tiger by the time Europeans arrived in the early 19th century, with a population of perhaps a few thousand large carnivorous marsupials persisting in the forested ecosystem of the island, having disappeared on the mainland thousands of years earlier.
Looking too much like a wolf for settler comfort, it didn’t take long for traps and bounties to do their job. Accidental trapping by fur traders and occasional caging for the exotic pet trade has pushed the last populations into remote areas of Tasmania’s rugged terrain. Habitat destruction and disease have undoubtedly also taken their toll, making recovery of the species virtually impossible.
Yet despite the animal’s notoriety, there’s a surprising lack of hard data informing speculation about their demise.
Keeping in mind the challenges of relying too heavily on anecdotes, the researchers behind this latest effort to definitively pinpoint a date for the animal’s demise have been digging through government records, newspaper reports , museum collections… anything that said something about the existence of wild Tasmanian tigers from 1910.
Organizing the collection according to dates, locations, type and quality, the team applied several statistical techniques to come up with a range of plausible scenarios detailing when the last true sighting was likely to have occurred.
If we rely only on confirmed physical specimens, the last thylacine died in the wild just five years after the death of its captured cousin. Include more dubious specimens, the lower limit of extinction could extend into the 1950s, with a chance that some survived into later decades.
Add in some high-quality, albeit uncertain, glimpses, or perhaps a few sightings by multiple witnesses, it’s possible that thylacines were still lurking in the brush when Bill Clinton became president.
Want to take each report account (including Uncle Frank’s)? It is unlikely that there are still a few families hiding there.
Don’t hold your breath. Although the data implies that thylacines lasted longer than we might have thought, scientifically speaking they are just as extinct. Run out of some kind of numbat breeding program attempting to bring them back in limited form, the Tasmanian tiger is no more.
If there is any hope, it is for the many species currently on the brink of extinction that we can still save if we learn a lesson or two from the tragic story of the mistaken Tasmanian wolf.
This research was published in Total Environmental Science.