2023 Author: Bryan Walter | [email protected]. Last modified: 2023-05-21 22:24
Marsupial wolf (Thylacinus cynocephalus)
The marsupial wolf died out not in 1936, but at the turn of 1990 and 2000. Tasmanian zoologists came to this conclusion after analyzing more than 1200 evidence of encounters with this predator, which came both before and after the official date of its disappearance. Moreover, the authors argue that there is a small, but not zero chance that marsupial wolves still live in remote areas in the west and southwest of Tasmania. You can view the research preprint on the bioRxiv preprint portal.
The marsupial wolf (Thylacinus cynocephalus) is the largest marsupial predator that has survived to the historical era, and is also a remarkable example of convergent evolution with canine mammals. Once this species was widespread throughout Australia, but due to competition with the dingo dogs (Canis familiaris dingo) brought by the aborigines, the species survived only in Tasmania by the arrival of European colonists.
Unfortunately, the island did not become a safe haven for marsupial wolves: cattle farmers mistakenly accused these predators of killing sheep (in fact, such prey was too large for them) and mercilessly exterminated them. Apparently, in the wild, marsupial wolves were destroyed by the beginning of the 20th century, and the last representative of the species, a male named Benjamin, died in 1936 (the latest video with his participation was recently published).
Although it is believed that the marsupial wolves became extinct more than eighty years ago, the people of Tasmania still report encounters with them from time to time. Professional zoologists do not take such claims seriously, considering them to be the local analogue of stories about the Loch Ness monster or Bigfoot. The skepticism of scientists is easy to understand, because none of those who have allegedly seen marsupial wolves in recent decades have provided reliable photographs or other material evidence.
A team of researchers led by Barry W. Brook decided to go against this tradition and impartially consider the claims of the existence of marsupial wolves after the official date of their extinction. After examining published reports, museum archives, newspaper articles and other sources, they compiled a database of all alleged encounters with these predators after 1910, when they were considered rare.
In total, the authors included 1,237 pieces of evidence in the analysis, each of which was assessed according to the level of reliability (for example, if several people reported a find at once, it was rated higher) and linked to points on the map. After examining them, Brooke and his colleagues found that since 1910, Tasmanians have reported sightings of marsupial wolves almost every year, with the exception of 1921, 2008, and 2013. In 1940-1999, the number of such messages was kept at about fifteen per year, but since 2000 it has decreased to 3, 6 annually.
Until 1936, about half of the evidence was related to the capture or killing of wild animals. The last reliable photograph of a wild marsupial wolf dates back to 1930, but the authors have no doubt that reports of successful hunting of these animals (or their capture and subsequent release), which continued to arrive until 1937, are true.
Although the actual evidence for the existence of marsupial wolves has ceased to exist since the 1930s, Brook and his co-authors believe that in reality this predator became extinct later. The fact is that as the population of a rare species decreases, the likelihood of meeting with it becomes lower and lower. In the case of marsupial wolves, this is compounded by the fear of humans they have developed in response to hunting. And the belated measures for the protection of marsupial wolves, adopted by the government in 1937, made farmers not dwell on the successful hunt for these animals.
Statistical analysis of unconfirmed reports, ranked according to the degree of reliability, made it possible to shift the estimated time of extinction of marsupial wolves to the period from 1980 to 2020 (more precisely, to the end of 1990 - early 2000). This result may sound unexpected, but it should be remembered that even forty years ago, the Tasmanian authorities sent full-fledged expeditions to search for elusive predators, inspired by evidence that was considered credible. According to the authors, in the hard-to-reach areas in the west and south-west of the island, marsupial wolves survived until about 1998. For comparison, the 2017 paper assumed that the wild population became extinct in 1936-1943, and in the most optimistic scenario, in 1956.
There is a small but not zero chance that the last marsupial wolves are still living in the wild, such as in Franklin-Gordon Wild Rivers National Park, Brook and colleagues said. Although the local forests may not be considered the optimal habitat for these predators, their favorite prey is still abundant: small kangaroos, wallabies and philanders. The lack of reliable evidence of the existence of marsupial wolves can be explained by the fact that large-scale projects to study the Tasmanian fauna using camera traps, which could confirm the existence of secretive predators, began relatively recently, about twenty years ago.
The authors believe that if the marsupial wolves are still not extinct, zoologists will receive evidence of this within the next ten years (in an interview with Mongabay, Brook estimates the likelihood of this being one in ten). Otherwise, we will have to admit that the history of this species ended at the turn of the 20th and 21st centuries.
It should be noted that not all colleagues agree with Brook's methodology. Many of them believe that people who talk about encounters with marsupial wolves are so often mistaken and wishful thinking that their words should not be taken into account. In addition, attempts to resume the search for this almost certainly extinct predator could divert attention and resources from protecting rare species that can still be helped.
Another cult inhabitant of Tasmania, the Tasmanian devil (Sarcophilus harrisii), may soon also repeat the fate of the marsupial wolf and disappear. The existence of this species is not threatened by farmers and hunters, but by an infectious cancer, which killed eighty percent of the population from 1996 to 2016 alone. However, the authors of a recent study argue that devils have a chance to survive because the disease spreads more slowly in a thinned population.
