The Tasmanian Tiger, Extinct, or Not?

The uncertain state of affairs

The question of exinction of the Tasmanian tiger (the thylacine) was raised in an interesting article, "Paper Tiger" (Brooke Jarvis, The New Yorker, July 2, 2018, pp. 44-54).  According to Jarvis, the last one in captivity died in a Hobart, Tasmania, zoo in 1936.  That was twenty years before I arrived and was mentored by Dr. Eric Guiler, an expert on many Tasmanian zoological topics, during my year as a Fulbright scholar at the University of Tasmania.

On several field trips with Dr. Guiler (see endnote), and others by myself, many other animals or their sign, such as tracks or droppings were seen.  But such lack of evidence is not very convincing because- such rarities as the Tasmanian devil and the platypus I only saw in zoos, Michigan mammals known to exist but seldom seen outside of zoos include badgers, bobcats, cougars, flying squirrels, mink, and otters.

It seems reasonable that with the bounty put on tigers, to reduce their predation on farm animals, their numbers may have been reduced beyond their ability to survive.  But Tasmania has much uninhabited potential tiger habitat where few would have chances to observe them.  Some suspect that some may still survive in wild country along the north coast of the Australian mainland.  Both are plausible, but seem to require better documented evidence than is presently known.

A few potential factors

In favor of their non-extinction is the possibility those most adapted to avoiding humans may have left some survivors.  Anecdotal reports would seem to support this view.  But the ease for humans to see what they want to see has caused the shooting death of numerous hunters and a few cattle during the hunting season in Michigan; eye-witness testimony is of questionable reliability.

Extinction is perhaps more likely when numbers are greatly reduced.  Habitat reduction is one cause.  But small numbers may increase inbreeding and thus increase the likely of mortality due to deleterious genes.  Small numbers can also interfere with opportunities for mating and consequent reproduction.  Other factors may also operate if social learning is involved, although I have not heard of Tasmanian tigers forming packs.

Extinct or not, it is still an open question.  Negative facts and hypotheses such as extinction are very difficult, if not impossible, for a scientist to prove.

endnote: Dr. Guiler is the one standing to the left in the picture in post number 51 -
https://evolutioninsights.blogspot.com/2014/06/the-baleen-whale-tooth.html

Joseph G. Engemann      Emeritus Professor of Biology    Western Michigan  University, Kalamazoo, Michigan       January 15, 2019