Animals we thought were extinct sometimes aren’t. From Julia Brown at New Scientist:
Will Bill Laurance and his team find Tasmanian tigers lurking in Australia’s remote Cape York peninsula? Numerous animals that were thought to be extinct have recently been rediscovered. Here are our top five species that came back from the dead – and two more that might also have been written off too soon. More.
This subject has heated up recently on account of possible sightings of the Tasmanian wolf (tiger), a marsupial that was believed to have gone extinct in the last century.
Possibly, current technology would help us determine the chances that an actual species has actually gone extinct. The fact that one hasn’t seen any of them around for a while may not be all we need to know in order to decide.
See also: Possible live Tasmanian wolf sightings? (2017)
and
Lazarus species: animals listed as extinct that turned up again.
The earth is a huge place. Determining conclusively that something has recently gone extinct will always be linked with a certain amount of error. And for marine creatures, even more so. But, generally, the longer the time since the last sighting, the more certain we become. As well, certainty is much easier with large animals. They just don’t have anywhere to hide.
Good points, hammaspeikko at 1, but it’s worth considering that some predatory species make a specialty out of being hard to detect. That was how they survived as long as they did.
Factoring that in, one might want tentatively to assign a higher probability of survival somewhere in such cases. The cougar in eastern Canada is worth considering in this regard.
http://www.torontosun.com/2015.....rn-ontario