On Thu, 31 Mar 2016 16:24:47 -0700 (PDT), Will in New Haven
wrote:

On Thursday, March 31, 2016 at 5:05:00 PM UTC-4, Jeßus wrote:
snip
The Tasmanian Tiger (not a real tiger, but a large dog-sized
carnivore) has supposedly been extinct since the 1930's, although some
people feel they are still around. Periodically there is an alleged
sighting. I wouldn't be surprised if there were still around, much of
the area around here is inaccessible and remote. There have been times
I have come across kills that I cannot explain... there are no other
animals around that could do it, including wild dogs (too cold for
them to survive our winters).

Wild (feral) dogs survive in the coldest parts of North America. The only limiting factors on their spread are human efforts and the presence of wolves.

Good point and so much for my theory
I don't know why, but feral dogs don't seem to surive here for very
long. The Mainland is another matter entirely...