I later learned that this was the result of people tossing unwanted pets into the woods.
Apparently this problem has existed for many years. Over 20 years ago I read a book called The Tracker. The author describes how he escaped on foot from a pack of feral dogs in the Pine Barrens. This book was originally published in 1978.
I'd love to read that. The "classic" work on the Pine Barrens was written many years ago by John McPhee. I don't know if it's still in print.
When I was a little kid I was entranced by the many stories about motorists (unfamiliar with the Pine Barrens) who would have auto problems on Rt. 70, pull over and wander into the woods looking for assistance they were sure could not be far away. They were never heard from again.
Part of the reason for this is that many were coming from nearby Philadelphia or were from other parts of urban NJ and couldn't possibly conceive that such a wilderness could exist in one of the most densely populated states in the nation.
We were also entertained (and scared!) by tales of the "Pineys".