That got me to thinking about why the animals were coming back. The first thing that crossed my mind was that life wants to evolve, radiation helps that fact. Is there an instinct that drives these animals to a location that may help them evolve faster?
The other thought is that life is starting to emerge there again. First come the plants, then the plant eaters, then the plant eater eaters. So as things again started to grow, animals would naturally migrate back.
Of course I like the first thought better. I’d like to think that nature is self-preserving and animals are drawn to a force that could lead to very quick evolutionary leaps.
Lets skip the turtles, lets get some Teenage Mutant Ninja Minks going, those things are nasty!