The most aggressive migration of wolves and grizzlies is facilitated in most cases by a USFW truck / personel. I watched them plant wolves at my house three times. The appearance of qrizzly bears is likewise accompanied by a USFW truck. Natural migration is very limited.
Every new grizzly we get should be matched with a griz on the east coast. Camping in a tent is certainly not in my future nor is hiking without a gun and a dog.