I don't know if the US issue of the new National Geographic magazine is the same as the european one but the march issue has a whole article about the reintroduction of wolves in yellowstone and the surrounding areas.
some positive facts;
less coyotes
more beavers
more trees
more insects
more fish
less deer and elk but constant numbers
idem for the wolves
1% loss of calves of livestock by wolf predation
higher tourist numbers

There are a few negative facts but the magazine concludes that this is because we are both highly adaptable creatures who try to live together and make the best of it.
I suggest you do....