There are several wolf subspecies even among the north American gray wolf.
http://www.cosmosmith.com/wolf_classification.html
It seems that our Federal govn't went out of its way to get the biggest and most aggressive subspecies that is out of place here in the Rockies. They are known to even kill grizzly bears in a similar manner to the way some Indians allegedly hunted deer by running them down over a couple day period of time until the deer are too exhausted to run any further. Wolves have been documented killing grizzly bears in a similar manner.
In addition, the Scandanavian nations have sought to eradicate wolves because of the severe public health problem caused by the parasite that they carry. In Idaho, 62% of wolves examined were infested as well with a parasite that is deadly to people. The Russians also spent decades trying to eradicate this parasite with little success. Now the Feds have introduced this invasive wolf subspecies carrying a truly invasive parasite. They propagate the false information that the wolf is good for the ecosystem when in fact, they are ravaging the northern Rockies with little to hope that they will ever be controlled anytime soon.