I do use a zoom lens. Generally about 200mm, but I recently bought a 100-400mm.
in this case the Haul road goes over Atigun Pass and the wolf happened to be going through at the same time I was. There is almost always sheep that hang around that area and I suspect he was targeting them. I know that certain wolves and certain packs pretty much single out a preferred species, like sheep, and only take the other critters on an incidental basis. I was within 50 yards at times.
I don't think that the only good wolf is a pelt, BUT, I would have liked to take this one home for the wall!