The antelope are all over in Wyoming, I have seen 50 at a time there- less common in Utah though. Technicly, they are actually Pronghorn Sheep, I believe- but they are so commonly called Antelope that everyone knows them as such- Antelope are only seen in Africa unless I'm mistaken.
I am not sure why, but my focus wasn't that sharp in some of those- I'm thinking I may have had the IS(100-400) on, not good on a tripod but I'm not sure and no way to check- either that or I was thrown off because I had a half an eye open on the Buffalo- didn't want them pissed off....