I've enjoyed reading this thread (aka procrastinating instead of studying).
A few encounters come to mind:
1) My husband and I were riding our mountain bikes down a dirt road at Keystone when we saw a large, chubby rodent and her babies. Apparently they were coming out of a den/hiding spot one by one, scoping the area for threats, and then running a few feet to another hiding spot while mom kept lookout. I, with my vast knowledge of all things wild, declared that they must be ocelots. That held until I did some research and discovered, of course, that ocelots are actually cats, and what we'd been observing were marmots. Now known to me and my husband as marmocelots.
2) Every now and then, you'll see a family of moose in Cucumber Gulch as you're riding the Breckenridge gondola up. It's also a popular place to cross country ski. Eep.
3) Someone a few pages ago mentioned porcupines in trees - I was riding up chair 6 at Breck with a buddy when he pointed one out. I'd never seen anything like it. Just this massive ball - looked like a sea urchin a couple of feet in diameter! Of course there's no way to hurry the lift to get away. I wonder if they can flick quills while in a tree.
4) One year, we rented a room in a house well up Boreas Road. When we visited in the late fall, the owner wasn't there, but one of the other renters was. He showed us how they would put the kitchen trash out on the deck until trash day. I asked him about bears, but he assured me they weren't a problem. When we came back the next week, the trash was no longer being kept on the deck. Apparently, his confidence in the deck being a bear deterrent was .. misplaced.