There are hot springs that bubble up in the area, making it prime territory or bison to spend the winter. They'll usually get off the trail for you, but not always. If they don't, go around and give them plenty of space.
Be wary of the stream crossing over Glen Creek as you approach the Fawn Pass. Upon this trip, it was very obvious but still tricky to cross in skis. I can imagine it could be more treacherous when concealed with more snow.
Looking back on the trail skied from the signpost junction where one can choose the route back. The peak shrouded in clouds is Electric Peak, the tallest mountain in the Gallatin Range.