Bighorn lambs can be very fun to watch. This little guy had a friend and the two of them would run up and down the steep cliffs before returning to their mothers. As for the moms, they seemed more interested in chewing grass than in looking after the babies.
Nikon D300 with Nikkor 200-400mm lens (at 400mm) ISO 800, f/4 at 1/200th of a second