I'm not certain, but I believe this is a female brewer's blackbird, singing her appreciation of the gorgeous day at Lily Lake.
The excursion was almost completely lacking in large animal sightings; our sole glimpse of Colorado's version of the Big Five -- bears, moose, elk, bighorn sheep and deer -- consisted of a couple of deer deep in the shadows of the trees. But if you liked smaller critters, Lily Lake was perfect. In addition to the chipmunks and the blackbirds, there were muskrats, snakes, salamanders, lots of birds and clouds of dragonflies. I've already seen all of the Big Five, but I'd never seen dragonflies in such brilliant colors, so I didn't really miss the bears.