In all the time I spend here I've never seen a chipmunk here or heard their "chirping". I have tons of chipmunks at home but there are no holes in my lawn at home. They live in the stone walls and brush.
Holes are too small to be skunks. I thought about snakes but I would have seen one basking in the sun at some point. I'm starting to think maybe something nocturnal because I've never seen anything go in or out of the holes during the day.
Might have to pull an all night vigil with a tall vodka drink.
P.S Not my crock in the photo. Just wanted to make that clear.