Happily, Michael & Kathleen's skunks left voluntarily. In the meantime, though, something has moved in under our house. The stairs that lead from the basement up to the room addition and then outside are lined with the same limestone as the foundation. Recently, after I spread some boric acid, tracks appeared near holes between the limestone blocks on either side of the steps.
To find out what was living there, I first consulted these ingenious little plastic tags. Each tag has sized examples of front and back foot tracks, none of which matched the tracks on the steps.
So then I turned to the only book of tracks we own. Even though this one's for the Rocky Mountain region, I figured it'd probably have something close. I started by looking at the tracks of rodents, of course. All the examples included drag marks from tails, which ours didn't. I then looked at the tracks of critters without tails, like chipmunks, but still found nothing similar.
I finally just started thumbing through the book, and found an exact match! I know they don't usually live under basement stairs, but stranger things have happened.
We're very excited.
We have otters.