Well, they're not going to be allowed on the deck any longer, as it appears they chewed into the gas line between the propane tank and the grill. I've no idea why, but it was pretty apparent. Of course, they'll chew into power lines as well, and again, nobody knows why.
But I blew $28 on a new gas line this evening, which I encased in a bit of razor wire. And from here on, I'll release the terrier whenever a squirrel shows up.