A chewed tomato: squirrel or woodchuck?

Hmm, I harvested a half-eaten red tomato this morning that had been chewed, but noticed evidence on this one (a green tomato) this afternoon.

There are distinct chew marks visible (diagnostic of a squirrel?);  I've never had squirrels eat my tomatoes, but I know through fellow garden bloggers that they do eat them.  I've never had woodchucks bother my tomatoes or anything else in the tomato (Solanaceae) family, but you never know.

My gardening companion spotted a very young woodchuck nibbling on Impatiens flowers (near my lower raised beds) this afternoon.  Hmmm.  I do hope s/he doesn't develop a taste for squash (or tomatoes)!