Our attempts to grow real tomatoes in the patio were largely disappointing for two reasons. One is the neighbor's tree, roots of which suck all the water and nutrients from the soil, and the other is that something was eating whatever grew. In the end it turned out to be rats, but we didn't know that until we bought a squirrel trap. We did see squirrels coming often - they even had a nest in our attic for a while - but never saw any rats until the squirrel trap caught one.
While we are in a process of getting rid of both the rats and the tomatoes (and cucumbers) altogether, I got a very interesting link about squirrels while trying to learn about them:
http://www.maniacworld.com/squirrel-obstacle-course.htmlI still think the squirrels are rats de luxe, the only difference being the fuzzy tail and warm and fuzzy tales about them in Disney production (until the most recent one, but that's still about 100 to 1 in favorable coverage).