Greg -- I'd say the chances are good of getting flying squirrels in a box. They are fond of bluebird boxes, and can be a real problem in red-cockaded woodpecker populations because they take over tree cavities. The typical adult call is a very very high pitched squeak. Years ago at my parents' house in Carroll County as I was watching activity at a screech owl nest, I heard some small-bird sounds coming from a wheel barrow on the carport just before dusk. Having enquiring mind, I investigated and found a half-grown flying squirrel. I picked the rodent up and carried it, still calling, out into the driveway. Some movement caught my eye and I looked up to see a squrrel gliding straight for me at a steep angle. The squirrel veered off at the last second and landed on a nearby oak. I could see that it had come from a gray squirrel nest in another oak. I placed the young squirrel on the tree the adult was now in and backed off. The adult came down and gathered up the little one, climbed the tree, glided back to the tree with the nest, and carried the young one to the nest.

Incidentally, I saw a courting screech owl knock a flying squirrel from a tree once, but not pursue it further as the squirrel lay squeaking on the ground. Just trying to impress its mate I guess. I don't think flying squirrels are taken often by screech owls.

Jim Ozier Forsyth