Cayenne Pepper and Birdseed?

Someone suggested adding cayenne pepper to birdseed to repel squirrels and other wildlife. But I've heard it can irritate membranes in birds' mouths and throats. Is this true?

—Dulcie Fralin, Wilmington, North Carolina

George: Cayenne pepper has no apparent effect on birds, whose sense of taste and smell is not well developed. Its effect on squirrels is also in question. I've tried it at my feeders, but the pepper doesn't seem to discourage squirrels from raiding them.