This female Downy was at Lowry for a recent banding. At Springbrook this past weekend, we had a Downy - with a possible brood patch already coming in!!!! In addition to size - the Downy Woodpeckers are about 6 inches long, the Hairy Woodpeckers are about 9 inches - there are a couple of other ways to tell them apart. Calls are different, the bills are MUCH shorter on Downys, and if you look at the second to the last picture - the Downys have barring on the white outer retrices (tail) feathers. The Hairys do not have that same distinct barring.