Both have feet with two toes in front and two in the back with long sharp claws. Their tails have an abundance of melanin pigment and are strong enough to use as a prop when they land on a tree. When you see a woodpecker attack a tree you wonder why he doesn’t get a raging headache. They have reinforced skulls, and their long barbed tongues extend to the top of their heads.
Males of both species have red caps, no two being alike.
Now is the time of year the Hairy starts his territorial drumming, his smaller cousin starting not far behind. Both excavate new nesting cavities each year. Downies will return to the same tree year after year while hairy will use a different tree each year. The babies of both are very noisy. You really don’t want a nest of them close to your bedroom window.
So, why would you welcome a bird that digs holes in your trees and has loud, obnoxious babies? There are several reasons actually. Their nesting holes are adapted by other cavity nesting birds that aren’t carpenters. They feed on insects that are harmful to trees.
If you are superstitious, they are supposed to protect one from being hit by lightning, although why you would be out in a thunderstorm is another question.