The Yellow-bellied Sapsucker is a woodpecker. As such, he has all the woodpecker characteristics.
For instance, he clings to the bark of trees and pecks at it incessantly. He doesn’t sing, but makes some loud non-musical calls.
He also stays close to trees almost all of the time.
This bird is different in one way, however. He loves the sap of the trees (hence its name).
If you look at the holes in tree trucks, and you find some (a lot) in a neat row or several neat rows, you will know that the sapsucker has been around.