This is a Red-Naped Sapsucker. Instead of pecking holes in trees to find insects, it makes holes in trees to get sap. That tree sap contains sugars and other nutrients that make up a large part of the bird's diet. Once a series of holes have been drilled into the tree, the Sapsucker must continue to maintain them by drinking the sap and scraping away any sap that starts to harden along the sides of the hole. If the bird leaves, the sap will quickly stop flowing. That means that the bird would have to start over with a new set of holes. Because of this, once the bird makes a set of holes, it will stay with them until it gets its fill of tree sap.