Most woodpeckers in Wyoming feed on the insects and grubs that reside just beneath the outer layer of bark and those found a bit deeper in old or rotting wood. They get at these foods by prying and wedging away flecks of bark or by hammering and chiseling out slivers of wood. Some, known as sapsuckers, drill holes in a pattern of parallel rows in birch or aspen trees and they return to these wells to consume the resulting flow of sap. A series of these trees also serves as a type of trapline and the sapsucker periodically flies a route to collect the insects that have become glued to the sticky fluid.
You can click on an image to enlarge it and display it in its own frame. You can also click on the video link to show a short video clip.