It is common to find Hairy and Downy woodpeckers associated with the Pileated, both on nesting grounds and when feeding. There is here, I believe, some measure of commensalism. I have in mind an observation upon a Downy on the same dead hemlock tree with a Pileated Woodpecker. The larger bird was scaling off the bark and feeding, the smaller Downy seemed to be gleaning over areas the Pileated had left.
Life Histories of North American Woodpeckers
Arther Cleveland Bent