Acorn woodpeckers are interesting birds. They feed on insects, fruit, seeds and sap. They are noted for drilling holes in trees and using the holes to stash acorns.
I got an e-mail a couple of years ago from a man who had a cabin in the Sierra that he stayed in during summer months. Behind the cabin was a small wooden tool shed. Arriving one summer, he noticed a small hole in the front of the shed. Opening the shed he found it knee-deep in acorns. Acorn woodpeckers had been shoving the acorns into the small hole, much as they would into holes they drilled in tree branches.
Given enough time, I wonder if they would have filled up the shed with acorns? /Gary