Here are a few holes I've found over the past few days. This new hole is in the base of a dead oak snag. Maybe it was made by a Pileated Woodpecker (Dryocopus "tree sword" pileatus "crested"). I saw a pair of Pileated Woodpeckers today, drumming quietly in the treetops with a few small calls to each other. They swooped from tree to tree, launching and gliding without a wingbeat through the thick tangle of oak and fir. How do they know their trajectory won't collide with a branch? Their flight path was a shallow curve, no deflecting, no turning left or right to avoid a limb--they just know the exact swoop and stall to end up at their next perch.
This old hole is a nesting place within a thick bark ring(about 6" thick, 36" d) that is all that remains of an ancient Douglas Fir stump. I'll have to watch it this spring to see who uses it. It is about 2" wide, facing nnw. Or maybe it's a chipmunk bunk. Here is a matrix of holes in the heartwood of a douglas fir stump. Beetles have done their work to begin breaking down the stump back into the soil.