These are not just plain old holes made by woodpeckers, that is why the post is entitled like it is.
This is the work of a Pileated Woodpecker which is a large bird more like the size of a crow.
That is my iPhone 4 in there to give you a size reference.
What on earth could have been so deep within the tree to warrant all that work?
The upper most hole in the same tree.
A picture of the culprit taken from the Internet.