Overmature and damaged black oaks become hollow in spectacular fashion sometimes. You always thump a black oak to see if it's all there when you measure it, and this is why. Carpenter ants love to eat black oak (and other red oak species, too).
They are like big, bad termites, and boy do they tear down a tree. The snag I dropped last weekend was riddled with them for several feet.
There is something peculiar about the red oaks that I can't figure out. A standing snag will have damp wood when you drop it and split it, but being an open pored wood, it dries fast, and burns well within a few weeks. However, red oak tree tops that are on the ground can be there (drying?) for several years, and when you work them up into firewood they are soppy and must dry for months before they will burn. I can understand a log lying on the ground being soaked, but tree tops are up off the ground with air moving all around them. If you are going to work up tree tops, do it while they are fresh so you don't waste your effort on half rotten, soppy wood. I have never found carpenter ants in wood lying on the ground...those bugs are as picky as I am.
