The Titmouse or Tufted Titmouse (two names for the same bird) are very common yet I never saw a nesting spot for it.  We were pulling in the driveway and I saw a titmouse fly out of a hole in a tree about five feet up across the street.  I investigated and another one flew out of the hole in the tree.  It must have a nest there.  That was a first.  I never found a nesting spot of a titmouse before.  I really do not want to disturb them any more than I have to.  I will just keep my eyes open for that hole in the tree.