There is no mistaking what bird is responsible for the large holes that a pileated woodpecker makes in an attempt to gain access to the carpenter ants living within a tree. No other bird in North America is capable of excavating holes of this size. Pileated woodpeckers tend to work vertically, and you often find one hole drilled above another. A look inside these holes reveals the galleries that the ants create in order to travel to all parts of their nest located within the dead center of the tree. (Carpenter ants, while omnivorous, do not consume or digest wood; they merely tunnel through it.) A tree’s inner core provides structural support, but is not essential for the tree’s survival. This eastern hemlock’s cambium layer, just inside the bark, is very much alive and the tree may continue to live long after its center becomes hollow.