To one who visits its haunts the presence of the pileated woodpecker is immediately made manifest by operations such in magnitude as to have astonished Thoreau. Dead Norway pines may be found, gaunt and bare, their bark split away in plates and lying heaped at the base, and living white pines, young trees, particularly, pierced to the core with deep pyramidical incisions. Great boles of maples and basswoods stand, furrowed from broken top to base, the ground below littered with splinters, often half a hand's breadth in extant. The cuts are roughly rectangular in outline. They may be 4, 5, or even 6 or 8 inches wide and are sunk deep into the heart of the tree. They might extend vertically for a few inches or for a foot or more. They may be aligned in vertical rows, and may run together in furrows of several feet in length. Crumbling stumps and moss covered logs lying on the forest floor will often be found ripped and torn by the woodpeckers beak.

Life Histories of North American Woodpeckers
Arthur Cleveland Bent
1939