Pileated woodpeckers are quite impressive to see, but they can do great damage to trees that have insects in them. A pileated can easily "chop" a 2" X 6" wide by 3" deep hole in a tree in an attempt to get to the insects. Trees with multiple pileated woodpecker holes in them seldom survive, but of course those trees are most likely infested with insects anyway so they are in poor health to begin with.
Here's a photo I took of a pileated woodpecker on the ground in our yard a couple years ago. Fortunately he didn't start pecking on any of our trees!