What on Earth Caused this Damage?

It looks like someone stood off to the side and fired a machine gun at your tree’s trunk. However, a bird is the real culprit. Sometimes it’s pileated woodpeckers and other times it’s yellow-bellied sapsuckers.

Either way, it’s no cause for concern. The birds work alone, and they seldom do enough harm to be of real concern. The trees usually heal quickly once the bird moves on. The presence of these birds does not signify presence of any particular insect, either.

There is usually no call to action. You certainly don’t want to do anything to harm the birds. All I do is protect smaller trunks like this with paper tree wrap. In some cases, I’ll cover the open wounds with black pruning sealant arborists use. I’ve even bought the sticky Tree Tanglefoot product that is put on the tree’s trunk, but I’ve never gotten around to using it. (Never needed to do so.)