In short, the tree is dying.
You may think it useless, but think again. Dead trees, aka snags, are precious homes for a host of birds such as wrens, chickadees, bluebirds, screech owls and Great Crested Flycatchers.
Woodpeckers often create the holes that are so important for these cavity nesters. Won't you please leave your trees be?
photo © adrian binns