Screech owls use the abandoned nests of other cavity nesters (woodpeckers, flickers, etc) to raise their young. Owls, and many other raptors (birds of prey) will perch at the top of trees to scan the area for prey.
If you have dead trees on your property, please consider allowing them to remain so that owls, hawks and falcons can benefit from them.
There's so much reward in hearing a pair of great horned owls calling to each other or a family of screech owls whinnying at night. It's very satisfying to know that the dead trees we've left on our property may be providing a nest site for babies or a hunting platform for the adults.