Free Guide For Birding by Ear
Aloha, if you haven't downloaded the Merlin bird app yet, we highly recommend it. You can see what birds occur in your region and it is a great tool for ID-ing birds by ear in the field or for leisure in your backyard. The Barn Owl and Pueo make distinctly different sounds. If you go to the Short-eared Owl 'Sounds' section on the app, the second and last call on the list are the most common sounds we hear coming from the Pueo.
Check out: http://merlin.allaboutbirds.org/