We have these owls. They will belt out this call at high volume late at night. Especially when I walk out in the dark with the dogs. I swear they do it for fun, because when they do, my dogs and I do the run- in-mid-air like Shaggy and Scooby. I bet they're up there in the tree getting a hoot out of scaring the crap out of us with that scream... "Hey Frank, shhhhh, here they come, let em get realllly close, 1, 2, 3... " then fall out the tree laughing.