Barn Owls can make some pretty big nests, too. We had one that had a big nest built high up in a huge ancient oak tree in the woods back behind our house when we lived out in the country. It used to cruise our backyard at night for rabbits. The rabbits would come eat apples that fell from our apple trees and the barn owl would kill and carry them back to it's nest. It would always rip the heads off and leave it laying and carry the headless carcass away.
