I am having owl issues as well with free-ranging birds that roost on top of designated roosts. Two owl species, great horned and barred, have come calling during the this production season. They do not come at same time since great horned will prey upon the smaller more gracile barred. Both have habit of knocking / pushing / driving chickens off unprotected roosts with latter falling to ground. With smaller chickens (< 1.25 lbs) they simply catch the bird and fly with it. Great horned can handle larger in flight but not full sized standard birds. Larger appear to be dispatched only while on ground. My dog detects ruckus and checks on situation driving owl off. Dog stops loss of bigger birds. Smaller birds can either be locked up as previously mentioned or directed to roost in locations where owl can approach chickens from below only. My owls seem unable to catch chickens from below. The owls do like to eat the heads off like other predators do. My owls are very consistent in respect to what time they visit each night.
Owls themselves might be tasty.