Over last 10 nights or so a great-horned owl has been visiting with intent of eating chickens. My birds are not all that vulnerable owing to a combination of roosting arrangements and dog that seems to stalk owl from front porch. When owl visits, chickens get riled and dog goes to investigate. On first night owl actually knocked a pullet off the top of a pen and breifly grappled her on ground before dog busted up the owl's efforts and chased it off. Most birds now under cover or roosting to close to dog's sleeping area to be vulnerable to owl. This does not seem to be stopping owls efforts. It still visits and many of the penned birds are visible to owl standing on power pole but otherwise not accessible owing to pen. On last few nights owing to moonlight chickens can see owl when it visits causing chickens to make a lot of odd cackling and doing some pretty consistent posturing while on roost. Somehow I think this behavior has potential for providing chickens better odds against owl although I do not know how. Most of us dealing with predators are concerned with simply did we loose a bird or did we get predator, but I was wondering if anybody took time to look and listen for what chickens are doing. I am trying record sounds and pictures but so far have slept through most recent visits. I am now to point where moving couch onto front porch and may tie string from dog to my toe for use as alarm. Anyone tried to observe what their chickens are doing when owls visit?