I have a 2 yr old great pyr male and a female anatolian shepherd that turns 2 in june. (both fixed) For the last 4 months or so I have had an issue with my chickens randomly turning up dead(no feather missing or obviously injured, just dead) or injured to their backs. The attacks seem random. At first I thought it could be hawks, fox, or coyote since I have seen all 3 in my yard. The dogs and chickens are together in just under an acre. They have both always been around chickens and when they were younger they stayed in the front yard where they could see the chickens and i gave them supervised chicken time while i did my chores and on weekends. For the past 7 months or so they had been getting more and more unsupervised chicken time with no problems. About 2 months ago 4 chickens were dead when I got up in the morning so I separated them for a few weeks until another one turned up dead in what seemed the same manner. It couldn't be the dogs i thought so I put up cameras and let them all run the whole yard together again. The male doesn't seem to care one way or another and the female is very attentive to them. She breaks up fights and makes sure they put themselves up at night in an orderly fashion. We went a whole month with no problems when I found that 2 were tore up pretty bad to their backs, missing feathers and ripped skin but still alive. The video shows them making their rounds when the male sees something in the back corner. The female starts to, i guess you could say heard them, toward the shed. He gets done barking at whatever it was and stands near her. Then they act odd. He is jogging back and forth and she is kind of bouncing with her front paws at the group for a few minutes. A few run off and they both just run straight for the main group. She caught one and just carried it around. She would set it down then catch it again when it tried to run off all while he tried to get at it. It seemed like a game of keep away for them. Whenever it got up to run away they chased and she went back to carrying it around. This went on for 30 minutes or more with a fight between them toward the end. The chicken got away and they went after another one and did the same thing again with him even grabbing it by the wing and trying to take it from her. Once the 2nd one got away they spent the next hour looking for it then finally went back to their normal behavior. All this happened while I was at work. I can only assume they were responsible for the 4 dead ones a few months ago too. I have separated them again. I am curious about you opinions on what could have triggered this since they went over a month with no issues after the last time. I also need advice on what to do to stop this behavior.