I have a half aussie shep and half black lab. 1 1/2 years old puppy still learning. She is a pretty good dog and she runs free on about 2/3 acre with an underground fence. We have open range chickens that have started to migrate into her territory. I was hoping that her aussie side would take over and herd them, it looks like her black lab side is taking over and she is more of a bird dog. I have been on her today to stay away from them, but she got a hold of one and had it pinned down. I was not sure if she was playing or getting ready to eat it. What should I do to train her away from them? Shock Collar?