So we thought that a few months ago one of the dogs were the ones that killed our 4 chicks (including my favorite). But all of them have gotten into the yard at least once while the chickens were out with no issues. One time I was working on a tree house and someone let my shepherd out and I had thrown some lasagna out for the chickens, I looked over and Annie was in the middle of 5 mad chickens eating their lasagna until they scared her off. We have had MANY hawks around lately and I am starting to wonder if it was a hawk that got them. The big chickens were fine. The old run blew over in a storm and something got the 2 month old chicks. So anyway, we still dont know and we still dont leave them out, or even let them out (unless they are leashed) while the chickens are out. BUT the other day my neighbor saw 3 opposums trying to get into our yard and the dogs scared them off. So my dogs may or may not be predators, but at least they are deterants for the other predators.