I have a small flock of 5 golden hybrid ducks. I am babysitting 10 mallards : 6 drakes and 4 hens. When I went out to put them in their night time cage, one of the drakes was dead. He was torn up. I had them in a fenced area separate but within view of my girls. I didn't see signs of a predator. I'm sad and I know the girls who own the birds will be crushed.(They are gone for the holidays) Any thoughts?