So sorry about your ducks! We have always wanted them but haven't gotten any for that reason; our pond is in the woods and there is a fox den so close that the Canada Geese won't even nest on the pond. But I would never deny our chickens free-ranging. We've lost more to predators in the barn then outside. A good rooster or two will help to protect the flock. They do come in at night; we feel they're safer that way than roosting in the trees, but that's when we've lost most of ours due to predators.