We lost a lame duckling to a hawk several years ago, but that was our only loss from a hawk. There is a pair of hawks that nest near us year after year, and we occasionally see in the trees near the barn, but they have never taken any of the grown ducks. We have bird feeders set up all over the place and when the little birds scatter, the chickens (especially the small breeds) head for cover as well. The grown ducks just keep going about and are never bothered. Now owls are a different story. They can easily take a grown duck. And while usually night hunters, owls have been known to hunt during the day. We have a LGD (Livestock Guardian Dog) that watches for aerial predators, so that helps.