I think they would certainly try. Hawks and owls don't always carry off their prey, but if they are undisturbed they will stay on the ground and eat their fill of what they have caught. I had a Great Horned owl make an attack on my free-ranging ducks at dusk one evening (that's when the owls are most active and I was going out to shut the ducks in their night pen), but either the owl was too immature or the ducks were too quick (or both!) and it was unsuccessful. Though it didn't stop the owl from sitting in the field and glaring at me as I penned the ducks. So the short answer is yes, I think hawks would make an attempt if they thought they could get away with it. If you're free-ranging them make sure you have plenty of day-time cover for them and a secure pen to lock them in at night. To be completely hawk-proof you'd have to have a secure day-time run for them as well.
A hawk will try to get a duck, and if the hawk happens to geab a duck, he will keep coming back to get an easy meal.