i have a fox living practically in my back yard, we also have raccoons that visit us and bears (idk what they would do...don't ever want to find out) and wild dogs. so far, our ducks have been fine but i don't want to jinks myself. we built a pen for them, which is 2 by 4s with chicken wire around it. its 8 by 8. then for the winter, we built them a house which is more 2 by 4s and a LOT of plywood. its 4 by 8 and its connected to the pen. since we live next to a pond, we've had some snake problems. one was so fat it couldn't fit through the chicken wire which was good and then the same one (its HUGE!!!) has gone after them a couple times when they were at the pond. it even tried to bite my once. the ducks have always been able to sense/hear it before it gets close. i would say your ducks would be okay as long as you put them somewhere safe at night, put them in before dusk and let them out after dawn, so most predators aren't out. good luck!