You will have to train her Not to chase ducks. you will need to train your dog to leave the ducks alone, Dogs can be taught it takes a bit of time and patience. My dogs.ducks/chickens/geese can all mingle together[I have to watch the geese though they will bully the dogs] and I don't let my dogs around ducklings/chicks it's just to easy for the prey drive to kick in when they are tiny. I found out the hard way. Always start training with your dog on a leash never give her/him that first opportunity to chase them. What breed is your dog?Okay my dog would probably go up to the pen and bark but if y'all think they will be okay I might do that. She chases ducks so I hope they are okay.