I have two Females Cayuga ducks, about 17 weeks old, and they were introduced to our flock of ducks at about 8-9 weeks old. Our flock consists of 1 male jumbo pekin, 1 female pekin, 1 male Swedish/runner, and 1 female Swedish runner. At first, the adult ducks were just scared of the ducklings, but now the ducklings like to shoe the others away from the food and water. we have them in a cage at night that's 6x10 with a 6x2 nesting house. The two Pekins just avoid the cayugas and just go into the house. However, the Swedish/runners are more persistent. They keep trying to get food, but after a while the cayugas push them away. I've seen the male go face to face with one of the cayugas before. I just don't know why they don't get along.