Ducklings attacking chicks

[AppMtnChickens]

So I have a dilemma... my 7 week old ducks have started attacking my chicks. They got along when they were around the same size, but now that the ducks are just a little bit bigger they attack the chicks when they're around. The chicks have lived in the hen house for 3 weeks now, completely divided, but through wire so they could see each other, and they also free range together. But now the ducks are horrible to them when there is not a divider. What should I do?

 

[sourland]

Depending upon the degree of aggression, it may be necessary to keep them separated.