The ladies are a Pekin and the rest are swedish. 3 of them are around 7 months oldI would think if your ducks are rather large, such as Pekins or Rouen Ducks that it would be fine. I have two Mallard Hens and one is larger than the other. The one that they would all try to pile on was my smaller one so that is why I rehomed two of the Calls. They say the female Calls are so loud and I looked it up on the internet and they really are loud. My boys love to make their little raspy noise but it is really quiet compared to my girls.