Right after our house sitter let the ducks sleep in the chicken coop (and we never separated them again since everyone seemed happy), the number of eggs our hens were laying reduced by half. Two months later, when the ducks were rehomed to a farm with other ducks, the hens' egg numbers went back up immediately. Coincidence, or is this something common? The drake wasn't harassing the hens, everyone seemed to get food and water when needed, the ducks stayed out of the coop all day. I'm not sure why they would have made a difference, but they did seem to.