Chickens eating my duck eggs >:(

[bettynoodlees]

My chickens and ducks free range all day, my ducks started laying in their pen, and the chickens have been going in there and rolling the duck eggs around, my husband has been gently repiling them in the nest... but then he went to check on them and caught a chicken running off with half a duck egg.

Grrrr!!

They don't do this to their own eggs (maybe because we take up the chicken eggs, and leave the duck eggs hoping the ducks will sit on them?)

Any advice would help!!