Duck eggs in chickens' nest box

[Henrietta23]

Two mornings in a row we have found a duck egg in one of the nest boxes in our coop. I have seen our khaki campbell duck standing on top of the feed can so I know she can get up high enough. She had been laying in a corner of the coop on the floor so this is a new thing. Is this unusual?

 

[WalkingWolf]

No I have been having the same thing. Except the entrances to the nest boxes are too small for my Pekin. The only conclusion I have is one of the hens is picking up and moving the duck eggs.

 

[Henrietta23]

I think I remember reading your post. I can't imagine one of my chickens picking an egg up as high as my nest boxes are though. And none of my hens seems to be broody. My nest boxes are big enough for the Khaki, but too high. Strange!
To top it all off, some of the chickens have been laying in the corner nest made by the other ducks! Maybe because they're put off by the duck in their box??