Honestly, they really are obsessed when broody. My one Muscovy was so obsessed and would not give up I put a piece of lattice over where she was brooding she actually laid on top of the lattice so then I took 2 bales of shaving still in the bags and put it over the lattice, she laid on top of them. Finally,
I locked her out during the day and it took 2 weeks of doing this before she finally gave up. here she is laying on the bales lol they honestly don't care what they lay on.