Just wait... They will. The nice thing though, duck poop washes away very very easily from a duck coop if you make sure you have linoleum down. Just take a pistol type sprayer... ALSO, set your duck coop on an angle so the poop and water go out the door... you know, how a house settles and water runs in one direction instead of just puddling... so, just enough so the water runs where you want it. Yup. AND get some bread crates if you can, so they can go in the far corner of the coop and the ducks will lay their eggs in the clean pine shavings and crap everywhere else. I use three, and they tend to lay in the farthest away one, and not crap in that one. Makes for much cleaner eggs.