One of my ducks ran away...

[brooder]

I live in the suburban Midwest and have a flock of four ducks. I haven't been cooping them at night lately due to the fact that they keep escaping from their pen and that their are not many predators native to the area. I was surprised to find one of my hens missing this morning. I'm assuming she is probably dead by now, but is there any advice you can give me on trying to find her? Thanks In advance.

 

[brooder]

Update: I found a clump of bloody feathers and nothing else, so I am assuming she fell prey to a hawk. I am checking the others for wounds as I found their feathers as well.