Guess I'm getting confused. I thought the ducks were outside in the open. What does normal wear and tear on a screen door have to do with your duck being mutilated outside in the grass?
Your poor duck, I'm so sorry she was injured.
The previous poster was correct, now that a predator has found your ducks, it will most likely be back. Check at your local stores, maybe you can get free wooden pallets to put together some type of structure. Look on Craigslist for an old play...