We placed him in a box in a shelter on the back deck for a week and a half. He didn't get any better with rest. So I let him out. Jill, the girl duck, was beside herself. She would hang around and quack at the box all day. So I let him out to live out the rest of his life, or until we could figure out what to do with him.
For about a month he would spend his days under the trees and flap back down- we'd carry him on his bad days- to eat and spend the night by the house. He was hanging on, even though we sort of wished he would give up. I am not the strongest farm-animal person...I am unable to put a bird out of it's misery. We had a similar issue with a chicken- Hopper a couple years ago...
She died of natural causes after about 6 months. And this morning when we went to find Bill to move him to safety before mowing the grass, we found him too. The boys took it well, since it was a long time coming. And I think Jill will be okay too. She's had a couple months to get used to not having him as her shadow and she has made good friends with the chickens....