This is our only duck.
We live in the desert south west. He is very well taken care of.
He is a rescue and has a damaged leg because of fishing line.
He has water and a kids pool to float and bathe, he can submerge his whole head.
We don't know how old he is, we rescued him 3 years ago. he was full grown at that time.
It's looked like this for a long time, more than 6 months. It's slowly progressed to the point it is at now.
He is fed a variety of grains, fruits, vegetables, and a bit of salmon and rice dog food. Also rinsed canned corn and cheerios.
He also scratched/cut his bill on the edge of a mirror, this is when the problem started.
We thought it would clear up but by now but it's obvious that it's getting worse. We don't have the means to take him to a vet. So we are going to try applying a daily anti fungal cream from the drugstore.
@casportpony Thanks for the comment. The inside of his mouth looks normal.
I really, really would not recommend applying an antifungal you pick up from a drugstore, especially in light of the fact that you said this started when he cut his bill on a piece of glass.
Kathy, there are other things I'm thinking of here, but would you mind saying what you think in light of what the OP said? It's so hard to say in these situations when you can't see something in person, but I'm very hesitant to apply a random antifungal to a duck based on a pic. I'm thinking a very arid environment could be a big part of the extreme shedding and that the cut from the glass more likely introduced something bacterial?