Angel Wing, a waterfowl wing deformity

[Catherine]

Angel wing is a condition where the last joint of the wing turns. It leaves the bird unable to fly. If they can't fly, they can't migrate or escape predators. It can only be reversed when it is caught early in a young bird.
It happens to ducks, geese and swans when humans feed them bread. Bread lacks proper nutritional requirements for water fowl. When the birds eat bread, they are not eating the foods they need. They are unable to develop properly.

https://www.insidehalton.com/news/humane...ccc98.html

Once again humans mess up. We want to be nice and feed the birds, but we feed them food that we are discarding. We don't find out what they can eat.
If you really want to feed the birds, find out what foods they need. Bring them something healthy. If you don't want to do that, just watch them. On their own, they will eat what they need and become healthy birds.