In Ducks And Geese Angel wing, also known as slipped wing, crooked wing or drooped wing, is a condition of ducks and geese where the last joint of the wing is twisted and the wing feathers point out, and do not lay smooth against the body. It is more common in geese and typically in either the left wing or both wings, only rarely in the right wing only.
Males develop it more than females.
The birds that develop the problem are perfectly healthy, they are just not as beautiful. Because of the discussions I have heard over the years on the cause of angel wing, I did a search for all research on the subject. The best article was one written by Janet Kear, who is the Senior Scientific Officer of The Wildlife Trust in Great Britain. Some of the researchers feel the condition is genetic, but others have proven it is not. Because she works with waterfowl from many parts of the world, Ms. Kear has come to the conclusion that it is a nutritional problem due to excess feed.