Unusual Bird: Diseased dove?

One of a pair of Mourning doves appeared to have some sort of abnormality, a sac or group of feathers hanging from its neck. When I saw the picture I took, I also thought the feet don’t look normal, as if it has some sort of fungus. Its behavior was normal and it didn’t seem unable to eat or drink. (We cleaned the bird bath after it had drunk from it.)