Hello we have mallards that are about a year and half old. We have 3 drakes and 7 hens. They all have really lost all their coloring. The drakes heads are no longer the brilliant green they have always been. Was wondering if it was that they were molting? Can someone explain the molting process to me? When do they do it? how long it lasts? etc. If its not molting is it something lacking in their diet? If thats the case I want to get what they need. We feed them layer crumble from southern states. Same product we feed our chickens. Thanks in advance for any help!