Alright I have a male mallard named Puddles. His head was entirely green, but it was never really bright like every other male mallard I've seen. It's now only a tinted green color. Is something wrong? Also, why is he so loud, I thought males were supposed to be quiet? He does have curled tail feathers and male feathers. He's a year and a half old by the way. I'll insert a couple images so you can see the most green his head has been. As I've said, it has since become more muted. 
