Some definitely quack, but I'm having a hard time telling which is which. Here are some pictures. There are a couple that are definitely drakes (heads are changing) but the others I'm not sure. I think this is a drake because of the colored feathers? I think the white on on the right is a drake. His head is changing colors. Here he is again in the back. I'm wondering about the one with a green bill. Its a saxony. Any input would be great. They are coming up to butcher age and we only want to keep one drake.