Well, there is no "right" answer to that question. The general rule is one drake for every 4-6 hens. However, there are always exceptions. Some people have to have even MORE hens, and some people less. In my adult flock, I have two drakes and two hens, and for us, it's worked out perfectly. One...
The black one definitely appears to be Cayuga. I agree on the mallards. The beige ducks could be buff but I am not for sure. The white one definitely looks Pekin. The black with white one the front could be a black Swedish, again, not sure. As for the blue duck, could be a blue Swedish??? Just...