So, with that many drakes and that few ducks (females), there is serious potential for trouble for the ducks. The general rule of thumb (granted there are exceptions, but they are in the minority) is one drake to three, four, five, or even six ducks.
Drakes will overdo it with ducks, and since it can be a pretty rough experience for the ducks anyway, ducks can be killed with too many drakes (sometimes three or four at a time trying to get on top of her in the water, drowning her, or on land, crushing her).
Please think about adding more females, or having a drake pen, or duck (just girls) pen to protect them. Please.