have used the quack test successfully in the past, and will probably just wait till they are older
i have found that the drakes usually calm down and accept them (allways had a little aggression towards new ducklings) and if i isolate them the problem is far worse when they are bigger and fight back - i was only really asking as 17 ducks plus all then hens and rabbits are taking up a decent section of the garden and I'm needing to start lining up homes for them but don't want to sell them as a girl and they are a boy!
thanks