I bought 6 ducks, bought them as hens. the joke is one me though. two of them I processed because they were drakes for sure.Seeing the curly tail. I can not see the curly tail yet on the other 4 but one is so aggressive, and chases all the others and want to bite them. I bought them for egg production only. I have them in a large secure dog kennel with their pool, lawn, feed and shelter, which they do not go in, even though there is bedding in their. I never had ducks before so I have been doing lots of research. They will be going in to another pen as soon as it is remodeled for them for safety from owe and hawks.. There must still be a drake in the bunch because there is head nodding. What other signs must I look for to determine what they are. They are a mixture of duck breeds.