I am going to get two little ducklings from Metzer farms through the mail. I am getting a cayuga and a welsh harlequin. I know what the WH will look like when its a baby and an adult. But I don't know how to tell if my cayuga is a male or female. How dod you tell if a cayuga is a male or female? Also, how do you introduce these two ,to a four month old khaki campbell? Thank you.