I have 3 10 week old Blue Swedish Ducks and cannot figure out the sex of them. They seem to be in the middle of a quack & rasp, no one has a curly tail and all are starting to get green irredecent feathers on their heads. We thought for sure one was a female . . . has always been very loud. Now that she/he is develping green feathers I'm wondering what I have lol!