My ducklings will be 3 weeks Sunday and one is quacking the other has not yet but is a bit smaller they were hatched the same day. But the black one has a full on quack almost like a honk and the gray is whistley. The lady I bought them from said the father was blue swedish and the mother was a mix of khaki campbell and white campbell but the black one looks like a black swedish. Also I heard with the blue swedish that the males head will be darker than the rest of his body. The duckling is darkening not sure if it's just the head.