We bought several ducklings from our local feed store in the spring and at the time they all looked pretty much alike except 2 had mottled bills. Now these ducks are twice the size as the other ducklings, now 4 months old (they are slightly larger than our largest Swedish) I am trying to find out the breed and possibly the sex of these ducks, I could not find anything that looked like them EXACTLY in books or on line. They were suppose to be rouen but I'm thinking maybe appleyard, saxony or welsh harlequin. They are hard to describe but here are the things I know for sure: they have mottled bills, orange feet, dark grey/brown heads with a partial ring around the neck, brown speckled chests, they are large heavy birds and have bright grey wings with white edging, their tails are sharply pointed and dark fading to a light under-belly. I'm going to try to include a photo but since this is my first post I'm not sure I can. I'm guessing they're males as they both have the low raspy voice and will try to "mate" anything in the yard, the smaller 1 is definitely a male as I vented him but I couldn't tell with the larger one as he/she was too strong.