The boyfriend and I just got some ducks on Tuesday. Two little dark ones, two big yellow ones. The yellow ones are probably Pekins, and little dark ones are either Rouens or Mallards (they're about 2/3s the size of our yellow ones, and I thought Rouens and Pekins would be closer in size). Anyhow, our yellow ducklings have different colored bills. One is pink, the other is orange. When they're side by side the difference is very noticeable. Does this indicate a different breed, different gender, or do we just have pigmentally special ducks?