Could somebody please tell me if Mallard ducks can have blue beaks? I saw one in Vivary park today with the other ducks, but only one had a blue beak. It was a male. Was it still a Mallard?
Yes, you will see this occasionally. Still a Mallard, but like many a village duckpond Mallard it will have some domestic duck genes in it, in this case showing out as the bill colour.