If you can't tell the difference between a mallard and a muscovy, you could be in trouble.
A poultry abattoir in New York's strictly Orthodox enclave of Kiryas Joel was recently ordered by rabbis to recall a consignment of doubtful ducks.
Now, the Torah specifies only what birds you cannot eat and duck is not among them. Later rabbis, however, instituted a rule permitting only birds where there existed an established local tradition of consumption.
Most kosher-edible duck descends from the mallard, but the first Jewish settlers in America enjoyed a local variety, the muscovy or barbary.
After the spilling of much rabbinical ink, the muscovy ended up on the banned list. It seems that some muscovy cross-breeds may have lately infiltrated the kosher net in New York.
And how do you tell a mallard from a muscovy? The kosher one quacks and the other hisses.