Caruncles are a major distinguishing Muscovy duck characteristic. Usually only present on males, caruncles are fleshy, red, warty bumps that cover the area around the eyes and extend to the base of the bill. Muscovy ducks weigh anywhere between 10 and 15 pounds (4 and 7 kg), and males are typically larger than females. They may appear solid white, solid black, or mottled, with males featuring an iridescent green or purple sheen to their feathers, unlike females of the species. They also have long, flat tails and large claws.