The term 'Common Duck' refers to three species of ducks that are commonly found in North America. The MALLARD (7 letters) is the most recognizable and widespread duck species, with its distinctive green head and yellow bill. The WIGEON (6 letters) is a smaller duck with a white crown and chestnut-colored sides. The TEAL (4 letters) is a small, colorful duck with a blue-green head and a white stripe along its neck. All three species are found in wetlands, ponds, and lakes throughout North America.