Duck is the collective name for waterfowl of the subfamily Anatinae of the order Ansidae, or true ducks. Ducks are relatively small, with short necks, and some species have larger beaks. The legs are set behind the body (like a swan), resulting in a staggering gait. Most true ducks (including several birds that are incorrectly called geese due to their size and shape) are different from swans and geese in that they have the following characteristics: the male moults twice a year, and the female lays several eggs per clutch. There are also many, with smooth egg shells; legs covered with matching scales; calls and some degree of gender difference.
