Although the males average a little larger, the male and female of the same stock are usually nearer the same size than in gallinaceous birds. The only marks by which sex can be distinguished in all ducks are the voice and the presence or absence of the small curled feathers on the tail which characterize the males. In party-colored varieties the color markings of the male and female are sometimes different. The "quack" of the duck is the note of the female; the male makes a very subdued similar sound, comparing with it as a hoarse whisper compares with the natural tones of the human voice. The duck derives its English name from its habit of ducking its head into the water in search of food at the bottom of the shallow waters, which it prefers. The term "duck" is applied to males and females collectively, and also to the female as distinguished from the male. The male is called a _drake_. The name "drake" is supposed to be derived from an Old German word meaning "the chief duck." Any one who is familiar with the habits of ducks will see at once the appropriateness of the term. Ducks often march in single file, and when they do so, all the drakes in a group go first, the ducks following them, usually with a little space between. So if there is only one male, he marches a little ahead of his flock, like a commander. Young ducks are called _ducklings_, the name being applied to both sexes. In our language there are no special terms applying to a young duck and a young drake as distinguished from adult birds. =Origin.= Useful domestic ducks are of two species. All the breeds of this class, except the Muscovy Duck, are derived from the wild Mallard Duck, specimens of which are still frequently captured and domesticated. The Mallard takes very readily to domestication. Although in the wild state it is a migratory bird, in domestication it soon becomes too heavy to fly far. After a few generations in domestication it becomes as large as common domestic stock, loses its power of flight, and cannot be distinguished from stock that has been domesticated for centuries. Mallard Ducks captured in the wild state and kept in captivity have been known to lay from eighty to one hundred eggs in a season, which is as many as the average domestic duck lays. [Illustration: Fig. 122. Domesticated Mallard Ducks, Brook View Farm, Newbury, Massachusetts]