NON-DIVING DUCKS.
Representatives of no less than three of the four sub-families into which the Ducks have been divided by systematists, are found on the British coast-line. Each sub-family contains some thoroughly marine species. We will deal first with the Anatinæ, containing the Sheldrakes and non-diving Ducks. The birds in this sub-family are distinguished from all others by having the tarsus scutellated or plated in front, and by having only a narrow membrane attached to the hind toe. A peculiarity about these Ducks is that they never dive for their food. This is obtained only in shallow water, by submerging the fore half of the body and dabbling and probing amongst the mud and weeds. In the Sheldrakes the sexes are nearly alike in colour, but in the remaining species there is usually considerable difference in this respect, the males or drakes being handsome, showy birds, the females or ducks brown and comparatively sombre-looking. The Sheldrakes moult once in autumn, the remaining species the same, but the drakes of these latter change their small feathers twice, once in early summer and once in autumn. The young are hatched covered with down, and able, to a great extent, to shift for themselves.