All ducks, except the merganser, have bills lined with bony notches for straining plant and animal matter from water. Most ducks of northern continents are migratory. Most males are bright colored with bold patterns. Ducks usually nest on the ground. Ducks vary in their migratory distances.
Disagreements exist about the classification of ducks, but there are a number of obvious groups.
They live primarily on fresh water. The pochards nest on fresh water but winter on inland lakes and along the coasts. Eiders and scoters nest in the far north and winter predominantly at sea. 3.To push suddenly under water . 3.To submerge the head or body briefly in water.