This duck grows 16-19 inches. It typically lives in swamps, wooded lakes and ponds, rivers and tidal marshes. It is a fish, aquatic insect and crustacean eater. They range from the western and southern portions of Canada into the United States - mostly eastern half.  Birds don't have teeth, but mergansers have serrated bills. This allows the birds to catch prey. They can change the refractive properties of their eyes underwater to increase their sight capabilities, so they are able to pinpoint the exact location of prey.

Exhibit: Cypress Creek Aviary