A pair of diving ducks.
diving duck definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
any of various ducks that dive for food or protection, as the redhead
diving duck definition by American Heritage Dictionary
Any of various ducks of the subfamily Aythyinae, including the scoters, eiders, goldeneyes, and scaups, that feed by diving beneath the surface of the water.