Despite their common features, waterfowl bills are very diverse and highly specialized. Similar to precision instruments, the bills of waterfowl have evolved in an array of sizes and shapes to exploit a variety of food items. Mallards are considered the generalists of the waterfowl world, foraging on seeds, waste grain, invertebrates, vegetation, and just about anything they can swallow. Compared to other species the shape of the mallard bill is broad and relatively unspecialized, allowing them to forage on a wide variety of food items.
In contrast to mallards, many other species have highly specialized bills. Among the most specialized are the bills of mergansers. All three North American species (common, hooded, and red-breasted) have long, narrow, serrated bills, which are uniquely adapted for grasping small fish. The wood duck bill is very short and narrow, which facilitates picking up acorns and cutting bulbs from wetland plants. Sea ducks like scoters and eiders dine on shellfish and mussels. Their strong, stout bills assist them in prying and opening shells to obtain the meaty treats inside.
The Jimmy Durante of ducks, the northern shoveler, has perhaps the most unique bill of all waterfowl. It's wide, shovel-like bill with well-developed lamellae functions as a large scoop and sieve for skimming invertebrates and seeds from the water's surface. It is not uncommon to see groups of shovelers foraging together like pelicans.
Waterfowl species that grub or rip up tubers and roots, such as canvasbacks and snow geese, have stout, wedge-shaped bills ideal for prying plant material loose from beneath the mud. Grubbing waterfowl species also have strong, muscular necks, which helps them uproot the buried plant parts that they savor.
The bills of Canada geese are uniquely adapted for grasping and snipping new shoots of grasses, leaves, and stems. While considered a dabbling duck, American wigeon also graze; the shape of their bill is very similar to that of a Canada goose. Thus it's not uncommon to see both of these aquatic grazers dining on lush grasses in pastures.
Through the ages, waterfowl have developed an assortment of adaptations and feeding modes to exploit the wealth of food resources available in diverse wetland and upland habitats. Regrettably, many of these habitats continue to be lost or degraded at an alarming rate. Fortunately, Ducks Unlimited and its partners are devoted to protecting and restoring the diversity of this continent's habitats that North American waterfowl require.
Dr. John Coluccy is director of conservation planning and Elizabeth St. James is a conservation specialist at DU's Great Lakes/Atlantic office in Ann Arbor, Michigan.