Waterfowl have as many as 12,000 separate skin muscles used for feather control. Ducks and geese lift or compress their plumage in various ways to help regulate body heat, dive underwater, and express emotions, such as aggression or amorousness.
Waterfowl ingest small particles of stone, gravel, and sand, which are kept in their gizzard to help them grind up hard foods like grain, acorns, and clams. In 1911, a gold rush was spurred in western Nebraska after hunters found small gold nuggets in the gizzards of ducks they had shot. The source of these gold nuggets, however, was never discovered.
Many female ducks and ducklings have drab plumage with darker feathers forming a cap on their head and stripes extending across their eyes. This "masking" helps camouflage the birds' shiny eyes, which could be seen by predators or pecked at by hungry offspring or siblings.
Several waterfowl—including redheads, canvasbacks, wood ducks, ruddy ducks, hooded mergansers, and snow geese—pursue a breeding strategy known as nest parasitism, where females lay eggs in the nests of other females of the same species. Some wood duck nest boxes have been found with as many as 50 eggs laid by multiple hens. Female redheads regularly lay eggs in the nests of other duck species. In one study conducted on Manitoba's Delta Marsh, more than 90 percent of canvasback nests contained redhead eggs. The unsuspecting foster hens raise the redhead ducklings as their own.
The long-distance flying champions of all waterfowl are black brant, which migrate nonstop from coastal Alaska to their wintering grounds in Baja California—a journey of roughly 3,000 miles—in just 60 to 72 hours. The birds lose almost half their body weight during this marathon flight. Pintails raised in Alaska and winter in Hawaii make a similar trans-Pacific flight of about 2,000 miles.
The coloration of waterfowl plumage is produced in two ways: by pigments or by the physical structure of the feathers. The two main types of pigments, known as melanins and lipochromes, produce black, brown, red, yellow, green, and violet shades. The appearance of blue and iridescent colors results from these pigments in combination with fine feather structures. This explains why some waterfowl feathers appear to change color as they are moved in sunlight.
In the fall, wood ducks largely feed on acorns in flooded bottomlands. Researchers who conducted a "taste test" on captive wood ducks found the birds preferred tiny willow oak acorns over larger acorns produced by other oak species. Biologists have found as many as 15 pin oak acorns packed into the gizzard and esophagus of a wood duck.
The location of the spectacled eider's wintering grounds remained a mystery until fairly recently. In March 1995, researchers followed birds marked with satellite transmitters into the heart of the Bering Sea, where they found massive concentrations of spectacled eiders gathered in fissures in the pack ice. Biologists assume the birds gather in these areas to feed, since they acquire heavy fat reserves during the winter months.
In January 1999, a tornado and violent hailstorm deposited more than 3,000 dead waterfowl across a seven-mile-long swath in eastern Arkansas.
Waterfowl wings provide the two essential elements of flight. Primary feathers (those on the tips of the wings) provide thrust, while secondary feathers (those on the rear edge of the wings) provide lift.