Buffleheads are diving ducks that reside on the Swanquarter National Wildlife Refuge during the fall and winter. They use shallow, sheltered coves, harbors, estuaries, or beaches. Buffleheads dive for aquatic invertebrates, crustaceans, and mollusks. They typically swallow their food while still underwater. Dives last on average about 12 seconds and rarely more than 25 seconds, typically staying on the surface another 12 seconds or so before diving again. Buffleheads forage in open, shallow water over sparse submerged vegetation or over mudflats that would be exposed at low tide. In saltwater, Bufflehead eat shrimp, crabs, amphipods, isopods, snails, mussels, herring eggs, sculpins, and ratfishes

Bufflehead swim buoyantly, dive easily, and take flight by running a short distance on the surface. They fly low over the water and higher over the land. To dive, Bufflehead compress their plumage to squeeze out air, then give a slight forward leap and plunge powerfully downward. They hold their wings tightly against their bodies underwater and use only their feet to propel themselves. At the end of a dive, they may bob to the surface like a cork. Throughout the day they alternate between bouts of feeding, swimming alertly, preening, and sleeping. Buffleheads are seldom seen on dry land.

Buffleheads are very small, compact ducks with large, rounded heads and short wide bills. Adult male Buffleheads have a white bodies, black backs, and dark heads with large white patches that wraps around the back of their heads. Females and first-year males are gray-brown overall with an oval, white cheek patch. In flight adult males have a large white patch on the upper wing; females and first-year males have a smaller white wing patch. They are 12 to 16 inches long, weight 9 to 23 ounces, and have a wingspan of 22 inches.