The "butterball" with its showy white crest, is the smallest of all diving ducks. Like its relative, the goldeneye, it nests in cavities in trees standing close to water. These holes often are the abandoned homes of woodpeckers or flickers. The bufflehead arrives late in spring and departs just in advance of freeze-up. It breeds in forested areas from west-central Alaska through western Canada and the northwestern states. The bufflehead was originally known as Buffalo Heads, their name has changed over time to bufflehead. The domed shaped head of the drake has brilliant bright iridescent metallic-green, purple and bronze. Drakes rarely exceed a pound and their female counterparts are seldom over 8 ounces in weight. With their small bodies they can spring off the water much easier than other diving ducks. They are also some of the fastest flying waterfowl. Buffleheads make brief, growling or guttural sounds along with weak, squeaky whistles. They are less sociable than many sea-ducks. Unlike other species they choose not to gather in large concentrations – flocks of over 40 birds are uncommon. They tend to dive in smaller groups with a few birds remaining on the top of the water watching for danger. Diving is usually more synchronous in winter, when a large number of birds will dive at the same time.