The bufflehead (Bucephala albeola) is a small American sea duck of the genus Bucephala, the goldeneyes. This species was first described by Linnaeus in his Systema naturae in 1758 as Anas albeola. The Bufflehead ranges from 32–40 cm (13–16 in) long and 270–550 g (9.5–19.4 oz), with the drakes larger than the females. Averaging 35.5 cm (14.0 in) and 370 g (13 oz), it rivals the green-winged teal as the smallest American duck. Adult males are striking black and white, with iridescent green and purple heads with a large white patch behind the eye. Females are grey-toned with a smaller white patch behind the eye and a light underside. The name bufflehead is a combination of buffalo and head, referring to the oddly bulbous head shape of the species. This is most noticeable when the male puffs out the feathers on the head, thus greatly increasing the apparent size of the head.