The bufflehead was formally described in 1758 by the Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae under the binomial name Anas albeola.

[2] Linnaeus based his account on the "little black and white duck" that had been described in 1747 by the English naturalist George Edwards in the second volume of his A Natural History of Uncommon Birds.

[4] The bufflehead is now placed with two goldeneye species in the genus Bucephala that was introduced in 1858 by the American naturalist Spencer Baird.

[5] The genus name is derived from Ancient Greek βουκέφαλος bouképhalos, 'bullheaded', from boûs 'bull', and kephalḗ, 'head', a reference to the oddly bulbous head shape of the species.

[9] Buffleheads have evolved their small size to fit the nesting cavity of their "metabiotic" host, a woodpecker, the northern flicker.

Nest competitors include mountain bluebird (Sialia currucoides), tree swallow (Tachycineta bicolor), and European starling.

[10] Incubation averages 30 days, and nest success is high (79% in one study) compared to ground-nesting species like the teal.

[12] Predators of adults include the peregrine falcon (Falco peregrinus), snowy owl (Bubo scandiacus), bald eagle (Haliaeetus leucocephalus), golden eagle (Aquila chrysaetos), red-tailed hawk (Buteo jamaicensis), great horned owl (Bubo virginianus), and Cooper's hawk (Accipiter cooperii).

[8] In freshwater habitats, they eat primarily insects, and in saltwater, they feed predominantly on crustaceans and mollusks.