Male and female buffleheads have distinct plumage. Males are striking with a black back, white body, and a large white patch extending from the eye to the back of the head. Females are primarily dark brown above and paler below, with a small white cheek patch.

Male Bufflehead:
• Head: Black, often with iridescent green and purple hues, and a large white patch extending from behind the eye to the back of the head.
• Body: Black back and white underparts.
• Wings: Black with a large white patch visible in flight.
• Bill: Short and dark.
• Legs and Feet: Tannish-pink.
• Size: Slightly larger than the female according to the Sacramento Audubon Society.

Female Bufflehead:
• Head: Dark brown with a small, oval white patch on the side.
• Body: Grayish-brown above, paler below according to the Sacramento Audubon Society.
• Wings: Grayish-brown with a small white patch, visible in flight.
• Bill: Dark brown.
• Legs and Feet: Gray.
• Size: Smaller than the male.