How to identify the Comb Duck

To correctly identify the Comb Duck (Sarkidiornis melanotos), check each of these features. Birds can be tricky: habit, habitat, and call often confirm a sighting that a single photo cannot.

Size at a glance

Length

56-76 cm (22-30 in)

Wingspan

116-145 cm (46-57 in)

Weight

1.2-2.9 kg (2.6-6.4 lbs)

Physical features to check

1. 1

   Plumage

   Overall feather coloration and pattern.

   Adults have a glossy blue-black cap and hindneck, extending down the back. The face, neck, and underparts are white, often with a yellowish or buff wash. The flanks are grey, and the back and wings are iridescent blue-black. Some individuals, particularly in the African subspecies, may show dark mottling or spotting on the flanks and breast. The tail is black.

2. 2

   Beak shape

   Shape and color of the bill: a key field mark.

   Large, broad, and flattened. Males possess a prominent, fleshy, black, erectile knob on the culmen, which is much reduced or absent in females.

3. 3

   Eye color

   Iris color and any distinctive eye markings.

   Dark brown

4. 4

   Leg color

   Leg and foot color.

   Dark grey to black

5. 5

   Distinguishing features

   Standout features that separate this species.

   The most distinctive feature is the large, black, fleshy knob on the male's bill. In flight, they show large white wing patches on the upperwing coverts, contrasting with the dark flight feathers. The overall large size and upright posture are also characteristic.

6. 6

   Juvenile appearance

   How young birds differ from adults.

   Juveniles are duller than adults, with a brownish-grey cap and back, and less distinct white underparts. The bill knob is absent in young males.

7. 7

   Seasonal changes

   Plumage variation between breeding and non-breeding seasons.

   The male's bill knob is most prominent and swollen during the breeding season, shrinking outside of this period. Plumage generally remains consistent year-round, though iridescence may appear more vibrant in breeding plumage.

8. 8

   Sexual dimorphism

   How males and females differ.

   Males are significantly larger than females and possess the prominent black knob on the bill, which is absent or very small in females. Females are generally duller in plumage, with less iridescence.

Key field marks

• Male's Bill Knob. Look for the distinctive large, black, fleshy knob on the male's bill, especially prominent during the breeding season. This is the most reliable field mark for males.
• Plumage Pattern. Observe the glossy blue-black cap and back contrasting with the clean white face, neck, and underparts. Note the grey flanks and iridescent sheen on the back and wings.
• In-flight Markings. When flying, look for the large, conspicuous white patches on the upperwing coverts, which stand out against the dark flight feathers.
• Size and Posture. Note its relatively large size for a duck and its often upright posture when standing or perching in trees.
• Habitat. Search in tropical freshwater wetlands, particularly those with emergent vegetation and scattered trees for perching.

Explore the Comb Duck