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Kidadl Team

AUGUST 27, 2021

Knob-Billed Duck: 15 Facts You Won't Believe!

Knob-billed duck facts include that the males have the distinct knob on their bill, while the females don't.

The knob-billed duck, also known as the African comb duck, is a water duck species endemic to South America, South Asia, Madagascar, and sub-Saharan Africa. They live in tropical wetlands, wet marshy areas like grassy ponds, forests along large rivers and lakes, swamps, pastures, and rice paddies. They are flocking birds and one male breeds with up to five females. Solitary males perch in trees and swoop down to breed. Their name comes from the distinctive fleshy knob or comb on their bill. The fleshy comb remains the same size around the year but grows in size during the breeding season, during the monsoons. The females lay 7-15 eggs in each breeding season. Its Latin scientific name, Sarkidiornis melanotos, translates to 'fleshy comb' and 'black back.'

For more relatable content, check out these merganser duck facts and muscovy duck facts.

Knob-Billed Duck Interesting Facts

What type of animal is a knob-billed duck?

The knob-billed duck (Sarkidiornis melanotos), or comb duck, is a water duck of the Anatidae family.

What class of animal does a knob-billed duck belong to?

The knob-billed duck (Sarkidiornis melanotos) belongs to the class Aves.

How many knob-billed ducks are there in the world?

The exact number of African comb ducks is unknown. It is listed as Least Concern in the IUCN Red List; meaning there are more than 10,000 mature individuals.

Where does a knob-billed duck live?

The knob-billed duck is commonly found in tropical wetlands of sub-Saharan Africa, South America, South Asia, and Madagascar.

What is a knob-billed duck's habitat?

This knob-billed duck species inhabits wet marshy areas like grassy ponds, forests along large rivers and lakes, swamps, pastures, rice paddies, etc.

Who do knob-billed ducks live with?

The knob-billed ducks, or comb ducks, can be found alone or in pairs but typically in flocks of 30-40 birds in the wet season and up to 100 birds in the dry season. Records show that sometimes they separate according to gender.

How long does a knob-billed duck live?

This duck species can live for 20-30 years.

How do they reproduce?

This duck species breeds during and after the rainy season and may choose not to breed if the rain is insufficient and knob-billed ducks nest mainly in tree holes, also in tall grass. Their nest is made of sticks and coarse grass, lined with grass, leaves, and feathers. The tree holes are usually 19.6-29.5 ft (6-9 m) high. Males may have two to five mates at once. Unmated males often perch in trees and fly down to mate with a female. Knob-billed ducks reproduce by laying 7-15 yellowish-white eggs incubated for 28-30 days. They may perform dump-nesting, with the clutch containing up to 50 eggs.

What is their conservation status?

 The knob-billed duck (Sarkidiornis melanotos) is listed as Least Concern in the IUCN Red List.

Knob-Billed Duck Fun Facts 

What does knob-billed duck look like?

The knob-billed duck has an impressive wingspan of 46-57 in (116-145 cm)

 Adults have a white head freckled with dark spots and a pure white neck and underparts in this species. The upper parts of the wings are glossy blue-black in color with bluish-green iridescence on the lower arm feathers. The male is distinctly different from the female; the male has a black knob on his bill and is much larger than the female. Young birds have a dull cream color on the face and neck, with dull brown upper parts, top of the head, and eyestripe. Knob-billed ducks are larger than comb ducks, and the sides are lighter (light grey in females, sometimes whitish).

Young knob-billed ducks in immature plumage look like a large grayish female Nettapus coromandelicus and may be difficult to tell apart without any other birds around to compare size and color. Young knob-billed ducks are rarely seen without adults nearby and thus can be correctly identified.

How cute are they?

This duck species is very fluffy and cute. Its white head, neck, and underparts give it a cute and innocent look balanced by the majestic sight of its iridescent wings.

How do they communicate?

Typically, the male knob-billed duck is silent except for a low croak when flushed. The ducks utter whistles and grunts during mating displays or when fighting against rivals or protecting the females and young ones. The only sounds the female utters are some low quacks and grunts. While flying, a hoarse whistle-like sound can be heard.

How big is a knob-billed duck?

This duck species is one of the biggest of all the other ducks. It is 22-30 in (56-76 cm) long with a wingspan of 46-57 in (116-145 cm). They are slightly larger than crested ducks and around twice the size of a small Argentinian lake duck.

How fast can a knob-billed duck fly?

The Knob-billed duck is not a very fast flyer but has large, strong wings, making it a great flier. It flies using slow, steady, and noisy wingbeats. When they move to find water, they may have to travel long distances. They fly in an irregular formation, in single-file lines, or in a loose V-formation.

How much does a knob-billed duck weigh?

This duck weighs 2.3-6.4 lb (1.03-2.9 kg) which is twice the weight of an American black duck and four times the weight of a long-tailed duck.

What are the male and female names of the species?

There are no specific names to differentiate between the two sexes of this species. They are simply referred to as female knob-billed ducks or male knob-billed ducks.

What would you call a baby knob-billed duck?

There is no specific name for the babies of this species; they are generally called chicks, babies, or young ones.

What do they eat?

The diet of knob-billed ducks includes foliage found in and around water sources like ponds, lakes, and swamps. They also feed on insects, larvae, grass, and to a lesser extent on small fish.

Are they dangerous?

No, they are not dangerous to humans or other animals. They only get territorial during the breeding season if they sense something threatening the safety of the females or young ones.

Would they make a good pet?

No, they would not be good pets. They are not the domestic variety and are indeed wild, untamed birds that are best left to themselves in their natural habitat.

Did you know...

The juveniles of knob-billed ducks are precocial, hatched in an advanced state, and can feed themselves almost immediately. Hatchlings are a grayish-brown color, with a yellow face and underparts.

This duck species performs dump nesting. Dump nesting is communal nesting where more than one female lays their eggs in one nest. Their dump nest can hold around 50 eggs.

Is the knob-billed duck endangered? 

No, this species of duck is not endangered. Still, the population of its subspecies, S.m. sylvicola found in South America, is considered Near Threatened. The knob-billed duck species is threatened by deforestation, poison in ricefields in S. America, and overhunting in Madagascar. Due to its extensive range, it is not considered globally threatened yet.

Do knob-billed ducks migrate?

No, the knob-billed ducks are non-migratory, largely resident apart from dispersion in the wet season. They may travel long distances in search of water bodies for their habitat or new territory.

Here at Kidadl, we have carefully created lots of interesting family-friendly animal facts for everyone to discover! Learn more about some other birds from our American golden plover facts and vulturine guineafowl facts pages.

You can even occupy yourself at home by coloring in one of our free printable knob-billed duck coloring pages.

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