Knob-billed duck

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Knob-billed duck
Male, Lake Ziway, Ethiopia
Female, India

Least Concern  (IUCN 3.1)[1]
CITES Appendix II (CITES)[2]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Anseriformes
Family: Anatidae
Genus: Sarkidiornis
Species:
S. melanotos
Binomial name
Sarkidiornis melanotos
(Pennant, 1769)
Global range
Synonyms

Anser melanotos Pennant, 1769

The knob-billed duck (Sarkidiornis melanotos) or African comb duck is a type of

Indochina
.

Most taxonomic authorities classify the knob-billed duck and the

extinct Mauritian comb duck was initially described from unrecognised remains of the Mauritius sheldgoose (Alopochen mauritiana); this was realised as early as 1897,[3] but the printed case of mistaken identity
can still, occasionally, be found in modern-day sources.

Systematics

Uncertainty surrounds the correct

shelducks. As the "perching ducks" were split up, the knob-billed duck was moved to the Tadorninae or shelduck subfamily.[4]

Analysis of

sequences of the cytochrome b and NADH dehydrogenase subunit 2 genes, however, suggests that it is a quite basal member of the Anatidae, vindicating the earliest placement. But its closest living relatives cannot be resolved to satisfaction without further study.[5]

Description

This common species is unmistakable. It is one of the largest species of duck. Length can range from 56 to 76 cm (22 to 30 in), wingspan ranges from 116 to 145 cm (46 to 57 in) and weight from 1.03 to 2.9 kg (2.3 to 6.4 lb).

buff below and on the face and neck, with dull brown upperparts, top of the head and eyestripe.[4][9]
Knob-billed ducks are generally larger in size when compared to comb ducks, and flanks are usually lighter (light grey, in females sometimes whitish).

Immature knob-billed ducks look like a large greyish female of the cotton pygmy goose (Nettapus coromandelicus) and may be difficult to tell apart if no other birds are around to compare size and hue. However, knob-billed ducks in immature plumage are rarely seen without adults nearby and thus they are usually easily identified too.[4]

The knob-billed duck is silent except for a low croak when flushed.[9]

Gallery

  • Specimens from the Royal Museum for Central Africa (female, male)
    Specimens from the Royal Museum for Central Africa (female, male)
  • knob-billed duck at edge of lake near Jodhpur, Rajasthan, India, feeding alongside feral pigeons.
    knob-billed duck at edge of lake near Jodhpur, Rajasthan, India, feeding alongside feral pigeons.
  • Flying knob-billed duck / comb duck at Chilika Lake, Odisha, India
    Flying knob-billed duck / comb duck at Chilika Lake, Odisha, India
  • Arampannai,Tamilnadu, india
    Arampannai,Tamilnadu, india
  • female, Jojawar, India
    female, Jojawar, India
  • Male knob-billed duck at Austin Roberts Bird Sanctuary in Pretoria, South Africa
    Male knob-billed duck at Austin Roberts Bird Sanctuary in Pretoria, South Africa
  • Knob-billed Duck (Sarkidiornis melanotos) alongside Eurasian Coot ((Fulica atra) in Keoladeo National Park, Rajasthan, India
    Knob-billed Duck (Sarkidiornis melanotos) alongside
    Eurasian Coot ((Fulica atra) in Keoladeo National Park, Rajasthan, India
  • Male at Jamnagar, India
    Male at Jamnagar, India
  • Close-up Male
    Close-up Male

Ecology

It breeds in still

freshwater swamps and lakes in the tropics. It is largely resident, apart from dispersion in the wet season.[4]

This duck feeds on vegetation by grazing or dabbling[4] and to a lesser extent on small fish, invertebrates, and seeds. It can become a problem to rice farmers. Knob-billed ducks often perch in trees. They are typically seen in flocks, small in the wet season, up to 100 in the dry season. Sometimes they separate according to sex.[9]

The knob-billed duck is declining in numbers locally, but due to its wide range it is not considered globally threatened by the

Agreement on the Conservation of African-Eurasian Migratory Waterbirds
applies.

Reproduction

African birds breed during and after the rainy season and may not breed if the rain is scanty. Knob-billed ducks nest mainly in tree holes,[4] also in tall grass.

Males may have two mates at once or up to five in succession. They defend the females and young but not the nest sites.

Females lay 7 to 15[4] yellowish-white eggs.

References

Wikispecies has information related to Sarkidiornis melanotos.
Wikimedia Commons has media related to Sarkidiornis melanotos.
  1. ^
    doi:10.2305/IUCN.UK.2016-3.RLTS.T45953631A95159254.en
    . Retrieved 19 November 2021.
  2. ^ "Appendices | CITES". cites.org. Retrieved 2022-01-14.
  3. doi:10.1111/j.1474-919X.1897.tb03281.x
    .
  4. ^
    ISBN 0-7470-2201-1
  5. JSTOR 4089339
    .
  6. ISBN 978-1-84330-328-2
  7. ISBN 978-1-4008-3409-9
    .
  8. ^ Sarkidiornis melanotos (Comb duck, Knob-billed duck) Archived 2012-04-14 at the Wayback Machine. biodiversityexplorer.org
  9. ^
    ISBN 0-691-01022-6

External links
Retrieved from "https://en.wikipedia.org/w/index.php?title=Knob-billed_duck&oldid=1197965785"