Knob-billed duck

Last updated

Knob-billed duck
Knob-billed duck (Sarkidiornis melanotos) male.jpg
Male, Lake Ziway, Ethiopia
Comb Duck (female) I IMG 0985.jpg
Female, India
CITES Appendix II (CITES) [2]
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Anseriformes
Family: Anatidae
Genus: Sarkidiornis
Species:
S. melanotos
Binomial name
Sarkidiornis melanotos
(Pennant, 1769)
Sarkidiornis melanotos distribution.png
Global range
Synonyms

Anser melanotosPennant, 1769

The knob-billed duck (Sarkidiornis melanotos) or African comb duck is a type of duck found along the tropical/sub-tropical wetlands and waterways of Sub-Saharan Africa and the island of Madagascar, as well as most of South Asia and mainland Indochina.

Contents

Most taxonomic authorities classify the knob-billed duck and the comb duck separately. A misidentified species of 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 systematic placement of this species. Initially, it was placed in the dabbling duck subfamily Anatinae. Later, it was assigned to the "perching ducks", a paraphyletic assemblage of waterfowl most of which are intermediate between dabbling ducks and shelducks. As the "perching ducks" were split up, the knob-billed duck was moved to the Tadorninae or shelduck subfamily. [4]

Analysis of mtDNA 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). [6] [7] [8] Adults have a white head freckled with dark spots, and a pure white neck and underparts. The upperparts are glossy blue-black upperparts, with bluish and greenish iridescence especially prominent on the secondaries (lower arm feathers). The male is much larger than the female, and has a large black knob on the bill. Young birds are dull 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]

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 IUCN. [1] It is one of the species to which 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.

Related Research Articles

<span class="mw-page-title-main">Anatidae</span> Biological family of water birds

The Anatidae are the biological family of water birds that includes ducks, geese, and swans. The family has a cosmopolitan distribution, occurring on all the world's continents except Antarctica. These birds are adapted for swimming, floating on the water surface, and in some cases diving in at least shallow water. The family contains around 174 species in 43 genera.

<span class="mw-page-title-main">Anatinae</span> Subfamily of birds

The Anatinae are a subfamily of the family Anatidae. Its surviving members are the dabbling ducks, which feed mainly at the surface rather than by diving. The other members of the Anatinae are the extinct moa-nalo, a young but highly apomorphic lineage derived from the dabbling ducks.

<span class="mw-page-title-main">Northern pintail</span> Migratory duck that breeds in northern Eurasia and North America

The pintail or northern pintail is a duck species with wide geographic distribution that breeds in the northern areas of Europe and across the Palearctic and North America. It is migratory and winters south of its breeding range to the equator. Unusually for a bird with such a large range, it has no geographical subspecies if the possibly conspecific duck Eaton's pintail is considered to be a separate species.

<span class="mw-page-title-main">Tadorninae</span> Subfamily of birds

The Tadorninae is the shelduck-sheldgoose subfamily of the Anatidae, the biological family that includes the ducks and most duck-like waterfowl such as the geese and swans.

<span class="mw-page-title-main">Gadwall</span> Species of bird

The gadwall is a common and widespread dabbling duck in the family Anatidae.

The term perching ducks is used colloquially to mean any species of ducks distinguished by their readiness to perch high in trees.

<span class="mw-page-title-main">Eurasian teal</span> Species of bird (duck)

The Eurasian teal, common teal, or Eurasian green-winged teal is a common and widespread duck that breeds in temperate Eurosiberia and migrates south in winter. The Eurasian teal is often called simply the teal due to being the only one of these small dabbling ducks in much of its range. The bird gives its name to the blue-green colour teal.

<span class="mw-page-title-main">Australian shelduck</span> Species of bird

The Australian shelduck, also known as the chestnut-breasted shelduck or mountain duck, is a shelduck, a group of large goose-like ducks part of the bird family Anatidae. The genus name Tadorna comes from Celtic roots and means "pied waterfowl". They have a striking chestnut-coloured breast and black body. They are protected under the National Parks and Wildlife Act 1974.

<span class="mw-page-title-main">Ruddy shelduck</span> Species of bird

The ruddy shelduck, known in India as the Brahminy duck, is a member of the family Anatidae. It is a distinctive waterfowl, 58 to 70 cm in length with a wingspan of 110 to 135 cm. It has orange-brown body plumage with a paler head, while the tail and the flight feathers in the wings are black, contrasting with the white wing-coverts. It is a migratory bird, wintering in the Indian subcontinent and breeding in southeastern Europe and central Asia, though there are small resident populations in North Africa. It has a loud honking call.

<span class="mw-page-title-main">Muscovy duck</span> Species of bird

The Muscovy duck is a duck native to the Americas, from the Rio Grande Valley of Texas and Mexico south to Argentina and Uruguay. Feral Muscovy ducks are found in New Zealand, Australia, and in Central and Eastern Europe. Small wild and feral breeding populations have also established themselves in the United States, particularly in Florida, Louisiana, Massachusetts, the Big Island of Hawaii, as well as in many other parts of North America, including southern Canada.

<span class="mw-page-title-main">Comb duck</span> Species of bird

The comb duck or American comb duck, is an unusual duck, found in tropical wetlands in continental South America south to the Paraguay River region in eastern Paraguay, southeastern Brazil and extreme northeastern Argentina, and as a vagrant on Trinidad.

<i>Aix</i> (bird) Genus of birds

Aix is a bird genus that contains two species of ducks: the wood duck, and the mandarin duck. Aix is an Ancient Greek word used by Aristotle to refer to an unknown diving bird.

<span class="mw-page-title-main">Crested shelduck</span> Species of bird

The crested shelduck, or Korean crested shelduck, is a species of bird in the family Anatidae. It is critically endangered and may be extinct. The male crested shelduck has a greenish-black crown, breast, primaries, and tail, while the rest of its face, chin, and throat are brownish black. The male's belly, undertail coverts, and flanks are a dark grey with black striations. The upper wing coverts are white, while its speculum is an iridescent green. The female has a white eye ring, black crest, white face, chin, throat, neck, and uppers wing coverts and a dark brown body with white striations. Additionally, both sexes have a distinctive green tuft of feathers protruding from the head.

<span class="mw-page-title-main">Falcated duck</span> Species of bird

The falcated duck or falcated teal is a gadwall-sized dabbling duck from the east Palearctic.

<span class="mw-page-title-main">Australian wood duck</span> Species of bird

The Australian wood duck, maned duck or maned goose is a dabbling duck found throughout much of Australia. It is the only living species in the genus Chenonetta. Traditionally placed in the subfamily Anatinae, it might belong to the subfamily Tadorninae (shelducks); the ringed teal may be its closest living relative.

<span class="mw-page-title-main">Blue-winged goose</span> Species of bird

The blue-winged goose is a waterfowl species which is endemic to Ethiopia. It is the only member of the genus Cyanochen.

<span class="mw-page-title-main">Torrent duck</span> Species of bird

The torrent duck is a member of the duck, goose and swan family Anatidae. It is the only member of the genus Merganetta. It is placed in the shelduck subfamily Tadorninae after the "perching duck" assemblage to which it was formerly assigned was dissolved because it turned out to be paraphyletic.

<span class="mw-page-title-main">White-winged duck</span> Species of bird

The white-winged duck or white-winged wood duck is a large species of duck, formerly placed in the genus Cairina with the Muscovy duck and allied with the dabbling ducks. However, mtDNA cytochrome b and NADH dehydrogenase subunit 2 sequence analysis indicate that the anatomical similarity to the Muscovy duck is deceiving and that the species is appropriately placed in a monotypic genus, as Asarcornis scutulata, which is evolutionarily closer to the redhead.

<span class="mw-page-title-main">Ringed teal</span> Species of bird

The ringed teal is a small duck of South American forests. It is the only species of the genus Callonetta. Usually placed with the dabbling ducks (Anatinae), this species may actually be closer to shelducks and belong in the subfamily Tadorninae; its closest relative is possibly the maned duck.

<span class="mw-page-title-main">Crested duck</span> Species of duck native to South America

The crested duck or South American crested duck is a species of duck native to South America, belonging to the monotypic genus Lophonetta. It is sometimes included in Anas, but it belongs to a South American clade that diverged early in dabbling duck evolution. There are two subspecies: L. specularioides alticola and L. specularioides specularioides. The Patagonian crested duck is also called the southern crested duck and its range lies in the Falklands, Chile, and Argentina.

References

  1. 1 2 BirdLife International (2016). "Sarkidiornis melanotos". IUCN Red List of Threatened Species . 2016: e.T45953631A95159254. doi: 10.2305/IUCN.UK.2016-3.RLTS.T45953631A95159254.en . Retrieved 19 November 2021.
  2. "Appendices | CITES". cites.org. Retrieved 2022-01-14.
  3. Andrews, C.W. (1897). "On some fossil remains of Carinate birds from central Madagascar". Ibis . 7 (3): 343–359. doi:10.1111/j.1474-919X.1897.tb03281.x.
  4. 1 2 3 4 5 6 7 Madge, Steve & Burn, Hilary (1987): Wildfowl: an identification guide to the ducks, geese and swans of the world. Christopher Helm, London. ISBN   0-7470-2201-1
  5. Johnson, Kevin P.; Sorenson, Michael D. (1999). "Phylogeny and biogeography of dabbling ducks (genus: Anas): a comparison of molecular and morphological evidence" (PDF). Auk . 116 (3): 792–805. doi:10.2307/4089339. JSTOR   4089339.
  6. Ogilvie & Young, Wildfowl of the World. New Holland Publishers (2004), ISBN   978-1-84330-328-2
  7. Hilty, Steven L. (2002). Birds of Venezuela. Princeton University Press. pp. 197–. 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. 1 2 3 Zimmerman, Dale A.; Turner, Donald A., & Pearson, David J. (1999): Birds of Kenya and Northern Tanzania. Princeton University Press, Princeton. ISBN   0-691-01022-6