Comb Duck
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 Common Comb Duck female
(Sarkidiornis melanotos melanotos) |
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| Sarkidiornis melanotos (Pennant, 1769) |
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The Comb Duck (Sarkidiornis melanotos) formerly known as Knob-billed Duck is an unusual duck. It is the only species of the genus Sarkidiornis (the supposed "Mauritian Comb Duck" was a misidentification of the Mauritian Shelduck).
Uncertainty surrounds the correct systematic placement. Initially, it was placed in the dabbling duck subfamily Anatinae[citation needed]. Later, it was assigned to the "perching ducks"[citation needed], a paraphyletic assemblage of waterfowl most of which are intermediate between dabbling ducks and shelducks. As the "perching ducks" were split up, the Comb Duck was moved to the Tadorninae or shelduck subfamily[citation needed]. Analysis of mtDNA sequences of the cytochrome b and NADH dehydrogenase subunit 2 genes (Johnson & Sorenson, 1999), however, suggests that it is a basal member of the Anatidae, vindicating the earliest placement, but the issue cannot be resolved to satisfaction without further study.
It breeds in the tropics in South America, sub-Saharan Africa and South Asia. It is largely resident, apart from dispersion in the wet season. It nests mainly in tree holes, laying 7-15 eggs.
The habitat is still freshwater swamps and lakes, where this duck feeds on vegetation by grazing or dabbling. They like to eat seeds so they become a problem to some farmers if they are in the area and are around their farms. It is very important for the comb ducks to have rain because it determines when they are going to mate and also if they are going to mate at all. This species of ducks is usually not found in any public displays due to them needed their special needs such as warm weather. They are usually found in warm areas where there is rain from time to time.
This common species is unmistakable. It has a white neck, head and underparts, and glossy blue- black upperparts. The head is freckled with dark spots. The male is larger than the female, and has a large black knob on the bill. Young birds are brown above and buff below. Both the female and male have white colored bellies. The wingspand of the male is much larger than that of a female comb duck. Baby comb ducks have a different appearance when they are younger in age. They do not resemble the parents in appearance as much. This type of duck does not like to be anywhere near where there might be humans inhabiting the area. Depending on what time of the year it is and what season will determine if they will be in small groups or in larger ones. The comb ducks usually fly together when they migrate. Sometimes the comb ducks may even separate themselves according to what sex they are into different groups. They in fact do not have much of a problem with other ducks that might be in the same area as them. The sounds made by female and male comb ducks sound somewhat different. It is common for one male duck to have more than one mating female comb duck.
South American birds, S. m. sylvicola, are smaller and have black flanks (light grey in Old World birds).
The comb duck is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.
[edit] References
- BirdLife International (2004). Sarkidiornis melanotos. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 11 May 2006. Database entry includes justification for why this species is of least concern
- Johnson, Kevin P. & Sorenson, Michael D. (1999): Phylogeny and biogeography of dabbling ducks (genus Anas): a comparison of molecular and morphological evidence. Auk 116(3): 792–805. PDF fulltext
- Madge, Steve & Burn, Hilary (1987): Wildfowl : an identification guide to the ducks, geese and swans of the world. Christopher Helm, London. ISBN 0-7136-3999-7
