Sarkidiornis melanotos
Silhouette: Sheatherius · PhyloPic
In 3 days <5% in a week ~10%
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.
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, but the printed case of mistaken identity can still, occasionally, be found in modern-day sources.
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.
Analysis of mtDNA sequences of the cytochrome b and NADH dehydrogenase subunit 2 genes, however, suggests that it is a quite basal member... Wikipedia →
Rare
Under 5% of wildlife watchers report a Comb Duck sighting in Vasai-Virar on a given day, based on 19 verified sightings from GBIF citizen-science data. It is the 170th most-seen of the 217 birds we can rate there. Over three days the chance rises to under 5%, and over a week to about 10%, if each day is a fresh chance.
June
In that month about 10% of wildlife watchers report a Comb Duck in Vasai-Virar on a given day, against under 5% in July to May, the lowest months. That is one of Vasai-Virar's wettest months, with about 520 mm of rain against almost none in January.
Between 8 and 11 am
Across all the parks we cover, that three-hour window holds the most Comb Duck sightings with a recorded time, and about 9 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
16th of 27
Of the 27 cities where we can rate Comb Duck sightings, Vasai-Virar ranks 16th at under 5%. The best odds are in Rajkot (India, about 30%), Antananarivo (Madagascar, about 30%) and Surat (India, about 20%).
Same family: Anatidae
The closest relatives of the Comb Duck that you can see in Vasai-Virar (family Anatidae, Ducks, Geese, and Swans) are Lesser Whistling-Duck (about 20%), Indian Spot-billed Duck (about 10%) and Garganey (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Comb Duck is recorded against all the birds logged in Vasai-Virar (19 verified sightings), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
