A knob-billed duck (comb duck). Picture by Firoz Hussain

Guwahati, May 7: Every other day Firoz Hussain, 35, a birder of Jorhat, goes with his camera to Borsola Beel at Kokilamukh in Jorhat to spot birds.

Yesterday, he was looking for lesser whistling duck, which is a common duck, but spotted a knob-billed duck (comb duck) instead — a rare one in Assam.

“I was trying to spot the lesser whistling duck yesterday when I saw a different duck... it looked like the white-winged wood duck from the distance. When I started zooming in, I saw the knob on the bill of the duck and then I realised it was a different duck and could not believe my eyes,” Hussain told this correspondent today. The duck was a male.

Though it was a bit cloudy, the young birder managed to take some shots.

The comb duck is classified as “least concern” on the IUCN Red List as it has an extremely large range and hence, cannot be classified as vulnerable.

“I came back home and posted the picture to the group Birds of Eastern India. They told me it was a rare one,” Hussain said.

Wikipedia says the knob-billed duck (Sarkidiornis melanotos), or comb duck, is an unusual, pan-tropical duck, found in tropical wetlands in sub-Saharan Africa, Madagascar and south Asia from Pakistan to Laos and extreme southern China.

It is also found in continental South America south of the Paraguay river region in eastern Paraguay, southeastern Brazil and the extreme northeast of Argentina and as a vagrant in Trinidad.

“My friend Pranabjyoti Rajbongshi, a birder from Guwahati, confirmed that it was a knob-billed duck,” he said.

It is one of the largest species of duck. Its length can range from 56cm to 76cm (22 to 30 inches), the wingspan ranges from 116cm to 145cm (46 to 57 inches) and weighs between 1.03kg and 2.9kg.

Anwaruddin Choudhury, a naturalist who has done extensive work on birds in the Northeast, said the spotting of knob-billed duck is rare in Assam.

The last spotting was from Jaingdia Beel in Kamrup district probably in the early 70s and from Dum Duma Dangori reserve forest in Tinsukia.

Assam, which has a rich avian diversity in the country, is estimated to have 900-1,000 of the total 1,200-1,300 species of birds in the country.

Assam had recorded the highest number of bird species in the country — 399 on Big Birding Day this year (February 16).

The species inhabits grassy ponds or lakes in savanna, open woodlands along large rivers and lakes and swamps. It nests close to water.