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 also occurs in continental South America south to the Paraguay River region in eastern Paraguay, southeastern Brazil and the extreme northeast of Argentina, and as a vagrant on Trinidad.

It is the only known species of the genus Sarkidiornis. The supposed extinct "Mauritian comb duck" is based on misidentified remains of the Mauritian shelduck (Alopochen mauritianus); this was realized as early as 1897, but the mistaken identity can still occasionally be found in recent sources.
Comb Duck
Date Location Count
2020-03-10 15:10Waterberg Wilderness Lodge1
2020-03-10 07:26Murchison Falls NP--Pakuba4
2020-03-10 15:00Akagera NP (southern area)1
2020-03-20 06:29Hwange NP--Shumba Camp1
2020-03-21 15:00Kgomo-Kgomo6
2020-03-14 15:38Zaagkuildrift Rd (Please be more specific)2
2020-03-31 05:30Buffelsdrift Conservancy
2020-03-10 07:17Sabaki River Estuary3
2020-03-10 05:40Kruger NP--Tshokwane Road28
2020-03-10 10:45Kruger NP--Old Tshokwane Rd/S12830
2020-03-17 17:11Lakhanka Dam20
2020-03-13 03:51Sabarmati Ashram12
2020-03-29 13:54Indroda Nature Park1
2020-03-15 08:00Limbasi-Vastana Rd5
2020-04-05 08:25Sant Sarovar100
2020-03-30 01:08Aranya Udhyan2
2020-03-17 09:30Pariej Lake8
2020-03-11 07:17Jawai dam1
2020-03-11 11:00Gharana ,Ranbir Singh Pura,Jammu3
2020-03-17 08:41Nagawli Talab1
2020-03-08 07:55Mula River -- Baner2
2020-03-11 19:17Nandur-Madhyameshwar bird sanctuary
2020-03-11 07:08Maina-Raia Wetlands1
2020-03-22 17:25Ajanta-andhari dam30
2020-03-15 13:36Mote Majra Lake20
2020-03-19 12:13SiliSerh30
2020-03-17 07:19Ranthambore NP--Zone 4--Rajbagh2
2020-03-28 09:40Basai Wetland10
2020-03-08 08:30Okhla Bird Sanctuary
2020-03-20 08:49Bund Baretha Wildlife Sanctuary17
2020-03-17 06:45Keoladeo Ghana NP, Bharatpur8
2020-03-14 08:40Dhanauri Wetlands -- Dhanauri Kalan East20
2020-03-22 09:05Ankasamudra Bird Sanctuary1
2020-04-06 16:39Wildlife Institute of India Campus2
2020-03-30 16:30Wildlife Institute of India Campus--Nature Trail2
2020-03-14 10:40Ganga Barrage Bijnor5
2020-03-14 08:00Sheikha Jheel (IBA IN-UP-21)7
2020-03-15 07:05Chhatri Lake--Backwaters, Amravati2
2020-03-26 06:25Reni Pani Jungle Lodge14
2020-03-08 09:24National Chambal Sanctuary -- Chambal River near Ater Road1
2020-03-21 06:00Singur Dam Reservoir, Medak2
2020-03-15 06:32Bettakote Lake4
2020-03-08 07:00Moharli, Chandrapur2
2020-03-18 14:25Lawari lake2
2020-03-13 23:36Setruthamarai Kulam, Nanguneri1
2020-03-09 07:02Koonthakulam Bird Sanctuary50
2020-03-11 06:25Karaivetti Bird Sanctuary6
2020-03-15 12:54Gosainganj Wetlands -- Sri Jharkhandeswar Baba Dham25
2020-03-12 10:30New Ash Pond Kachujor4
2020-03-19 13:36Phattalung Botanical Garden14
2020-03-10 07:51Thale Luang Non-hunting Area--Songkhla Side3
2020-03-14 06:30Ang Trapeang Thmor50
2020-03-09 06:30Prek Toal Bird Sanctuary100
2020-03-16 06:20Phnom Krom--rice fields8
2020-03-17 06:12Bengal Florican Reserve62