Masked duck
Adult males, Tobago
Conservation status
Least Concern  (IUCN 3.1)[1]
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Anseriformes
Family:	Anatidae
Genus:	Nomonyx Ridgway, 1880
Species:	N. dominicus
Binomial name
Nomonyx dominicus (Linnaeus, 1766)
Synonyms
Anas dominica Linnaeus, 1766 Oxyura dominica (Linnaeus, 1766)

The masked duck (Nomonyx dominicus) is a tiny stiff-tailed duck ranging through the tropical Americas.

The only member of the genus Nomonyx, it is intermediate between the rather primitive black-headed duck (Heteronetta) and the very apomorphic true stiff-tailed ducks. It is sometimes included with the latter in the genus Oxyura, but the masked ducks are now considered the descendants of a missing link in the Oxyurini evolution, having changed little for millions of years.^[2][3]

They are found from southern Texas and Mexico to South America and also in the Caribbean. Primarily not migratory, masked ducks are reported as very uncommon vagrants in the southernmost United States, along the Mexican border and in Florida. As of 2000, the conservation status for masked ducks in Texas is 3,800 birds.^[4] On April 1, 1962, it was recorded from Lowndes County, Georgia, where it was photographed by Alexander Wetmore.^[5] Masked ducks breed in any freshwater body with marsh vegetation and surrounded by heavy tree cover. They also occur in mangrove swamps.

Breeding adult males have a rust-colored body with a black face and mottled wings. Adult females, winter males, and juveniles have a barred brownish gray body, with two horizontal, dark-colored stripes running through the buff-colored face.

These ducks mainly feed on seeds, roots, stems,^[6] and leaves of aquatic plants. They also eat aquatic insects and crustaceans. They feed by diving. These ducks are usually very secretive, but they are not rare and not considered threatened by the IUCN.^[1]

• del Hoyo, Josep; Elliott, Andrew & Sargatal, Jordi (eds.) (1992): Handbook of Birds of the World (Volume 1: Ostrich to Ducks). Lynx Edicions, Barcelona. ISBN 84-87334-10-5
• National Geographic Society (2002): Field Guide to the Birds of North America. National Geographic, Washington DC. ISBN 0-7922-6877-6
• Sibley, David Allen (2000): The Sibley Guide to Birds. Alfred A. Knopf, New York. ISBN 0-679-45122-6

v t e Genera of waterfowl and their extinct allies
Kingdom: Animalia Phylum: Chordata Class: Aves Clade: Neognathae Superorder: Galloanserae Avemetatarsalia see Avemetatarsalia Theropoda see Theropoda Maniraptora see Maniraptora Anserimorphae see below↓
Anserimorphae Anserimorphae †Conflicto †Gastornis? †Dromornithidae? †Pelagornithidae? †Vegaviidae? †Presbyornithidae Bumbalavis Headonornis? Murgonornis Presbyornis Proherodius Telmabates Teviornis Wilaru †Anachronornithidae Anachronornis Danielsavis? Anseriformes sensu stricto †Agnopterus? †Eonessa †"Headonornis"? †Naranbulagornis †Palaeopapia †Peioa †Petropluvialis? †Proherodius? †Wunketru Anhimae †Chaunoides Anhimidae Anhima †Chainkanas Chauna Anseres Anseranatoidea †Anatalavis? Anseranatidae Anseranas †Anserpica †Eoanseranas Anatoidea †Paranyrocidae Paranyroca Anatidae See below ↓
Anatidae Anatidae †Aldabranas? †Allgoviachen †Ankonetta? †Awengkere †Bambolinetta? †Caerulonettion †Cayaoa? †Chelychelynechen? †Cousteauvia †Eonerornis? †Eutelornis? †Garganornis? †Helonetta? †Heteroanser? †Lavanttalornis †Loxornis? †Mioquerquedula? †Nogusunna? †Notochen †Proanser? †Protomelanitta? †Ptaiochen? †Selenonetta †Sharganetta? †Sinanas? †Tagayanetta †Talpanas? †Teleornis? †Thambetochen? †Wasonaka? †Romainvillinae Paracygnopterus Romainvillia Saintandrea Dendrocygninae Dendrocygna Thalassornis †Dendrocheninae Dendrochen Manuherikia Mionetta Stictonettinae Stictonetta Anserinae †Afrocygnus †Annakacygna Anser †Anserobranta †Asiavis †Bonibernicla Branta Cereopsis †"Chenopis" †Cnemiornis Coscoroba †Cygnavus Cygnus †Cygnopterus †Eremochen †Megalodytes †Paracygnus †Presbychen Tadorninae Alopochen †Australotadorna †Brantadorna Cairina †Centrornis Chloephaga Cyanochen Hymenolaimus †Kaikenia Merganetta †Miotadorna †Nannonetta Neochen Plectropterus †Pleistoanser Radjah Sarkidiornis Tachyeres Tadorna †Tamtamia Anatinae Aix Amazonetta †Anabernicula Asarcornis Biziura Callonetta †Chenoanas? Chenonetta †Dunstanetta †Eoneornis? †Lavadytis Lophonetta Malacorhynchus Marmaronetta Netta Nettapus †Pinpanetta Pteronetta †?Rhodonessa Salvadorina Speculanas Oxyurini Heteronetta Nomonyx Oxyura †Tirarinetta Mergini Bucephala †Camptorhynchus †Chendytes Clangula Histrionicus Lophodytes Melanitta Mergellus Mergus Polysticta †Shiriyanetta Somateria Anatini Anas Mareca †Matanas Sibirionetta Spatula Aythyini Aythya