Anatidae

(vertebrate zoology) A family of waterfowl, including ducks, geese, mergansers, pochards, and swans, in the order Anseriformes.

(Anatidae)

Class: Aves

Order: Anseriformes

Suborder: Anseres

Family: Anatidae

Thumbnail description
Medium to very large-sized birds of predominantly brown, white, black, and metallic green colors, with a broad stocky body, webbed feet, and a flattened bill

Size
13–71 in (34–180 cm); 0.56–29.8 lb (255 g–13.5 kg)

Number of genera, species
41 genera, 147 species

Habitat
Marshlands, coastal waters, lakes, rivers, and streams

Conservation status
Extinct: 5 species; Endangered: 5 species; Critically Endangered: 5 species; Vulnerable: 11 species; Near Threatened: 7 species

Distribution
All continents except Antarctica

Evolution and systematics

The taxonomic history of the Anatidae began early with the work of F. Willughby and J. Ray who, in 1676, wrote the first comprehensive classification of aquatic birds. The systematics of the Anatidae have evolved considerably since then; however, at the beginning of the twenty-first century much controversy remains. The different classificatory schemes by J. Delacour, R. Verheyen, B. C. Livezey, and others, recognize anywhere from two up to 14 subfamilies. Here we follow P. A. Johnsgard who divided the Anatidae into seven subfamilies: the Anseranatinae (magpie goose), Dendrocygninae (whistling-ducks), Anserinae (geese and swans), Tadorninae (shelducks), Anatinae (wood ducks, dabbling ducks, pochards), Merginae (sea ducks), and Oxyurinae (stiff-tailed ducks).

The earliest fossils that can be identified as anseriform were those of Anatalavis rex. Two bones recovered from the Hornerstown Formation of New Jersey may date back to the Late Cretaceous or early Paleocene (80–50 million years ago). Similar bones, about 40 million years old, were found in England and helped identify these fossils as a member of the Anseranatinae. The most common anseriform in the fossil record is Presbyornis from the Paleocene and early Eocene (65–50 million years ago). According to S. L. Olson, Presbyornis may have looked like "a duck-like skull on the body of a long-legged wading bird." On the evolutionary tree of the anseriformes, Presbyornis branched off between the Anseranatinae and the other six subfamilies.

Physical characteristics

The Anatidae range in size from the minute African pigmy geese (Nettapus auritus), measuring only up to 13 inches (33 cm) and weighing no more than 0.51 lb (230 g), to the large trumpeter swan (Cygnus buccinator), which reaches a body length of 70.87 in (1.80 m) and a weight of 30 lb (13.5 kg). Some mute swans (Cygnus olor) may even weigh as much as 49.6 lb (22.5 kg). Plumages range from dull and inconspicuous, as in the greylag goose (Anser anser), to spectacularly colorful as in the mandarin duck (Aix galericulata).

Despite their variety, the Anatidae have a characteristic "Bauplan," or external morphology, which makes them readily distinguishable from all other groups of birds. The most obvious characteristics are a somewhat flattened bill with horny lamellae, a broad body, and partially webbed feet. The members of this family also share a hard process, the "nail," at the tip of the bill, long necks, a large preen gland crowned by a tuft of feathers, and a large external penis in males.

The structure of the bill and the lamellae are perfectly suited to the bird's diet and feeding methods. True geese are mostly herbivorous and feed by grazing. The bills are therefore strong, the "nail," used to grasp vegetation, is wide and the lamella stout and flat. Ducks that strain food particles from the water or mud have blade-like lamellae. These are tightly packed in filtering specialists such as shovelers. Shovelers also have a very broad, spatula-like bill to enhance straining efficiency. The "nail" is small in dabblers and filter-feeders. A

striking adaptation to feeding can be found in the mergansers (Lophodytes, Mergus). The backward pointing lamellae are serrated, almost tooth-like, and the horny bill is unusually narrow. Thus mergansers are able to get a firm grasp on slippery fish, their main diet.

The broad cross-section of the body is a result of powerful, bulging pectoral muscles needed for continuous beating of the narrow, pointed wings during flight. Except for a few island endemics and three species of steamerducks (Tachyeres brachypterus), all waterfowl are strong flyers.

Short thighs and tarsi form a powerful lever arm that makes waterfowl good swimmers. With the exception of the magpie goose (Anseranas semipalmata) and the Hawaiian goose (Branta sandvicensis), all Anatidae have webs between their front toes. Trapped air in the plumage and in the respiratory system provides buoyancy. Because of the wide body and relatively short legs, ducks and geese have a distinctive waddling gait.

Males of all ducks, geese, and swans have a copulatory organ which is evaginated from the cloaca for copulation. The sperm do not flow through a central canal of this erectile penis, as in mammals, but along grooves on the outside.

The palette of colors found in the Anatidae is very varied and spans all colors from red to blue and white to black. Nuptial plumages are also decorated by modified feathers or whole regions of the plumage. There are curled hoods, as in the muscovy duck (Cairina moschata) and crests as in the mergansers. A mane on the neck adorns the maned duck (Chenonetta jubata). Even more striking are the sickle feathers of the falcated teal (Anas falcata) and the elongated lancet-like flank feathers of the plumed whistling-duck (Dendrocygna eytoni). The wide, upward-bent inner vanes of the shoulder feathers of the mandarin duck (Aix galericulata) look like orange sails. In the male oldsquaw (Clangula hyemalis) the tail feathers are greatly elongated. Some members of the Anatidae are able to produce acoustic signals with their flight feathers. Lesser whistling-ducks (Dendrocygna javanica) produce a whistling sound, and golden-eyes (Bucephala) and the black scoter (Melanitta nigra) produce ringing sounds.

In some Anatidae, parts other than the plumage contribute to the decorative effect of the nuptial plumage. A highly colored fleshy hump at the base of the beak is present during the breeding season in many species, such as in some swans, scoters, and others. The bill may also be intensely colored in black, yellow, red, and blue.

In all ducks and geese, the flight feathers are molted only once a year. They are lost simultaneously so that the bird is incapable of flight for a short period of time. Only the magpie goose sheds its primaries sequentially and never loses its ability to fly. The contour feathers are usually molted twice a year, but three times in the oldsquaw (Clangula hyemalis). The "nest-down" on the abdomen grows before the onset of the breeding season. Before the clutch is complete, the incubating bird plucks down with its bill and pads the nest with it.

Distribution

From the Arctic Circle to Tierra del Fuego, South Georgia Island, New Zealand, and the Cape of Good Hope, ducks can be found on all continents except Antarctica.

The magpie goose lives in Australia and New Guinea. The Dendrocygninae are mostly restricted to tropical or subtropical regions of North, Central, and South America, the West Indies, Africa, Asia, and Australia. They are absent in Europe. The Anserinae are limited in their distribution to mostly temperate and Subarctic regions and, with the exception of a few vagrants, are absent from Africa. The Hawaiian goose lives only on Hawaii Island. The Tadorninae have South American (10 species), African (five species), and Australasian representatives (five species). The Anatinae (86 species) are cosmopolitan. With 33 resident and nonresident species, Central and South America have the highest species richness, followed by Asia (28 species) and Africa (27 species). Europe and North America harbor 16 species each and Australia 11. This group includes the well-known mallard (A. platyrhynchos) and the American black duck (A. rubripes). Five species and 2 subspecies are limited entirely to islands, such as New Zealand, Madagascar, and Hawaii. The Merginae are a group of the north temperate and Arctic regions. Most species can be found in North America. The Oxyurinae are distributed on all continents, but are more prevalent in South America, Africa, and Australia.

Habitat

The Anatidae can be found anywhere as long as some wetland or body of water is present. For instance, the marbled teal (Marmaronetta angustirostris) lives in arid regions of the Mediterranean, the oldsquaw in the high Arctic tundra, and the Brazilian teal (Amazonetta brasiliensis) in the lush rain-forests of South America. Five species require fast flowing streams and two hardly depend on aquatic habitats at all. The Cape Barren goose (Cereopsis novaehollandiae) enters the water only while molting its wing feathers or rearing young and the Hawaiian goose inhabits the lava fields of volcanoes. In contrast, the scoters (Melanitta) rarely go ashore except during reproduction. Several species can be found at high elevation. A good example is the bar-headed goose (Anser indicus) which breeds on the highland plateaus of the central Asia, between 13,100 and 16,400 ft (4,000–5,000 m).

Behavior

Almost half of the species (47.6%) in this family are either completely or partially migratory. Of the remaining species the vast majority wander over wide areas in response to changing water levels. During migration, waterfowl may fly at high altitudes, as high as 32,800 ft (10,000 m) in some geese.

One of the most notable aspects of waterfowl behavior are the highly ritualized displays. The specific functions of displays are to aid in family group cohesion, convey information about the reproductive status, establish pair bonds, defend a mate or territory, and prevent hybridization. The displays may have originated from common behavioral patterns as they bear a remarkable resemblance to movements used in plumage maintenance (e.g. preening, bathing, and shaking), feeding, and locomotion.

Typical for the Anserinae is the so-called "triumph ceremony," which is used to establish dominance status in wintering flocks as well as to advertise territories in the breeding season.

The Dendrocygninae are gregarious and to large degree nocturnal or crepuscular. Auditory signals are therefore very important. Within the Tadorninae, the highly aquatic steamerducks (Tachyeres) stretch their necks and cock their tails as the most conspicuous means to signal from the water surface. Paired females in Tadorna (also in Aythya) perform a display called "inciting." It shows an intruding male that she already has a partner and stimulates her mate to attack the intruder.

The voices of the Anatidae vary from whistling sounds in whistling-ducks and sea ducks, to a variety of typical "quack" sounds in dabbling ducks and deep honks in swans. Most species posses a bulla, a more or less ossified enlargement at the union between that trachea and the bronchi, that acts as a resonating body.

The Anatinae are a very diverse group with a variety of habitat-specific displays. The torrent duck (Merganetta

armatta) is especially interesting because it does not share its display repertoire with any other species of ducks. For instance, it uses its legs in hostile displays in which it also reveals painful wing spurs.

The Merginae have complex signaling systems as courtship occurs mainly on the water. Vocal repertoires are diverse and many species use courting flights and/or underwater pursuits. The precopulatory behaviors in common eiders (Somateria mollisima) are extremely, and puzzlingly, complex.

The Oxyurinae have many distinct behavioral features not shared with any other group. Birds may be seen contorting their necks and tails into bizarre postures.

Feeding ecology and diet

Although most swans, geese, and ducks require wetlands or other water-bodies for their survival, not all species forage in the water. The subfamilies Anseranatinae, Dendrocygninae, Anserinae, and some Tadorninae (especially Chloephaga) feed mostly on land on a largely vegetarian diet. Tachyeres steamerducks eat almost exclusively on aquatic invertebrates. The Anatinae are largely omnivorous and the Merganinae are largely piscivorous and insectivorous. The Oxyurinae, complement a diet based on aquatic invertebrates with seeds and green parts of aquatic plants.

The methods used in feeding are as varied as the diets. Vegetarians often graze or browse on land. Most species that feed in the water dabble, dip their heads into the water, or upend by immersing half of their body head down. The more aquatic species mostly forage by diving. The duration of the dives is usually 60–70 seconds, but may be as long as 2 min in some scoters (Melanitta).

Reproductive biology

Most species of Anatidae are monogamous. The Anserinae, Dendrocygninae, and Tadorninae may stay paired for several seasons, mute swans even for life. With the exception of some promiscuous stifftails, most ducks are seasonally monogamous. Pair bonds often last only halfway through the breeding season until midincubation or hatching of the young. The Anseranatinae are unusual among the waterfowl in that they form polygamous "trios."

Breeding in the temperate regions usually begins in the spring. In those species that are not perennially monogamous, pair formation is most often achieved before the breeding season. In other species, such as the ruddy duck (Oxyura jamaicensis), pair formation takes place on the breeding grounds. In tropical latitudes the beginning of the breeding season is variable, depending to large degree on water levels.

The nests are made on the ground with surrounding vegetation or in cavities. Most species also line their nests with down and feathers. The magpie goose builds its nest on a mound of floating vegetation. Most Dendrocygninae, Anserinae, and Anatinae make ground nests. The Tadorninae has both ground and cavity nesters. The Merginae nest on the ground, oftentimes in nothing more than a small depression. The Oxyurinae build their nests of vegetable matter on the ground although some stiff-tails reuse nests of other species.

On average, clutch size is of 4 to 16 eggs. Should a clutch fail, relaying occurs after 4–20 days. Incubation lasts between 22 and 40 days. Sexual maturity is usually attained after the first to third year. The eggs are large, and the young hatch completely covered with down and are able to swim and dive within a few hours.

An interesting aspect of anatid reproductive behavior is that many species parasitize the nests of other birds, most often of the same species. Up to 30 eggs may accumulate in socalled "dump nests." The black-headed duck (Heteronetta atricapilla) is entirely parasitic.

Male parental care (incubation and protection of young) is uncommon in the Anatidae. It can be found mostly in species that are perennially monogamous and in several tropical Anatinae. In the latter, an unpredictable environment and breeding season force the drake to secure a mate before environmental conditions are favorable. The male magpie goose and the comb duck even feed the young.

Conservation status

Five species have already become extinct due to over-hunting in historic times and at least 14 more in prehistory. The latter are almost all island species that disappeared as people colonized the Pacific islands and New Zealand. Thirty-three species (22%) and 5 subspecies are under some category of threat as defined by the IUCN. Most of these species come from Asia or islands, such as Hawaii, New Zealand, and Madagascar. Of the four species listed as Critically Endangered, three, the crested shelduck (Tadorna cristata), the pink-headed duck (Rhodonessa caryophyllacea), and the Madagascar pochard (Aythya innotata) may already have become Extinct. Five species and two subspecies are Endangered. The Vulnerable list includes 11 species and two subspecies. An additional seven species are considered Near Threatened.

The greatest threat comes from overhunting and wetland drainage. Large quantities of waterfowl are still hunted during migration, especially in Siberia. In Asia, a largely poor rural population also puts pressure on waterfowl by subsistence hunting. Wetland drainage results in a loss of suitable breeding habitat. The destruction of habitat surrounding the main breeding areas can also be detrimental. The river specialists, for instance, suffer from increased siltation caused by deforestation.

Significance to humans

The Anatidae have always had a close relationship with humans. At least four species have been domesticated: the greylag goose, swan goose (Anser cygnoides), muscovy duck, and mallard (Anas platyrhynchos). More than 23 variants of mallard are known. The mute swan and Canada goose (Branta canadensis) are kept in semi-liberty.

Waterfowl have been hunted ever since Homo sapiens walked the earth. Considered a delicacy by almost all cultures, at the end of the twentieth century their hunting and observation has also become a lucrative business with significant economic impact. In America, outdoor stores sell millions of dollars worth of hunting gear and many states also derive benefit through hunting licenses. More importantly, they are an important element in the maintenance of wetland ecosystems.

Ducks, geese, and swans figure prominently in myths and stories. For example, in Greek mythology Zeus took on the form of a swan in order to conquer Leda. In the Germanic Lohengrin saga, the knight is pulled over a lake by swans, which symbolize purity and love.

In science, observations on waterfowl displays have advanced our knowledge on animal behavior in general. Waterfowl still promise to be great model species for studies on sexual selection, the origin of mating systems, and the mechanistic basis of behavior.

Species accounts

Resources

Batt, D. J., Alan D. Afton, Michael G. Anderson, C. Davison Ankney, Douglas H. Johson, John A. Kadlec, and Gary L. Krapu, eds. Ecology and Management of Breeding Fowl. Minneapolis: University of Minnesota Press, 1992. del Hoyo, J., A. Elliot, and J. Sargatal, eds. Ostrich to Ducks. Vol. 1 Handbook of the Birds of the World. Barcelona: Lynx Edicions, 1992.

Johnsgard, P. A Ruddy Ducks and Other Stifftails: Their Behavior and Biology. Norman: University of Oklahoma Press, 1996.

Madge, S., and H. Burn. Waterfowl: An Identification Guide to the Ducks, Geese and Swans of the World. Boston: Houghton Mifflin, 1988.

Schneck, M. Ducks and Waterfowl. New York: Todtri Book Publishers, 2000.

Todd, Frank S. Ducks, Geese, and Swans of the World. San Diego: Seaworld, 1979.

Callaghan, Des A. "Conservation status of the torrent ducks Merganetta." Wildfowl 48 (1997–1998): 166–173.

Johnson, Kevin P., Frank McKinney, and Michael D. Sorenson. "Phylogenetic constraint on male parental care in dabbling ducks." Proceedings of the Royal Society of London, Series B 266 (1999): 759–763.

Livezey, Bradley C. "A phylogenetic classification of waterfowl (Aves: Anseriformes), including selected fossil species." Annals of Carnegie Museum 66 (1997): 457–496.

Olson, Storrs L. "The anseriform relationships of Antalavis Olson and Parris (Anseranatidae), with a new species from the Lower Eocene London clay." Smithsonian Contributions to Paleobiology 89 (1999): 231–243.

Ducks Unlimited, Inc. One Waterfowl Way, Memphis, Tennessee 38120 USA. Phone: (800) 453-8257. Fax: (901) 758-3850. E-mail: mlafarge@ducks.org Web site:

Japanese Association for Wild Geese Protection. Minamimachi 16, Wakayangi, 989-5502 Japan. Phone: +81 228 32 2004. Fax: +81 228 32 2004. E-mail: secretariat@jawgp.org Web site:

Miyabayashi, Yoshihiko, and Taej Mundkur "Atlas of key sites for Anatidae in the East Asian flyway" . (1999)

Sauer, J. R., J. E. Hines, and J. Fallon. The North American Breeding Bird Survey, Results and Analyses 1966–2000. Version 2001.2. Laurel, Maryland: USGS Patuxent Wildlife Research Center, 2001.

The International Union for Conservation of Nature and Natural Resources Species Survival Commission "2000 IUCN Red List of Threatened Species" . (2000).

[Article by: Markus Patricio Tellkamp, MS]

Family of aquatic birds, including the ducks, geese and swans.

The noun has one meaning:

Meaning #1: swimming birds having heavy short-legged bodies and bills with a horny tip: swans; geese; ducks
  Synonym: family Anatidae

It has been suggested that this article or section be merged into Waterfowl. (Discuss)

This article or section is missing citations or needs footnotes. Using inline citations helps guard against copyright violations and factual inaccuracies.

Waterbird redirects here. See also shorebirds and seabirds.

Ducks, geese and swans
Black-bellied Whistling Duck (Dendrocygna autumnalis)
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Aves Order: Anseriformes Family: Anatidae Vigors, 1825
Subfamilies
Dendrocygninae Thalassorninae Anserinae Stictonettinae Plectropterinae Tadorninae Anatinae Aythyinae Merginae Oxyurinae and see text

Anatidae is the biological family that includes the ducks and most duck-like waterfowl, such as geese and swans. These are birds that are modified for swimming, floating on the water surface, and in some cases diving in at least shallow water. (The Magpie-goose is no longer considered to be part of the Anatidae, but is placed in its own family Anseranatidae.)

Extant species range in size from the Cotton Pygmy Goose, at as little as 26.5 cm (10.5 inches) and 164 grams (5.8 oz), to the Trumpeter Swan, at as much as 183 cm (6 feet) and 17.2 kg (38 lbs). They have webbed feet and bills which are flattened to a greater or lesser extent. Their feathers are excellent at shedding water due to special oils. Anatidae are remarkable for being one of the few families of birds that possess a penis; they are adapted for copulation on the water only. Duck, eider and goose feathers and down have long been popular for bedspreads, pillows, sleeping bags and coats. The members of this family also have long been used for food.

While the status of the Anatidae as a family is straightforward, and there is little debate about which species properly belong to it, the relationships of the different tribes and subfamilies within it are poorly understood. The listing in the box at right should be regarded simply one of several possible ways of organising the many species within the Anatidae; see discussion in the next section.

Relationship with humans

Humans have had a long relationship with ducks, geese and swans; they are important economically and culturally to humans, and several duck species have benefited from an association with people. On the flip side some anatids are damaging agricultural pests, and have acted as vectors for zoonosis such as avian flu. Numerous ducks and geese have become extinct due to the activities of humans, and many more are currently considered threatened species.

Systematics

The systematics of the Anatinae is currently in a state of flux. Previously divided into six subfamilies, anatomical characters (Livezey 1986) suggest that the Anatidae are better treated in nine subfamilies. This classification has been followed by Madge & Burn (1987). But mtDNA sequence analyses (Sraml et al. 1996, Johnson & Sorenson 1999) indicate that for example the dabbling and diving ducks do not belong into the same subfamily. While there are certainly shortcomings in Livezey's analysis, mtDNA is a bad source for phylogenetic information in many waterfowl (especially dabbling ducks) due to their ability to produce fertile hybrids (Carboneras 1992), in rare cases possibly even beyond the level of genus (see for example the "Barbary Duck"). Due to the small sample size of many molecular studies available to date, mtDNA results must be considered with caution.

But while a comprehensive review of the Anatidae which unites all evidence into a robust phylogeny is still lacking, the reasons for the confusing data are at least clear: As the Late Cretaceous fossil Vegavis iaai - an early modern waterbird which belonged to an extinct family - demonstrates, the Anatidae are an ancient group among the modern birds. Their earliest direct ancestors, though not documented by fossils yet, can likewise be assumed to have been contemporaries with the dinosaurs. The long period of evolution and shifts from one kind of waterbird lifestyle to another have obscured many plesiomorphies, while apomorphies apparently are quite often the result of parallel evolution, for example the "non-diving duck" type displayed by such unrelated genera as Dendrocygna, Amazonetta, and Cairina. For the fossil record, see below.

Alternatively (e.g. Terres & NAS 1991), the Anatidae may be considered to consist of 3 subfamilies (ducks, geese, and swans, essentially) which contain the groups as presented here as tribes, with the swans separated as subfamily Cygninae, the goose subfamily Anserinae also containing the whistling ducks, and the Anatinae containing all other clades.

Dendrocygninae: whistling ducks

One pantropical genus, of distinctive long-legged goose-like birds:

• Dendrocygna: whistling ducks (9 living species)

Thalassorninae: White-backed Duck

One genus in Africa, most closely related to the subfamily Dendrocygninae, though also showing convergent similarities to the subfamily Oxyurinae:

• Thalassornis: White-backed Duck

Mute Swan

Anserinae: swans and geese

Three to seven extant genera with 25-30 living species, mainly cool temperate Northern Hemisphere but also some Southern Hemisphere species, with the swans in one genus (two genera in some treatments), and the geese in three genera (two genera in some treatments):

• Cygnus: true swans (7 species, 4 sometimes separated in Olor)
• Anser: grey geese (7 species)
• Chen: white geese (3 species, sometimes included in Anser)
• Branta: black geese (8 living species)

Stictonettinae: Freckled Duck

One genus in Australia, formerly included in the Oxyurinae, but with anatomy suggesting a distinct ancient lineage perhaps closest to the Anserinae, especially the Cape Barren Goose:

• Stictonetta: Freckled Duck

Plectropterinae: Spur-winged Goose

One genus in Africa, formerly included in the "perching ducks", but closer to the Tadorninae:

• Plectropterus: Spur-winged Goose

Tadorninae: shelducks and sheldgeese

Male Common Shelduck

This group of larger, often semi-terrestrial waterfowl can be seen as intermediate between Anserinae and Anatinae. Livezey's 1986 revision has resulted in the inclusion of 10 extant genera with about two dozen living species (one probably extinct) in this subfamily, mostly from the Southern Hemisphere but a few in the Northern Hemisphere, but the affiliations of several presumed tadornine genera has later been questioned (Johnson & Sorenson 1999) and the group in the traditional lineup is likely to be paraphyletic:

• Pachyanas: Chatham Island Duck (prehistoric)
• Tadorna: shelducks (7 species, one probably extinct) - possibly paraphletic
• Salvadorina: Salvadori's Teal
• Centrornis: Madagascar Sheldgoose (prehistoric)
• Alopochen: Egyptian Goose and Mascarene Shelducks (1 living species, 2 extinct)
• Neochen: Orinoco Goose
• Chloephaga: sheldgeese (5 species)
• Hymenolaimus: Blue Duck
• Merganetta: Torrent Duck

A female mallard duck

Anatinae: dabbling ducks and moa-nalos

The dabbling duck group, of worldwide distribution, were previously restricted to just one or two genera, but had been extended by Livezey (1986) to include 8 extant genera and about 55 living species, including several genera formerly known as the "perching ducks"; mtDNA on the other hand confirms that the genus Anas is over-lumped and casts doubt on the diving duck affiliations of several genera (see below):

• Anas: wigeons, gadwalls, teals, pintails, mallards, shovelers, etc (40-50 living species, 3 extinct) - paraphyletic
• Lophonetta: Crested Duck
• Speculanas: Bronze-winged Duck
• Amazonetta: Brazilian Duck

The moa-nalos, of which 4 species in 3 genera are known to date, are a peculiar group of flightless, extinct Anatidae from the Hawaiian Islands. Gigantic in size and with massive bills, they were believed to be geese, but have been shown to be actually very closely related to mallard. They evolved filling the ecological niche of turtles, ungulates and other megaherbivores.

• Chelychelynechen: Turtle-jawed Moa-nalo (prehistoric)
• Thambetochen: Large-billed Moa-nalos (2 species, prehistoric)
• Ptaiochen: Small-billed Moa-nalo (prehistoric)

Aythyinae: diving ducks

Some 15 species of diving ducks, of worldwide distribution, in 2-4 genera; Livezey's 1986 analysis suggests that the probably extinct Pink-headed Duck of India, previously treated separately in Rhodonessa, should be placed in Netta, but this has been questioned (Collar et al. 2001). Furthermore, while morphologically close to dabbling ducks, the mtDNA data indicates that a treatment as distinct subfamily is indeed correct, with the Tadorninae being actually closer to dabbling ducks than the diving ducks are (Johnson & Sorenson, 1999):

• Netta: Red-crested Pochard and allies (4 species, one probably extinct)
• Aythya: pochards, scaups, etc (12 species)

Merginae: eiders, scoters, sawbills and other sea-ducks

Common Goldeneye couple, male on the right.

There are 9 extant genera and some 20 living species; most of this group occur in the Northern Hemisphere, but two Mergus in the Southern Hemisphere:

• Chendytes: Diving-geese (prehistoric)
• Polysticta: Steller's Eider
• Somateria: eiders (3 species)
• Histrionicus: Harlequin Duck
• Camptorhynchus: Labrador Duck (extinct)
• Melanitta: scoters (3 species)
• Clangula: Long-tailed Duck (1 species)
• Bucephala: goldeneyes (3 species)
• Mergellus: Smew
• Lophodytes: Hooded Merganser
• Mergus: mergansers (5 living species, one extinct).

Oxyurinae: stiff-tail ducks

A small group of 4 genera, 3 of them monotypic, with 8 living species:

• Oxyura: stiff-tailed ducks (5 living species)
• Nomonyx: Masked Duck
• Biziura: Musk Ducks (1 living species)
• Heteronetta: Black-headed Duck

Unresolved

The rare White-winged Wood Duck, a species of unclear affiliation.

The largest degree of uncertainty concerns whether a number of genera are closer to the shelducks or to the dabbling ducks. See also the monotypic subfamilies above, and the "Perching ducks"

• Coscoroba: Coscoroba Swan - Anserinae or same subfamily as Cereopsis?
• Cereopsis: Cape Barren Goose - Anserinae, Tadorninae, or own subfamily?
• Cnemiornis: New Zealand geese (prehistoric) - as Cereopsis
• Malacorhynchus: Pink-eared ducks (1 living species) - Tadorninae or Oxyurinae?
• Sarkidiornis: Comb Duck - Tadorninae or closer to dabbling ducks?
• Tachyeres: steamer ducks (4 species) - Tadorninae or closer to dabbling ducks?
• Cyanochen: Blue-winged Goose - Tadorninae or more distant clade?
• Nettapus: pygmy geese (3 species) - Anatinae or part of Southern Hemisphere radiation?
• Pteronetta: Hartlaub's Duck - traditionally dabbling ducks, but may be closer to Cyanochen
• Cairina: Muscovy Duck and White-winged Wood Duck (2 species) - traditionally dabbling ducks, but may be paraphyletic, with one species in Tadorninae and the other closer to diving ducks
• Aix: Mandarin Duck and Wood Duck (2 species) - dabbling ducks or Tadorninae?
• Callonetta: Ringed Teal - dabbling ducks or Tadorninae?
• Chenonetta: Maned Duck (1 living species) - dabbling ducks or Tadorninae?
• Marmaronetta: Marbled Duck - Formerly dabbling ducks; actually a diving duck or a distinct subfamily

Wood Duck Aix sponsa

From subfossil bones found on Kaua‘i (Hawaiian Islands), two enigmatic waterfowl are known. The living and assignable prehistoric avifauna of the archipelago contains as Anseriformes Branta geese and their descendants, and the moa-nalos as mentioned above. The following taxa, although certainly new species, cannot be assigned even to subfamily; that Kaua‘i is the oldest of the large Hawaiian Islands, meaning the species may have been evolving in isolation for nearly up to 10 mya (since the Late Miocene), does not help in determining their affinities:

• Long-legged "Shelduck", Anatidae sp. et gen. indet.
• Small-eyed Duck, Anatidae sp. et gen. indet.

Similarly, Wetmore's Goose (Geochen rhuax) from the Big Island of Hawai‘i, and a gigantic goose-like anatid from O‘ahu are known only from very incomplete and in the former case much damaged bone fragments. The former has been alleged to be a shelduck (Short 1970), but this was generally dismissed because of the damage to the material and biogeographic considerations. The long-legged Kaua‘i bird, however, hints at the possibility of a former tadornine presence on the archipelago, however.

Fossil genera

The fossil record of anatids is extensive, but many prehistoric genera cannot be unequivocally assigned to present-day subfamilies for the reasons given above. Some (such as Eonessa) seem to belong to subfamilies which are completely extinct. For prehistoric species of extant genera, see the respective genus accounts.

• Paracygnus (Kimball Late Pliocene of Nebraska, USA) - anserine
• Eremochen (Pliocene) - anserine
• Cygnavus (Early Oligocene of Kazakhstan - Early Miocene of Germany) - anserine
• Presbychen (Temblor Late Miocene of Sharktooth Hill, USA) - anserine
• Anabernicula (Late Pliocene ?- Late Pleistocene of SW and W North America) - tadornine
• Brantadorna (Middle Pleistocene of Vallecito Creek, USA) - tadornine
• Nannonetta (Late Pleistocene of Peru) - tadornine?
• Eonessa (Eocene of Utah, USA)
• Romainvillia (Early Oligocene of Belgium ?- Late Eocene of France)
• Cygnopterus (Middle Oligocene of Belgium - Early Miocene of France)
• Guguschia (Oligocene of Azerbaijan)
• Mionetta (Late Oligocene - Middle Miocene of C Europe)
• Megalodytes (Middle Miocene of California, USA)
• "cf. Megalodytes" (Haraichi Middle Miocene of Annaka, Japan)
• Anatidae gen. et sp. indet. (Sajóvölgyi Middle Miocene of Mátraszõlõs, Hungary: Gál et al. 1998-99)
• Afrocygnus (Late Miocene ?- Early Pliocene of C Sahara, Africa)
• Balcanas (Early Pliocene of Dorkovo, Bulgaria) - tadornine? May be synonym of Tadorna or even Common Shelduck
• "Chenopis" nanus - at least 2 taxa (Pleistocene of Australia)
• Aldabranas (Pleistocene of Aldabra, Indian Ocean)
• Dendrochen
• Sinanas
• Wasonaka

Putative or disputed prehistoric anatids are:

• Loxornis (Deseado Early Oligocene of Argentina)
• Paracygnopterus (Early Oligocene of Belgium and England)
• Limicorallus (Indricotherium Middle Oligocene of Chelkar-Teniz, Kazakhstan)
• Teleornis (Deseado Early Oligocene of Argentina)
• Paranyroca (Rosebud Early Miocene of Bennett County, USA)
• Eoneornis (Miocene of Argentina) - a nomen dubium
• Eutelornis (Miocene of Argentina)

References

• Carboneras, Carles (1992): Family Anatidae (Ducks, Geese and Swans). In: del Hoyo, Josep; Elliott, Andrew & Sargatal, Jordi (editors): Handbook of Birds of the World, Volume 1: Ostrich to Ducks: 536-629. Lynx Edicions, Barcelona. ISBN 84-87334-10-5

• Collar, N. J.; Andreev, A. V.; Chan, S.; Crosby, M. J.; Subramanya, S. & Tobias, J. A. (editors) (2001): Pink-headed Duck. In:Threatened Birds of Asia: The BirdLife International Red Data Book, p.489-501. BirdLife International. ISBN 0-946888-44-2 HTML fulltext

• Gál, Erika; Hír, János; Kessler, Eugén & Kókay, József (1998-99): Középsõ-miocén õsmaradványok, a Mátraszõlõs, Rákóczi-kápolna alatti útbevágásból. I. A Mátraszõlõs 1. lelõhely [Middle Miocene fossils from the sections at the Rákóczi chapel at Mátraszőlős. Locality Mátraszõlõs I.]. Folia Historico Naturalia Musei Matraensis 23: 33-78. [Hungarian with English abstract] PDF fulltext

• 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

• Livezey, Bradley C. (1986): A phylogenetic analysis of recent anseriform genera using morphological characters. Auk 103(4): 737-754. PDF fulltext

• Madge, Steve & Burn, Hilary (1987): Wildfowl : an identification guide to the ducks, geese and swans of the world. Christopher Helm, London. ISBN 0-7470-2201-1

• Short, Lester L. (1970): A new anseriform genus and species from the Nebraska Pliocene. Auk 87(3): 537-543. PDF fulltext

• Sraml, M.; Christidis, L.; Easteal, S.; Horn, P. & Collet, C. (1996): Molecular Relationships Within Australasian Waterfowl (Anseriformes). Australian Journal of Zoology 44(1): 47-58. doi:10.1071/ZO9960047 (HTML abstract)

• Terres, John K. & National Audubon Society (1991): The Audubon Society Encyclopedia of North American Birds. Wings Books, New York. ISBN 0-517-03288-0

External links

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Anatidae

• Anatidae videos on the Internet Bird Collection
• Anatidae sounds on the xeno-canto collection

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