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Anatidae

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iDucks, geese and swans
(Greater) White-fronted Goose (Anser albifrons)
(Greater) White-fronted Goose (Anser albifrons)
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 swan. The Magpie-goose is no longer considered to be part of the Anatidae, but is placed in its own family Anseranatidae. These are birds that are modified for swimming, floating on the water surface, and in some cases diving in at least shallow water.

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 and care must be taken when breeding ducks or geese that a pool is provided for this purpose as attempts to copulate on dry land will often lead to injury of the drake's penis. 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.

Contents

[edit] 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 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.

[edit] Dendrocygninae: whistling ducks

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

[edit] Thalassorninae: White-backed Duck

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

Mute Swan

[edit] Anserinae: swans and geese

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

  • Coscoroba: Coscoroba Swan
  • 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)

[edit] 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:

[edit] Plectropterinae: Spur-winged Goose

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

[edit] 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:

Image:Duck UConn 01.jpg

[edit] 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):

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.

[edit] 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)

[edit] Merginae: eiders, scoters, sawbills and other sea-ducks

Image:Bucephala clangula ja 01.jpg

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:

[edit] Oxyurinae: stiff-tail ducks

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

[edit] Unresolved

Image:White-winged.wood.duck.arp.jpg

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"

  • 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

From subfossil bones found on Kaua‘i (Hawaiian Islands), two bizarre and 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.

[edit] Fossil genera

The fossil record of anatids is extensive, but most 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.

  • Eonessa (Eocene of Utah, USA)
  • Cygnavus (Early Oligocene of Kazakhstan - Early Miocene of Germany)
  • 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 - Early Miocene)
  • 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)
  • Afrocygnus (Late Miocene ?- Early Pliocene of C Sahara, Africa)
  • Presbychen (Temblor Late Miocene of Sharktooth Hill, USA)
  • Paracygnus (Kimball Late Pliocene of Nebraska, USA)
  • Anabernicula (Late Pliocene ?- Late Pleistocene of SW and W North America)
  • "Chenopis" nanus - at least 2 taxa (Pleistocene of Australia)
  • Aldabranas
  • Brantadorna
  • Dendrochen
  • Eremochen
  • Sinanas
  • Wasonaka

Putative or disputed prehistoric anatids are:

  • Paracygnopterus (Early Oligocene of Belgium and England)
  • Limicorallus (Indricotherium Middle Oligocene of Chelkar-Teniz, Kazakhstan)
  • Paranyroca (Rosebud Early Miocene of Bennett County, USA)

[edit] 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
  • 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
  • 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)

[edit] External links

da:Egentlige andefugle de:Entenvögel es:Anatidae eo:Anasedoj fr:Anatidae fy:Einfûgels it:Anatidi he:ברווזיים ka:იხვისებრნი nl:Anatidae ja:カモ科 (Sibley) no:Andefamilien nn:Andefamilien pl:Kaczkowate pt:Anatidae ru:Утиные fi:Sorsat sv:Egentliga andfåglar tr:Ördek zh:鸭科

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