The diving ducks, commonly called pochards or scaups, are a category of

duck Duck is the common name for numerous species of waterfowl in the family (biology), family Anatidae. Ducks are generally smaller and shorter-necked than swans and goose, geese, which are members of the same family. Divided among several subfam ...

which feed by diving beneath the surface of the water. They are part of

Anatidae The Anatidae are the biological family (biology), family of water birds that includes ducks, goose, geese, and swans. The family has a cosmopolitan distribution, occurring on all the world's continents except Antarctica. These birds are adapted f ...

, the diverse and very large

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

that includes ducks, geese, and

swan Swans are birds of the genus ''Cygnus'' within the family Anatidae. The swans' closest relatives include the goose, geese and ducks. Swans are grouped with the closely related geese in the subfamily Anserinae where they form the tribe (biology) ...

s. The diving ducks are placed in a distinct tribe in the subfamily

Anatinae The Anatinae are a subfamily of the family Anatidae (swans, geese and ducks). Its surviving members are the dabbling ducks, which feed mainly at the surface rather than by diving. The other members of the Anatinae are the extinct moa-nalo, a ...

, the Aythyini. While morphologically close to the

dabbling duck The Anatinae are a subfamily of the family Anatidae (swans, geese and ducks). Its surviving members are the dabbling ducks, which feed mainly at the surface rather than by diving. The other members of the Anatinae are the extinct moa-nalo, a y ...

s, there are nonetheless some pronounced differences such as in the structure of the

trachea The trachea (: tracheae or tracheas), also known as the windpipe, is a cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all animals' lungs. The trachea extends from ...

. mtDNA cytochrome ''b'' and

NADH dehydrogenase NADH dehydrogenase is an enzyme that converts nicotinamide adenine dinucleotide (NAD) from its reduced form (NADH) to its oxidized form (NAD+). Members of the NADH dehydrogenase family and analogues are commonly systematically named using the f ...

subunit 2

sequence In mathematics, a sequence is an enumerated collection of objects in which repetitions are allowed and order matters. Like a set, it contains members (also called ''elements'', or ''terms''). The number of elements (possibly infinite) is cal ...

data indicate that the dabbling and diving ducks are fairly distant from each other, the outward similarities being due to

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last comm ...

. Alternatively, the diving ducks are placed as a

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...

Aythyinae in the family Anatidae which would encompass all duck-like birds except the whistling-ducks. The seaducks commonly found in coastal areas, such as the

long-tailed duck The long-tailed duck (''Clangula hyemalis'') or coween, is a medium-sized sea duck that breeds in the tundra and taiga regions of the arctic and winters along the northern coastlines of the Atlantic and Pacific Oceans. It is the only member of ...

(formerly known in the U.S. as oldsquaw),

scoter The scoters are stocky seaducks in the genus ''Melanitta''. The drakes are mostly black and have swollen bills, the females are brown. They breed in the far north of Europe, Asia, and North America, and bird migration, winter further south in te ...

goldeneye ''GoldenEye'' is a 1995 spy film, the seventeenth in the List of James Bond films, ''James Bond'' series produced by Eon Productions, and the first to star Pierce Brosnan as the fictional Secret Intelligence Service, MI6 agent James Bond (lit ...

s, mergansers,

bufflehead The bufflehead (''Bucephala albeola'') is a small sea duck of the genus ''Bucephala'', the goldeneyes. It breeds in Alaska and Canada and migrates in winter to southern North America. This species was first described by Carl Linnaeus in his lan ...

and eiders, are also sometimes colloquially referred to in North America as diving ducks because they also feed by diving; their subfamily (Merginae) is a very distinct one however. Although the group is

cosmopolitan Cosmopolitan may refer to: Internationalism * World citizen, one who eschews traditional geopolitical divisions derived from national citizenship * Cosmopolitanism, the idea that all of humanity belongs to a single moral community * Cosmopolitan ...

, most members are native to the

Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar ...

, and it includes several of the most familiar Northern Hemisphere ducks. This group of ducks is so named because its members feed mainly by diving, although in fact the ''Netta'' species are reluctant to dive, and feed more like dabbling ducks. These are gregarious ducks, mainly found on fresh water or on

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environm ...

, though the greater scaup becomes marine during the northern winter. They are strong fliers; their broad, blunt-tipped wings require faster wing-beats than those of many ducks and they take off with some difficulty. Northern species tend to be migratory; southern species do not migrate though the hardhead travels long distances on an irregular basis in response to rainfall. Diving ducks do not walk as well on land as the

s; their legs tend to be placed further back on their bodies to help propel them when underwater.

Systematics

Three

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

are included in the Aythyini. The marbled duck which makes up the

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

genus ''Marmaronetta'', however, seems very distinct and might have diverged prior to the split of dabbling and diving ducks as indicated by morphological and molecular characteristics. The probably extinct pink-headed duck, previously treated separately in ''Rhodonessa'', has been suggested to belong into ''Netta'', but this approach has been questioned.

DNA sequence A nucleic acid sequence is a succession of bases within the nucleotides forming alleles within a DNA (using GACT) or RNA (GACU) molecule. This succession is denoted by a series of a set of five different letters that indicate the order of the nu ...

analyses have found it to be the earliest diverging member of the pochard group. The molecular analysis also suggests that the white-winged duck should be placed into a

genus ''Asarcornis'' which is fairly close to ''Aythya'' and might belong into this subfamily. Aythya australis female - Hurstville Golf Course

Family Anatidae

* Subfamily Anatinae ** Tribe Aythyini *** Genus '' Rhodonessa'' **** Pink-headed duck (''Rhodonessa caryophyllacea'') ; probably

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

(1945?) ***Genus '' Marmaronetta'' **** Marbled duck (''Marmaronetta angustirostris'') ***Genus '' Netta'' (provisionally including ''Rhodonessa'') **** Red-crested pochard (''Netta rufina'') **** Southern pochard (''Netta erythrophthalma'') **** Rosy-billed pochard (''Netta peposaca'') *** Genus '' Aythya'' **** Canvasback (''Aythya valisineria'') **** Common pochard (''Aythya ferina'') **** Redhead (''Aythya americana'') **** Ring-necked duck (''Aythya collaris'') **** Hardhead (''Aythya australis'') **** Baer's pochard (''Aythya baeri'') **** Ferruginous duck (''Aythya nyroca'') **** Madagascar pochard (''Aythya innotata'') – feared to be extinct, rediscovered (2006) ****Réunion pochard, (''Aythya'' cf. ''innotata'') – extinct (c. 1690s) **** New Zealand scaup (''Aythya novaeseelandiae'') **** Tufted duck (''Aythya fuligula'') **** Greater scaup (''Aythya marila'') **** Lesser scaup (''Aythya affinis'')

References

{{DEFAULTSORT:Diving Duck Aythyinae Diving ducks Articles containing video clips