''Aix'' is a bird

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

that contains two

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

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 ...

s: the

wood duck The wood duck or Carolina duck (''Aix sponsa'') is a partially migratory species of perching duck found in North America. The male is one of the most colorful North American waterfowls. Taxonomy The wood duck was Species description, formal ...

(''Aix sponsa''), and the

mandarin duck The mandarin duck (''Aix galericulata'') is a perching duck species native to the East Palearctic. It is Sexual dimorphism, sexually dimorphic – the males are elaborately coloured, while the females have more subdued colours. It is a medium- ...

(''Aix galericulata''). ''Aix'' (αἴξ, genitive αἰγός) is an

Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

word used by

Aristotle Aristotle (; 384–322 BC) was an Ancient Greek philosophy, Ancient Greek philosopher and polymath. His writings cover a broad range of subjects spanning the natural sciences, philosophy, linguistics, economics, politics, psychology, a ...

to refer to an unknown diving bird.

Taxonomy

The genus belongs to the

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 ...

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 ...

in the waterfowl

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Anseriformes Anseriformes is an order (biology), order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest f ...

. They were formerly placed in the "

perching duck The term perching ducks is used colloquially to mean any species of ducks distinguished by their readiness to perch high in trees. Until the late 20th century, perching ducks meant ''Cairinini'', a tribe of ducks in the duck, goose and swan fam ...

s", a

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

group somewhat intermediate between

shelduck The shelducks, most species of which are found in the genus ''Tadorna'' (except for the Radjah shelduck, which is now found in its own monotypic genus ''Radjah''), are a group of large birds in the Tadorninae subfamily of the Anatidae, the biolog ...

s and

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, and it is not quite clear whether they should be placed in the

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 ...

(dabbling duck) or

Tadorninae The Tadornini is a biological tribe that includes the shelducks and sheldgeese, which is placed in subfamily Anatinae of family Anatinae, which includes the ducks and most duck-like waterfowl such as the geese and swans. It has been treated a ...

(shelduck)

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 ...

Extant species

Habitat

Both species

migrate Migration, migratory, or migrate may refer to: Human migration * Human migration, physical movement by humans from one region to another ** International migration, when peoples cross state boundaries and stay in the host state for some minimum le ...

from the northern parts of their respective ranges to winter in the south of the range. They inhabit quiet wooded streams and ponds.

Description

The two species are generally considered to be very attractive, particularly the multi-coloured drakes. The genus shows marked

sexual dimorphism Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

(differences between the sexes), with the females being smaller and less colorful.

Diet

Wood ducks will consume small

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

s, and plant matter. Mandarin ducks are mainly vegetarian.

Breeding

Wood ducks are reproductively capable around the age of one year. They are monogamous for the season. Mating occurs between February and April, depending on latitude. The

clutch size A clutch of eggs is the group of eggs produced by birds, amphibians, or reptiles, often at a single time, particularly those laid in a nest. In birds, destruction of a clutch by predators (or removal by humans, for example the California condor b ...

is between 6 and 15, and the incubation period is about 30 days. The young are precocial. They venture from the cavity nest at one day old and are cared for by the mother for about 60 days. The young have a very high mortality rate. Wood ducks normally live 3 to 4 years. Mandarin ducks are also monogamous. The courtship ritual, like the plumage, is rather showy. The female lays between 9 and 12 eggs in a cavity nest, then incubates them for about 30 days. Parental care by the mother is a little shorter in this species, lasting about 40 days.

Conservation

Both species are affected by loss of habitat. As human development continues to expand, the woodland areas preferred by these ducks continues to shrink. As of 2016, both species had been evaluated for the

Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological sp ...

of the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...

(IUCN), and given a "least concern" rating.