thumb|Tadorna ferruginea
thumb| Tadorna ferruginea - [[MHNT]]
The ruddy shelduck (Tadorna ferruginea) is a bird species in the family Anatidae. It is a distinctive waterfowl, in length with a wingspan of . It has orange-brown body plumage with a paler head, while the tail and the flight feathers in the wings are black, contrasting with the white wing-coverts. It is a migratory bird, wintering in the Indian subcontinent and breeding in southeastern Europe and central Asia, though there are small resident populations in North Africa. It has a loud honking call.
The ruddy shelduck mostly inhabits inland water-bodies such as lakes, reservoirs and rivers. The male and female form a lasting pair bond and the nest may be well away from water, in a crevice or hole in a cliff, tree or similar site. A clutch of about eight eggs is laid and is incubated solely by the female for about four weeks. The young are cared for by both parents and fledge about eight weeks after hatching.
In central and eastern Asia populations are steady or rising, but in Europe they are generally in decline. Altogether, the birds have a wide range and large total population, and the International Union for Conservation of Nature has assessed their conservation status as being of least concern.
Taxonomy and etymology
alt= Ruddy Shelduck|left|thumb|At Chilika Lake, Mangalajodi, Odisha, India
The ruddy shelduck (Tadorna ferruginea) is a member of the shelduck genus Tadorna in the wildfowl family Anatidae. The bird was first described in 1764 by the German zoologist and botanist Peter Simon Pallas who named it Anas ferruginea, but later it was transferred to the genus Tadorna with the other shelducks. Some authorities place it in the genus Casarca along with the South African shelduck (T. cana), the Australian shelduck (T. tadornoides) and the paradise shelduck (T. variegata). Phylogenetic analysis shows that it is most closely related to the South African shelduck. In captivity, the ruddy shelduck has been known to hybridise with several other members of Tadorna, with several members of the dabbling duck genus Anas, and with the Egyptian goose (Alopochen aegyptiaca). No subspecies are recognised.
The generic name Tadorna comes from the French , the common shelduck, and may originally derive from a Celtic word meaning "pied waterfowl". The English name "sheld duck" dates from around 1700 and means the same.
Description
thumb|Ruddy shelduck at , [[Chandra Taal, Spiti, Himachal Pradesh]]
The ruddy shelduck grows to a length of and has a wingspan. The male has orange-brown body plumage and a paler, orange-brown head and neck, separated from the body by a narrow black collar. The rump, flight feathers, tail-coverts and tail feathers are black and there are iridescent green speculum feathers on the inner surfaces of the wings. Both upper and lower wing-coverts are white, this feature being particularly noticeable in flight but hardly visible when the bird is at rest. The bill is black and the legs are dark grey. The female is similar but has a rather pale, whitish head and neck and lacks the black collar, and in both sexes, the colouring is variable and fades as the feathers age. The birds moult at the end of the breeding season and the male loses the black collar, but a further partial moult between December and April restores it. Juveniles are similar to the female but are a darker shade of brown.
The call is a series of loud, nasal honking notes, it being possible to discern the difference between those produced by the male and the female. The calls are made both on the ground and in the air, and the sounds are variable according to the circumstances in which they are uttered. Eastern populations are mostly migratory, wintering in the Indian subcontinent.
This shelduck mostly frequents open locations on inland bodies of water such as lakes, reservoirs and rivers. It is seldom seen in forested areas but does occur in brackish water and saline lagoons. Though more common in the lowlands, it also inhabits higher altitudes and in central Asia is one of the few waterbirds, along with the bar-headed goose (Anser indicus), to be found on lakes at .
A stable population exists in Moscow, settling the city parks' ponds alongside the endemic mallards. These birds are feral descendants of escapees from the Moscow Zoo, the population most likely forming after 1948, when the policy of clipping the birds' wings was repealed. Unlike the wild population, these ducks are non-migratory, wintering instead in the non-freezing parts of the city's bodies of water. Population increased from 1990's to 2020's by over 20 times, reaching 3300 by 2025.
Behaviour
thumb|A ruddy shelduck flying over a lake
The ruddy shelduck is a mainly nocturnal bird. and this gives the birds some protection in central and eastern Asia, where the population is thought to be steady or even rising. The Pembo Black-necked Crane Reserve in Tibet is an important wintering area for ruddy shelducks, and here they receive protection. In Europe on the other hand, populations are generally declining as wetlands are drained and the birds are hunted. However, in Europe and Italy the ruddy shelduck is protected, with hunting banned. They are less vulnerable than some other waterfowl because of their adaptability to new habitats such as reservoirs.
The ruddy shelduck has a very wide range and an estimated total population size of 170,000 to 225,000 individuals. The overall population trend is unclear as some local populations are increasing while others are decreasing. The bird does not appear to meet the higher criteria necessary to be considered threatened, and the International Union for Conservation of Nature assesses that its conservation status is of least concern.