[order] ANSERIFORMES | [family] Anatidae | [latin] Tadorna radjah | [authority] Lesson, 1828 | [UK] Raja Shelduck | [FR] Tadorne radjah | [DE] Radjahgans | [ES] Tarro Raja | [NL] Radjah-eend
The shelducks, genus Tadorna, are a group of large birds in the Tadorninae subfamily of the Anatidae, the biological family that includes the ducks and most duck-like waterfowl such as the geese and swans. The namesake genus of the Tadorninae, Tadorna is very close to the Egyptian Goose and its extinct relatives from the Madagascar region, Alopochen. While the classical shelducks form a group that is obviously monophyletic, the interrelationships of these, the aberrant Common and especially Raja Shelducks, and the Egyptian Goose were found to be poorly resolved. Fossil bones from Dorkovo (Bulgaria) described as Balcanas pliocaenica may actually belong to this genus. They have even been proposed to be referable to the Common Shelduck, but their Early Pliocene age makes this rather unlikely.
Both the male and female of the species are mostly white, with dark wing-tips and a distinctive “collar” of dark feathers. Seen from above in flight the birds have green bands on the tops of their wings. The female has a harsh rattle and the male has a breathy, sore-throat whistle.
Listen to the sound of Raja Shelduck
Copyright remark: Most sounds derived from xeno-canto
Australasia : North Australia, New Guinea
The species prefers the brackish waters of mangrove flats and paperbark tree swamps, but will visit freshwater swamps, lagoons, and billabongs further inland during the wet season. Prefer water of only up to 5 cm (2 inches) deep.
The Raja Shelduck forms long-term pair-bonds, and is usually encountered in lone pairs or small flocks. During the wet season the males commonly become very irritable, and have been observed attacking their mates. Pairs start searching for nesting sites during the months of January and February. They nest close to their primary food source, often in the hollow limbs of trees, which makes habitat destruction a particular issue. The Raja Shelduck does not use nesting materials except for some self-supplied down feathers. Egg-laying is usually done by May or June, but depends on the extent of the wet season. The clutches range from 6 to 12 eggs. Incubation time is about 30 days.
The diet consists mainly of mollusks, insects, sedge materials and algae.
copyright: Josep del Hoyo
This species has a very large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size may be moderately small to large, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
The Raja Shelduck or Radjah Shelduck (Tadorna radjah), also known as the Burdekin Duck in Australia, is a species of shelduck. Placed in the genus Tadorna, it differs markedly in external morphology, and mtDNA cytochrome b sequence data suggests its status should be reinvestigated.
The New Guinea population is primarily sedentary; the Australian population disperses in dry season, sometimes even seen in southern Australia.