Radjah Shelduck (Radjah radjah)

By /
Image of a Radjah shelduck
Birds Duck

Introduction

The Radjah Shelduck (Radjah radjah), also known in Australia as the Burdekin Duck, is a distinctive tropical shelduck of northern Australia, New Guinea and parts of eastern Indonesia. It is associated mainly with freshwater and brackish wetlands, estuaries, mangroves and floodplain habitats. The species is the only living member of the genus Radjah under current IOC World Bird List taxonomy. (worldbirdnames.org)

Physical Description

The Radjah Shelduck is a medium-sized waterfowl species measuring approximately 48–61 cm in length. Adults have a white head, neck and underparts, contrasting with a dark back, rump, wings and tail. A dark chestnut to brown breast band separates the white neck from the lower breast and belly. In flight, the wings show an iridescent green speculum bordered by contrasting dark and light areas.

The bill, legs and feet are pale pink, and the iris is notably pale or whitish. Males and females are broadly similar in appearance. The female may have a slightly narrower breast band, while differences in voice are often more useful than plumage for distinguishing the sexes. Juveniles resemble adults but generally have duller, less sharply contrasting plumage, with brownish shading on the head and neck. (perthzoo.wa.gov.au)

Australian birds are commonly described as having brown or chestnut-brown upperparts, whereas birds from New Guinea and nearby islands may appear darker, sometimes almost black-backed. Geographic variation is also reflected in the recognised subspecies. (waterfowl.org.uk)

Range and Habitat

The Radjah Shelduck occurs across northern Australia, including the Kimberley region of Western Australia, the Top End of the Northern Territory and northern Queensland. Its range extends through New Guinea and into parts of eastern Indonesia, including the Moluccas. It is principally a resident species, although local movements may occur in response to rainfall, water levels and food availability.

Typical habitats include mangrove-lined estuaries, tidal flats, coastal swamps, paperbark wetlands, lagoons, billabongs, floodplains and the margins of slow-flowing rivers and creeks. The species uses both freshwater and brackish environments, usually where shallow water, mudflats, wet grassland or nearby vegetation provide feeding opportunities.

During the dry season, individuals may gather around permanent wetlands, estuaries and other reliable water sources. They may roost in trees, mangroves or other elevated locations, an unusual but characteristic habit among ducks. (perthzoo.wa.gov.au)

Behaviour and Diet

Radjah Shelducks are often seen in pairs, family groups or small flocks. They are strong swimmers and fliers, but frequently forage in shallow water, on mudflats or on wet ground beside wetlands. They may be most active at night or during the cooler parts of the day, although they can also be observed feeding in daylight.

The diet is varied and includes aquatic and terrestrial invertebrates such as molluscs and insects, together with algae, sedges, grasses, seeds and other plant material. The birds feed by dabbling, grazing and probing or filtering food from shallow water and soft mud. Small crustaceans and other aquatic organisms may also be taken where available. (perthzoo.wa.gov.au)

Breeding is generally associated with the wet season in northern Australia, although timing varies across the species’ broad range. Pairs establish and defend breeding territories, and males can become strongly territorial during this period. The species is usually monogamous, with both parents involved in caring for the young.

Nesting commonly occurs in a tree hollow close to water and feeding habitat. The nest is lined with down and feathers. Clutches commonly contain 6–12 cream-coloured eggs, and incubation lasts about 28–30 days. The female performs most or all of the incubation, while both parents care for the ducklings after hatching. The young are precocial and leave the nest soon after hatching to follow the adults to water. (perthzoo.wa.gov.au)

Identification Tips

Look for the following combination of features:

  • A white head, neck and lower body.
  • A dark chestnut or brown breast band.
  • Dark back, wings and tail, with green iridescence visible in flight.
  • A pale pink bill, legs and feet.
  • A pale or whitish iris.
  • An upright, shelduck-like stance near shallow water, mudflats or wet grassland.

The Radjah Shelduck is unlikely to be confused with the Australian Shelduck (Tadorna tadornoides), which has a dark head and neck, a white neck ring and a much darker overall body pattern. The Radjah Shelduck’s white head and prominent dark breast band are its most useful field marks.

In flight, the green wing panel and sharply contrasting white, brown and black plumage can help confirm the identification. Its relatively quiet, wheezy or rattling vocalisations may also distinguish it from louder ducks in the same wetlands. (perthzoo.wa.gov.au)

Conservation Status

The Radjah Shelduck is currently assessed as Least Concern on the IUCN Red List. Its broad distribution and generally secure populations support this global assessment, although the species is not free from local pressures. (epbcpublicportal.environment.gov.au)

The principal conservation concern is the loss, degradation and fragmentation of tropical wetlands, including mangroves, paperbark swamps, floodplains and estuaries. Pollution, alteration of water regimes, disturbance around nesting sites and hunting may also affect local populations. Maintaining wetland connectivity, protecting mature trees with suitable hollows and limiting disturbance during the breeding season are important conservation measures.

In Australia, the species is protected under wildlife legislation, and many important habitats occur within national parks, wetlands reserves and other protected areas. Local monitoring of major wetlands can help identify changes in distribution and abundance.

Frequently Asked Questions

Where does the Radjah Shelduck live?

It occurs mainly in northern Australia, New Guinea and parts of eastern Indonesia. It favours tropical freshwater and brackish wetlands, estuaries, mangroves, floodplains, lagoons and paperbark swamps.

What does a Radjah Shelduck look like?

It has a white head, neck and underparts, a dark chestnut or brown breast band, dark upperparts and a pale pink bill and legs. Green iridescence is visible in the wings during flight.

What does the Radjah Shelduck eat?

Its diet includes molluscs, insects, other aquatic invertebrates, algae, sedges, grasses and seeds. It usually feeds by dabbling, grazing or probing in shallow water and mud.

Where does the Radjah Shelduck nest?

It commonly nests in a tree hollow close to water and feeding habitat. The nest is lined with down and feathers, and the female typically lays between six and twelve cream-coloured eggs.

Is the Radjah Shelduck migratory?

It is generally resident, but it can make local or seasonal movements in response to rainfall, changing water levels and the availability of food and suitable wetlands.

Is the Radjah Shelduck endangered?

No. The species is currently listed as Least Concern globally by the IUCN. Local populations may nevertheless be affected by wetland loss, habitat degradation, disturbance and hunting.

References

Views: 1,287

Related posts

Scroll to Top