Radjah Shelduck (Rajah rajah) Fact Sheet: Physical Characteristics

Body measurements

Data sources:
Carboneras and Kirwan (2018): weight, head–body length
Frith (1967): wing length
Pizzey (2012): wing span

Body

• Large duck (Pratt and Beehler 2014)

Plumage

• Adult
  • Sexes similar (Johnsgard 1965; Frith 1967)
  • Head, neck, and underbody
    • White (Pratt and Beehler 2014)
    • Sometimes rust-stained (Pizzey 2012)
  • Breast band (Pratt and Beehler 2014)
    • Narrow
    • Reddish-brown (chestnut)
  • Upperwing
    • Distinctive in flight (Pratt and Beehler 2014; Carboneras and Kirwan 2018)
    • Primary feathers (Johnsgard 2010a; Pratt and Beehler 2014; Carboneras and Kirwan 2018)
      • Dark
      • Subspecies differences; considerable variation
        • R. r. rufitergum more reddish-brown (chestnut)
        • R. r. radjah more black
    • Shoulder patch
      • White
    • Wing patch (speculum) on secondary feathers
      • Iridescent green
      • Edges have a white and a narrow black band
  • Underwing
    • White with dark outer wing (Marchant and Higgins 1990)
      • Looks “dipped in ink” (Pizzey 2012)
  • Tail
    • Dark brown to black (Marchant and Higgins 1990)
• Juvenile
  • Crown and back of neck have dull brown wash (Marchant and Higgins 1990)
  • White areas less bright and tinged with brown or gray flecks (Marchant and Higgins 1990)
  • Green wing patch more dull (Carboneras and Kirwan 2018)
• No seasonal plumage changes (Marchant and Higgins 1990)

Head

• Bill
  • Pale pink (Pizzey 2012; Carboneras and Kirwan 2018)
  • Broad with round tip (Marchant and Higgins 1990)
  • Nostrils large and round (Marchant and Higgins 1990)
  • Inner edges have rigid lamellae
    • Used for filter feeding
      • Also see Feeding
• Eyes
  • Adults
    • Iris white to pale yellow (Marchant and Higgins 1990)
  • Juveniles and ducklings
    • Dark brown (Marchant and Higgins 1990)

Legs and feet

• Pale pink (Pizzey 2012; Carboneras and Kirwan 2018)
• Slender (Marchant and Higgins 1990)

Breast band

• More narrow in female (Pizzey 2012)

Vocalizations

• See Vocalizations

Easily identified

• Only large duck in its distribution with an all-white head, neck, and underparts, and a narrow chestnut breast band (Pratt and Beehler 2014)
• White/Cotton Pygmy Goose (Marchant and Higgins 1990; Pratt and Beehler 2014)
  • Much smaller
  • Crown has black
  • Shoulder has no white
  • Wing pattern differs

The Radjah Shelduck is easily identified by its white head, and pink bill and feet.

At close distance, the white to yellow eye is also distinctive for adults.

Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.

The Radjah Shelduck has a narrow band of dark feathers across its chest.

Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.