Sexual maturity
- Not reported for Radjah Shelduck
- Most likely similar to other shelducks—at about 2 years of age (Johnsgard 2010b)
Breeding range
- Assumed to breed throughout main range but not well known (Marchant and Higgins 1990)
Breeding season
(observations from Northern Territory)
- Breeding coincides with end of wet season/early dry season (as floodwaters recede and mudflats become exposed) (Johnsgard 2010a)
- Increased sexual activity early in wet season (Frith 1967)
- “Timing and duration…may depend on extent and intensity of wet season” (Marchant and Higgins 1990)
- Breeding territories established January to February (Frith 1967; Marchant and Higgins 1990)
- See Breeding habitat, below
- Clutches laid February to July or later, depending on seasonal rainfall (Frith 1967; Shurcliff and McKean 1990)
- Peak in May and June (late wet season/early dry season), when more food available (Frith 1967)
Breeding habitat
- Pair defends a breeding territory (Marchant and Higgins 1990)
- Contains a nesting site and a feeding area (Johnsgard 2010a)
- Use freshwater pools, lagoons, and river banks (Marchant and Higgins 1990)
- Territory size
- Up to 2.5 to 3.0 km (1.6 to 1.9 mi) long (on rivers) (Royal Australasian Ornithologists Union 1984; Carboneras and Kirwan 2018)
- May remain in breeding territory during dry season (Marchant and Higgins 1990)