Radjah shelducks can be found in brackish mangroves and paperbark tree swamps, or in freshwater wetlands, lagoons, and billabongs. There, they forage for food and eat mollusks, insects, algae, and sedges—and occasionally small fish, crabs, larvae, and seeds.
They use their bill to filter through the water and scoop up food. These birds feed mainly at night, grazing or dabbling in shallow water, grasslands, and mudflats.
During the wet season, November through April, radjah shelducks establish breeding grounds, and the males become very aggressive in defending them. When radjah shelducks mate, they remain monogamous and form long-term pair bonds.
The pair will scout out a place to nest that is near good locations for finding food, often in a tree hollow. They build their nest out of their own soft down feathers, using no other materials.
