The Swamp Harrier (Circus approximans) is largely dark brown, becoming lighter with age, and has a distinct white rump. It hunts by flying slowly, low to the ground, on upswept wings. The body length is 50 to 58 cm (20–23 in), and the wingspan is 120 to 145 cm. The recorded weights of adults range from 580 to 1100 g, and females are significantly larger than the males.
The Swamp Harrier mainly feeds on ground and water birds, rabbits and other small mammals, reptiles, frogs and fish. During the winter months, harriers feed to a large extent on carrion, including roadkill.