Swamp Harrier

Circus approximans

Swamp Harrier. Photo: Jeff Groves

Swamp harriers are often seen flying slowly and close to the ground in wetland areas searching for their prey. This hunting strategy is often known as “quartering”. Other raptors use this technique but harriers are specialists at it (their generic name “Circus” refers to their circling flight). Like owls they use hearing to locate their prey, and like owls, they have a disc of feathers around the sides of their heads, which serves to funnel sound into their ears.

Swamp Harriers prey on a wide variety of vertebrates including rabbits, aquatic birds (e.g. coots, grebes and small ducks), seabirds (Little Penguin. prions etc), amphibians, and fish. It will also take aquatic insects and crustaceans. After locating prey by slow quartering or soaring, it is captured by the harrier suddenly diving and dropping to the ground or water surface.

Breeding occurs mainly in spring and early summer. Courting aerial displays can be spectacular with the normally silent male uttering short whistles. The nest is a platform of sticks, reeds and dry grass, on the ground, or over water among reeds or tall grass. The clutch size is normally 3-4 with an average of 1.75 nestlings per nest fledging. Harriers are shy at the nest and may desert it if disturbed.

Description

Swamp Harriers have long rectangular wings with prominent “fingers”, the ideal shape for slow gliding. The plumage is generally dark with the upperparts being dark brown and the underparts more rufous. In flight the prominent white rump is diagnostic. The underwings are paler with a dark trailing edge. The legs are long and yellow. The cere and eyes are yellow and the beak black. As is usual with raptors the female is larger than the male (by as much as 50% by weight). Females also darker and browner and her underparts are more rufous. Older males can become quite pale and their tail lacks bars. Juvenile birds are dark brown with brown irises and an orange-rufous rump. As the bird ages, it becomes lighter.

Where to find it

Swamp Harriers favour terrestrial, estuarine and coastal wetlands where they can nest in dense ground cover and hunt in open country. They can be found in suitable habitats in the wetter southern and eastern parts of South Australia, but are absent from the dry north and west.

The race is found in South Australia is Circus approximans gouldi.