Swamp Harrier

The Swamp Harrier, known scientifically as Circus approximans, is a bird of prey of notable size and grace. It is also referred to as the Australasian Marsh Harrier or simply the Australasian Harrier. In New Zealand, it is embraced with the Māori name kāhu. Exhibiting a predominantly dark brown plumage that lightens with maturity, this raptor is distinguished by a conspicuous white rump. It glides with a slow, deliberate flight, wings held in a characteristic upswept V-shape, close to the ground as it searches for prey. The adult Swamp Harrier spans a body length of 48 to 62 centimeters and a wingspan of 118 to 145 centimeters. Weights range from 580 to 1,100 grams, with females being significantly larger than males.

Identification Tips

When observing the Swamp Harrier, look for a large, slim raptor with dark brown feathers that become paler with age. The white rump is a key feature for identification, especially noticeable in flight. The bird's flight pattern is also distinctive, with slow, low passes over the landscape on upswept wings.

Habitat

The Swamp Harrier thrives in wetlands and well-watered open country. It has adapted well to human-altered landscapes and is commonly found in open farmland.

Distribution

This species enjoys a wide distribution across Australasia, including much of Australia, New Zealand, Fiji, Vanuatu, New Caledonia, and occasionally on some subantarctic islands. It is particularly common in New Zealand's open country.

Behaviour

Swamp Harriers face antagonism from Australian magpies, masked lapwings, and European starlings. They are known to predate on the young of New Zealand falcons and are sometimes persecuted for hunting domestic fowl. In New Zealand, they are the sole bird of prey used in falconry, typically hunting pūkeko and young rabbits.

Diet and Feeding

The diet of the Swamp Harrier is varied, including ground and waterbirds, rabbits, small mammals, reptiles, frogs, and fish. In winter, they often resort to scavenging carrion, such as roadkill, which unfortunately leads to collisions with vehicles.

Breeding

Swamp Harriers nest on the ground, favoring the shelter of dense vegetation in wetlands or agricultural fields. Clutch sizes range from two to seven eggs, with three or four being most common. The female incubates the eggs for 31 to 34 days. Both parents feed the chicks, which are fully feathered by 28 days and fledge approximately 45 days after hatching.

Conservation status

The IUCN Red List classifies the Swamp Harrier as Least Concern, indicating a stable population without significant threats at present.