The swamp harrier, also known as the Australasian marsh harrier or Australasian harrier, is a large, slim bird of prey widely distributed across Australasia. In New Zealand, it is also known by the Māori name kāhu. It arrived in New Zealand within the last 700 years, replacing the larger species, the extinct New Zealand endemic Eyles's harrier.
Region
Australasia and Southwest Pacific
Typical Environment
Found widely across Australia, Tasmania, and New Zealand, with occurrences on nearby Southwest Pacific islands. It favors wetlands such as swamps, reedbeds, and marshes, but also hunts over open grasslands, coastal dunes, heath, and agricultural landscapes. The species readily uses human-modified habitats, including pasture and croplands where prey is abundant. Breeding typically occurs in dense marsh vegetation or tall grasses near water. Outside breeding, individuals disperse widely following prey and seasonal conditions.
Altitude Range
Sea level to 1800 m
Climate Zone
Temperate
Ease of Keeping
Beginner friendly: 1/5
Also called the Australasian marsh harrier or kāhu in New Zealand, this large harrier specializes in low, buoyant quartering over open country and wetlands. It arrived in New Zealand within the last 700 years, replacing the larger, extinct Eyles's harrier. It nests on the ground in dense vegetation and is highly adaptable, often hunting over farmland and marshes. A conspicuous white rump and long wings held in a shallow V are classic field marks.
Temperament
solitary and territorial
Flight Pattern
low, buoyant quartering with slow wingbeats and frequent glides
Social Behavior
Generally solitary outside the breeding season, though loose roosting groups can form in rich habitats. Pairs are seasonally monogamous and nest on the ground in dense reeds or tall grasses, building a bulky platform. Courtship includes aerial displays and food passes. Both adults attend the nest, with the female brooding and the male providing much of the prey early on.
Migratory Pattern
Partial migrant
Song Description
Usually quiet away from the nest. Near breeding sites it gives sharp, repeated kek-kek calls or piercing whistles during displays and territorial encounters.
