[order] ACCIPITRIFORMES | [family] Accipitridae | [latin] Circus approximans | [authority] Peale, 1848 | [UK] Swamp Harrier | [FR] Busard de Gould | [DE] Sumpfweihe | [ES] Aguilucho lagunero del Pacifico | [NL] Australische bruine kiekendief
The genus Circus is a cosmopolitan genus of about ten species. They are medium-sized, slender hawks, the female being considerably larger than the male. They are characterised by long, narrow, rounded tails, small beaks and long, slender legs. The most notable characteristic is the owl-like ruff of facial feathers that cover unusually large ear openings – an adaptation not for low-light hunting, but to locate prey by their rustling and squeaking in tall grasses.
The Swamp Harrier is a large slim-bodied raptor, with long slender legs and a long tail, rounded at the tip. It is mainly dark brown above and the white rump is prominent. It has an owl-like face mask. The wings are long and broad, with 5 ‘fingers’ on the wing tips in flight. Females are larger with rufous underparts, while the smaller male is lighter underneath. The legs and eyes are yellow. This species has a slow sailing flight on up-swept wings, flying low over water. It is also known as the Marsh Harrier.
Listen to the sound of Swamp Harrier
Copyright remark: Most sounds derived from xeno-canto
Australasia : widespread. The Swamp Harrier is widespread in Australasia and the South Pacific. It is the commonest raptor in New Zealand
Typically seen flying low over open country, including lakes, swamps, wetlands, grasslands, coastal heaths, and croplands. Roosts on the ground, often in large communal roosts of 20 to 200 birds in New Zealand and, in Fiji, usually among long grass or sedges. Normally a solitary forager, but large groups sometimes congregate in areas of high food density in Fiji.
Pairs nest solitarily or in loose “clumps” with other pairs, and the nest is a platform of sticks, reeds, grass, and other plants placed among tall grass, shrubs or reeds, either on the ground, in water, or, rarely, in a low bushy tree. Clutch size is usually 3 or 4 bluish-white eggs (range 2-7), the incubation period is about 33 days, and the nestling period is 43-46 days. The period of dependence after fledging lasts about four to six weeks.
Feeds on mammals, birds and their eggs, rats, reptiles, amphibians, fish, insects, and carrion. Forages by low, slow quartering and soaring, and it seizes prey by diving or dropping to the ground or water surface, sometimes after hovering. It also harries waterbirds to exhaustion or sometimes drowns them, and it robs other raptors.
copyright: Brooke Clibbon
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size may be moderately small to large, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Migratory in South; resident at lower latitudes where numbers swelled by wintering birds. Winter migrants reach North Australia and New Guinea. In New Zealand, juveniles disperse both north and south between the two main islands, and small numbers may arrive on islands as far as the Kermadecs (900 km NW), and then depart in spring. Birds in their second and third years that have not held a territory may also disperse during autumn. It also disperses widely in Fiji and Tonga and outlying islands, and the local name for it on Rotuma indicates periodic visits there. Breeding adults are generally sedentary.