The swamp harrier (''Circus approximans''), also known as the Australasian marsh harrier or Australasian harrier, is a large, slim

bird of prey Birds of prey or predatory birds, also known as (although not the same as) raptors, are hypercarnivorous bird species that actively predation, hunt and feed on other vertebrates (mainly mammals, reptiles and smaller birds). In addition to speed ...

widely distributed across

Australasia Australasia is a subregion of Oceania, comprising Australia, New Zealand (overlapping with Polynesia), and sometimes including New Guinea and surrounding islands (overlapping with Melanesia). The term is used in a number of different context ...

. In

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

, it is also known by the

Māori Māori or Maori can refer to: Relating to the Māori people * Māori people of New Zealand, or members of that group * Māori language, the language of the Māori people of New Zealand * Māori culture * Cook Islanders, the Māori people of the Co ...

name . It arrived in New Zealand within the last 700 years, replacing the larger species, the extinct New Zealand endemic Eyles's harrier. The swamp harrier belongs to the subfamily Circinae and genus ''Circus'', which are represented worldwide, except Antarctica. The subfamily and genus are derived from the characteristic behaviour of circling flight during courtship and hawking.

Description

The swamp harrier 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 , and the wingspan is . The recorded weights of adults range from . Females are significantly larger than the males. In New Zealand, 54 males averaged and 66 females averaged . Going on mean weights and linear measurements, the swamp harrier may be by a slight margin the largest extant species of harrier but it is only marginally larger than some other species, like the marsh harriers and the

Réunion harrier The Réunion harrier (''Circus maillardi''), also known as Réunion marsh harrier, is a species of bird of prey belonging to the marsh harrier group of harrier (bird), harriers. It is now found only on the Indian Ocean island of Réunion, althoug ...

. File:Circus approximans - Peter Murrel.jpg, Adult male soaring in flight File:Circus approximans -Coolart Wetlands, Mornington Peninsula, Australia -flying.jpg, Immature flying in Victoria, Australia

Distribution and habitat

The swamp harrier is widespread through Australasia and many islands in the south-west Pacific region, including much of

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

(except the arid region), New Zealand (where it is common in open country),

Fiji Fiji, officially the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean. It lies about north-northeast of New Zealand. Fiji consists of an archipelago of more than 330 islands—of which about ...

Vanuatu Vanuatu ( or ; ), officially the Republic of Vanuatu (; ), is an island country in Melanesia located in the South Pacific Ocean. The archipelago, which is of volcanic origin, is east of northern Australia, northeast of New Caledonia, east o ...

New Caledonia New Caledonia ( ; ) is a group of islands in the southwest Pacific Ocean, southwest of Vanuatu and east of Australia. Located from Metropolitan France, it forms a Overseas France#Sui generis collectivity, ''sui generis'' collectivity of t ...

and as stragglers on some subantarctic islands.A Guide to Canterbury Museum's Edgar Stead Hall of New Zealand Birds It is usually found in wetlands and well-watered open country. The swamp harrier only became established in New Zealand within the last few hundred years, after lowland forests were extensively cleared by the first Polynesian settlers. It is absent from the fossil record. According to archeological and genetic research, humans arrived in New Zealand no earlier than about 1280, with at least the main settlement period between about 1320 and 1350, consistent with evidence based on genealogical traditions. The Eyles's harrier (''Circus teauteensis''), a larger harrier species

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to New Zealand, became extinct after human settlement. All swamp harrier remains from New Zealand that have been studied in detail are some 1000 years old at most, meaning that they post-date human settlement. There is no evidence for widespread coexistence of swamp and Eyles's harriers in New Zealand. Apparently, despite their considerable differences, the two harriers were still ecologically similar enough to competitively exclude one another, and only when the endemic Eyles's harrier became extinct could the swamp harrier become established. The swamp harrier has benefited from European settlement, and is now very common, especially in open farmland.Seaton, R.; Galbraith, M.; Hyde, N. 2013
Swamp harrier
''In'' Miskelly, C.M. (ed.) ''New Zealand Birds Online''. www.nzbirdsonline.org.nz

Behaviour

Common enemies of harriers are

Australian magpie The Australian magpie (''Gymnorhina tibicen'') is a black and white passerine bird native to Australia and southern New Guinea, and introduced to New Zealand, and the Fijian island of Taveuni. Although once considered to be three separate ...

masked lapwing The masked lapwing (''Vanellus miles'') is a large, common and conspicuous bird native to Australia (particularly the northern and eastern parts of the continent), New Zealand and New Guinea. It spends most of its time on the ground searching for ...

s which dive bomb and

European starling The common starling (''Sturnus vulgaris''), also known simply as the starling in Great Britain and Ireland, and as European starling in North America, is a medium-sized passerine bird in the starling family, Sturnidae. It is about long and ha ...

s which mob individuals. They have been known to kill the young of New Zealand falcons and have also been heavily blamed and persecuted for killing chickens, pheasants and ducklings. Swamp harriers are the only bird of prey used for falconry in New Zealand. The quarry is usually pūkeko and young rabbits.

Diet

The swamp harrier mainly feeds on ground birds and

waterbird A water bird, alternatively waterbird or aquatic bird, is a bird that lives on or around water. In some definitions, the term ''water bird'' is especially applied to birds in freshwater ecosystems, although others make no distinction from seabi ...

s, rabbits and other small mammals,

reptile Reptiles, as commonly defined, are a group of tetrapods with an ectothermic metabolism and Amniotic egg, amniotic development. Living traditional reptiles comprise four Order (biology), orders: Testudines, Crocodilia, Squamata, and Rhynchocepha ...

s, frogs, and fish. During the winter months harriers feed to a large extent on carrion, including

roadkill Roadkill is a wild animal that has been killed by collision with motor vehicles. Wildlife-vehicle collisions (WVC) have increasingly been the topic of academic research to understand the causes, and how they can be mitigated. History Essenti ...

, frequently falling victim to vehicles themselves.

Breeding

This species nests on the ground, often in wetlands, on a mound in reeds or other dense vegetation. In some districts they nest in fields of oats or barley. The clutch size may range from two to seven, but is usually three or four. The incubation period is 31 to 34 days, and is carried out by the female alone. Chicks are fed by both parents, are fully feathered by 28 days and

fledging Fledging is the stage in a flying animal's life between hatching or birth and becoming capable of flight. This term is most frequently applied to birds, but is also used for bats. For altricial birds, those that spend more time in vulnerable c ...

about 45 days after hatching.

Notes

References

* BirdLife International (2006). Species factsheet: ''Circus approximans''. Downloaded from http://www.birdlife.org on 4/12/2006 * Marchant, S.; & Higgins, P. J. (eds.). ''

Handbook of Australian, New Zealand and Antarctic Birds The ''Handbook of Australian, New Zealand and Antarctic Birds'', known as ''HANZAB'', is the pre-eminent scientific reference on birds in the region, which includes Australia, New Zealand, Antarctica, and the surrounding ocean and subantarctic ...

. Vol. 2: Raptors to Lapwings''. Oxford University Press: Melbourne. .

External links

Wingspan Birds of Prey Trust
- The national centre for the conservation, education and advocacy of birds of prey in New Zealand. Location: Rotorua, NZ {{Authority control

swamp harrier The swamp harrier (''Circus approximans''), 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 . It arriv ...

Diurnal raptors of Australia Birds of prey of Oceania

Taxa named by Titian Peale