Western Marsh Harrier (Circus aeruginosus)

Western Marsh Harrier

[order] ACCIPITRIFORMES | [family] Accipitridae | [latin] Circus aeruginosus | [authority] Linnaeus, 1758 | [UK] Western Marsh Harrier | [FR] Busard des roseaux | [DE] Rohrweihe | [ES] Aguilucho Lagunero Occidental | [NL] Bruine Kiekendief


Monotypic species


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.

Physical charateristics

Plumage variable. Male generally brown above particularly on back, underparts streaked, but solid dark brown at least on belly and vent. plumage becomes progressively paler with age.
Female averages larger, usually brown with yellowish cream crown, throat and forewing.
All dark or melanistic morph in some adults. Race harterti has much paler underparts than nominate.

Listen to the sound of Western Marsh Harrier

[audio:http://www.planetofbirds.com/MASTER/ACCIPITRIFORMES/Accipitridae/sounds/Western Marsh Harrier.mp3]

Copyright remark: Most sounds derived from xeno-canto

wingspan min.: 115 cm wingspan max.: 140 cm
size min.: 43 cm size max.: 55 cm
incubation min.: 31 days incubation max.: 38 days
fledging min.: 30 days fledging max.: 38 days
broods: 1   eggs min.: 3  
      eggs max.: 8  


Eurasia : West, Westcentral


This species is a bird of swamps, marshes, flood plains or rice fields and reed beds. On migration it is much less likely to be seen in dry open grassland than other harriers and principally follows river valleys or coasts, though it must cross dry areas sometimes. ln its winter quarters it is often very common, e.g. in rice fields in South India.


During courtship the male carries out spectacular aerobatics over the nest and surrounding area. He soars in high circles, sometimes flying with exaggerated wing beats, and occasionally calling. Sometimes the pair display together, when he dives down at her and she rolls over to present her talons.
The nest is well hidden in the dense reed bed or other thick vegetation in shallow water. The female takes about 10 days to build the pile of sticks, reeds and grass that serves as a nest. Meanwhile, the male makes a platform for resting and feeding. Both parents add material to the main nest during fledging.
The female incubates for 31-38 days per egg, usually starting with the first. The male provides for the female near the nest.
For the first week or so the chicks are brooded by the female, who feeds them beak-to-beak, but later they feed themselves in the nest, often with some ferocity, especially if the female is not very attentive. During lean times the bigger chicks may kill and eat their smaller siblings. The male brings food in the typical harrier way, dropping it for the female to catch in the air. As the young develop, the female helps with the hunting. She can rear the brood on her own if her mate is killed or deserts her. After a month or so the chicks scatter into the surrounding vegetation. They fledge at 35-40 days. The male soon leaves after that, but they usually remain with the female for a further 15-25 days.

Feeding habits

Being a good bit bigger than the Hen Harrier, the Marsh Harrier can take a wider variety of prey. During the breeding season his hunting area is reduced and it must take advantage of local abundances. At that time he concentrates on marsh birds and small mammals which are easily caught, relying on surprise rather than speed. The Harrier generally quarters flat areas at a height of only a few meters, always taking advantage of cover, sometimes hovering or performing impressive aerobatics before dropping with claws outstretched. Prey is sometimes spotted from a low perch.
Birds taken include poultry, ducks, waders, coot, moorhen, water rail, gulls, young pheasants and partridges, and songbirds and their young. Mammals include voles, mice, rabbits, moles, rats and young hares. Frogs are also important.

Video Western Marsh Harrier


copyright: youtube


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 increasing, 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 is very large, and hence does not 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.
This harrier inhabits open swamps in northern Africa and Eurasia, between 30 degrees N and 62 degrees N. The birds of the south and south-west are largely sedentary, but those from the north and the north-east are mainly wintering in sub-Saharan Africa. About 10000 breeding pairs inhabit the European Union. Some populations have definitely increased in western Europe, but those of the southern part of the continent are steadily decreasing, e.g. in the Iberian Peninsula
Western Marsh Harrier status Least Concern


Mainly migratory in Northern & Eastern Europe and Central Asia; sedentary and dispersive in South of breeding range. Northern breeders winter from France and North Africa through Mediterranean to Turkey, Middle East and Nile Valley, and South to sub-Saharan Africa. Easternmost Asian populations winter in Indian Subcontinent and Sri Lanka.
Migration in Western Europe begins with young birds of the year in mid-August, followed by adults in September and October. Males migrate later than females and young, and arrive in wintering grounds later.
The rate and extent of migration varies according to the place of origin, northern birds leaving earlier, moving faster and travelling further than do birds from Southern Europe, which may remain most of the winter quite close to their breeding areas. The southern migration from Europe follows well-marked routes through Gibraltar or the Bosphorus, and rarely crosses large bodies of water; they may reach high altitudes up to 9,000 feet when crossing mountain passes on migration, but usually favour low ground.
Northward migration begins again in February and March, and both at this time and in autumn they are more gregarious than usual, roosting communally in swamps like some other harriers, with up to 300 together in some races. The northward migration frequently crosses the Mediterranean, so that evidently they can cross large bodies of water if necessary. Returning birds arrive in their breeding haunts from late March onwards, as late as early May in the northern parts of the range. They generally migrate singly or in small parties, not in large flocks, but often roost gregariously even when hunting singly. In winter quarters the same individuals may frequent the same area for weeks at a time.

Distribution map

Western Marsh Harrier distribution range map


Title Main migratory direction of Marsh Harrier
Circus aeruginosus: an analysis of recovery data of
specimens ringed in Latvia from 1925 to 2004
Author(s): Janis Reihmanis
Abstract: Th is paper describes the main migratory direction..[more]..
Source: Acta Universitatis Latviensis, 2005, Vol. 691, Biology, pp. 51-57

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Title Nest-site selection by Marsh Harrier (Circus aeruginosus) in the shore belt of Helophytes on large lakes
Author(s): Vitas Stanevicius
Abstract: Nest-site selection by Marsh Harrier (Circus aerug..[more]..
Source: Acta Zoologica Lituanica, 2004, Volumen 14, Numerus 3

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Title Factors influencing nest material selection in Marsh Harrier (Circus aeruginosus)
Author(s): Vitas Stanevicius, Ausrys Balevicius
Abstract: Marsh Harrier used at least 30 plant species from ..[more]..
Source: Acta Zoologica Lituanica, 2005, Volumen 15, Numerus 1

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Title The effect of predation by Marsh Harriers Circus aeruginosus on the survival of ducklings and game bird chicks.
Author(s): Underhill-Day J.C.
Abstract: The level of predation by a pair of Marsh Harriers..[more]..
Source: ARDEA 77 (1): 47-56.

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Title New material supplies in the Marsh Harrier Circus aeruginosus sexual roles daily and seasonal activity patterns and rainfall influence
Author(s): Fernandez C.
Abstract: Nest maintenance is an important part of parental ..[more]..
Source: ARDEA 80 (2): 281-284

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Title Reproduction of the Marsh Harrier Circus aeruginosus in recent land reclamations in The Netherlands.
Author(s): Dijkstra C. & Zijlstra M.
Abstract: We studied temporal variation in reproductive perf..[more]..
Source: ARDEA 85 (1): 37-50.

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Title Changes in the frequency of prospecting fly-overs by Marsh Harriers Circus aeruginosus in relation to short-term fluctuations in dabbling duck abundance
Author(s): Fritz H., Guillemain M. & Guerin S.
Abstract: Wintering waterfowl gathering in large flocks duri..[more]..
Source: ARDEA 88 (1): 9-16.

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Title Predation by a Marsh Harrier Circus
aeruginosus on Yellow-legged Gull
Larus michahellis nests
Author(s): Albert Bertolero
Abstract: This note reports a case of predation by an adult ..[more]..
Source: Revista Catalana d?Ornitologia 19:38-40, 2002

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