Marsh Harrier

Western Marsh Harrier – Circus aeruginosus


  • Kingdom: Animalia
  • Class: Aves
  • Order: Accipitriformes
  • Family: Accipitridae
  • Genre: Circus
  • Species: Circus aeruginosus

Identification characters

The length is 43-55 cm, being the largest erect, slightly larger than the common eared eel. The male has reddish-brown plumage, but the wings and tail are greyish. The female is brownish.


The Western Marsh Harrier has a large nesting range stretching from Europe to Central Asia. It is a migratory species throughout much of its range. It winters in southern Europe, Africa, the Arabian Peninsula and the Indian subcontinent. There are 99,300-184,000 breeding females in Europe, with an increasing population trend. The largest flocks are in Russia, Ukraine, Poland and Belarus. In Romania, the reed warbler is a widespread breeding species, very common in the Danube Delta and rarer in Transylvania. It is absent in mountainous areas. It is mainly found during the passage and nesting season. In the cold season it can be seen wintering only in Dobrogea and the southernmost parts of Romania. The population in Romania is estimated at 9,334-22,314 nesting females.

Living environment and biology of the species

Western Marsh Harrier prefer wet areas with extensive reed beds for nesting. Rarely, it nests in intensive agricultural crops such as cereal crops. Foraging territory includes wetlands and farmland. It feeds mainly on small to medium-sized aquatic or terrestrial vertebrates such as rodents, baby rabbits, ducks, lizards, etc. It also eats eggs, frogs, larger insects and even fish. It flies between 2 and 6 m above the ground, and when it identifies prey, it dives suddenly.

The pair formed can last for several seasons. The mating ritual is spectacular. The male flies in circles over the nesting territory, then dives to the ground, rolling in the air. Sometimes the female accompanies him in flight and they roll together in the air, claws together. The male can be seen offering food in the air to the female. Polygamy can occur, in which case the male may mate with 2-3 females. Can live up to 20 years.

The nesting period is from the second half of April to mid-June. The nest is built by the female in dense and extensive reed beds of branches and reeds, lined inside with grass, and can be up to 80 cm in diameter. The clutch consists of 3-8 eggs, laid in the second half of April. The eggs are incubated by both parents for 31-38 days. The chicks are nestlings. They leave the nest 35-40 days after hatching. The chicks are cared for by the female only. It is the male that hunts and feeds his family during the nesting period. After leaving the nest and being able to fly, the juveniles remain close to their parents for another 25-30 days and only then become independent.

Threats and conservation measures

Western Marsh Harrier are threatened by pollution, poor water management and poaching. Conservation measures are recommended: respect of restrictions in riparian areas, waste management in wetlands, conservation of reedbeds and reedbeds with permanent water, prohibition of harvesting or burning reeds, measures to avoid drying and sudden artificial change of water regime in wetlands. Only selective and low-toxicity agrochemicals should be used on agricultural land in the vicinity of wetlands. Hunting legislation should be respected, with the cooperation of environmental protection organisations, hunting organisations, the gendarmerie and the Environmental Guard. Inventory of current and potential breeding areas, migration, feeding and aggregation areas important for the conservation of the species and in particular promotion of studies on the biology of the species and study of demographic parameters are needed.


  • Fântână Ciprian, Kovács Istvan, Benkő Zoltán, Daròczi Szilárd, Domșa Cristian, Veres-Szászka Judit (editors), 2022, Atlas of bird species of community interest in Romania, 2nd edition – Love birds, save nature!, Project financed by the European Regional Development Fund through the Large Infrastructure Operational Programme 2014-2020, Ministry of Environment, Water and Forests – Biodiversity Directorate, scientific coordination Romanian Ornithological Society and Association for the Protection of Birds and Nature Milvus Group, produced by EXCLUS PROD SRL, p. 144.
    Svensson (text and maps), 2017, Guide to bird identification. Europe and the Mediterranean area, translation and adaptation into Romanian: Romanian Ornithological Society, Emanuel Ștefan Baltag, Sebastian Bugariu, Alida Barbu, p. 102.
    Radu Dimitrie, 1983, Small Ornithological Atlas – Birds of the World, Albatros Publishing, Bucharest, p. 135.
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