Western Marsh Harrier - Distribution and Ecology

Distribution and Ecology

This species has a wide breeding range from Europe and northwestern Africa to Central Asia and the northern parts of the Middle East. It breeds in almost every country of Europe but is absent from mountainous regions and subarctic Scandinavia. It is rare but increasing in Great Britain where it has spread as far as eastern Scotland. In the Middle East there are populations in Turkey, Iraq and Iran, while in Central Asia the range extends eastwards as far as north-west China, Mongolia and the Lake Baikal region of Siberia.

Most populations of the Western Marsh-harrier are migratory or dispersive. Some birds winter in milder regions of southern and western Europe, while others migrate to the Sahel, Nile basin and Great Lakes region in Africa, or to Arabia, the Indian subcontinent and Myanmar. The all-year resident subspecies harterti inhabits Morocco, Algeria and Tunisia.

Vagrants have reached Iceland, the Azores, Malaysia and Sumatra. The first documented (but unconfirmed) record for the Americas was one bird reportedly photographed on December 4, 1994 at Chincoteague National Wildlife Refuge in Accomack County, Virginia (USA). Subsequently, there were confirmed records from Guadeloupe (winter of 2002/2003) and from Laguna Cartagena National Wildlife Refuge on Puerto Rico (early 2004 and January/February 2006).

Like the other marsh-harriers, it is strongly associated with wetland areas, especially those rich in Common Reed (Phragmites australis). It can also be met with in a variety of other open habitats, such as farmland and grassland, particularly where these border marshland. It is a territorial bird in the breeding season, and even in winter it seems less social than other harriers, which often gather in large flocks. But this is probably simply due to habitat preferences, as the marsh-harriers are completely allopatric while several of C. aeruginosus grassland and steppe relatives winter in the same regions and assemble at food sources such as locust outbreaks. Still, in Keoladeo National Park of Rajasthan (India) around 100 Eurasian Marsh Harriers are observed to roost together each November/December; they assemble in tall grassland dominated by Desmostachya bipinnata and Vetiver (Chrysopogon zizanioides), but where this is too disturbed by human activity they will use floating carpets of Common Water Hyacinth (Eichhornia crassipes) instead – the choice of such roost sites may be to give early warning of predators, which will conspicuously rustle through the plants if they try to sneak upon the resting birds.

It hunts in typical harrier fashion, gliding low over flat open ground on its search for prey, with its wings held in a shallow V-shape and often with dangling legs.