Western Marsh HarrierCircus aeruginosusWhere and when to see them

The Western Marsh Harrier is a large, long-winged bird of prey closely associated with reedbeds and other wetlands. It occurs across much of Europe and parts of Asia, with resident and wintering populations extending into Africa. Along the Seine, suitable marshes and estuarine wetlands provide breeding, feeding and passage habitat. In the Nile region, it is particularly associated with wetlands during migration and winter. Although globally classified as Least Concern, it remains vulnerable to wetland drainage, disturbance and persecution.

Size

43–54 cm long, with a wingspan of 115–130 cm.

Weight

Approximately 400–800 g; females are generally heavier than males.

Lifespan

Can live around 15–20 years in the wild, although many birds die younger.

Status

Least Concern (IUCN).

Western Marsh Harriers hunt by quartering slowly over reeds, marshes and nearby fields. They alternate shallow wingbeats with glides, often holding their wings in a shallow V. When prey is detected, they drop into the vegetation or onto the water's edge to seize it. During the breeding season, males perform conspicuous aerial displays involving climbs, dives and turns. A male may pass food to a female in flight during courtship and nesting. The nest is usually built among dense reeds or other tall wetland vegetation, close to the ground or above shallow water. Outside the breeding season, birds may gather at communal roosts in reedbeds. Northern and eastern populations are largely migratory, while some populations in milder regions remain closer to their breeding grounds.

• Females are larger and heavier than males.
• Pairs can exchange food in mid-air.
• Some birds share communal reedbed roosts outside the breeding season.
• Unlike many raptors, it usually nests in dense wetland vegetation rather than in trees.

Wildlife opportunities depend on the river reach, water levels and species. River-specific viewing months have not been confirmed; general species seasons are not a local sighting forecast.

This harrier favours extensive wetlands with reedbeds, shallow water and open hunting areas. It uses freshwater marshes, lake margins, river floodplains, coastal lagoons and estuaries. Along the Seine, suitable habitat includes the lower river's marshes and estuarine reedbeds. In the Nile region, it uses delta wetlands, lakes, marshes and some irrigated agricultural landscapes. It also hunts over grassland and cropland, so birds may be seen away from open water.

Its diet includes small mammals, birds and their young, amphibians and other available prey. It also takes fish, reptiles, large insects and carrion opportunistically. The balance of prey varies with location, season and local abundance. Most food is captured on or near the ground, in low vegetation or at wetland margins.

Common name

Western Marsh Harrier

Scientific name

Circus aeruginosus

Animal group

Birds

Size

43–54 cm long, with a wingspan of 115–130 cm.

Weight

Approximately 400–800 g; females are generally heavier than males.

Lifespan

Can live around 15–20 years in the wild, although many birds die younger.

Status

Least Concern (IUCN).

Identification

Look for a large, long-tailed harrier with broad wings held in a shallow V during low, searching flight. Adult males typically combine a brown body with grey areas on the wings and tail, contrasting with black wingtips. Adult females are mostly dark brown, often with a creamy crown, throat and pale shoulder patches. Juveniles are usually darker and more uniformly brown, with a buff or golden crown and throat; plumage varies with age and sex.