Western marsh harrier

Latin Circus aeruginosus (L.)
Estonian Roo-loorkull

Also known as: Eurasian marsh harrier

Status in Estonia

Breeding and migratory bird.

Description

The Western marsh harrier is slightly larger than the common buzzard but has a more slender body, narrower wings and a longer tail. From a distance, it resembles the dark appearance of the black kite and the booted eagle, but the wing tips have shorter ‘fingers’, the back edge of the tail is more rounded and the flight pattern is different. The male bird has visible black wing tips, a bluish-grey tail, a yellowish-white head and breast and a three or four colours on the top side of the wing. Some are quite bright, with a reddish-brown belly and a brownish tinge to the top wing coverts. The female bird is dark brown with a greyish-white nape, neck and front edge of the wings as well as a light breast patch. The juvenile is blackish-brown with a yellowish-brown nape and throat and occasionally the front edge of the wings are yellowish-brown as well.

Size

Body length 43–55 cm, wingspan 115–140 cm. The female bird weighs 420–540 g and the male bird 615–840 g.

Similar species

Montagu’s harrier, hen harrier, common buzzard, black kite.

Distribution

The Western marsh harrier is widespread in Eurasia’s temperate zone, northern and southern parts of Africa, Australia and the islands of Oceania. It spends the winter south of Central Africa and in South Asia.

Population

Estonia has 1000–1300 breeding pairs.

Occurrence in Estonia

It arrives in late March or early April and departs in late September to October.

Diet

Its diet consists of small rodents, Eurasian water shrews, birds that are duck-sized (mostly Eurasian coots), chicks and eggs of other birds, amphibians and dead or sick fish floating on the water’s surface. It is a skilled nest predator.

Habitat

It prefers large reed beds with boggy meadows surrounding them but can also be found in bogs and raised bogs. It can also be seen in coastal areas during migration.

Nesting

The nest is built in the middle of a reed bed in shallow water or on nearby dry land. Nests are usually made of reeds, although the nests on dry land also include branches of broad-leaf trees, hay and woody plant stems. The nest has a diameter of roughly one metre and is lined with reed leaves and dry grass. In mid-April, the female lays 3–6 eggs, which she incubates alone for 31–38 days. The chicks hatch in mid-June and hide immediately in the reeds, where they will remain until they are able to fly in the second half of July.

Conservation status and protection

The Western marsh harrier belongs to the protected species of category III. Its natural enemies are mustelids and bigger falcons.

Distribution and population in Lääne County

The Western marsh harrier is common everywhere in Lääne County, where there are reed beds ideal for nesting. It breeds most commonly around Matsalu Bay and in the Silma Nature Reserve.
In Matsalu National Park, the Western marsh harrier is frequently spotted from Keemu, Suitsu and Haeska observation towers. It is also good to observe the Western marsh harrier from the observation towers near the Sutlepa Sea.