Western Marsh-Harrier - Circus aeruginosus

Western Marsh-Harrier

Circus aeruginosus

Order : Accipitriformes

Family : Accipitridae ;

Biometrics :

Size : 48 à 56 cm
Wingspan : 120 à 135 cm
Weight : Femelle : 500 à 800 g ; Mâle : 400 à 650 g

Longevity : 17 years

IUCN conservation status :

Extinct

Threatened

Least
concern

Extinc
in the Wild

Near
threatened

Not
evaluated

EX EW CR EN VU NT LC NE

Geographic range :

Synonyms : Bolotny Lun (ru), Brun kärrhök (sv), Aguilucho lagunero (es), Falco di palude (it), Rohrweihe (al), Bruine Kiekendief (nl), Western Marsh-Harrier (en)

Physical description :
The Western-Marsh-Harrier is the largest of the four species living in Europe. It has fine silhouette with long bent wings. Its plumage is dark brown, as the mantel. Male has ash-grey tail and wings. Its rump is darker than in the other harriers, and it is more robust.
The adult male has brown back and dark reddish-brown head and nape, both streaked of dark brown. Throat is dark, chest is reddish and underparts are chestnut, heavily streaked with brown. Tail is silver-grey. On the wings, the most part of the secondaries is bluish grey, and when the wing is spread, this area forms a vast oblique wing bar which crosses the wing, contrasting with the extreme black of the primaries and the brown plumage. Legs are yellow and tarsi are unfeathered, and it has reddish-brown feathered thighs.
Adult female is more uniform in colour than male; she has creamy head and throat, and fewer streaks than male. Wings and tail are brown. Underparts are dark brown. Female is slightly larger than male.
Immature is very dark brown with colour variations on head, nape and back where we can see various creamy areas. After the first moult, the two sexes are similar to the adult female.
The Western-Marsh-Harrier reaches its sexual maturity at three years.

Voice :
Sound from CD 'Tous les Oiseaux d'Europe' by Jean C. Roché by courtesy of Sittelle and CEBA. The Western-Marsh-Harrier is very quiet outside breeding season. During courtship displays, male insistently utters a sad and loud 'kiiuu' in flight. Female calls 'iiuu' in response. The male's alarm call is a repeated 'chakara-chakara', that of female is a high-pitched 'chiuk-chiuk'. When an intruder approaches the nest site, a weak 'ki-ki-ki' is uttered. The cry is a mono or dissyllabic 'psii', and a brief, dry or shrill 'kit-kit' or 'kiyet' for alarm and high flights.

Habitat : Fairly common although localized, the Western-Marsh-Harrier nests in marsh reedbeds, sometimes in meadows, fallow lands, marshes or lake edges and streams, less often in peat bogs.
The Western-Marsh-Harrier is a typical marsh raptor. In migration, it frequents coasts and open country, but never so far from water. It animates lakes and ponds. At other times, it also frequents grassy areas, cultivated lowlands and salt-water marshes.
GEOGRAPHIC RANGE: the Western-Marsh-Harrier breeds from Southern Scandinavia, Great Britain and France, Spain and Morocco, and through the most part of Europe and southern Russia.

Behaviour : The Western-Marsh-Harrier is an extremely lazy and apathetic raptor, which does not hunt too much. It chooses easy preys like young shore birds, or injured or sick birds. While flying for hunting, when it selects a prey, it retains itself in the air and turns, throwing several times into the water to catch a frog or a coot.
The Western-Marsh-Harrier invariably carries its preys in its left leg's talons, but despite its size, a lot of preys escape from its claws, or by forming an enormous gathering which attracts other aquatic birds and which end up obliging the raptor to flee by leaving its prey.
The Western-Marsh-Harrier is gregarious, roosting in groups of up to 5 or 25 individuals where sedges are abundant.
Flight displays include fast dives and ascensions, ending in a descent almost until the ground, with closed wings and calling strongly.
There is a distance minimum to be respected between two nests. Any attempt by another pair for building a nest within 60 meters, causes a reaction of immediate aggressiveness. If an intruder approaches too close from the nest, within about 50/60 meters, its presence causes a silent removal of the Harriers. They call and fly above the intruder.
Male feeds female during the incubation and the young after hatching. Female goes to meet the male which carries a prey. Female pursues it during a few moments, then it lands on the ground where it leaves the prey to female, but it also may releases the prey in flight while the female easily catches it.

Flight : When we see the Western-Marsh-Harrier flying in profile, we can see that its wings are forming an open V. It flies with 4 to 5 wing beats, and then it soars at very low altitude, above the aquatic marsh and shore vegetation. But more often, it flies between 3 to 5 metres higher, alternating short beats with very raised wings, and then, much more flexibly. It flies at about 50 km per hour, being the fastest harrier despite of its larger size.

Reproduction-nesting : Egg-laying takes place during the first days of April, in a nest built mainly by the male. Two or three weeks before the laying, male brings nest materials and female arranges and woven them on the reeds. When moment of laying approaches, female remains almost permanently near the nest. During this period, it is fed by male which brings one or two preys per day, and according to the days, three to four.
Female lays 3 to 8 eggs, at intervals of two or three days, up to five days. Eggs are bluish white, dull and often speckled with dark points.
Incubation lasts about 33 to 38 days, at least 36 days for each egg. A great difference in size separates chicks between oldest and youngest, but there is not any aggressiveness between them, and they can be successfully raised.
The tubes of the feathers start to grow on the wings at 7 days. At 21 days, they have already many feathers and the whole plumage at 28 days. They start to fly between 35 and 40 days.
Like all young harriers, young are very aggressive when intruder is approaching, defending themselves with the claws ahead, moving wings and opening their bills in a threatening way. The female is very requested by chicks and rarely abandons the nest, generally in the evening if male is too late in bringing preys and does not answer its calls.
Young follow the parents when they are 55/60 days old, but they feed preys brought by adults, flying out of the reeds when parents approach and call them.

Food habits : The Western-Marsh-Harrier feeds primarily on frogs, but also on small mammals of the size of a young rabbit, snakes, lizards and insects. It is an important predator of water birds' eggs and chicks.

Protection / threats : The populations of Western-Marsh-Harrier are threatened by habitat loss, with draining of the wet areas and reedbeds

Other links :
Iucn
Birdlife

Specification sheet created by Nicole Bouglouan

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