Hen Harrier - Circus cyaneus

Hen Harrier

Circus cyaneus

Order : Accipitriformes

Family : Accipitridae ;

Biometrics :

Size : 44 à 52 cm
Wingspan : 105 à 125 cm
Weight : Femelle : 400 à 700 g ; Mâle : 300 à 400 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 : Polevoy Lun (ru), Blå kärrhök (sv), Aguilucho pálido (es), Albanella reale (it), Kornweihe (al), Blauwe Kiekendief (nl), Hen Harrier (en)

Physical description :
Hen Harrier male and female are quite different. Male is entirely slate grey above, except bright white rump conspicuous in flight. Head, underwings and tail are grey. Throat and breast are grey with slight bluish tinge according to the light. The rest of underparts are pure white. Unfeathered tarsi are yellow. Claws are black. Bill is yellow with black tip. It has yellow-orange eyes. In flight, black flight feathers are conspicuous, as the dark border of the rear side of wings. When we can see it in front, it has a kind of facial circle of slightly undulated short feathers drawing its face. Undertail coverts are whitish, barred with grey.
Female has dark brown head and nape, with pale edges, almost as streaks. Back and upperwing feathers are slightly golden on middle coverts and pure brown on secondaries. Rump is pure white and conspicuous in flight. Greyish tail has brown or reddish-brown stripes, the last larger with terminal whitish edge, easy to see when she fans is tail. Facial circle extends until throat in a dark line. Underparts are pale brown, with blackish or black waves. Eyes are brow-yellow, legs are yellow, and bill is yellow and black.
Juvenile resembles female, but is has underparts feathers with paler and conspicuous edges, mainly on head and nape, and more reddish general colour, mainly below. Eyes are brown, bill is greenish and legs are yellow.

Voice :
Sound from CD 'Tous les Oiseaux d'Europe' by Jean C. Roché by courtesy of Sittelle and CEBA. Hen Harrier is silent during migration and outside breeding season. It becomes noisier when in its nesting territory. When an intruder approaches, it is excited and it calls, with a high-pitched and repeated 'kiki-ki'. When incubation begins, female utters a very high and repeated 'quiia-quiia', while flying above the nest. When male arrives with food, it calls to female with a soft 'tchek-tchek', which can become an alarm call for the male if an intruder approaches to the nest. While it repeats several times 'kek-kekkek', it calls to female to leave the nest, and both adults fly above the nest site calling.

Habitat : Hen Harrier lives in semi-mountainous lands with scrubby vegetation, on foothills with meadows, avoiding forests, preferring north and northeast slopes, but nesting on those turned towards south and southwest. It also frequents wet areas and marshes when in migration.
GEOGRAPHIC RANGE: Hen Harrier breeds in Europe, in Scandinavia, Great Britain, southwest of Ireland, northern Portugal, northwest and north Spain, and throughout Europe (except extreme south) to east, in Russia and Siberia.

Behaviour : To hunt, Hen Harrier flies very low, continuously looking towards the ground, dissecting all places, following the unevenness of the ground, disappearing briefly to appear again, as coming from anywhere. It regularly alights on the ground, but more often on a scrub or prominent place. It is one of the birds of prey the most active, often flying, about 40% of the day, and travelling about 160 kilometres by day.
During nesting period, it is very aggressive against other Harriers, attacking them without hesitation. If an intruder approaches to the nest, adults harass it in flight while cheeping. Young chicks attacked in the nest with threatening manner are able to defend themselves, kicking out their claws forwards, opening their bills, and producing a large blow which discourages numerous predators.
When weather is wet, it remains perched most of the day. If weather is sunny, its activity begins at dawn. It may fly above the ground, suspending its flight with raised wings in V, and falling down on prey with forward claws. If it misses its goal, it hops on the ground always with raised wings, with great agility. Sometimes, it soars again, turning while gliding, and attacks again.
Each pair occupies a territory in two parts. A large hunting area (more of 25 square km) for the male, and the nesting area (1 square km) is occupied by female. During incubation, male brings food to female. When it approaches to the nest, it calls with characteristic manner to meet female. When they approach to each other, male is slightly above female, she still approaches, turns towards it, and call it with soft voice. It is a signal and the male leaves its prey which female seizes immediately in flight. Sometimes, she takes it from the male's claws just before to drop it. Failure is rare. When female leaves the nest for a few moment, male immediately appears and stands close to the nest until she comes back.
This species is known as bigamous, and sometimes polygynous, that means the lost of broods, male can't assume to feed several females and clutches.

Flight : When it is hunting at low flight, (between 1, 50 and 2 metres, sometimes between 20 and 30 metres) Hen Harrier performs slow wing beats 4 or 5 times, then it glides with half-raised wings, and dives bomb on its terrestrial prey.
It performs wonderful acrobatic flights during courtship display. It soars vertically, turning with a looping at the top of its trajectory, ending in fall with closed wings. Female remains perched, almost indifferent, while male performs several dives from 20 to 25 metres of high, sometimes until 60 metres, and arriving near the ground, soaring again performing looping in the air, and soaring each time less high. Suddenly, female begins to fly, soaring very high to join the male, and together, while cheeping, seem to play or to fight, diving towards the ground, one after the other. And when she begins another ascent, she turns and presents its claws to the male without touch it.
When we see Hen Harrier in front while flying, its wings are in open V, but when gliding, it tends to have very flat wings and even sometimes, slightly curved. It performs rapid wing beats, and short glides. Female is heavier than male and less graceful in flight.

Reproduction-nesting : Hen Harrier occupies the same territory year after year. In early March, female occupies and surveys its small nesting territory. She builds the nest, almost always on the ground, on flat brooms. She uses dried grasses or small dry broom twigs. Nest is very minimal and small (45 to 50 cm of diameter, and 7 to 10 cm of thickness). In late April, female lays 4 to 6 pale blue-white eggs, two days apart. Incubation begins with the second or third egg laid, by female. It lasts about 29 to 30 days, and 3 to 4 days more until all eggs have hatched.
Chicks are covered with bright white down; they have closed eyes, circled with brown, giving them an owl appearance. Female broods them for 8 to 10 days. She feeds them with prey brought by male and yet skinned. At about 20 days of age, feathers are growing. Chicks grow rapidly and leave the nest, hiding them in scrubs, at about 3 to 4 metres from the nest, but they are fed at nest, and brooded by female when it is raining. They perform their first flights at about 31 to 35 days with both parents. They are similar flights to flight displays, and juveniles seem very clumsy. They rapidly learn to seize preys while flying, but they are not completely independent. They remain together and leave territory in September.

Food habits : Hen Harrier feeds on small mammals (mice and until small rabbit), birds (small and medium size) eggs, frogs, grass snakes and lizards, and numerous insects such as grasshoppers.

Protection / threats : Decline of this species is due to habitat loss and destruction of nesting areas, direct persecution and destruction of the nests.

Other links :
Iucn
Birdlife

Specification sheet created by Nicole Bouglouan

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