Hen harrier

Circus cyaneus

The hen harrier or northern harrier is a bird of prey. It breeds throughout the northern parts of the northern hemisphere in Canada and the northernmost USA, and in northern Eurasia. This species is polytypic, with two subspecies. Marsh hawk is a historical name for the American form.
Hen harrier male - Circus cyaneus Accipitridae,Accipitriformes,Animalia,Austria,Aves,Bird,Bird of prey,Burgenland,Chordata,Circus cyaneus,Europe,Fall,Geotagged,Hen harrier,Wildlife

Appearance

The hen harrier is 41–52 cm long with a 97–122 cm wingspan. It resembles other harriers in having distinct male and female plumages. The sexes also differ in weight, with males weighing 290 to 400 g, with an average of 350 g, and females weighing 390 to 750 g, with an average of 530 g. Among standard measurements, the wing chord is 32.8 to 40.6 cm, the tail is 19.3 to 25.8 cm and the tarsus is 7.1 to 8.9 cm. It is relatively long winged and long tailed, having the longest wing and tail relative to its body size of any raptor occurring in North America.

The male of the nominate race, "C. c. cyaneus", which breeds in Europe and Asia, is mainly grey above and white below except for the upper breast, which is grey like the upperparts, and the rump, which is white; the wings are grey with black wingtips. The female is brown above with white upper tail coverts, hence females, and the similar juveniles, are often called "ringtails". Their underparts are buff streaked with brown.

The race "C. c. hudsonius" breeds in North America and is sometimes considered a distinct species, "C. hudsonius". The male's plumage is darker grey than that of "C. c. cyaneus" and the female is also darker and more rufous. In both North American and Eurasia, the adult male is sometimes nicknamed the "Grey Ghost", because of his striking plumage and spectral aura.

The female gives a whistled "piih-eh" when receiving food from the male, and her alarm call is "chit-it-it-it-it-et-it". The male calls "chek-chek-chek", with a more bouncing "chuk-uk-uk-uk" during his display flight.
Ringtail - Isle of Jura Hunting over the moorland on the wonderful Isle of Jura. Unfortunately the male that we saw was a lot further away. Circus cyaneus,Hen harrier,Isle of Jura,Scotland

Status

This species has a large range, with an estimated global extent 1–20 million km², and a population estimated at 1.3 million individuals. There is evidence of a population decline, but the species is not believed to approach the thresholds for the population decline criterion of the IUCN Red List. It is therefore classified as "least concern".
Hen Harrier (Circus cyaneus) I only took this photo as an instinctive reaction when a single bird among a flock of gulls struck me as being a little darker than expected. It was a full 24hrs before I casually downloaded the days photos and realised it as a Hen Harrier, one of the UK's rarest birds of prey. Driven to extinction in mainland Britain in the 19th century, since recolonising England in the 1960s they have remained rare due to illegal persecution and disturbance, particularly on grouse moors where some gamekeepers view them as a threat to their grouse stocks. This species is strictly protected under Schedule 1 of the Wildlife and Countryside Act 1981 and The Nature Conservation (Scotland) Act 2004 and are included on the Red List of UK birds of conservation concern. However, since killings tend to occur away from public view, prosecutions for their slaughter are few. However, even though as recently as 2013 there were no breeding pairs in the UK, 54 nests were recorded in 2023 with 141 chicks successfully fledged, so progress is hopefully being made. The winter population is sometimes boosted by immigrants from northern & central Europe, the total population reaching no more than 750 birds in the best years, which puts into perspective how fortunate this sighting was. The Hen harrier male is distinctive, being silver-grey on top and white underneath, with a white rump and black wingtips. Females like this individual are dark brown with lighter markings on the wing and have a long grey-brown tail with dark bands from which the description 'ringtail' derives. They too have a white rump. Hen harriers live in open areas with low vegetation, feeding on small birds and mammals such as Meadow Pipits and voles, but are known to tackle species up to the size of hares and gamebirds. The summer breeding season is spent in upland areas such as heather moorlands and young conifer plantations. In winter they move to lowland marshes, fenland, farmland and coastal regions. Hen harriers arrive back on their breeding grounds in March or April and the males soon begin to indulge in spectacularly aerobatic display in order to attract a female and for this reason they sometimes go by the description 'Skydancers', Long may they continue to do so. Circus cyaneus,Geotagged,Hen harrier,United Kingdom,Winter

Behavior

This medium-sized raptor breeds on moorland, bogs, prairies, farmland coastal prairies, marshes, grasslands, swamps and other assorted open areas. The nest is built on the ground or on a mound of dirt or vegetation. Nests are made of sticks and are lined inside with grass and leaves. Four to eight whitish eggs are laid. The eggs measure approximately 47 mm × 36 mm. These are the only hawk-like bird known to practice polygyny – one male mates with several females. When incubating eggs, the female sits on the nest while the male hunts and brings food to her and the chicks. Up to five females have been known to mate with one male in a season. A male will maintain a territory averaging 2.6 km2, though male territories have ranged from 1.7 to 150 km2. The eggs are incubated mostly by the female for 31 to 32 days. The male will help feed chicks after they hatch, but doesn't usually watch them for a greater period of time than around 5 minutes. The male usually passes off food to the female, which she then feeds to the young, although later the female will capture food and simply drop into the nest for her nestlings to eat. The chicks fledge at around 36 days old, though breeding maturity isn't reached until 2 years in females and 3 years in males.

In winter, the hen harrier is a bird of open country, and will then roost communally, often with merlins and marsh harriers. There is now an accepted record of transatlantic vagrancy by the American subspecies, with a juvenile being recorded in Scilly, Great Britain from October 1982 to June 1983.This is a typical harrier, which hunts long wings held in a shallow V in its low flight during which the bird closely hugs the contours of the land below them. Northern or hen harriers hunt primarily small mammals, as do most harriers. Preferred prey species can include voles, cotton rats and ground squirrels. Up to 95% of the diet is comprised by small mammals. However birds are hunted with some regularity as well, especially by males. Preferred avian prey include passerines of open country, small shorebirds and the young of waterfowl and galliforms. Supplementing the diet occasionally are amphibians, reptiles and insects. Larger prey, such as rabbits and adult ducks are taken sometimes and harriers have been known to subdue these by drowning them underwater. Harriers hunt by surprising prey while flying low to the ground in open areas, as they drift low over fields and moors. The Harriers circle an area several times listening and looking for prey. Harriers use hearing regularly to find prey, as they have exceptionally good hearing for diurnal raptors, this being the function of their owl-like facial disc. This harrier tends to be a very vocal bird while it glides over its hunting ground.
Hen Harrier female flying up, taken with ProCapture Circus cyaneus,Georgia,Geotagged,Hen harrier,Winter

Food

This is a typical harrier, which hunts long wings held in a shallow V in its low flight during which the bird closely hugs the contours of the land below them. Northern or hen harriers hunt primarily small mammals, as do most harriers. Preferred prey species can include voles, cotton rats and ground squirrels. Up to 95% of the diet is comprised by small mammals. However birds are hunted with some regularity as well, especially by males. Preferred avian prey include passerines of open country, small shorebirds and the young of waterfowl and galliforms. Supplementing the diet occasionally are amphibians, reptiles and insects. Larger prey, such as rabbits and adult ducks are taken sometimes and harriers have been known to subdue these by drowning them underwater. Harriers hunt by surprising prey while flying low to the ground in open areas, as they drift low over fields and moors. The Harriers circle an area several times listening and looking for prey. Harriers use hearing regularly to find prey, as they have exceptionally good hearing for diurnal raptors, this being the function of their owl-like facial disc. This harrier tends to be a very vocal bird while it glides over its hunting ground.
Northern Harrier Circus cyaneus,Geotagged,Hen harrier,United States,Winter

Predators

Little information is available on longevity in Hen or Northern Harriers. The longest lived known bird is 16 years and 5 months. However, adults rarely live more than 8 years. Early mortality mainly results from predation. Predators of eggs and nestlings include raccoons, skunks, badgers, foxes, crows and ravens, dogs and owls. Fledgings are also predated regularly, especially by great horned owls in North America. Both parents attack potential predators with alarm calls and striking with talons. Short-eared owls are natural enemies of this species that favor the same prey and habitat, as well as having a similarly broad distribution. Occasionally, both harriers and Short-eared Owls will harass each other until the victim drops its prey and it can be stolen, a practice known as kleptoparasitism. Most commonly, the harriers are the aggressors pirating prey from owls.

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