Hen Harrier

Overview

The hen harrier (Circus cyaneus) is a medium-sized bird of prey that breeds in open areas such as marshes and grasslands across Eurasia. It is a migratory species, though birds in milder regions like Great Britain may remain resident year-round, while higher altitudes are largely deserted in winter.

Identification

• Males are smaller, predominantly grey and white with black wingtips, while females and juveniles are larger, brown above with buff, barred underparts.
• Both sexes feature a white rump patch, which is more noticeable on females and juveniles, often referred to as 'ringtails'.
• The male produces a 'chek-chek-chek' call and a bouncy 'chuk-uk-uk-uk' during display flight, while the female emits a whistled 'piih-eh' when receiving food and an alarm call of 'chit-it-it-it-it-et-it'.

Habitat

This species inhabits open habitats including moorland, bogs, farmland, marshes, grasslands, and swamps across Eurasia. In winter, it frequents open country and may roost communally with other harriers. In Britain and Ireland, the population is critically low and concentrated mainly in Scotland, despite suitable habitat existing elsewhere.

Diet

Hen harriers primarily consume small mammals, which make up up to 95% of their diet, but also regularly hunt birds such as sparrows, larks, and young waterfowl. They forage by flying low over open fields and moors in a shallow V-shape, using their exceptional hearing and owl-like facial disc to locate prey. They occasionally supplement their diet with amphibians, reptiles, insects, and even bats, and can subdue larger prey like rabbits by drowning them.

Did you know?

Hen harriers are one of the few raptors known to practice polygyny, where a single male may mate with up to five females in a season. Their mating success is directly influenced by food availability, as males with more resources support more breeding partners.