This bird of upland blanket bogs and young forestry plantations visits farmland in winter. Its ancestors may have raided chicken coups, but today’s harriers don’t. They are partial to the odd grouse chick, however, which infuriates game-keepers.
The sexes differ so much in appearance that Francis Willughby, in the late 17th Century, listed them as separate species. The brown-plumaged female is bigger than her pearly grey mate. Francesca Greenoak in British Birds, their Folklore Names and Literature, claims that the species was known as the ‘seagull hawk’ in Connemara; the pale plumaged male resembles a gull at a distance. Both sexes have conspicuous white rumps. Harriers fly close to the ground, mounting surprise attacks on unsuspecting birds and mammals. Small songbirds are their usual victims but mice voles and young rabbits are also taken. Harriers nest on the ground in young conifer plantations but these areas are abandoned once the trees are about 15 years old.
According to the Bird Atlas, there were 662 hen harrier pairs in Britain in 2010. Their numbers are declining, however. According to the Hen Harrier Life Project, the population overall fell by 20% between 2004 and 2010 and only a few isolated pairs still breed in England. The Welsh population has fared better recently but the species is strongest in Orkney, the Scottish highlands and the Inner Hebrides. However, numbers at these locations are lower than scientists think they should be. The maturing of conifer plantations and increased habitat disturbance are factors in the decline but the chief culprit is illegal persecution, particularly in grouse-shooting areas.
In an attempt to identify locations of particular risk, a new tracking project is being initiated. Harriers travel widely. Chicks in the nests are to be fitted with electronic tags to record their movements when they fledge. Transmitters send the information to scientists over a satellite link, enabling the birds’ movements to be mapped. The data will be put on line for the public to access. Disclosing a bird’s location renders it vulnerable, so there will always be a two-week delay in making sensitive information available. If a tagged bird is shot, its final location will be known immediately, so that the police can investigate. Volunteers will monitor harriers on the ground, complementing the tagging work.
Satellite tagging has been deployed in Ireland. The hen harrier was widely distributed here long ago but Richard Ussher and Robert Warren, writing in 1900, thought that the species was never very abundant. Ireland, long denuded of its forests, had little of the young woodland cover in which harriers nest. In 1937, George Humphreys noted that numbers had declined greatly and, by the early 1950s, harriers no longer bred here. Then a slow recovery began. Liam O’Flynn, who carried out a nationwide survey for the Irish Wildbird Conservancy (now BirdWatch Ireland), estimated that we had at least 37 breeding pairs by the mid-1960s. Government sponsored afforestation projects provided stands of young conifers in which harriers had started to nest.
According to the Bird Atlas, there were between 158 and 205 breeding pairs of harriers in Ireland in 2010. They nest in upland areas of Sligo Leitrim and Fermanagh area and there are some in the Slieve Blooms. Kerry, west Limerick, north Cork and the mountains of Waterford.
Illegal killing is an ongoing problem. In 2014 a young harrier, christened ‘Heather’ by local school children, was satellite tagged by the National Parks & Wildlife Service, supported by the community group IRD Duhallow. Heather travelled widely throughout Ireland, her progress being monitored by followers on the Web. Then, last January, she returned home to Kerry, where she was shot. As David Scallan of the NARGC commented, ‘no right-minded hunter would do something like this’.