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Hen harrier

Adult female hen harrier in flight

Image: Andy Hay

RSPB nature reserves hold around 7% of the UK hen harrier population, even though moorland managed by the RSPB accounts for just under 1% of the UK's total.

Species status

  • Phase of recovery: Recovery 
  • Red list Bird of Conservation Concern 
  • BAP priority: Wales and Northern Ireland     

What is the problem? 

The hen harrier population declined markedly during the 19th century as a result of persecution. By 1900, hen harriers were only found on Orkney and the Western Isles in the UK. By the 1970s, they had recolonised the mainland, but numbers were well below the carrying capacity of the available habitat.  

Hen harriers continue to decline in northern England, and south and east Scotland, areas dominated by heather moorland that is managed for driven grouse shooting. Illegal persecution is the main factor behind the hen harrier’s continued unfavourable status here. 

Food for harriers 

Hen harriers are declining in other parts of Europe because of habitat degradation. This may also have been true of Wales, Orkney and Northern Ireland, though numbers have shown a recovery in both countries since the late 1990s. 

On Orkney, we found that the problem was a shortage of food. Farm intensification, particularly the ploughing and reseeding of heather moorland and in-bye, had reduced the natural food available, particularly Orkney voles. To overcome this, grazing trials were carried out to enhance the quality of rough grazing areas for foraging hen harriers. 

The outcome of these has helped to inform the prescriptions in agri-environment and management schemes for Sites of Special Scientific Interest (SSSIs). 

Illegal killing 

RSPB research has also been fundamental in showing the acute impact of illegal persecution on hen harriers. They are killed or prevented from nesting successfully because they eat red grouse, sometimes in large quantities, before the grouseshooting season starts in August.  

Hen harrier survival is twice as good on moors not managed for driven grouse shooting than those that are, and nesting success is three times greater. The RSPB has contributed to a greater understanding of the impact that hen harriers have on stocks of red grouse, through part-funding of the Joint Raptor Study and trials to test the benefits of providing alternative food for hen harriers to reduce the number of red grouse that they eat. 

Such is the scale of illegal killing, the RSPB has stepped up its efforts to secure protection for nesting and wintering hen harriers. This has helped to raise the profile of hen harriers and has resulted in several convictions for hen harrier-related persecution offences. 

Nature reserves 

Numbers of hen harriers on RSPB reserves have almost doubled since 1999. RSPB nature reserves provide secure areas for hen harriers to nest, with average productivity almost double that on grouse moors in Scotland and England. The birds simply need a varied heather and grass structure, with long heather for nesting and shorter grassy vegetation full of voles and meadow pipits as food. 
Graph showing breeding success of hen harriers on RSPB reserves, 1991-2004

Image: The RSPB

Legal protection 

Illegal interference of hen harriers is considered the number one wildlife crime by the police and government. Advocacy by the RSPB is helping to ensure that strong legal protection is maintained for hen harriers, and that action to reduce the conflict with managers of driven grouse shoots is approached in a measured and scientifically rigorous way that does not further threaten the species’ conservation status. 

The scale of illegal killing has prompted a range of initiatives by the government, police and statutory conservation agencies, including Operation Artemis (a police crackdown on hen harrier destruction) and English Nature’s Hen Harrier Recovery Project. 

What next? 

The prospects for the hen harrier are mixed, in the short-term at least. In the west of the UK, where there is little driven grouse-shooting and fewer sheep, the prospects are better than for several decades. 

Populations in Wales, Northern Ireland, the Isle of Man and some of the Hebrides are at their highest since the 1970s. In 2004, there were 749 nesting pairs in the UK, a 44% increase in just six years. New agri-environment schemes provide an even greater opportunity for land managers to help upland wildlife, including hen harriers. 

However, numbers in England and south and east Scotland, where driven grouse shooting is a major land use, have fallen. An end to persecution would allow the population to rise by an estimated 13% each year. For hen harrier numbers to recover in these areas, moorland managers need to consider whether driven grouse shooting can only be sustained by killing rare and protected birds. 

In the longer term, climate change could have a major impact on upland birds and grouse shooting. However, the hen harrier may prove more adaptive than many other species, as it is equally at home in grassland.

Acknowledgements 

We would like to acknowledge landowners and managers across the UK, who permit access to their land for the RSPB and Raptor Study Groups to monitor hen harriers and other upland birds, and who ensure that birds are not killed illegally on their land. The survival of nesting hen harriers in England is due to a partnership between the RSPB and United Utilities, Raptor study groups, volunteers and other enthusiasts who monitor the fortunes of birds of prey across the UK.