Critical link between Hen Harrier and livestock numbers
New research by RSPB Scotland has shown that hill farming can play a fundamental role in assisting the fortunes of one of Britain's most threatened birds — the Hen Harrier.
Hen Harrier, undisclosed site, Outer Hebrides (Photo: Stephen Hiscock)
Known for its dramatic, tumbling "sky-dance" courtship displays in the spring, where the males and females gyrate and spin wildly whilst in flight, the Hen Harrier is still perhaps the most persecuted bird of prey in the UK. Indeed, illegal killing, nest destruction and intentional disturbance are the main factors impeding its population recovery and restricting its range in Scotland and the rest of the UK. However, scientists and land managers keenly welcome any addition of scientific knowledge to help towards its conservation, and this represents a significant growth in understanding.
The new study, which is published in the Journal of Applied Ecology, shows how getting the grazing regimes in upland areas right can deliver major benefits for nature and wildlife. Targeted agri-environment schemes and other Common Agricultural Policy (CAP) payments have a vital role to play in achieving this, and helping to support farmers. The RSPB would like to see a larger share of CAP funds directed to High Nature Value farming that benefits wildlife.
Orkney is largely free from persecution of birds of prey, and since 1975 the Hen Harrier population of the islands has been closely monitored. Between the early 1980s and mid-1990s sheep numbers on Orkney doubled, largely in response to CAP subsidies, and this was associated with dramatic declines in Hen Harriers — from 100 breeding females in the 1970s to just three successful nests in 1993. Subsequently, as sheep numbers have fallen in response to changes and reform of CAP subsidy, the harrier population has recovered.
Scientists at the conservation charity examined whether these reductions in sheep numbers have led to increases in the birds' favoured hunting habitat or their prey, as well as whether the breeding output over the last 33 years is correlated with this. They found that Hen Harrier productivity is directly related to the stocking densities of sheep that are present in its main breeding and hunting areas. Over the period that sheep numbers declined, the study revealed a significant increase in both rough grassland and the vole population — the harriers' favoured hunting ground and prey species.
Hen Harrier, undisclosed site, Dumfries & Galloway (Photo: Brian Henderson)
Dr Arjun Amar, Senior Conservation Scientist with RSPB Scotland, who led the study, said: "This is an major addition to our understanding of the conservation needs of Hen Harriers. Illegal disturbance and killing continues to be the main barrier to this beautiful bird returning to many parts of the country where it should be commonplace. We now know that, where the species is freed from persecution, grazing management can be a pivotal tool in helping Hen Harrier populations to recover, and may also benefit other species that rely on grassland voles as prey — Kestrels, Barn Owls and Short-eared Owls, for example."
Vicki Swales, Head of Land Use Policy at RSPB Scotland, said: "This study shows the crucial importance of getting the right balance in grazing systems. Too many livestock and we lose valuable species; if sheep and livestock and numbers decline too far, this too is likely to cause a decline in the habitat quality, and have profoundly detrimental impacts on Hen Harriers and other vole-dependent species. This is why we need to avoid the broad-brush approach of encouraging more livestock everywhere, as was the case before the CAP was reformed and farmers used to get paid according to the 'headage' of sheep on their land. Supporting High Nature Value farming should encourage appropriate grazing that benefits a wide range of wildlife, and this show the dividends it would pay."
On 17th November 2010 the European Commission will publish a communication on the future of the CAP. RSPB Scotland wants to see a much larger share of CAP funds directed to supporting High Nature Value farming systems and to targeted agri-environment schemes. Scotland has a high proportion of HNV farming systems — without appropriate support, farmers are faced with the choice of intensifying production or giving up farming altogether, neither of which will help wildlife such as the Hen Harrier.
The RSPB Report Uplands: Time to change? addresses many of the issues concerning management of our upland habitats, in particular those affecting farming, sporting management, forestry and recreation.
Sheep numbers on Orkney's West Mainland in the areas where Hen Harriers nest and forage increased from 20,000 in 1975 to 50,000 by 1998; over the next decade numbers have subsequently declined by around 10,000 (to 40,000 in 2008). These changes mirror those found nationally for much of Northern and Western Scotland as revealed in the Scottish Agricultural College report Farming’s Retreat from the Hills.
