The hen harrier (Circus cyaneus) is a medium-sized bird of prey with long wings and tail. It is found mainly on moorland in the breeding season but can occur in a wide range of habitats in winter as most move to lowland and coastal areas. Males are striking birds with pale grey upper-parts, white underparts and black wing tips. Females and juveniles are largely mottled brown with a long, barred tail. All birds have an obvious white rump.
Legal and conservation status
The hen harrier is listed on Annex 1 of the EC Birds Directive and is protected under Schedules 1 and 1A the Wildlife and Countryside Act 1981, as amended. It has an 'unfavourable' conservation status across Europe.
Hen harriers have long been subject to illegal persecution, notably over some areas of moorland managed for driven red grouse shooting, though in some parts of Scotland there are signs of recovery. In recent years, considerable scientific research has been undertaken into the relationship between red grouse and hen harriers to try to inform management. A major study has already shown that providing additional food to nesting hen harriers can substantially reduce the number of red grouse chicks that they take.
A major demonstration project is underway at Langholm, (www.langholmproject.com ) to determine how hen harrier, red grouse and habitat interests can be sustained.
Under the auspices of the Partnership for Action Against Wildlife Crime in Scotland (PAWS) we are running the 'Heads up for Harriers' project to raise awareness of the bird and its vulnerability to persecution: www.scotland.gov.uk/Topics/Environment/Wildlife-Habitats/paw-scotland/what-you-can-do/hen-harriers
Habitat, distribution and abundance
Hen harriers breed on moorlands, peatlands and conifer plantations usually below 500m. In Scotland breeding strongholds include Orkney, Argyll mainland, the Inner Hebrides, Arran and the Uists. The species also breeds across the Highlands and Southern Uplands. Elsewhere in the British Isles, it breeds in small numbers in Wales, Northern Ireland and Isle of Man, with currently a handful of pairs in Northern England. In 2010, the most recent national survey year, there were 662 nesting pairs in the UK with 505 of those in Scotland. This was a decline of approximately 20% from the previous survey in 2004. The European population is estimated at 32,000-59,000 breeding pairs.
The species continues to be absent from many areas which are apparently suitable. Although not used for breeding, grasslands provide valuable foraging habitats. In winter, birds move to open countryside (lowland farmland, marshland, fenland, heathland and river valleys).
Hen harriers are predominantly ground nesting birds favouring areas of rank vegetation. The female normally lays four to six eggs between April and the end of May. The chicks fledge at 37-42 days. Occasionally a male can mate with and provide for two or more females, although the additional females tend to raise fewer young.. Hen harriers feed mostly on small birds and rodents, especially voles.
History of decline, contributory factors and current threats
The hen harrier population declined markedly during the 19th century. By the early 20th century hen harriers were only found in Scotland, and even here they were virtually absent from the mainland and much of the Inner and Outer Hebrides, surviving in numbers only on Orkney. By the 1970s, they had recolonised the mainland, but numbers were well below the carrying capacity of the available habitat. Large declines occurred from 1970-1990, although the UK level was unchanged between 1988-89 and 1998. Hen harriers continue to decline in northern England, and south and east Scotland, areas dominated by heather moorland managed for grouse shooting, but numbers have increased in parts of west Scotland, including the southern islands of the Outer Hebrides.
The hen harrier has long been subjected to illegal persecution, and is the most intensively persecuted raptor in the UK. Persecution has persisted even though it has been illegal since 1954; it is the main factor behind the hen harrier's continued unfavourable status in northern England, and south and east Scotland.
In the west of Scotland, including the larger islands, many hen harriers continue to breed within conifer forests where trees have failed to grow or where patches were left unplanted. A decrease of 70% in the Orkney population over the last 20 years has been linked to reductions in the area of unmanaged grassland. This population has now recovered, due largely to an improvement in availability of habitat with suitable prey. This improvement has partly come about via targeted management initially under a management scheme but now through the Scottish Government's Rural Development Plan environmentally friendly agricultural scheme.
The 'Species Lead' at Scottish Natural Heritage
Andrew.Stevenson@snh.gov.uk Tel: 01878 710 381
Note: Des Thompson Des.Thompson@snh.gov.uk is the key contact for The Langholm Moor Demonstration Project, and for the PAWS work.
Last updated on Wednesday 6th January 2016 at 09:19 AM. Click here to comment on this page