The recent golden eagle Aquila chrysaetos framework analyses (Fielding et al 2003a; Whitfield et al 2006a, 2008a) provided new insights into factors influencing the distribution and population viability of this species in Scotland, and highlighted the potential for using national data sets to identify key constraints on bird species. This approach has now been applied to the hen harrier Circus cyaneus, a species of high conservation concern which is listed on SNH’s Species Action Framework (SNH 2010) as a priority species for action. It is included on the red-list of birds of conservation concern in the UK (Eaton et al 2009) and, because it is considered vulnerable within Europe, on Annex 1 of the EU Birds Directive (79/409/EEC). It has also been identified as a UK Government priority species in terms of combating wildlife crime (UK NWCU 2009; PAW 2009). In England the hen harrier is threatened with extinction because of illegal persecution (Natural England 2008), and as such Defra have recently added it to the government’s list of species considered of principal importance for conserving England’s wildlife.

 

Hen harriers have undergone large changes in distribution and abundance in the UK and are red-listed because of population declines during the period 1800–1995 (Eaton et al 2009). The species was virtually eliminated from mainland Britain during the 19th century, almost certainly due to persecution by gamekeepers, although land use changes may also have played a part. During this time, populations of hen harriers persisted on Orkney and the Western Isles of Scotland. They returned to mainland Britain during the 20th century, probably initially due to reduced gamekeeping activities during the two world wars. By the mid–1970s the British population was estimated at 500 pairs, with a further 250–300 pairs in Ireland (Watson 1977).

 

A national survey in 1988–89 estimated that the UK and Isle of Man had 478-669 pairs (Bibby & Etheridge 1993). About one third (33%) of the pairs nesting in Scotland (excluding Orkney) were recorded in young forestry plantations, with the remainder on grouse moor (27%) and other heather moor (38%). It was thought that the distribution of harriers would change as forestry plantations matured and the habitat became less suitable for nesting and foraging hen harriers. These predictions were borne out by the results of the 1998 national survey (Sim et al 2001) when the estimate of 570 territorial pairs suggested no significant change from that of the 1988-89 survey. In Scotland (excluding Orkney), 55% of hen harriers were found to be nesting on grouse moor, 29% on other heather moor, and only 11% in young plantations.

 

The most recent national survey of hen harriers, carried out in 2004, showed a 41% increase in the UK and Isle of Man population to 806 territorial pairs (Sim et al 2007). In Scotland, the Orkney breeding population of hen harrier, which had formerly acted as an important refuge for the species, had increased from a decline which began in the late 1970s (Amar et al 2003) and had reached a low point in the late 1990s when the previous survey took place. Compared with the 1998 survey however, in 2004 there were decreases in the East Highlands and the Southern Uplands. Overall there were decreased numbers of harriers breeding on grouse moor and signs of occupation of new habitats with nearly 10% of the Scottish population associated with brash/scrub and mature conifer plantation – two land management classes from which there were no breeding records in previous surveys (Sim et al 2007). 

 

The UK has classified a suite of Special Protection Areas (SPAs) for hen harriers.  Incentives for managing these sites for the benefit of hen harriers and other qualifying species are available from government.  SPAs and other sites of national importance (SSSIs) for hen harriers are monitored by the country conservation agencies.  Together with surveillance programmes covering the species and its habitats in the wider countryside, this enables government to report to the EU on the fulfilment of its obligations under the Birds Directive “to ensure their survival and reproduction in their area of distribution”.  Such national reporting enables the EU to assess the status of the species at European scale.  In this report we will refer to favourable conservation and favourable condition targets, with Section 7 providing the context for this.

 

Several studies have investigated the factors influencing the distribution, abundance and productivity of hen harrier. These studies have implicated a number of factors including principally: habitat change (Redpath et al 1998, Arroyo et al 2006, Amar et al 2008); persecution (Etheridge et al 1997; Summers et al 2003, Whitfield et al 2008b, Anderson et al 2009, Redpath et al 2010) and prey abundance (Redpath & Thirgood 1997, Amar et al 2003).  

 

The conflict between hen harrier conservation and grouse moor management has been highlighted by a number of key publications, with the UK Raptor Working Group (Anon 2000) providing a definitive overview on management and legal matters. Recently, some important reviews have quantified the magnitude of hen harrier persecution.  For example, Redpath et al. (2010) found that there were records of only 5 successful hen harrier nests on the estimated 3,696 km² of driven grouse moors in the UK in 2008; an area of habitat estimated to have the potential to support about 500 pairs.

 

There are some  important on-going activities to address the conflict.  The Langholm Moor Demonstration Project in south Scotland is exploring whether economically viable driven grouse shooting and hen harriers can co-exist.  The Project, run by SNH, Buccleuch Estates, Game and Wildlife Conservation Trust (GWCT), Royal Society for the Protection of Birds (RSPB) and Natural England, is trialling diversionary feeding of hen harriers (to divert them from grouse in the breeding season).  It is putting in place significant improvements in land management practices (including muirburn, predator control and livestock reductions), and has a well defined programme of scientific monitoring (Langholm Moor Demonstration Project 2011). This Project was borne out of discussions within Scotland’s Moorland Forum, which is addressing wider issues concerning the sustainable management of the uplands in Scotland (Scotland’s Moorland Forum 2011).   Natural England in conjunction with the Environment Council is leading a conflict resolution process to tackle persecution of hen harriers in England (but with a reach to Scotland).  The Environment Council, an independent body with experience in conflict resolution, is mediating discussions between interested parties in this conflict, and many supporting papers have been produced as part of this (Environment Council 2011).  Some scientific studies have been published recently on the conflict, with Redpath et al. (2010) providing an overview of the current evidence base and options for addressing the conflict.

 

This framework presented here complements and extends earlier analyses of national hen harrier datasets by looking for environmental factors that correlate with or are otherwise associated with the distribution of breeding hen harriers in the UK, and at a regional scale within Scotland.   A national survey of hen harriers was undertaken in 2010, and is likely to report towards the end of 2011 or early 2012; a further revision to the framework will be made on publication of that survey.