Supplementary evidence

Langholm Moor – southern Scotland

Studies on Langholm Moor have provided much-needed evidence to both identify and resolve the conflict between the interests of driven grouse shooting and hen harriers. The first was the Joint Raptor Study (JRS). Between 1992 and 1997, hen harrier numbers rose from 2 to 20 pairs in six years on a driven grouse moor. Shooting was abandoned because the hen harriers ate over a third of all grouse chicks that hatched. With no grouse shooting, the local culture, economy and employment suffered and the control of generalist predators ceased. By 2003, 20 harrier nests were back down to 2, and numbers of breeding grouse and waders had more than halved. Predation was identified as the most likely cause of the declines. Grouse moor managers felt their worst fears had just been proven – this was a real lose/lose situation.

The second study is the ten-year Langholm Moor Demonstration Project (LMDP), started in 2008 with five gamekeepers being employed to restore the driven grouse moor at a cost of £227,000 a year (£450,000 a year when capital and operational costs are combined). The gamekeepers demonstrated that diversionary feeding did not work well enough to allow both the recovery of harrier numbers and red grouse (for all work see here). The gamekeepers stopped working on the moor in the spring of 2016 and harrier numbers have remained above target levels in their absence in the first year post-keepering. There is no evidence to suggest these harrier numbers at Langholm are sustainable in the long term in the absence of gamekeepers. There is evidence, from the 1992-97 JRS, to suggest that harrier numbers may fall below the target again in the absence of gamekeepers.

Those choosing to make selective use of data (GRO0532) to suggest the current harrier population on Langholm Moor will thrive in the absence of gamekeepers should be asked why they have decided to ignore the long-term evidence from this site that they will not.

There is also strong evidence from the Isle of Skye that hen harrier breeding success can be limited by foxes: “There was little evidence that adult hen harriers can successfully defend their young against an incursion by a fox either in daylight or darkness.” Less than a year after gamekeepers stopped managing the moor, fox predation on nesting harriers has been captured on camera at Langholm in 2016.

A scientific study by the GWCT, published in the Journal of Applied Ecology, identifies that the control of predators such as foxes and crows, carried out to protect red grouse, can benefit one of our most striking birds of prey – the hen harrier.

The long-term data predict that the current hen harrier population on Langholm Moor will fall now that gamekeepers are no longer managing the moor.

Berwyn and Ruabon Moors – northeast Wales

Elsewhere in the UK, there is a strong correlation between grouse moor management and the abundance and productivity of species such as lapwing, curlew and golden plover, which are otherwise increasingly rare.

The uplands of Wales once supported the most productive grouse moors in the UK as well as abundant populations of other birds. However, since the Second World War, almost half of the heather cover in Wales has been lost. Since the 1990s, owing to disease, overgrazing and, from the moor owners’ perspective, a lack of support from conservation agencies, grouse management has been all but abandoned and numbers of some of the more threatened upland bird populations have been in long-term, severe decline.

This was studied by the GWCT in the Berwyn Special Protection Area (SPA) in North Wales. The results recorded that between 1983 and 2002 red grouse declined by 54%. Over the same period, golden plover declined from 10 birds to 1, and curlew declined by 79% (not 90% as given in response to Q80).

Our work at Berwyn was published, after peer review, and forms part of the scientific literature on this subject. Those seeking an end to driven grouse shooting may wish to dismiss it (Q27 and GRO0530) but the evidence stands. We also note that there is no suggestion from this group that numbers of some of the more threatened upland birds increased on these moors as a result of the cessation of driven grouse shooting.

At Ruabon Moor (NE Wales), predator control introduced as part of a commercial red-legged partridge shoot and then maintained for grouse moor restoration has, together with improved heather habitat management, been associated with an increase in lekking male black grouse from circa 20 in 1995 to 320 in 2015 (also recent increases in breeding curlew (from 8 to 16 pairs) and golden plover (from 0 to 3 pairs)).

Continued declines in all three species have occurred on otherwise similar sites in the adjacent Berwyn SPA (Ruabon is not in the SPA), where improved habitat management has been conducted, but without predator control. For example, in 2015 there were only five displaying black grouse and two pairs of curlew on the RSPB’s flagship Vyrnwy reserve (SSSI, SAC, SPA).

Critics of grouse moor management continually fail to provide data that refute the clear and substantial evidence that driven grouse moors can protect conservation priority habitats and some of the more threatened upland species for the nation.

The Defra Hen Harrier Action Plan

The Plan was drafted by a wide range of organisations (including the RSPB), has been published, and is being implemented on the ground by those that support it, including the GWCT.

Some other organisations have stated that they could not support it until there has been an end to all wildlife crime. We note that this type of condition was not applied while other ‘remedies’ were trialled. Diversionary feeding, for example, was tested at Langholm for eight years (including years when the hen harrier population was declining) without applying this rule, and we see no reason to adopt it for the Defra trial.

Those calling for the banning or licensing of grouse moors to protect birds of prey should be asked to explain why they are calling for these divisive and damaging actions when there are potentially workable solutions to be tested.

Alternative land use

Those seeking a ban on driven grouse shooting (GRO0530) have suggested that a cessation of driven grouse shooting would not result in a change to forestry, windfarms or more grazing because most are designated protected sites. If that were the outcome, we are still faced with how to retain traditional management techniques, necessary to maintain these sites in favourable condition, including burning and high nature value grazing (2016 State of Nature Report), without any alternative economic land use other than eco-tourism. Langholm Moor has failed to attract tourism revenue, despite being publicly known to have a high number of hen harriers.

Those proposing changes to ban or restrict driven grouse shooting have not produced evidence of the net gain that the alternative land uses they propose will bring to society – economic, social and environmental.


The evidence on burning is highly contested; this is demonstrated by the high level of debate amongst 16 scientists from six nations in recent exchanges in the journal of the Royal Society, the world's longest-standing scientific society. They agree that more research is needed here. Examples of the wider debate include:

  • (a) Peat formation – As well as negative impact (Q12) there is also evidence that burning heather has a positive impact on the Sphagnum mosses that are important in peat formation. The authors “found no evidence to suggest that prescribed burning was deleterious to the abundance of peat-forming species; indeed, it was found to favour them”. So we can’t, as suggested (Q20), use the scale of burning as a proxy for the scale of damage. Those claiming it causes extensive damage should provide data to support this claim.
  • (b) Dissolved Organic Carbons (DOC) – There is also some evidence that DOC levels are unaffected or decline where burning has taken place. We note for clarity that DOC is not the same as “the brown colour you get in water”, although critics appear to sometimes think it is the case (Q12). One paper specifically identifies that using colouration as a substitute measure for DOC is not reliable.
  • (c) Water table – Whilst the EMBER study suggests heather burning lowers the water table (Q12), others suggest it does the opposite. The evidence that burning dries out peat bogs is contradictory. However, it is agreed that drains, dug to improve the grazing for livestock, can at least, in the immediate vicinity of the drain, dry out peat.
  • (d) Scale of burning – Other authors expressed concern that more burning, rather than less, should be occurring, to reduce potential fuel build-up and wildfire risk. Recent evidence from the Peak District shows that burning is generally carried out in accordance with guidelines, with appropriately sized burns and only 0.9% area being burnt per year, well below the recommended 10%.
  • (e) Carbon budgets – Another review assessed that the evidence for overall carbon budgets is limited and contradictory.


We continue to fail to find an extensive body of literature suggesting that heather burning will increase flood risk (Q14). No further evidence to support this claim has been provided. And government committee reports do not implicate increased burning in increased flood risk (Q14).

Once again we note there are contradictory elements to the evidence (Q21-22). For instance, the EMBER study also suggests overland flow is less common on burnt peat than unburnt peat. For the lowest 80% of rainfall events, the lag period is greater on burnt areas, and there is no difference for the top 20% (heaviest storms). For the top 20% of storms, the hydrograph intensity is higher for burnt areas but the lag time is not affected. This means that the peak discharge (amount of water in the stream), is higher for these heavy storms, but it does not happen faster.

Beyond further work by the authors of the EMBER report, there is no new evidence provided supporting the implied suggestion (Q21) that wider opinion currently supports these views.

Supporters of a ban on driven grouse shooting have failed to acknowledge the contradictory evidence on heather burning and flooding, which is possibly due to the complexity of the ecological system; with no clear evidence of risk, we are confident there is space and time for more research. More ‘test and trial’ on the ground is needed.

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