For months shooting men have been eagerly awaiting publication of the Langholm Report about the predation of raptors on grouse, for they were convinced that it would confirm one of their most firmly held beliefs: that hen harriers - the beautiful, long-winged hawks that hunt low over moorland - are a major factor in the decline of grouse, and kill so many birds as to make commercial shooting impossible.
Now at last the report has come out, and the sportsmen's claims have been startlingly vindicated. The five-year study, carried out mainly on the Duke of Buccleuch's moor at Langholm in south-west Scotland, reveals that hen harriers and peregrines killed 30 per cent of the grouse's potential breeding stock in the spring, 37 per cent of the chicks in summer, and 30 per cent of the survivors in the autumn.
During the study period the population of harriers increased from two to 14 breeding females, and that of peregrines from three to six breeding pairs. At the same time, grouse stocks dived: in 1992 they were high enough for 2,000 birds to be shot, but in 1996 the bag was only 100.
The survey was nothing if not thorough. It was carried out by staff from the Game Conservancy Trust and the Institute of Terrestrial Ecology, and other bodies sponsoring the pounds 500,000 study included Scottish Natural Heritage and the Royal Society for the Protection of Birds. In other words, fair play and scientific accuracy were guaranteed. The Buccleuch estates provided two houses, a vehicle and the help of their four gamekeepers.
The leading researchers, Steve Repath and Simon Thirgood, put in an immense amount of time not only at Langholm, but on five other moors as well. For counting prey species, they walked the moors with pointers to find the grouse, noted the numbers of songbirds which they flushed, and caught small mammals such as voles in snap-traps.
As for the predators, the team found their nests at the start of each year and watched them through the breeding season. They analysed the diet of peregrines by collecting prey remains from nests and roost sites, but with the harriers they worked by direct observation. Having set up a little canvas box about 30 yards from a nest, they would gradually move the hide closer until it was only five yards off, and they could see exactly what the females were bringing in.
The researchers inhabited the hides, on average, for six hours at a stretch, and altogether spent more than 2,000 hours in observations at Langholm alone.
Nobody, then, can reasonably query the data which they amassed, and its implications are unavoidable. If the downward trend of grouse numbers were to continue, the following series of events would occur:
1. Commercial shooting would become unviable.
2. The Buccleuch estate would no longer employ gamekeepers to cull other predators such as foxes and crows.
3. With no labour to maintain the heather by controlled burning, the moor would revert to rough grass, or be planted with conifers.
4. The grouse would decline to the point of local extinction, as would the harriers and other moorland birds.
5. In the end 50 square kilometres of attractive moorland would be destroyed.
The question now is how to alleviate pressure on grouse without killing raptors. One idea is that gamekeepers should provide the hawks with other food at their time of maximum need, when they are rearing chicks. Peregrines and harriers do not normally pick up carrion, but experience has shown that they will use dead birds - for instance, pigeons - to feed their young if they find them at their nests. Some gamekeepers have already established dovecotes near peregrine eyries in the hope of furnishing the raptors with less valuable prey than grouse.
A more ambitious scheme, proposed by the Game Conservancy Trust, is that the harrier population should be evened out by translocation: eggs should be removed from nests in areas where the birds are already numerous, and artificially-reared birds introduced on to moors where at present there are none. The long-term result would be to leave each landowner with a quota of harriers which he would be bound to protect.
No doubt many landowners will find the proposal outrageous, and whether or not any will accept it remains to be seen. The lead, now, must come from Scottish Natural Heritage, the government body, whose next step will be to organise a discussion of possible ways ahead. For the time being, the research team has funds to continue work for another year.
The moral of the Langholm Report is that intelligent, practical management benefits not only wildlife but the landscape as well, and that management for shooting is often the most beneficial of all.
If the RSPB sanctions the culling of crows and foxes - as it has on its reserve at Abernethy, on Speyside, in attempts to promote the welfare of black grouse and capercaillie - will it now modify its hitherto fanatical defence of raptors, and agree to some degree of control by the lifting of eggs?Reuse content