Sir

Further to Robert May's News and Views article1 on the illegal persecution of hen harriers on grouse moors, figures can be put on the potential economic gains to the grouse-shooting industry of such persecution. They are in fact minimal.

In the same paper that May discussed, Etheridge et al.2 calculate that 55-74 breeding harriers are removed from moors each year. The birds’ main prey is usually song birds, small rodents and young hares and rabbits3,4; they do take grouse chicks, but healthy breeding adults only rarely.

A hen-harrier nesting territory may encompass several hundred red grouse territories each producing, in a good year, as many as five young grouse. Were the harriers that are being illegally destroyed each year allowed to live, far fewer than 5,000 grouse chicks would escape their predation — a tiny proportion of the million or so young produced by Scotland's 250,000 breeding pairs of red grouse5.

Another paper6 indicates that many more red grouse, most of them breeding birds, are killed against deer fences each year than are taken by the hen harriers. In a survey of 135 km of deer fences, carried out over a year at 27 different sites, there were 188 red grouse collisions — and, more seriously, 37 and 36 of the bigger and rarer black grouse and capercaillie. Almost all collisions would have led to the death of the birds.

These fences are extensive. There are estimates, from the best grouse areas, of 2,000 km of deer fence in woodland and much more in moorland. They are typically 1.8 metres high, and are made partly of mesh and partly of tight horizontal wires. Most grouse that hit them are travelling at great speed as they are used to blasting their way through the twigs of trees.

In many instances the fences have been erected, with public subsidy, by the very landowners implicated in killing hen harriers. Some fences are still needed to protect young forest trees from deer, but many are old and redundant.

Putting deer into the equation, if deer numbers were reduced to a third of current levels (to about six animals to the square kilometre from 15-20), natural regeneration of forest would take off. In most areas there would still be plenty of deer for stalking; and the better cover, produced by removing the surplus of feeding deer, would provide much improved habitat for the coexistence of game birds and hen harriers.

As May points out1, the management of moorland for grouse shooting is infinitely preferable to overgrazing by sheep or deer, or planting conifers. It remains to be seen whether the shooting interests are able to bring themselves to obey the law and stop persecuting hen harriers, and to realize the consequences of their other management activities.