Red grouse by sheep. Conservation measures taken on foot of the judgment have seen the population in the area double from 400 to 800. The red grouse is considered a game bird and is shot in large numbers during the shooting season which traditionally starts on August 12, known as the Glorious Twelfth. There is a keen competition among some London restaurants to serve freshly killed grouse on August 12, with the birds being flown from the moors and cooked within hours. Shooting can take the form of 'walked up' (where shooters walk across the moor to flush grouse and take a
Red grouse recover. The main driver of this cyclic pattern is thought to be the parasitic nematode worm "Trichostrongylus tenuis". However, in his book, V. C. Wynne-Edwards suggests that the primary reason for mortality in grouse population is homeostasis depending largely on food availability and that the 'Grouse disease', due to the parasitic worm "Trichostrongylus tenuis" is a mistaken diagnosis of the after effects of social exclusion. The red grouse is endemic to the British Isles; it has developed in isolation from other subspecies of the willow ptarmigan which are widespread in northern parts of Eurasia and North America. It is found