400 THE GROUSE IN HEALTH AND IN DISEASE 



late winter and early spring up to two hundred and fifty grains of heather are 

 found in the average afternoon crop as against fift}^ grains at any other time 

 of the year. It is therefore reasonable to say that as the Grouse have to increase 

 the amount of their food they will naturally go to those places where edible 

 Calluna is most readily obtained, and thus by congestion of the stock on a small ■ 

 area will not only over-crop the food there, but also, as will be shown later, will be 

 exposed to an increase of infection by the nematode worm and by the Coccidium. 

 Before leaving the question of the comparison of feeding areas of well and 

 badly burned moors, one further point should be mentioned. On a well-maua*ged 

 „ , J. moor the heather fired is all under twenty years old, and when it is 

 should be burned the young heather springs from the root the same year. On a 



burned jo i o ./ 



young. badly burned moor, where old stick heather forms the main crop, the 

 heather springs from seed,^ and in many cases only afi'ords food for Grouse 

 after the area burned has passed through successive stages of grass and cross- 

 leaved heather varying in point of time from six to twenty years. If the soil 

 has a tendency to grow bracken the heather may be lost for ever. That is 

 to say, in a fifty years' rotation moor, probably 20 |)er cent, of the moor is either 

 black ground, bracken, grass, or cross-leaved heather, and is not yielding its 

 proportionate quota of food. When we consider this loss of food area as well 

 as the generally recognised fact that on a frequently burned moor the heather 

 o-rows thicker and more luxuriantly than on one badly burned, it is no 

 exao'geration to say that the food-bearing capacity of a moor at its best and 

 worst is as ten to one. 



This change in the flora of a moor after burning is specially noticeable in 



the case of accidental fires, such as occurred on a large scale in York- 



ac'^c'we^utai shirc in 1887 and 1893. Accidental fires are commonest in very dry 



weather, and thus there is a danger of the peat and soil being burned 



to a depth of several feet, thus destroying the roots of the heather. 



The second reason for burning is to keep the birds at all seasons split up 

 over the ground. Grouse are not naturally gregarious, nevertheless they 

 frequently get together into big packs for purposes of safety after frequent 

 disturbance, or for shelter on the a])proach of storms, or in search of food, or 

 to avoid snow or drought, or to prepare for migration, but, once the immediate 

 cause of packing is removed, their instinct is to get away from their brethren 

 and take up their family life apart. To help the birds to develop this instinct, 



' Vide PL LVii. Fig. 2. 



