320 THE GROUSE IN HEALTH AND IN DISEASE 



representative formations are graptolite shale, Llandovery, 

 old red sandstone, Ludlow, and Wenlock. 



With regard to meteorological conditions the case is different, 

 as may be seen at a glance from the Rainfall Map of Scotland 

 published by Messrs Bartholomew for the Journal of the Scottish 

 Meteorological Society for the years 1866 to 1890, and here 

 reproduced by the kind permission of Messrs Bartholomew 

 and of the Society. It will be seen that the principal Grouse- 

 producing areas coincide almost exactly with the districts of 

 low and moderate rainfall, the only exceptions being in the 

 western districts of Sutherland and Ross and the islands of 

 the Outer Hebrides. Whether the heavy rainfall has a directly 

 detrimental effect upon the Grouse, or merely affects it 

 indirectly by preventing the best development of the heather 

 on which it feeds, may be a matter of conjecture, though the 

 latter seems the more probable explanation. The fact remains 

 that where the rainfall is heavy Grouse are few, and it is 

 feared that this fact will always prevent the Grouse moors in 

 certain rainy districts from being brought to the same standard 

 of productiveness as in more favoured region. 



The points brought out by the series of maps may be 

 summarised as follows : 



(1) " Grouse Disease " is one of the natural risks to which 



Grouse are subject, and is to be found wherever 

 Grouse are numerous. 



(2) Except in specially favourable seasons there is always 



a certain amount of " Grouse Disease " in one district 

 or another. 



(8) " Grouse Disease " does not usually persist in the same 

 locality for more than one or two years. This is 

 probably due to the fact that by the reduction of 

 the stock the risk of further infection is lessened. 



(4) There is no connexion between "Grouse Disease" and the 



geological formation of the district in which it occurs. 



(5) Where the rainfall is heavy there are few Grouse and 

 Where the rainfall is heavy there is little " Grouse 



Disease," 



