26 THE GROUSE IN HEALTH AND IN DISEASE 



and the reason commonly given is that the hard weather kills 

 off the weaklings. There is no evidence to support this theory. 

 Grouse are seldom found dead during the winter months, and 

 when they are the cause can never be ascribed directly to the 

 effects of weather. If the belief that snow is beneficial is well 

 founded, some other reason must be sought ; perhaps the fact 

 that the weather has caused the stock to shift, and so introduced 

 new blood where required, may have something to do with 

 the improvement : more likely, however, the solution is con- 

 nected with the question of food supply. Ground which has 

 been covered by snow for a period of several months provides 

 better and more wholesome food than ground which has been 

 heavily stocked, for when birds return in the spring they find 

 the food supply still untouched by Grouse or Sheep, and the 

 fact that it has been out of reach for so long has prevented it 

 from being so heavily infected by the larvae of Trichostrongylus 

 as the lower moors which were crowded with Grouse throughout 

 the winter. The melting of the snow may also have the effect 

 of washing the Strongyle larvae out of the heather. 



If the birds are well matured by August 12th they often 

 begin to " pack " after the first few days' shooting, and will 

 not then readily lie to dogs. Packing may at times take place 

 so early as to make shooting over dogs an impossibility. On 

 this account the poor results formerly obtained on most English 

 moors led to the introduction of " driving." In Caithness 

 and some other districts the Grouse, being more backward, 

 do not pack except under exceptional conditions. 



This custom of packing is worthy of study, for it may 

 be found to have a direct bearing upon the questions of 

 disease, migration, interbreeding, and the preservation of the 

 stock. 



In the first place, it may be stated that it is the young birds 

 rather than the old birds that tend to form into packs in the 

 earlier months of autumn, though the older birds will follow 

 suit as the winter advances. Consequently, when packing first 

 begins, it is the older birds that suffer the greatest loss in a 



