" GROUSE DISEASE " COCCIDIOSIS 265 



second series of deaths was due to Strongylosis and not Coccidi- 

 osis, though in every case the victims showed traces of an earlier 

 infection of Coccidiosis. The case is remarkable, for it is now 

 established that Strongylosis is essentially a spring disease, 

 and it is very exceptional for birds to contract it after the 

 month of May. 1 It would appear that Coccidiosis had so 

 weakened the birds as to make the survivors particularly 

 vulnerable to the other form of disease. 



Certain experiments have been made with a view to finding 

 a means of destroying the coccidian cysts on the moor without 

 killing other forms of life. 



This is not an easy matter, for while it is relatively easy to 

 take preventive measures in the case of Coccidiosis in fowls, on the moor, 

 it is most difficult to take active measures in the case of Grouse. 

 The remedy of heather-burning is efficacious to some extent, for B y n ? ath 



. . burning. 



the coccidian spores which are present in the tract burned 

 are then destroyed, but as the heather most likely to be in- 

 fected is probably that growing on the best feeding ground the 

 immediate result of burning would be the reduction of the 

 food supply of the moor, not only for the year in which the burn- 

 ing is carried out, but for several years thereafter. Another 

 practical objection to this remedy is the difficulty of knowing 

 which areas of the moor are most seriously infected with the 

 coccidian spores, and lastly, heather-burning is forbidden by 

 the law of Scotland at the time of the year when coccidian 

 infection is most dangerous. As a remedy against an existing 

 outbreak, therefore, heather-burning is of little value, but as 

 a preventive measure a course of systematic burning is to be 

 recommended. Any condition tending to raise the general 

 vitality of the birds makes them much more resistant to disease. 

 An abundant supply of healthy young heather, by raising the 

 general standard of health of the birds, is probably one of the 

 best safeguards against the insidious disease, Coccidiosis. 



Another advantage of providing a good supply of young 



1 Qf. pp. 180, 238. 



