MOOR MANAGEMENT 379 



of the food-yield of the moor ; greater perhaps than the health of 

 the weaker birds will stand. 



Second Theory. — It is stated that disease conies every seven years : that 

 it is a recognised order of creation, and that no effective steps can 

 be taken to alter the periodicity of its recurrence. This ^9) Periodic 

 theory, like the preceding frost theory, is quite beside the °1^^^.o\a^ 

 point. In the first place, "Grouse Disease" does not occur '^^^*'- 

 on any moor in the regular order of once in seven years. The 

 examination of some hundreds of Grouse records show that the 

 disease occurs, on those moors which are liable to the epidemic, 

 at irregular intervals of three to eight years. 



The ordinary sequence of events is, one year of disease, one or 

 two years of recovery, two or three avei'age seasons, one or occasion- 

 ally two bumper years, followed by disease in the following spring. 

 Disease after a record year is due partly to a heavy Strongyle 

 infection in the winter months, resulting from an overstock at a 

 time when the birds are packed together on the lower portions of 

 the moor, partly also to the Grouse's decreased power of resistance 

 arising from a heavier stock without a corresponding increase of the 

 food-supply. As has been already pointed out this food shortage is 

 most marked in spring, and the outbreak of the disease accordingly 

 occurs at that time. 



Tliird Theory: Kleins Disease. — The third theory, associated with what 

 is commonly called Klein's disease, is that the mortality can assume 

 two forms, the first or epidemic form (pneumo-enteritis), 



■^ ^^ '' (3) Two 



which sweeps the moor, and in which the birds are said forms of 



. disease. 



to die in plump condition, fully feathered ; the other a 

 lingering disease in which birds waste away and die only after loss 

 of plumage and weight. The Committee have paid very close 

 attention to Klein's disease, and the remarks on p. 200 should be 

 read. It should be noted that in all the outbreaks investigated 

 not one single case was found of birds dying in good condition, i.e., 

 at normal weight. 



On seventeen different occasions durins the course of the Com- 

 mittee's investigations keepers have reported birds dying plump and 



