MOOR MANAGEMENT 331 



long enough time for the larval nematode to go through its 

 changes and infect the heather, the birds may become so charged 

 with Strongyle that they die as soon as they return to their own 

 ground, however lightly stocked that ground may be. There 

 are very few owners of high-lying moors who have not heard 

 the remark : " The birds were quite healthy before the last 

 winter storm ; as soon as they returned to the high ground 

 they began to die." 



(2) " Grouse Disease " occasionally appears the second and 

 third year after a severe epidemic, especially on wet, badly- 

 drained moors, and this notwithstanding the small stock that 

 may have survived the first outbreak. As has been shown in 

 chapter viii., 1 the Strongyle worm flourishes best in damp 

 surroundings, and it is possible that on a wet moor a smaller 

 quantity of ova may be sufficient to cause fatal infection. 



(3) On the west coast of Scotland a very light stock some- 

 times contracts disease. West coast heather is, as a rule, 

 of ranker growth and more open habit than what is found on 

 the east coast ; it is therefore more liable to be scorched by 

 the frost and cold winds of early spring. The food-supply in 

 consequence is apt to become so short that the normal quota 

 of Strongyle worms are enabled to become actively pathogenic 

 without the aid of further and outside infection. 



Fifth Theory. Another theory put forward is that a hard (5) Hard 

 winter affects the health of a moor. This theory takes two winters - 

 forms. First, that a hard winter makes for healthy stock, 

 and secondly, that a hard winter causes disease in the following 

 spring. 



These theories are mutually destructive, but,* paradoxical 

 as it may appear, both are conceived on a certain basis of truth. 

 A hard winter tends to kill off sickly birds, to shift the stock 

 and to mix the breed ; snow lying on the heather till far into 

 the spring protects it from larval infection during the critical 

 months of February and March, and so ensures a fresh, untainted 



1 Chap. viii. p. 237. 



