THE GROUSE IN HEALTH AND IN DISEASE 37 



September berries are added to the Grouse's diet, and in the 

 late autumn and early winter the seed or fruit of the heather 

 is largely eaten. In fact it may be said that from the middle 

 of May to the middle of the following January the food 

 supply, even on the worst moors, is almost inexhaustible, and 

 during this period the ground is capable of supporting a stock 

 far larger than it could possibly carry during the subsequent 

 three months." The capacity of a moor to carry a healthy, 

 disease-resisting stock of birds has therefore to be gauged by 

 the quantity of the food supply available during the first 

 months of the year. If the ground be overstocked at this 

 season, disease will almost certainly assert itself, either then 

 or later, whatever the capacities of the moor at other seasons. 

 " If we consider that birds may be packed in large numbers 

 on one portion of the feeding area, for perhaps weeks at a 

 time, herded together by stress of weather or shortage of 

 food, that the number of strongyles will increase by geometri- 

 cal progression as the birds get more heavily infected, and 

 therefore increasingly able to foul the moor, it is not difficult 

 to realise, despite the countless thousands of larvae destroyed 

 by drought, mishap, heather-burning, etc., how the moor may 

 become more and more tainted, until at last every shoot of 

 heather bears the seeds of ' Grouse Disease.' " 



The burning of the heather in regular and systematic 

 rotation is the best preventive to an outbreak of " Disease." 

 Given a sufficient food supply, the strongyle worms do not 

 seem to cause much inconvenience to Grouse which are 

 otherwise in good health. They are practically always 

 present, nor do their numbers appear to vary with the season 

 of the year. In fact, it is only when the numbers of the 

 invading host have become overwhelming that the specific 

 symptoms of " Disease " become outwardly conspicuous. 

 " Recent scientific investigation appears to indicate that 

 [in every form of infection] the power of resistance varies 

 directly with the health of the subject, and as far as the 

 Committee's investigation goes, the Grouse appears to be 

 no exception to the rule. Once allow the vitality or weight 

 to go below a certain recognised figure, then immediately 

 the strongyle worm appears to operate on the tissues of 



