MOOR MANAGEMENT 327 



in its lowest condition ; that in early spring the cock-birds, 

 wearied out with fighting for their nests and mates, lightened 

 in condition and without time to feed, die in the proportion of 

 seven or ten to one hen ; whereas in late spring and early summer, 

 when the hens are weakened after their moult, and light in weight 

 through shortage of food during the sitting period, the relative 

 proportions in the death-rate are reversed. 1 



From the consideration of the two factors set out above, 

 the immediate objective of the moor-owner stands out clearly 

 to keep the Strongyle infection at its lowest, to keep the power 

 of resistance of the stock at its highest, and at the same time 

 to maintain the greatest number of birds that the moor is 

 capable of supplying with suitable food. 



Successful moor management may therefore be defined as Definition 

 the maintenance of a margin in the power of resistance of the 



weakest individual Grouse, sufficient to enable it to overcome ment 

 the greatest nematode infection to which the surrounding 

 circumstances may render it liable. To put it briefly and in 

 practical language : Moor management is the science of distributing 

 the stock of birds over the moor, so that at no period of the year can 

 any area be so infected by the Strongyle worm as to make it a source 

 of danger to the least well-nourished bird (that is, to the bird of 

 the lightest weight) on that area. 



In considering this definition it is important to realise not 

 only the main factors connected with " Grouse Disease," but 

 also the contributory causes which produce them, (a) the power 

 of resistance of the Grouse, which varies directly with diet, 

 moult and seasonal conditions, (b) the liability to infection, 

 which varies with the number of larval nematodes on any given 

 feeding-ground. These contributory causes in turn depend on 

 the number of birds on the given area, the number of nematode 

 eggs deposited in each caecal dropping, and the length of time 



1 N.S. Investigation in the Frimley area has shovm that light birds and birds 

 not in good plumage die more easily from artificial infections of nematode worms, and 

 measurements go to show that light and weakly birds of one year, without sufficient 

 strength to feed themselves at the time of stress in winter and autumn, are the piners 

 and diseased birds of the year following. Vide Report, chap, xxi. pp. 469-470. 



