MOOR MANAGEMENT 377 



supply is at its shortest, aud when the bird is iu 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 ai'e 

 reversed. ' 



From the consideration of the two factors set out above, the immediate 

 objective of the moor-owner stands out clearly — to kee^J 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 orreatest number of birds that the moor is 

 capable of supplying with suitable food. 



Successful moor management may therefore be defined as the maintenance 

 of a margin in the power of resistance of the weakest individual Grouse, suflicient 

 to enable it to overcome the greatest nematode infection to which the ueanition 

 surrounding circumstances may render it lialjle. To put it briefly and n^anage- 

 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 ivor)n as to make it a sou7'ce of danger 

 to the least ivell-iiourished bird (that is, to the bird of the lightest iveight) on 

 that area. 



In considering this definition it is important to realise not only the main 

 factors, but also the contrilmtory causes which produce them, [a) the power of 

 resistance of the Grouse, which varies directly with diet, moult aud seasonal 

 conditions, {b) the liabilitj^ 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 that area, the number of nematode eggs 

 deposited in each csecal dropping, and the length of time that the stock has 

 been congested on any portion of the ground. 



It must be clearly understood that the Committee do not wish to lay down 

 that " Grouse Disease " is dependent on any fixed number of Strongyles in 

 the csecal intestines, or that any fixed standard of power of resistance guarantees 

 immunity from the disease, but rather that the epidemic depends on the relation 



^ N.B. — Investigation in the Friniley area has shown that light birds and birds not in good plumage 

 die more easily from artificial infections of nematode worms, and measurements go to sliow 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 chap. xxi. pp. 469-470 



