44 THE GROUSE IN HEALTH AND IN DISEASE 



Disease Committee's existence the collection of some six hundred 

 Red Grouse skins, representing every age, phase, and change 

 of plumage in that bird, has given a unique opportunity for 

 an independent revision of the work already done an oppor- 

 tunity such as has never occurred before in the study of any 

 single species of British bird for observing the effect of disease 

 upon moult and feather growth. And although the work as 

 it stands has been so nearly completed by the labours of the 

 two ornithologists already mentioned, there are still points of 

 interest to which attention may be drawn, especially in connec- 

 tion with the marked effect which parasitism and other wasting 

 diseases have upon the moult and growth of feathers, and it 

 is to this influence of disease that attention will be particularly 

 drawn in the present chapter. 



It is important to note the extraordinary irregularities 

 which so commonly occur in the plumage of the Red Grouse 

 owing to disease, whereby the deferred moult becomes in some 

 years almost the rule, and the rule of health becomes almost 

 the exception. Diseased conditions often entirely mask the 

 normal plumage changes, and it is far more important to realise 

 this than to examine thousands of more or less healthy birds 

 shot in the ordinary course of events in the shooting season. 



It is almost incredible that a moult should be deferred 

 from one season to another, or even to a third, and that the 

 right plumage should eventually be produced if the bird, by 

 means of good food and good weather, is at last enabled to 

 recover its health and grow any new feathers at all. It is 

 interesting to know that bare featherless legs and feet, which 

 have so long been considered a sure sign of disease in the Red 

 Grouse, may, in certain months of the year, be a natural 

 accompaniment of really good health, while thickly feathered 

 legs in the same month are a sure sign of deferred moult and of 

 sickness. It is only when the proper season for the moult of 

 the leg and foot-feathering is completely understood that we 

 can attach an unfavourable prognosis to heavy leg-feathering 

 when the legs should have been featherless, and an equally 



