PLUMAGE CHANGES OF THE COCK GROUSE 31 



deferred moult becomes in some years almost the rule, and the rule of 

 health becomes almost the exception. It is a very difficult matter, Effects of 

 indeed, for any one who has not had the opportunity of examining 'i'^^'^^^- 

 an extensive series of Grouse skins, in disease as well as in health, and cover- 

 ing every month of the year, to come to any true conclusion about the moult. 

 Diseased conditions often entirely mask the normal plumage changes from 

 time to time, 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. A study of abnormal plumage changes in diseased 

 Grouse is essential if the discrepancies which arise in the moult of what 

 are often wrongly considered normal birds, are ever to be explained. Once 

 this point is grasped the question becomes much simpler, and it is because 

 the Grouse Disease Committee has had such ample opportunity for studying 

 both sides of the question that it has been deemed necessary to enter into 

 these plumage changes at such length. 



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 



1 i- 1 11 Effect on 



last enabled to recover its health and grow any new feathers at all. feet and 



I • • • 1 1 legs. 



it IS interesting, and to some people, such as sportsmen and game- 

 keepers, even useful 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 begin to understand the 

 reason for attaching an unfavourable prognosis to heavy leg-feathering when the 

 legs should have been featherless, and an equally favourable prognosis to bare 

 legs when the legs should certainly have been bare (PI. xiii., Figs. 1-2). 



To return, however, to the two plumages of the healthy cock Grouse. They 

 are distinguished by Mr Ogilvie-Grant as the autumn plumage and the winter- 

 siimmer plumage, and he says further that the cock "has no distinct summer 

 plumage."^ It is perfectly easy to see what is meant by this, and also b}^ the 

 statement which follows, that the cock "retains the winter plumage throughout 

 the breeding season." 



^ " Handbook to the Game Birds," p. 28. (Allen's Naturalists' Library). London : W. H. Allen & 

 Co., Ltd., 1895. 



