46 THE GROUSE IN HEALTH AND IN DISEASE 



is also quite intelligible, since the old winter plumage of the 

 breast and abdomen is being quickly shed and replaced by a 

 similar new winter plumage at the time when the autumn 

 plumage on the rest of the body is being cast. There are in 

 addition very frequently a few feathers of the copper-red 

 plumage on the chin really belonging to and remaining over 

 from the previous winter plumage. 



Instead of going into further details, however, with regard 

 to the two moults and plumages of the cock Grouse, it will 

 be simpler at this point to take its plumage changes in detail, 

 successively month by month, explaining as nearly as possible 

 what can be gathered from the examination of a series of skins, 

 including a number of specimens in all stages of disease as 

 well as in health. 



The specimens illustrate every month of the year and most 

 of the local variations to be found in England, Scotland, and 

 Ireland ; and there are a sufficient number of sick as well as 

 healthy birds to show the very great influence that disease 

 has in altering the individual capacity for feather growth. 

 Unless this effect, which results as a rule from excessive para- 

 sitism, is fully recognised, there will always be misunderstand- 

 ings upon the moult of this bird, for almost every Grouse in the 

 country is to some extent infested with parasitic worms, and 

 there are years when irregularity of moult is the rule rather 

 than the exception. Moreover, it so happens that in autumn, 

 when birds are being shot in large numbers, the survivors of 

 the two worst months of the year for " Grouse Disease " 

 mortality, that is, the survivors of May and June, are all con- 

 valescing ; but they are convalescing with their plumage 

 changes all retarded and put completely out of order and routine. 

 In this way it is possible in September to kill two birds on the 

 same day, both of which have the chestnut-coloured feathers 

 of the winter plumage on the chin and throat ; but upon 

 examination it may be seen that in one bird the edges of these 

 feathers are frayed and worn and the colour faded, showing 

 that they have survived from the previous winter plumage ; 



