ON THE CHANGES OF PLUMAGE IN THE RED GROUSE 135 



one can generally tell by the feathers of the under parts to 

 what form any individual belongs. In the average female in 

 full summer plumage the upper parts may be described as 

 black, each feather being rather widely margined, barred and 

 marked with orange buff (Plate VI. Fig. i). The protection 

 afforded by this plumage is so perfect that, when the 

 bird is sitting on its nest among heather and dead grass, 

 it may easily remain unnoticed though only a few yards 

 distant. 



This plumage, however, varies much in different indi- 

 viduals, birds from Yorkshire and Ireland having the rufous 

 or orange-brown bars much brighter and wider than in the 

 more finely mottled and darker specimens generally charac- 

 teristic of the east of Scotland. 



As already mentioned, the autumn plumage of the upper 

 parts in the commonest or buff-spotted type is black, finely 

 barred or mottled with rufous, most of the feathers having 

 a triangular buff spot at the extremity (Plate VI. Figs. 2 

 and 3). 



b. Feathers of the Sides and Flanks. 



By the first week in May the summer plumage of the 

 female Grouse is fairly complete, and many of the finely 

 mottled rufous and black autumn flank feathers are replaced 

 by widely and often irregularly barred buff and black feathers 

 similar to those of the chest. It must be particularly noted 

 that in none of the many females examined in breeding 

 plumage were the whole of the autumn flank feathers cast 

 or changed in the summer moult, a large proportion being 

 retained till the next (autumn) moult. The summer flank 

 feathers are produced in two ways, either by the gradual 

 rearrangement and change in the pigment of the autumn 

 feathers (Plate VI. Figs. 6-8) or by moult (Plate VI. Fig. 9). 

 In some birds the whole of the alteration in the plumage of 

 the flanks is produced by change of pattern in the old autumn 

 feathers, in others the change is entirely produced by moult, 

 while sometimes both methods are employed by the same 

 individual. In the former case the first indication of the 

 coming change may be observed in the beginning of the 



