1010.] PLUMAGE OF THE RED GROUSE, 1003 



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. 

 Moreovei', it so happens that in autumn, when birds are being shot 

 in lai'ge numbers, the survivors of tlie worst two months of the 

 year for C! rouse-disease moi'tality, that is, the survivors of May 

 and June, are all convalescing ; Init they are convalescing with 

 their plum;ige-clianges all retardeil 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 feathei's 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 ai'e frayed and worn and the colour faded, 

 showing that they have survived from the previous winter- 

 plumage ; whereas in the other bird they are hardly free of the 

 scaly sheaths in which they grew, and are really precocious 

 feathers of the coming winter-plumage. This is only one of the 

 many traps which I'esult from the deleterious influence which 

 disease exerts upon a bird's capacity for feather-growth and 

 replacement and so upon the regularity of its moult. 



There is another point to which attention must be drawn before 

 entering upon a systematic description of the monthly changes of 

 feather in the cock Grouse. It is as to whether the autumn- 

 plumage of the cock can be cori-ectly described as an " Eclipse " 

 plumage, comparable as it obviously is in character with the 

 Spring breeding-plumage in the hen, but appearing just two 

 months later and after the breeding-season. In each sex the 

 general change from winter to summer may be described as a 

 change from a. more richly pigmented, darker, black and chestnut, 

 or rufous-chestnut plumage with rather fine transverse black 

 markings, sometimes almost vermiculate in character, to a less- 

 richly pigmented, paler, buft'or rufous-bufi'ortawny-bufF plumage 

 with characteristically broad black bars and transverse markings. 



To each sex, moreover, the characteristic buff and black broad- 

 banded summer-plumage is given its special appearance on the 

 dorsal aspect by the growth of feathers with large l)lack centres 

 and a few buff or tawny-buff subterminal bars of considerable 

 width and a terminal border or spot of the palest buff, which is a 

 very conspicuous feature on the back of most hens, and often only 

 less conspicuous in the cock. In the cock, however, this plumage 

 appears just two n>onths later, and is less beautifully developed 

 than in the hen. 



There is without doubt a general broad resemblance first 

 between the cock and the hen Grouse when the former is in its 

 "winter-plumage" and the latter in its "autumn-plumage"; 

 and, secondly, between the cock and the hen Grouse when the 

 former is in its " autumn-plumage " and the latter in its "spring- 

 plumage." 



The per^ilexing fact is that these general resemblances are not 

 synchronous in the two sexes, a peculiarity first discovered by 



