RED GROUSE 
plumage being unnecessary in the localities it inhabits, the winter -moult 
had been gradually dropped. 
Now this is the case with the female only, and we find the male, for no 
very apparent reason, changing his newly acquired black and buff-barred 
autumn -plumage for a winter -garb of chestnut and black. Dr E. A. Wilson, 
the Field Observer to the Grouse Disease Inquiry, who has for some years 
been studying the plumage question, has suggested a possible explanation 
of this strange want of agreement. He believes that the autumn -plumage 
of the male grouse, which in many respects closely resembles the summer- 
or breeding-plumage of the female, was originally a breeding-dress, 
but that owing to disease it has gradually been deferred till the end of 
May or beginning of June. This postponement, at first a matter of neces- 
sity, has now become an established habit. He says : “ It appears almost 
as though the pathological postponement of the moult, which is, after all, 
nothing but a sign and a symptom of disease, has gradually developed 
into a normal habit in the life of a bird ; and one is led to think that this 
habitual disability in the cock grouse, which results from Strongylosis 
during the nesting, courting, and breeding -season (a disability which 
causes the death of about eight cocks to every hen in April and in May) 
may have caused the alteration in the season of the moult, simply because 
the vis vitce of the cock bird, insufficient as we now know it to be at the 
close of winter for the ordinary calls of reproduction, would be still more 
disastrously insufficient if preceded by an early moult. 
“ At the present time the cock undoubtedly breeds in the winter - 
plumage, without any further acquisition of new feathers, and, as has 
recently been pointed out by Mr Ogilvie-Grant, what have been re- 
garded as new ‘ spring -feathers ’ on the neck by Mr Millais, are in fact 
the old autumn -feathers, which on that part of the body do not become 
worn or faded.” 
The changes of plumage in the genus Lagopus are the more difficult 
to understand from the fact that the species are subject to great individual 
variation, and this is especially the case with the red grouse. These 
variations or types of plumage may be classed under three headings 
in the male, and under five in the female, but it should be remembered 
that when the male is in autumn -plumage (June to October), and the 
female is in summer-plumage (April to July), and the greater part of 
the plumage of the upperparts, chest and sides of the body is black, 
margined and barred with tawny -buff, all individuals, be they male or 
45 
