196 LAGOPUS CINEREUS. 



When much mottled with white the bird has a singular ap- 

 pearance, although it is not then nearly so beautiful as in the 

 grey plumage of September and the beginning of October. 



It appears to me that the moult takes place in the following 

 manner : The quills and tail feathers are changed only once in 

 the year, new ones beginning to appear about the middle of 

 summer, and the growth of all being generally completed by 

 the end of October. The middle tail-feathers are later than 

 the rest. The smaller feathers are changed four times every 

 year ; for white in winter are substituted dark grey, and black 

 on the greater part of the body, yellow and black on the head 

 in spring ; for these, yellow and black feathers in summer ; 

 then white and black, or the grey plumage, in autumn ; and 

 lastly pure white, completed by the end of December, and con- 

 tinuing until the beginning of spring. But at no period are 

 the colours characteristic of the seasons to be found pure, ex- 

 cepting occasionally for a short time in winter, although even 

 then it is very rare to find an individual without some coloured 

 feathers interspersed among the white. The Grey Ptarmigan 

 thus undergoes a perpetual moult, but so partial and gradual, 

 that no part is ever denuded. The feet are not so thickly 

 clothed in winter as some represent them ; nor are they more 

 so at any period than those of the Brown Ptarmigan or Red 

 Grouse. The case, however, is diiFerent with the Willow or 

 Red Ptarmigan, which has even the soles most densely covered 

 in vv^inter v^^ith bushy feathers. The notion of the coloured 

 plumage of summer and autumn being changed to white, not 

 by a substitution of feathers, but by a bleaching of those exist- 

 ing, is certainly untenable, not being in the least degree coun- 

 tenanced either by the appearances presented during the progress 

 of change, or by analogy. IMost of the wdiite feathers that 

 gradually spring up towards winter are found to be white to 

 the base, even while still partially enclosed in their sheaths. 

 The action of cold, then, in changing to w^hite previously 

 formed coloured feathers, does not apply to them ; although 

 it is very probable that cold produces the effect. Possibly 

 the reason why birds inhabiting equally cold regions, do not 

 become white in vrinter, is that they do not moult like the 



