120 HILL BIRDS OF SCOTLAND 



may appear — on the neck ; and during March and April 

 there is a gradual moult of the winter dress, the breast 

 feathers being the last to appear. I have, however, seen 

 a specimen still in almost full winter plumage in mid- April. 

 The winter feathers are gradually lost until, in the last 

 days of May, the summer dress is almost complete. In 

 June the males generally show white tips to the feathers 

 and white feathers still in the tail coverts — where a single 

 white feather is retained until July. The white tips on the 

 back and breast of the male have by now worn off, and 

 the plumage is much darker. In the female the plumage 

 is more rusty and faded. During the last week of July 

 the blue grey feathers of autumn make their appearance, 

 and the feathers fall off the legs. In August both cock 

 and hen Ptarmigan change to their full autumn plumage, 

 and at the end of that month the feathers of the feet have 

 appeared. During September the feathers of both male 

 and female fade. In October the feathers of the tail and 

 wings are renewed, and it is stated that at the middle of 

 this month the first pure white feathers make their ap- 

 pearance, but as far as my personal experience goes, the 

 commencement of the assumption of winter plumage 

 takes place a full fortnight before this date ; and on the 

 last day of the month, I on one occasion flushed a cock 

 Ptarmigan in full winter plumage, so far as could be seen. 

 In November a few of the old feathers of autumn still 

 remain on the back and head — by now the feet are fully 

 covered. 



During December, as a rule, the white feathers of the 

 full winter plumage are assumed. I doubt whether INIr. 

 Millais is correct in his supposition that the assumption 

 of winter plumage varies with the mildness of the weather, 

 though I think that those Ptarmigan living at the highest 

 levels of their range retain their white dress further into 

 the spring than those having their homes on hills where 



