and Colour-change in Birds. 467 



in spring, we find the white feathers on the breast in all 

 stages of colour between white and black. Messrs. Allen and 

 Stone would have us believe that these are all new feathers, 

 which have grown of that colour, and which will always 

 remain of that colour. I have shot and examined many 

 birds in the full summer dress, and it is very rare to find 

 more than one or two feathers in this half-and-half stage on 

 any single individual. What, then, has happened to the 

 parti-coloured feathers so common on birds in spring ? 

 Have they been again cast ? Moreover, it should be noticed 

 that while feathers of various shades are found on the breast, 

 the back is assuming, by direct moult, the full summer 

 plumage, showing no tendency to any half-measures. But 

 surely, if parti-coloured feathers are growing on the breast, 

 and we suppose they are not going to be renewed, in such a 

 case the bird would never acquire a purely black breast, and 

 we should meet with the phenomenon of an individual with 

 full breeding-dress on the back and only an apology for 

 it on the breast. And if, on the other hand, the parti- 

 coloured feathers are to be moulted again, we should find 

 the bird having tw^o moults in about six weeks, which is, to 

 say the least, a very unlikely occurrence. That is about 

 the limit of evidence that can be obtained from skins alone ; 

 but I have kept several specimens of this species in captivity, 

 in a large open aviary, and have watched the moult till 

 it -was completed, frequently catching up and examining 

 the birds, and although I have never actually marked any 

 individual feather, yet the observations seemed to me so 

 conclusive, and at the same time so obvious, that I did 

 not realize that there were still doubts on the subject. The 

 moult is first noticeable by several feathers showing a slightly 

 darker tinge ; day by day more dark feathers show on the 

 breast, and, as the moult becomes advanced, fewer parti- 

 coloured ones^, till, finally, the bird has assumed its full 

 summer plumage. 



That the white feathers actually do change may be further 



* See V. Fatio, Mem, Soc. de Pliys. et d'Hist. Nat. de Geneve, xviii. 

 (1866) p. 240. 



