204 



ON THE CHANGE OF 



soon after moulting. The differences of colour in 

 the plumage of many birds in winter and summer, 

 Mr Whitear supposes may be referable to the 

 second way, or the acquirement of colour after the 

 structure of the feather itself has been completed, 

 I should, however, conceive, for example, when a 

 Ptarmigan changes the mottled colour of its plu- 

 mage to white, as it does in autumn, that a second 

 crop of white-feathers grow out; and that those 

 which previously existed in a mottled colour, also 

 become white. Therefore I infer, that the colour 

 in this instance may both accompany the growth 

 of some, and be changed after it has actually been 

 exhibited upon the substance of other feathers. 



The mottled-ashed colour of the spring-crop of 

 feathers, probably accompanies their growth, which 

 takes place whilst the winter or white plumage is 

 casting off ; and the autumnal crop seems to become 

 white from both processes, viz. the one forming with 

 the feather, the other after it has been matured. 

 Mr Whi tear's observations, therefore, may not, on 

 reflection, seem so novel as they appear at first 

 sight ; for no remark is more common, than that 

 the plumage of birds and coats of animals inhabiting 

 Arctic Regions, become thicker and whiter on the 

 approach of winter, without either feathers or hairs 

 being shed at this period. 



Respecting the changes of plumage in winter, 

 some good remarks will be found in the same volume 

 of the Linnean Transactions, by Captain Sabine, 



