152 THE BIRDS OF HELIGOLAND 



of the birds of the Snipe species which had become indented or ser- 

 rated through wear, were restored to their former perfect condition. 



The change from the winter plumage to the breeding dress 

 without moulting is accomplished in three different ways. The 

 simplest of these consists in the shedding of the edges of the 

 feathers of the winter plumage, which are mostly of a rusty grey 

 colour ; this process goes on during the spring months, and takes 

 place in the case of the Chats, the Shorelark, the Finches, 

 Buntings, and many other species. It is most easily seen in 

 those species whose breeding plumage displays a pure and glossy 

 black, e.g. the head of the Snow Bunting, the head and fore-neck 

 of the Reed Bunting, the head and back of the Brambling, the 

 black head and the breast-markings of the Shorelark, the head and 

 back of the Stonechat, the black plumage of the Common and Black 

 Redstarts, and in a large number of other species. With the aid of 

 a magnifying lens of moderate power, one can quite distinctly 

 follow the course of this change in the feathers of the back of the 

 Snow Bunting. The light tips of the barbs of these do not all 

 fall off simultaneously along their whole length down to the black 

 portion, but gradually and unequally, so that in one and the same 

 feather rusty grey plumules, as yet in their entire length, may 

 be found mixed with others reduced to half or even a quarter 

 of their original length. Finally, there remains only a fairly regular 

 fine light edge, which, however, also vanishes when the breeding 

 garb is complete. The inconspicuously coloured edges of the 

 smaller feathers of the plumage disappear in a similar manner in 

 all the above-named species, thereby exposing the invariably purer 

 and handsomer colours of the breeding plumage. 



A less simple manner, in which the change from the winter 

 plumage to the breeding garb is accomplished, consists, so far as I 

 have been able to determine without the help of a microscope, in 

 a peeling off' of the separate barbs of the feathers, whereby these 

 are stripped of a thin inconspicuously coloured envelope, so that 

 the purer and finer colour previously concealed beneath the latter 

 becomes exposed. This colour is in many cases extremely beautiful, 

 e.g. the carmine of the Linnet and Mealy Redpole, or the azure blue 

 of the Bluethroats (Sylvia leucocyana, S. wolfii and 8. suecica). In 

 other cases, as in the Pied Wagtail and the Pied Flycatcher, a dusky 

 slate grey or rusty grey in this way gives place to a pure glossy 

 black. In the Rock Pipit the olivaceous brown of the winter 

 plumage vanishes before a lighter greenish grey, and, in the feathers 

 of the neck and upper breast, is replaced by a faint vinous tint. In 

 the course of this process, as the facts of the matter prove, the 

 texture of the feathers also undergoes an alteration ; their barbs, 



