COLOUK-CHANGES WITHOUT MOULTING 155 



which the changes of colour have been observed to proceed in two 

 or even three different ways in separate feathers of one indi- 

 vidual. We shall here confine ourselves to illustrating the cases 

 of the Knot, Dunlin, and especially the Sanderling to which we 

 might add that of the Curlew Sandpiper, and of many other 

 species whose breeding plumage is more or less of a rusty red 

 colour. In these, as is well known, the upper parts in the winter 

 plumage are of a pure or dingy ash-grey colour, the shafts of the 

 feathers being slightly less dark than the webs ; in the summer 

 plumage, however, the colour of these parts is a glossy black, with 

 a broad ferruginous border, in many cases accompanied by lateral 

 spots, which often pass into broad irregular band-like markings. 



In the Dunlin the change of colour develops itself in the fol- 

 lowing manner: In the ash-grey feathers of the back the shaft 

 first becomes black ; this colour spreads rapidly over the feather, 

 finally leaving only broad grey margins. The latter at first 

 change to a dull rusty grey, which, however, subsequently passes 

 into a beautiful ferruginous colour. At the same time the dull 

 ash-grey tips of the feathers pass into a whitish grey, their margins 

 being simultaneously rounded off to their former entirety. This 

 shows that these feathers also, which in winter are worn in such a 

 way as to assume a lanceolate shape, undergo a renovation of struc- 

 ture, and that their tips do not acquire their whitish colour simply 

 by fading. In the Dunlin this change does not extend to the long 

 posterior flight-feathers and the smaller outer plumage of the 

 wings, in which the colour only becomes somewhat blacker, and 

 the margins somewhat more even, but which do not acquire the 

 appearance of newly developed feathers, like those of the upper 

 parts of these birds. 



In the Sanderling we meet with an actual threefold change of 

 colour in the feathers of the upper parts of the winter plumage, each 

 one of which undergoes a transition from a uniform light grey to a 

 deep black, and from a beautiful ferruginous colour to a pure white. 

 The black, which forms the ground colour of the feathers of the 

 summer plumage, at first appears above their subsequently white 

 terminal markings, and advances with increasing intensity towards 

 the radical portions of the feathers. Soon dull rust-coloured lateral 

 borders are developed, side by side, with this ground colour, and a 

 blurred spot of similar colour is formed on each web of the feathers ; 

 these spots increase in size, become purer in colour, and partially 

 pass into transverse bands ; simultaneously with these changes the 

 dull light grey of the tips of the feathers becomes transformed to a 

 pure white ; not, however, by mere fading, but in this case also by 

 a restoration of the worn and blunted barbs to their previous 



