156 THE BIRDS OF HELIGOLAND 



entirety. When the change of colour is complete, the feathers are 

 of a deep glossy black, with broad pure white borders, and beautiful 

 sharply defined ferruginous spots at the sides, or transverse bands 

 of the same colour : their tips, too, which had been worn down to a 

 lanceolate shape, have now reassumed their formal beautiful rounded 

 form and enthety of margins. In this species the change of colour, 

 and simultaneous restoration of the edges of the feathers, extends 

 to the long posterior flight-feathers and outer wing-coverts ; the 

 white plumage of the breast and sides likewise undergoes alteration 

 of colour in this species ; for though the feathers of these parts 

 may be described as perfectly pure white, even in the winter plumage, 

 this colour is still further heightened to what we must term a 

 snowy white in the perfect wedding garment. A similar pheno- 

 menon is also observable in the formation of the breeding plumage 

 of the Snow Bunting ; nor can such a change be brought about by 

 the mere falling off of the rust-coloured edges of the feathers of the 

 head and breast. 



In the Knot, the change of colour to the beautiful breeding 

 plumage proceeds in a similar manner, except that in this species 

 the plumage of the upper parts lacks the broad white terminal 

 borders, and displays more of the beautiful ferruginous colour 

 in broad irregular spots at the sides and tips of the feathers. 

 The change of colour commences by the grey feathers of the winter 

 plumage becoming darker at the tips, and thence gradually becom- 

 ing blackish ; while, simultaneously, the subsequent ferruginous 

 markings make their appearance very faintly in the form of blurred, 

 whitish rusty grey irregular jjatches upon each web of the feathers, 

 or as stripes along the sides of them : by degrees this marking is 

 brought to perfection, the ground colour of the feathers passing 

 into a deeper black, while their markings assume a more definite 

 shape, and acquire a more intensely ferruginous tint. "\\'hen the 

 change of colour is complete, the feathers are of a pure glossy 

 black, the ferruginous patches and lateral markings of a very 

 intense colour, and sharply defined, while the worn and blunted 

 tips of the feathers have, in the course of these changes, gradually 

 reassumed their former beautifully rounded form and entirety of 

 margins. In this species the change of colour and form of the 

 feathers of the upper parts extends also to the greater and lesser 

 wing-coverts, and in part also to the posterior flight-feathers. 



The change of colour of the white lower parts of this species 

 passes into fexTUginous in a nearly similar manner, the latter colour 

 first appearing on the lower third of the feathers on both sides of 

 the shafts, as a very pale blurred film, and thence, increasing in 

 intensity, comes to spread itself over the whole surface of the 



