COLOUR-CHANGES WITHOUT MOULTING 163 



with. In a young spring specimen of the Grey Plover, in my col- 

 lection, the alteration of colour extends also to the plumage of the 

 upper parts, the brownish, ash-grey, 'smoky-pale' (rauchfahlen) 

 feathers acquiring at first a faint blackish colour, which extends 

 from their lower ends upwards, leaving crescentic ash-grey tips. 

 As the black colour becomes deeper and purer, these grey tips pass 

 into whitish grey colour. This alteration of colour spreads almost 

 simultaneously over the whole upper plumage of the bird, the long 

 broad flight-feathers alone excepted. In some of these latter the 

 change of colour has advanced so much that their marginal mark- 

 ings in form already approach those of the old birds ; others, again, 

 as yet only display narrow whitish edgings and tips, while a few 

 still retain their worn lanceolate shape and serrated margins. The 

 renovation of the feathers proceeds at exactly the same pace as the 

 alteration of colour, so that those feathers in which the latter 

 change has advanced furthest already possess beautifully rounded 

 tips and equal margins. In others, again, where the light markings 

 are only about half-completed, the edges in places still display 

 indentations ; while, finally, those in which the later markings are 

 still in the form of a narrow light border, have their edges indented 

 in the form of a continuous undulated line. 



What has been stated above in regard to the change of the 

 winter plumage of birds to their breeding dress is based throughout 

 on observations made on fresh examples, in which, by examination 

 of the inner cutaneous surface, it was possible to determine with 

 certainty whether moulting actually took place or not. In fact, it 

 is only material of this kind that ought to be employed in these 

 observations, and not examples belonging to species in which the 

 change of colour, instead of affecting all the feathers of a particular 

 part of the body equally at the same time, commences instead in 

 isolated feathers, while others are left in the unaltered colour of the 

 winter plumage at its completion. Where the change of colour 

 proceeds by gradational stages in this manner, the bird under 

 examination completely gives one the impression of being fully in 

 the moulting state, and, hi fact, examples of this kind have been 

 sent me by ornithologists of repute in proof of a moulting process. 

 A close and exact examination, however, at once reveals the fact 

 that all these scattered and newly coloured feathers are of perfectly 

 normal size ; nor do we find among them any others of half or 

 more than half their full growth, still within the dermal quill, as 

 would be the case if one were dealing with a moulting individual. 



There can be no doubt that an alteration of colour and renova- 

 tion of worn parts of the feathers takes place to a greater or less 

 extent in the great majority of birds. I have, however, limited 



