W. p. PYCRAFT : NESTLING BIRDS. 105 



every g'radation between striped and whole-coloured 

 young. 



The Gulls and Plovers show these intermediate grada- 

 tions extremely well. In their downy state the young of 

 these birds appear to be more or less irregularly mottled; 

 but if these markings are more carefully studied, they will 

 clearly be found to have been derived by the breaking 

 up of strij^es. The Skuas have passed beyond the mottled 

 into the whole-coloured stage, while other whole-coloured 

 nestlings, such as. those of the Rails, show in certain 

 lights distinct traces of the earlier striped plumage. 



Are these differences due to the needs of protection, or 

 to the inevitable progress of a striped plumage through a 

 mottled stage to one of uniform colour ? A comparison 

 of a series of young Gulls and Terns and of Plovers, such 

 as the Lapwing, Oyster-catcher, and Ringed Plover- — I use 

 the term Plover in a wide sense — seems to show that 

 protective coloration is still a factor at work. 



When the young remain for a long while helpless the 

 down is always of the whole-coloured kind, and this, for 

 many reasons, one would expect ; and especially so if the 

 striped down-plumage is a protective device, for this would 

 benefit active young which scatter when alarmed, whereas 

 this same strijjed livery displayed in a mass would serve 

 only to betray the wearers thereof. Further, the down of 

 most nestlings of the helpless type is of a very degenerate 

 character, and the loss of the original pigmentation has 

 followed as a consequence of this degeneration. 



While immature birds are commonly duller in hue than 

 their parents, there are certain cases wherein the downy 

 nestling displays vivid colouring, which is in no way 

 represented during later life. 



The young of the Great Crested Grebe, for example, has 

 in the middle of the crown a brig'ht vermilion, heart- 

 shaped patch of bare skin. Does this patch of colour 

 serve any purpose, or is it merely a precociously-developed 

 ornament ? And the same question may be asked of the 

 curious, fleshy, scarlet papillse which adorn the face of 



