YOUNG BIRDS AND RECORDS OF THE PAST 125 



groups of birds have come to rely either on protective 

 coloration alone, or at most they run for a few yards 

 and then squat down, instead of trusting to the uncertain 

 safety of precocious flight : and with this change of tactics 

 the evidence of the earlier arboreal habits has been swept 

 away. 



The young of aquatic birds obviously do not need to 

 seek safety in flight. Concealment amid reed-beds or 

 other aquatic vegetation afiords them ample protection. 

 Indeed, among all these non-flying, nidifugous young we 

 find the development of the quills has been retarded rather 

 than accelerated, so that they appear together with the rest 

 of the body-plumage when the downy stage is finally passed. 



Among the ducks, however, the whole wing remains 

 in its downy state until the bird is almost completely 

 feathered as to the rest of the body : more than this, the 

 growth of the bony skeleton is also retarded, so that for 

 a brief period after they are feathered young ducks have 

 the appearance of flightless birds in which the wings 

 have been reduced to mere down-clad vestiges, recalling 

 the condition which obtains, say, in apteryx or the emu. 



Herein the conditions, as compared with the young 

 chick, are exactly reversed, for in the latter the wings 

 are large and fully feathered, while the rest of the body 

 is down-clad. Here we get the extremes of development 

 met with in the wings of nestling birds : in the one case 

 the growth of the quills has been greatly accelerated to 

 provide a means of escape from the numerous enemies 

 which beset ground-dwelling birds living in areas favourable 

 to carnivores of all types ; in the other flight has been 

 retarded, as if to compel the young to take the more secure 

 cover afforded by the reedy growths of pools and streams. 



Now let us turn to the consideration of nestlings of 



