COLOURS AND PATTERNS OF BIRDS 103 



plumage is well formed at the time of hatching. In most birds 

 this first plumage has been suppressed entirely. In some of the 

 ducks, traces of the first plumage are found ; in most of them, as in 

 all the game birds, only the second plumage appears. In the 

 nestling pigeon, even the second plumage is degenerate and appears 

 only as a few scattered thread-like hairs, whilst this nakedness is 

 carried still further in nearly all the singing and perching birds. In 

 kingfishers, hornbills, swifts and humming-birds, there is no down 

 either in the nestling or in the adult, and the final contour feathers 

 appear early, so that the nestlings look like small spiny hedgehogs. 

 In hawks, eagles and vultures, on the other hand, although there is 

 a thick coating of down, it is composed almost entirely of feathers 

 which are afterwards replaced by the true down feathers of the adult ; 

 whilst in cormorants, the nestling downy plumage is altogether a fore- 

 runner of the adult downy feathers. 



It is not easy to form a general picture of the differences in colora- 

 tion between young birds and adults. The number of species of 

 birds is enormous, and although naturalists have devoted them- 

 selves to collecting examples in the field and forest, and to studying 

 them in museums, with the greatest patience and enthusiasm, there 

 remain many gaps in our knowledge, especially as to the changes 

 that individuals pass through in the course of their lives. Nature 

 seems to have lavished colour and pattern on the group, and to be 

 displaying her eccentricities, her exuberance and her whimsicalities, 

 rather than pursuing her usual orderly course. None the less it is 

 just possible to get an idea of a general course of events, an idea, 

 however, which must not be taken too rigidly, for there are probably 

 exceptions which cannot readily be brought into harmony with it. 



The colours of young birds are never brighter than those of their 

 parents. There is one apparent exception to this, but it applies to 

 the skin and not to the feathers. The naked and helpless nestlings 

 which are reared in trees, in holes, and other rather dark and well- 

 concealed places, are provided with heads that seem much too large 

 for their bodies, and with mouths that seem too large for the heads. 

 The mouths are actually enormous, and when the parent birds come 

 carrying their spoil of worms or grubs, the huge opening seems even 

 larger than it is, because it is marked at the sides with bright patches 

 of colour, sometimes yellow as in the starling, sometimes white. The 

 inside of the mouth is also brightly coloured, yellow perhaps being 

 the most common tint, as in larks and thrushes, but red and yellow 

 in some of the titmice. These colours fade away as the young birds 



