186 SEXUAL selection: birds. PartIL 



Although many young birds belonging to various 

 orders thus give us a glimpse of the plumage of their 

 remote progenitors, yet there are many other birds, both 

 dull-coloured and bright-coloured, in which the young 

 closely resemble their parents. With such species the 

 young of the different species cannot resemble each other 

 more closely than do the parents ; nor can they present 

 striking resemblances to allied forms in their adult 

 state. They give us but little insight into tho. plumage 

 of their progenitors, excepting in so far that when the 

 young and the old are coloured in the same general 

 manner throughout a whole group of species, it is pro- 

 bable that their progenitors were similarly coloured. 



We may now consider the classes of cases or rules 

 under which the differences and resemblances, between 

 the plumage of the young and the old, of both sexes or 

 of one sex alone, may be grouped. Rules of this kind 

 were first enounced by Cuvier; but with the progress 

 of knowledge they require some modification and ampli- 

 fication. This I have attempted to do, as far as the 

 extreme complexity of the subject permits, from infor- 

 mation derived from various sources ; but a full essay 

 on this subject by some competent ornithologist is 

 much needed. In order to ascertain to what extent 

 each rule prevails, I have tabulated the facts given in 

 four great works, namely, by Macgillivray on the birds 

 of Britain, Audubon on those of North America, Jerdon 

 on those of India, and Gould on those of Australia. I 

 may here premise, firstly, that the several cases or rules 

 graduate into each other ; and secondly, that when the 

 young are said to resemble their parents, it is not 

 meant that they are identically alike, for their colours 

 are almost ahvavs rather less vivid, and the feathers 

 are softer and often of a different shape. 



