Ch. XVI. THE YOUNG LIKE ADULTS OF SAME SEX. 219 



and sex ; but it would not be worth while to attempt to 

 follow out these complex relations. 



Class VI. The young in their first ]^himage differ 

 from each other according to sex ; the young males 

 resembling more or less closely the adult males, and the 

 young females more or less closely the adult females. — 

 The cases in tlie present class, though occurring in 

 various groups, are not numerous ; yet, if experience 

 had not tauofht us to the contrary, it seems the most 

 natural thing that the young should at first always 

 resemble to a certain extent, and gradually become 

 more and more like, the adults of the same sex. The 

 adult male blackcap (Sylvia atricaj)illa) has a black 

 head, that of the female being reddish-brown ; and I 

 am informed by Mr. Blyth, that the young of both sexes 

 can be distinguished by this character even as nestlings. 

 In the family of thrushes an unusual number of similar 

 cases haye been noticed; the male blackbird (Turdus 

 merula) can be distinguished in the nest from the female, 

 as the main wing-feathers, which are not moulted so 

 soon as the body-feathers, retain a brownish tint until the 

 second general moult.'^^ The two sexes of the mock- 

 ing bird (Turdus polyglottus, Linn.) differ yery little 

 from each other, yet the males can easily be distin- 

 guished at a yery early age from the females by shew- 

 ing more pure white.^^ The males of a forest-thrush 

 and of a rock-thrush (viz. Orocetes erythrogastra and 

 Petrocincla cyanea) have much of their plumage of a 

 fine blue, whilst the females are brOwn ; and the nestling- 

 males of both species have tlieir main wing and tail- 

 feathers edged with blue, whilst those of the female are 



46 Blyth, in Charlesworth's ' Mag. of Nat. Hist.' vol. i. 1837, p. 362 ; 

 and from information given to me by him. 



'*'" Audubon, ' Ornith. Biography,' vol. i. p. 113. 



