Chap. XV L Birds — Young like Adult Males. 479 



plumes with more strongly contrasted colours ; nevertheless he 

 undertakes the whole duty of incubation. 24 



I will specify the few other cases known to me, in winch the 

 female is more conspicuously coloured than the male, although 

 nothing is known about the manner of incubation. With the 

 carrion-hawk of the Falkland Islands (Milvayo leucurus) I was 

 much surprised to find by dissection that the individuals, which 

 had all their tints strongly pronounced, with the cere and legs 

 orange-coloured, were the adult females; whilst those with 

 duller plumage and grey legs were the males or the young. In 

 an Australian tree-creeper (Climacteris trythrops) the female 

 differs from the male in " being adorned with beautiful, ra- 

 " diated, rufous markings on the throat, the male having this 

 " part quite plain." Lastly, in an Australian night-jar "the 

 " female always exceeds the male in size and in the brilliance 

 " of her tints ; the males, on the other hand, have two white 

 " spots on the primaries more conspicuous than in the female." Z5 



We thus see that the cases in which female birds are moro 

 conspicuously coloured than the males, with the young in their 

 immature plumage resembling the adult males instead of the 

 adult females, as in the previous class, are not numerous, though 

 they are distributed in various Orders. The amount of differ- 

 ence, also, between the sexes is incomparably less than tbat 

 which frequently occurs in the last class ; so that the cause of 

 the difference, whatever it may have been has here acted on the 

 females either less energetically or less persistently than on the 



24 Mr. Sclater, on the incubation than that of the male ; the head of 

 of the Struthiones, ' Proc. Zool. Soc.,' the male is of a rich dark bronzed 

 June 9, 1863. So it is with the colour, and his back is clothed with 

 Rhea darwinii : Captain Musters says finely pencilled slate-coloured fea- 

 (' At home with the Patagonians,' thers, so that altogether he may be 

 1871, p. 128), that the male is considered as the more beautiful of 

 larger, stronger and swifter than the two. He is larger and more 

 the female, and of slightly darker pugnacious than the female, and 

 colours ; yet he takes sole charge of does not sit on the eggs. So that 

 the eggs and of the young, just as in all these respects this species 

 does the male of the common species comes under our first class of cases; 

 of Rhea. but Mr. Sclater (' Proc. Zool. Soc' 



25 For the Milvago, see 'Zoology 1866, p. ISO) was much surprised 

 of the Voyage of the Beagle, ' to observe that the young of both 

 Birds, 1841, p. 16. For the Climac- sexes, when about three months old, 

 teris and night-jar (Eurostopodus), resembled in their dark heads and 

 *ee Gould's ' Handbook to the Birds necks the adult males, instead of 

 :f Australia,' vol. i. pp. 602 and 97. the adult females; so that it would 

 The New Zealand shieldrake ( Ta- appear in this case that the female3 

 dorna variegata) offers a quite ano- have been modified, whilst the males 

 /nalous case ; the head cf the female and the young have retained a 

 is pure white, and her back is redder farmer state of plumage. 



