346 A HISTORY OF BIRDS 



the performance with the greatest unconcern, one of the males 

 goes off for a time and returns with a sand-eel in his bill, after 

 which he again struts about with wings and head in the same 

 position, offering the sand-eel from one to another of the females 

 as he passes along unnoticed, until at last he meets one who 

 accepts his offering, when he sits down beside her to settle their 

 arrangements for the season." 



Having ah^eady given many instances of the courtship of 

 birds in Chapter X, we may now proceed to refer to the 

 objections which have been raised against the theory of sexual 

 selection, and to set down a few facts in vindication thereof. 



The arguments put forward by Dr. Alfred Russel Wallace 

 and Mr. H. Eliot Howard are each, in their way, noteworthy. 

 And these alone will be considered here. 



Dr. Wallace contends, and he has found an able champion 

 in the naturalist De Varigny, that the brilliant colours of males 

 are to be regarded as the outcome of excessive vigour — the 

 method of expending the surplus energy over and above what 

 is required for the purposes of procreation. In the females^ 

 as a rule, there is no surplus of this kind. Where such exces- 

 sive vigour has been developed by females which breed, like 

 Pheasants, in exposed situations, they have been exterminated 

 by natural selection, their bright colours making them a mark 

 for prowling enemies ; where, however, the females nest in holes 

 there they have acquired this extravagance of habit unchecked. 

 No facts which support the hypothesis of excessive vigour have 

 yet been brought forward. The dull plumage of females of 

 say, Ducks and Pheasants, may very probably be due to the 

 action of natural selection as suggested. But it must be re- 

 membered that there are many species wherein the females 

 are markedly duller than the males, and wherein the sitting 

 females cannot be regarded as exposed to danger through 

 discovery, when in the nest, by predatory foes. The Common 

 Sparrow affords a case in point ; and many other Finches 

 furnish similar evidence. 



Furthermore, he objected to the interpretation of the evolu- 

 tion of the Peacock's train as given by Darwin on the grounds 

 that it implied a rigid and uniform standard of beauty on the 

 part of the females such as is not to be met with even in human 

 society, since the train of the Peacock shows remarkably slight, 



