The Making of Species 



Those males which have not managed to secure 

 a mate are apt to persecute the females while 

 sitting on the eggs, to the detriment of these 

 latter. Natural selection, says Stolzmann, is 

 concerned with the well-being of the species 

 rather than of the individual. Hence anything 

 that would tend to lessen the number of males 

 would be a good thing for the species, so that 

 a peculiarity, such as bright plumage, which 

 renders the males conspicuous, or ornamental 

 plumes, which cause their flight to be slow, and 

 so leads to their destruction, will be seized upon 

 and perpetuated by natural selection. He points 

 out that the cock of one species of humming- 

 bird Loddigesia mirabilis has not only longer 

 tail feathers, but a shorter wing than the female, 

 and must, in consequence, find it comparatively 

 difficult to obtain food, and be more liable to fall 

 a victim to birds of prey than the hen. Stolz- 

 mann further suggests that the excessive pug- 

 nacity of male birds at the breeding season may 

 lead to the destruction of some individuals, and 

 so prove of advantage to the species. 



Several objections seem to present themselves 

 to this most ingenious theory. 



In the first place, there does not appear to 

 be any satisfactory evidence to show that more 

 cocks than hens are born. 



We may grant that a superfluity of cocks is 

 injurious to any species, since the unmated ones 



328 



