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—Lodazgesta mzrabzlis—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 
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