BIRDS 95 



are found in the wing-feathers of birds, and are only 

 exposed during flight. It is the same with colours 

 in the tail, which only meet the eye when it is spread. 

 Brighter colours are, as a rule, not found on the 

 upper parts of females, but may be developed in the 

 male ; because even if they carry destruction to many 

 of them, the species is in no danger, as the males 

 are always in excess. 



But, it will be asked, how can peculiarities of 

 colouring serve as marks of the species, when these 

 generally act at a distance ? How, for instance, can we 

 explain the eyes in the peacock's tail ? The explanation 

 given above seems to fail here ; and as we have 

 rejected that form of sexual selection according to 

 which " the finest eyes " charm the females most, we 

 must find a better explanation. 



We have seen that it is very important for all 

 animals to have specific characters, so that the sexes 

 may easily find each other, and be not liable to make 

 the fatal error of confusing their fellows with their 

 foes. It is clear that the specific colours of many 

 species have arisen in this way as means of recognition. 

 But it is also clear that visible characters do not suffice 

 in the case of the birds. The light creature soars high 

 up into the air, and is not tied to the ground like the 

 mammal. With its keen eyes it looks down on a 

 broad expanse of territory. But how can the finest 

 eyes pierce through the canopy of leaves to find its 

 fellows sitting beneath? And how can the nocturnal 

 birds, such as the owls, find each other so well ? Even 

 if their eyes can pierce the darkness, they must fail 



