50 ORGANIC EVOLUTION 



springs from the ground and on whistling wings sweeps out 

 on the first loop of a spiral which may take him three hun- 

 dred feet away from the ground. Faster and faster he goes, 

 louder and shriller sounds his wing song; then, after a 

 moment's pause, with darting, headlong flight he pitches in 

 zigzags to the earth, uttering as he falls a clear, twittering 

 whistle. He generally returns to near the place from which 

 he arose, and the peent is at once resumed as a preparation 

 to another round in the sky." 



In most birds the males are colored more conspicuously 

 than the females, and in many species the males show 

 special development of certain feathers, or of spurs, or comb 

 and wattles, which are less marked or wholly absent in the 

 females. 



Wallace has called attention to the fact that natural 

 selection could hardly allow the females of the birds, which 

 are chiefly occupied in brooding the eggs and caring for 

 the young, to be conspicuously colored because of the dan- 

 ger to the nest and young that would thus result. It has 

 also been suggested that brilliant coloration in the male 

 may aid him to serve as a decoy to distract attention from 

 the female and the nest. Unfortunately for both of these 

 suggestions, some brilliantly colored males help the female 

 in brooding the eggs and caring for the young. 



Among the spiders also are seen good examples of 

 certain courting colors and habits (Plate 28), 1 Here the 

 males of many species have brilliantly colored legs or have 

 other portions of the body brightly colored. The eyes also 

 are like splendid little jewels of different shades of red 

 and green and blue. As the diminutive male approaches 

 the often much larger female, he advances with a swaying, 



1 Compare also Plate 85. 



