20 EVOLUTION OF BIRD-SONG 



subsequent remarks upon the so-called noisy combats 

 of this bird, which are not rights at all, but affairs 

 of love. When sparrows really fight they make 

 but little noise, and then the sound just described 

 can be distinctly heard by an observer who is fairly 

 close to the combatants. 



It is to be regretted that the sounds made by 

 fighting birds have been, like those uttered by birds 

 disturbed on the nest, so little investigated or re- 

 corded by ornithologists. If Darwin's theory, that 

 the voice was first occasioned by the involuntary 

 contraction of muscles, consequent upon excitement 

 of the sensorium, is sound, it is equally true that 

 the greatest excitement of the sensorium is occa- 

 sioned by the attack or the mere presence of an 

 enemy (actual or supposed) ; for several animals, 

 such as cats, rabbits, and rats, will remain quiet when 

 in a trap, although enduring great physical suffering, 

 but, if approached by a person, they begin to make 

 an outcry. The same behaviour is noticeable in 

 many birds ; and in the reptile kingdom we often 

 observe the only attempts at vocal utterance to 

 be intended as expressions of intense anger or 

 fear. 



We may consider the voice to have been evolved 

 from a toneless puffing, indicative of anger, or from 



