EVOLUTION OF BIRD- SONG 



CHAPTER IV 



THE CALL-NOTE 



PAGES 



Erroneous descriptions of call-notes Chaffinch's cry pink not 

 a call-note Distress-cries of young are of use as call-notes 

 when the birds leave the nest Influence of gregariousness 

 and of fear Absence of call-notes from the songs of extrava- 

 gant singers : prevalence of them in songs of inferior singers 41-48 



CHAPTER V 



THE SIMPLEST SONGS 



Repetition of call-notes in the breeding season Construction of 

 strains by this method Examples Call-notes concluding 

 spring songs of skylark Movements of wings during song 

 Repetition of same intervals of pitch . . . 49-58 



CHAPTER VI 



NOTICEABLE INCIDENTS CONNECTED WITH BIRD-SONG 



Songs are generally uttered by males : exceptions Not until birds 

 have attained full size: exceptions Most frequently at 

 morning and evening : influence of weather Tendency to 

 rise in pitch with vehemence Only small birds properly 

 sing Singers arboreal birds generally Effect of living amid 

 foliage : on size, hearing, and voice Accent in songs 

 Singers clad in sober hues Development of the eyes in 

 detecting danger Necessity of leisure Labours of parent- 

 birds Laborious and stealthy birds habitually poor in song 

 Flight in song : for purposes of display Fluttering of wings 

 a means of address Ventriloquism Singing in chorus . 59-85 



