Viu E VOL UTION OF BIRD-SONG 



CHAPTER IV 



THE CALL-NOTE 



PAGES 



Erroneous descriptions of call-notes — Chaffinch's cry phik 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 



