32 EVOLUTION OF BIRD-SONG 



warning - note is uttered, even at a considerable 

 distance, the strokes and complaining instantly 

 cease, and the chick will then remain quiescent for 

 a long time, or until the parent, by a changed note, 

 conveys to it an intimation that the danger is over " 

 {Naturalist in La Plata^ p. 89). 



I have during many years observed with some 

 amusement the warnings by which, at daybreak, old 

 house-sparrows silence their impatient young. The 

 sparrows have been accustomed to sleep, with their 

 broods, among creepers affording excellent shelter 

 immediately beneath the open window of my bed- 

 room. At morning twilight the young birds would 

 begin to cheep, and the old ones had some difficulty 

 in keeping them quiet. This they effected by utter- 

 ing various (and certainly, as they seemed to me, 

 rather suggestive) inflections of the favourite note 

 of warning and occasional song - note, tell. At 

 intervals of a minute or two the young would 

 recommence their importunate cries, and an old bird 

 would at once impose silence by a sharp note, 

 followed by various sotto voce admonitions. 



