28 EVOLUTION OF BIRD-SONG 



is in sight But I have known them utter the same 

 sound when a jackdaw attacked their young. I 

 have often discovered the presence of a hawk from 

 hearing the starlings utter sounds which I will term 

 their " hawk-alarm," namely, cries sounding like cack- 

 cack. The starling has other notes also employed to 

 express alarm ; but this cry is certainly of general 

 and almost exclusive use when a hawk suddenly 

 appears. But I cannot say that it announces any 

 particular species of hawk, for I have heard it em- 

 ployed by starlings which were approached by a 

 tame kestrel, and by others at which a tame pere- 

 grine falcon swooped ; and the wild sparrow-hawk is 

 always announced by this exclamation. 



Blackbirds utter a loud metallic chirp when their 

 nests or young are approached by a cat, or when 

 they find an owl. A friend informed me that he 

 observed in his garden a number of blackbirds utter- 

 ing this cry very noisily near a cucumber-frame, in 

 which a female blackbird had accidentally become 

 enclosed. The captive was liberated, and the outcry 

 immediately ceased. I trained a little Dandie terrier 

 to recognise the cries which blackbirds in the garden 

 uttered when a cat was near their nest. This was a 

 frequent occurrence ; and as soon as the birds began 

 to rate their enemy, the dog would run into the 



