TEE EVOLUTION OF ElRD-SONG. 237 



eaten by the Wren.* The jarring sound produced by the Night- 

 jar is only the repetition of a single note, a sort of " click" (like 

 the noise of breaking the wing-case of a large beetle), and this 

 note, rapidly repeated, reproduces the "blurring" of the wings 

 of a beetle, as they vibrate against the beak of a bird seizing it 

 in flight. The " tell-tell " cries of the Greenfinch, House Sparrow, 

 and some other finches seem to have been derived, like the " pink, 

 pink" of the Chaffinch, from the sounds made by these birds 

 in cracking cases of hard seeds, such as hemp. The "did-it" 

 cries of the Greenfinch, Chaffinch, Goldfinch, Linnet, Yellow 

 Bunting, and Cirl Bunting may have similarly originated in the 

 noises made in the breaking or moving of food within the beak. 

 Both of these cries — "tell, tell" and "did-it" — are always call- 

 notes, except sometimes in the House Sparrow, when the " tell, 

 tell" is used as an alarm. The hard cry, " clit," of the Hawfinch 

 is distinctly a brittle sound. This bird is a berry-breaker. The 

 notes of the Green Woodpecker are distantly like the sounds 

 produced by the strokes of his bill on dry, hollow wood. The 

 harsh tones of the Eails suggest the crashing of the tender shells 

 of the mollusks upon which they partly subsist. In the song of 

 the Starling are some "whirring" sounds (generally uttered near 

 the beginning of a phrase), which resemble the noise made in 

 pulling a large worm from his hole. The "cup, cup" calls of 

 the common fowl are not unlike the sounds made by it in eating 

 grain, which rattles within the beak of the bird. 



Males wishing to attract the females during the season of 

 courtship would make great use of the call-note. Some males 

 would certainly be able to utter this note in louder tones than 

 others, and would possibly on this account be more pleasing to 

 the other sex. It is also possible that in the rivalry between the 

 males various modifications would be introduced, and that those 

 uttering the most pleasing call-notes and variations would be 

 preferred by the females. Of these modifications those that most 

 closely resemble the noises made in eating or obtaining food 

 would very probably have been most pleasing to the females. A 

 male bird having only one note, or character-sound, in his voice 



* This is very doubtful, the insect prey of the Wren being much more 

 minute. — Ed. 



