1 34 E VOL UTION OF BIRD- SONG 



birds physically allied. The titmice, woodpeckers, 

 and cuckoos, whether of Europe or America, provide 

 illustrations of the theory already stated. Pigeons 

 and doves of Europe, America, and Australia respect- 

 ively have the same habit of cooing. The young of 

 the common pigeon, turtle-dove, and collared turtle- 

 dove squeak in much the same tones. The cry of 

 the chick of the common fowl greatly resembles 

 those of the young of the partridge and pheasant. 

 Birds of the same order, in Europe, America, and 

 Australia, have sometimes similar cries and often 

 similar manners. The young of the swan and duck 

 utter whistling cries similar to those of the adult 

 shelduck. 



Enough evidence has now been adduced to show 

 that frequently, if not in the great majority of 

 genera, the physical resemblances existing between 

 birds of a family have their analogues in similarities 

 of voice in the same species. The instances 

 mentioned in this connection are merely a small 

 fraction of those available ; yet so slight has been 

 the attention paid by observers to this most interest- 

 ing theme, that probably only a few of my readers 

 will be able to criticise from personal knowledge 

 the accuracy of my remarks on the voices of 

 British species. Enough, however, has been said 



