THE SONG OF BIRDS. 495 



it breathes through its whole frame and flesh, and glows 

 with air in its flying ; like a blown flame it rests lipon the air, 

 subdues it, surpasses it, outraces it ; is the air, conscious of 

 itself, conquering itself, ruling itself." 



The Song vf Birds. — Singing is a natural expression of 

 emotional wealth. The song rises in the bird, Richard 

 Jefferies said, as naturally as the sap in the bough. It is 

 richest at the climax of emotion in the breeding season, and 

 is always best and often solely developed in the males. But 

 song in any excellence is the gift of comparatively few birds, 

 though nearly all have a voice of some sort, often so 

 characteristic that the species may be recognised by its call 

 alone. The twittering of swallows, the cawing of rooks, the 

 melancholy voice of the sea-mew, the lapwing's prayerful 

 cry, the weird call of the curlew, are familiar to most of us. 

 A few birds, notably the parrot and the jackdaw, can be 

 taught to pronounce articulate words ; but the power of 

 imitation is widespread among birds, the case of the canary 

 learning the song of the nightingale being a well-known 

 instance. This power of imitation has some importance in 

 relation to the general theory of instinct, for the song of all 

 birds is probably in great part imitative, though to a certain 

 extent the musical talent is really inherited. Young birds 

 taken away from their nests when very young, so that they 

 have hardly heard the voices of their kind, will sing the 

 characteristic song of the species, but do so imperfectly. 



The vocal organ of Birds is not situated in the larynx as it 

 is in Mammals, but in the syrinx — a song-box at the base of 

 the windpipe. In this syrinx there are vocal membranes or 

 folds of skin ; their vibration as the air passes over them 

 causes sound ; the note varies with the muscular tension of 

 the folds, with the muscular state of the complex associated 

 parts, and with the column of air in the windpipe. 



Courtship. — Birds usually pair in the springtime, but 

 there are many exceptions. Some, such as the eagles, live 

 alone except at the pairing time ; others, notably the doves, 

 always live together in pairs, and are thus remarkable for 

 the constancy and refinement of their affections ; many, 

 such as rooks, parrots, and cranes, are sociable gregarious 

 birds. A few, like the fowls, are polygamous ; the cuckoo 

 is polyandrous. 



