1920 Townsend, Courtship in Birds. 391 



most marked in the courtship season and are probably of court- 

 ship origin. The V-shaped pose of the tail-feathers of the Bronzed 

 Grackle is probably of the same nature for it is discarded in mid- 

 summer. 



Both the Savannah and the Vesper Sparrow stand or walk on 

 the ground and elevate and sometimes vibrate their wings rapidly 

 above their backs. They also fly slowly a short distance above 

 the ground with head and tail up and wings rapidly fluttering and 

 deliver their song. 



The rapid headlong plunges of the Nighthawk may be classed 

 as a display of motion, a form of the dance. Incidentally, and 

 perhaps accidentally at first, a loud booming sound is produced 

 by the rush of air through the wing feathers. This instrumental 

 music is now the important feature, although the dance is by no 

 means a negligible one. The Raven turns a rolling-over somer- 

 sault in the air, and the Marsh Hawk plunges from a great height, 

 loops the loop or turns a sidewise somersault. The Chat with 

 dangling legs dances crazily about in the air, and the Kingbird 

 executes a series of zig-zag and erratic flights, emitting at the same 

 time a harsh double scream. This is a true courtship flight song 

 but it is neither graceful to our eyes or pleasing to our ears. The 

 taste of the Kingbird in these matters appears to us to be poor. 



The impossibility of treating in turn only one of the primary 

 divisions — display, dance and song — is well shown by these ex- 

 amples. The case of the courtship of the Heath Hen is still more 

 difficult for all three factors are inextricably mingled. I have 

 already alluded to the display of the neck-sacks of this bird, 

 orange in color and shape, a very striking and beautiful feature, 

 but secondary or incidental to the production of 'song' to be 

 described later. The erection of the neck-wings which ordinarily 

 help cover the deflated neck-sacks, the spreading and erection of 

 the tail, the vibration of the down-stretched wings, the pirouetting 

 and turning of the body and the rapid stamping of the feet in this 

 species are all forms of the dance. 



Lastly, in this brief review and rough classification of the court- 

 ship actions of birds, the song is to be considered. By song I do 

 not mean necessarily a melody or musical strain pleasing to human 

 ears — although many of these produced by the higher species of 



