COURTSHIP IN BIRDS 263 



orange-yellow tarsi and feet above the water as 

 he performs his song and dance before the modest 

 duck. Incidentally, and perhaps accidentally at 

 first, he increases the display by the spurt of water 

 caused by the movement of the foot. In the 

 mxrganser this spurt of water has evidently be- 

 come of primary importance and is a most con- 

 spicuous feature, but it is plain that it arose from 

 an endeavor to display a colored foot. From a 

 display of color it has become a form of a 

 dance with an added mechanical feature. All 

 three factors of courtship are so intricately 

 mingled that is not always possible to treat of 

 a single one alone. 



Secondly the dance, using the word in the 

 broadest sense, is frequently employed in avian 

 courtship. In the simplest form the bird spreads 

 its tail, slightly opens its wings and puffs out its 

 feathers. This may be done rhythmically, and, 

 with each motion, the song is emitted, for song 

 and dance are almost always associated. The 

 bronzed grackle illustrates this simple dance and 

 at the same time very simple song. In slightly 

 more elaborate form the bird may also bob its 



