232 VERTEBRATES I BIRDS. 



of a mile a minute. The migrations are wholly for the 

 purpose of procuring food, and hence do not take place 

 at any particular season of the year. Pigeons go wher- 

 ever they can find a supply of grain, rice, or nuts. The 



Fie. la& 



Wild Pigeon, E. migratoria, Sw. 



numbers that sometimes move together are vast beyond 

 conception. Millions associate in a single roost, com- 

 pletely filling a forest for thirty or forty miles in length 

 and several miles in breadth, and literally loading and 

 breaking down large trees. From their roosts they fly 

 off hundreds of miles, in some cases, to feeding-grounds, 

 and return at night. Sometimes, in their migrations, 

 they fill the air like a cloud, and thus continue to pass 

 for a whole day, and even for two or three successive 

 days. The nest is built on high trees, and is composed 

 of a few dry sticks and twigs crossing each other, and 

 supported by the forks of the branches ; and more than 

 a hundred nests are sometimes placed on a single tree. 

 The Genus Zenaida, represented by the Zenaida Dove, 

 Z. amabiiis, Bonap., of the Florida Keys, has the tail 

 short, rounded, and the orbits feathered. 



