AVES 



427 



GallincB. With the doves are included the pigeons. About a 

 dozen species are found in America. None of these species is 

 very numerous. A century ago the passenger pigeon occupied 

 the region east of the Mississippi River in great flocks number- 

 ing millions of individuals. In the hope of saving the species 

 there has been for some years a standing offer of consider- 

 able sums of money for information of a nesting pair of this 

 species. It seems to be extinct. The domestic pigeon, in its 

 numerous varieties, has arisen by breeding and selection from 



Fig. 228. 



Fig. 228. Gold-finch (Astragalinus iristis trisHs). U. S. Dept. Agriculture Year-book, 1S98. 



the blue rock pigeon of the Old World. In cross breeding we 

 frequently get "reversions" to this type, showing that the 

 characters are being carried in the germ plasm even when the 

 combinations were not such as to make them appear in the body. 



In this group the young are fed with food digested by the 

 parent and regurgitated into the mouth of the helpless but 

 willing young. 



The Pici {woodpeckers) have two toes directed forward and 

 two backward in adaptation to the position they take in climb- 

 ing. The tail m-ay have stiff, pointed feathers with which they 



