THE BIRDS' AIR LINE 



and what was a good direction at one time may 

 not have been at another. 



HIGHWAYS AND HABIT 



It seems to be a law among bird travelers that 

 every bird must follow the route over which its 

 parents flew. This the ornithologist calls "in- 

 herited habit." It is just as though children born 

 in Arizona whose ancestors had emigrated across 

 the continent from New York City should go 

 to New York City over the route made by their 

 father, grandfather, and great-grandfather, and 

 perhaps great-great-grandfather. 



The first part of this route over which their 

 great-great-grandfather traveled may have led 

 to what was then the western border of civiliza- 

 tion at Pittsburgh. Then their great-grand- 

 father, like a true pioneer, pushed onward to 

 St. Louis. Here their grandfather was born, and 

 when he became a man he emigrated to the great 

 wheat-growing region of Dakota. In Dakota 

 their father was born and when he grew up he 

 moved to the copper mines of southern Arizona. 

 33 



