BIRD TRAVELERS 9 



chimney swift fell through an opening in a chimney 

 into a room of a house located in Meriden, New 

 Hampshire. Mr. E. H. Baynes was in the room and 

 placed on the bird a small numbered leg-band and 

 let the bird go. About one year later, on June 15, 

 191-2, a chimney swift again fell through the same 

 hole into the same room, and when Mr. Baynes took 

 up the bird he found it to be the same one he had 

 banded the year before. This bird had traveled to 

 Central America, spent the winter there, and then 

 traveled back to the same town, and to exactly the 

 same chimney it had occupied the previous year. 

 How had it been able to find its way over this long 

 route back to the same nesting-site? 



Bird's sight. Many theories have been advanced 

 to explain how birds find their way. Probably no one 

 theory will satisfy all conditions. There are doubt- 

 less many factors needed to give a satisfactory ex- 

 planation. One important factor is the bird's sight. 

 Birds have very keen eyesight, and it seems probable 

 that birds flying at a great height may be guided by 

 conspicuous landmarks, such as mountain-chains, 

 coast-lines, and river-valleys which extend in the 

 same direction as the routes of migration. In North 

 America, the coast-lines and mountain-chains and 

 the Mississippi Valley extend in the general direction 

 in which most of the birds migrate. But this expla- 

 nation alone is not sufficient, as birds may migrate at 

 right angles to these landmarks, and may find their 



