BIRDS 



173 



marsh bird would die of hunger on arriving in a very dry- 

 country. 



The landmarks of the route are mountains, rivers, valleys, 

 and coast lines. This knowledge is handed down from one 

 generation to another. It includes the location of certain 

 places on the route where food is plentiful and the birds 

 can rest in security. Siebohm and others have studied 

 the routes of migration in the Old 

 World. The route from 

 the nesting places in 

 northern Eu- 

 Africa fol- <,/ «~*> *^ ro P e t0 



lows the Rhine, 

 the Lake of Geneva, 

 the Rhone, whence some spe- 

 cies follow the Italian and others the Span- 

 ish coast line to Africa. Birds choose the 

 lowest mountain passes. The Old World 

 martin travels every year from the North 

 Cape to the Cape of Good Hope and back again ! An- 

 other route has been traced from Egypt along the coast 

 of Asia Minor, the Black Sea and Ural Mts. to Siberia. 



Field Study of Migration. — Three columns may be filled 

 on the blackboard in an unused corner, taking several 

 months in spring or fall for the work. First column, birds 

 that stay all the year. Second column, birds that come 

 from the south and are seen in the summer only. Third 

 column, birds that come from the north and are seen in 

 winter only. Exact dates of arrival and departure and 

 flight overhead should be recorded in notebooks. Many 

 such records will enable American zoologists to trace the 

 migration routes of our birds. Reports may be sent to the 

 chief of the Biological Survey, Washington, D.C. 



Fig. 317. — Cranes 

 Migrating, with 

 leader at point of 

 V-shaped line. 



