WILD LIFE OF ORCHARD AND FIELD 



of direction " different from that possessed by other 

 wild animals to a greater or less degree. 



Every continent shows certain main routes or 

 highways of bird -travel, which, when sketched 

 upon a map, are seen to bear definite relations 

 to the coast -lines, mountain ranges, and great 

 river systems of the globe. In North America, 

 Europe, and eastern Asia, where we know the 

 subject best, these mainly lie in a north-southerly 

 direction. Such bodies of water as the Mediterra- 

 nean Sea or our Great Lakes are crossed without 

 deviation, but lofty mountains are avoided as far 

 as possible. This is strikingly exemplified by the 

 highlands of southeastern Europe. Siberia and 

 northern Russia get their summer birds by way 

 either of the Volga or of the Rhone-Rhine and 

 Baltic Valley, and the Danube forms a regular 

 migration-route of certain European species that 

 never cross the Alps to Italy and Africa, but go 

 east to Persia and India for the winter. Our own 

 birds do not regularly cross either the Rocky or 

 Appalachian mountain ranges. 



It is probably to get a wide outlook upon the 

 landscape spread it like a map beneath their 

 glance that birds fly at so great a height as they 

 usually do during their migrations. The sight 



III 



