ROUTES OF MIGRATION. 109 



follow them, just as coast-lines and valleys do. 

 They also enable birds to make certain well- recog- 

 nized and easily-remembered entrances to countries 

 they pass on passage, or visit during summer or 

 winter. We have direct evidence that the lower 

 slopes of mountains are direct highways of migra- 

 tion. Even in England the Downs are a noted 

 path for migrants ; and a great many species may 

 be traced along the mountain chains of our islands 

 during the season of their passage. Birds that 

 belong to a mountain or upland habitat are the 

 most addicted to these routes. The Ring Ouzel 

 [Merula torquata), various species of Chat [Saxicola 

 and Pratincola), the Dotterel (Eudromias morinelhis), 

 and a few Waders, are all decided mountain fol- 

 lowers. We have also the direct testimony of the 

 most accurate field ornithologists to prove that 

 flocks of birds on passage may frequently be seen 

 above mountain ranges, following the chain. Some 

 of the most interesting instances of migration may 

 be witnessed at the great mountain passes, birds 

 journeying through lofty defiles with as much 

 appreciation of their usefulness as human travellers. 

 Great numbers of birds pass the Pyrenees, the 

 Caucasus, and the Alps on migration. One of the 

 most famous passes for migrants in the Pyrenees 

 is the " Jaisquivel," another the '' Palomeras de 

 Eshalar"; whilst the "Albula" and "'Bermina" 

 passes into the Adda Valley and Lake Como, in 

 the Alps, are others. The Himalayan passes are 

 also great routes of migrants. Dr. Scully, an 



