LINES OF MIGRATORY FLIGHT 137 



lines of North America has been made with careful 

 consideration of known facts. Professor Cooke, in 

 his studies, plotted seven main lines of flight in 

 which more modern knowledge has suggested modi- 

 fications, and has added several minor or subsidiary- 

 lanes. 



It must be emphasized that the dotted lines on the 

 accompanying diagram represent direction of flight. 

 They must not be construed as narrow pathways. 

 Migration movement is continent wide, so that the 

 flow of migrants resembles a tremendous stream in 

 which currents tend in different directions, with the 

 difference that with birds we may see distinct cross- 

 ing of lines of flight. To avoid confusion as few 

 lines have been used in the diagram as has been 

 found practicable. Thus the line paralleling the 

 eastern coast represents southward flight along the 

 coast and in the interior, and lines in the interior are 

 intended to convey the idea of movement through 

 broad adjacent areas. 



In following paragraphs the discussion is directed 

 mainly to the southward flight in autumn. North- 

 ward migrations, except as elsewhere noted, flow in 

 general through the same channels. 



To begin in the east, the first of the major north 

 and south lines is one that leads directly south across 

 the Atlantic Ocean from the coasts of Nova Scotia 

 and Labrador through or past Bermuda, perhaps 



