THE BIRDS' AIR LINE 



regions. If we look at a map we will see that 

 Nova Scotia is directly north of Colombia in 

 northern South America. The Cliff Swallows 

 pass through Colombia on their northern jour- 

 ney. We might, therefore, expect them to follow 

 one of the most traveled of birds' air lines. This 

 leads across the Caribbean Sea and Gulf of 

 Mexico and up the Atlantic coast through New 

 England to their summer homes. But instead 

 of going by this, the most direct way, they go 

 westward through Panama, then northwest 

 through Central America and Mexico. It is not 

 until they reach Texas that they fly directly 

 toward the place they desire to reach. They 

 cross the United States by going up the Missis- 

 sippi and Ohio Valleys, and avoid the south- 

 eastern states entirely. 



Why is it that they thus travel two thousand 

 miles more than is necessary? We can only be- 

 lieve that they are following the route made by 

 their ancestors. The Cliff Swallow is a bird of 

 the West. There it builds its singular, bottle- 

 shaped mud nest under overhanging cliffs and 

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