THE BIRD STUDY BOOK 



good reason for their travelling at this time, as they 

 need the daylight for gathering food. 



There appear to be certain popular pathways of 

 migration along which many, though by no means 

 all, of the aerial voyageurs wing their way. As to 

 the distribution of these avian highways, we know 

 at least that the coastlines of the continents are 

 favourite routes. Longfellow, in the valley of the 

 Charles, lived beneath one of these arteries of migra- 

 tion, and on still autumn nights often listened to the 

 voices of the migrating hosts, "falling dreamily 

 through the sky." 



A small number of the species migrate by day; 

 among these are the Hawks, Swallows, Ducks, and 

 Geese. The last two groups also travel by night. 

 The rate at which they proceed on their journey is 

 not as great as was formerly supposed. From twenty 

 to thirty miles an hour is the speed generally taken, 

 and perhaps fifty miles an hour is the greatest rapid- 

 ity attained. Flights are usually not long sustained, 

 a hundred and fifty miles a day being above the 

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