NATURAL HISTORY STUDIES 



observations lead to the conclusion that it is very 

 unusual for birds to migrate at altitudes above 

 3,000 feet. Some astronomers, however, report 

 seeing birds at elevations of 10,000 feet. 



Gatke estimated the speed of migrating plovers, 

 curlews, and godwits, crossing Heligoland, at nearly 

 four miles a minute, and he calculated the speed of 

 hooded crows, crossing the North Sea, at 108 

 geographical miles per hour. Dr. J. Thienemann's 

 observations at Kossitten in 1909 led to lower 

 averages such as the following : Sparrow-hawk, 

 25| miles per hour ; hooded crow, 31 J ; rook, 

 32 \ ; chaffinch, 32| ; linnet, 34f ; peregrine 

 falcon, 37 ; jackdaw, 38J ; starling, 46J. 



It is reported that a marked swallow flew from 

 Compiegne to Antwerp, about 145 miles, in 1 hour 

 8 minutes ! It is certain that many a bird may 

 attain in its everyday life to a velocity of fifty miles 

 an hour, and it is probable that twice as fast is a 

 safe estimate for the rate of many a nu'gratory flight, 

 when the whole life is raised to a higher pitch. 



As to meteorological conditions, it becomes in- 

 creasingly clear that birds in their migrations are 

 somewhat strikingly indifferent to the weather, 

 unless, indeed, it reaches a high degree of storminess 

 or fogginess or unpropitiousness generally. It 

 seems that the weather conditions which obtain 

 when and where a mass movement begins are of 

 much more moment than those into which the birds 

 pass in the course of their flight. 



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