58 THE MIGRATIONS OF BIRDS 



Speed of Flight in Birds 



The speed that birds regularly make in flight, a 

 subject of considerable speculation and theory in the 

 past, but one concerning which there has been little 

 definite information available until recent years, is a 

 matter of pertinent inquiry when considering 

 migration. 



Early observers had few definite data at hand 

 regarding speed, but were conservative in their 

 estimates. Gatke, however, in his studies on Heligo- 

 land, became obsessed with the idea that most birds 

 performed the greater part of their migration flight 

 in a single night, and with this as a basis, deduced 

 extraordinary rates of travel, which, unfortunately, 

 have been widely quoted and copied. Through in- 

 genious but misleading estimates he rates the mi- 

 gratory flight of the northern blue-throat, a thrush 

 smaller than the American hermit thrush, at i8o to 

 240 miles per hour, the hooded crow at 108 miles, 

 the golden plover at 212 miles, and plovers, curlews, 

 and godwits in general at about 4 miles per minute, 

 or 240 miles per hour ! These tremendous speeds he 

 believed possible through flight at great altitudes, up 

 to 40,000 feet above the earth, where he supposed 

 that the rarefied air offered less resistance! His 

 statements are exceeded by a correspondent of "The 

 Field" who considers that the "cave-swallow" of 



