VELOCITY OF THE MIGRATION FLIGHT 69 



the way from their breeding places in Labrador to Northern Brazil. 

 The distance between the coasts of the two countries amounts to 

 three thousand two hundred geographical miles, and since there is 

 along this whole stretch of route not a single iDoint on which the 

 travellers could alight for rest, they are obliged to perform the 

 whole length of this enormous journey in one uninterrupted flight. 



\Ye may probably assiuue fifteen hours as the longest spell 

 durina: which a bird is able to remain on the wing without taking 

 sustenance of anj- kind. On this assumption, the velocity of flight 

 of the above-named birds would amount to two hundred and twelve 

 geographical miles per hour. 



Though an achievement like this is in the highest degree 

 astonishing, there is no necessity for assuming it to be either 

 exceptional or isolated. On the other hand, Ave are justified in 

 concluding that good flyers, such as this Plover specially happens 

 to be, may be able to accomplish even greater feats during their 

 spring migrations, when we reflect that a small and feeble bird like 

 the Bluethroat attains to so high a speed as one hundred and 

 eighty geographical miles per hour during the latter period of 

 migration. In the case of this bird, too, there is hardly a doubt 

 but that the velocity of its migration flight may exceed even this 

 already remarkable figure ; for, in discussing its flight, we only took 

 into account the rather moderate distance from North Africa to 

 Heligoland as representing the whole distance covered in its 

 migration. Now on the one hand, its winter quarters are known to 

 extend to 12° and 10° north latitude : and on the other, those of the 

 birds which for the moment alight on Heligoland can only form an 

 mconsiderable fraction of the complete migratory stream setting 

 from Africa to the Scandinavian peninsula, while the predominant 

 majority of individuals continue their journey to at least as far 

 as Central Norwaj^ and therefore accomplish, during the same 

 May night, a distance of from two thousand to two thousand four 

 hundred geographical miles. This would, of course, give as result 

 a velocity of four miles a minute. To an attentive observer in 

 Heligoland, however, such a result would in no way appear beyond 

 the bounds of possibility. He need, in fact, only consider the case 

 of the numerous individuals of such species as Plovers, Curlews, 

 Godwits, which, flying across the island at a rushing speed during 

 bright warm afternoons in earty summer, are observed to reach 

 the oyster-bed, 22,000 feet to the east, within the space of a single 

 minute. 



The case of the American Plover just discussed further shows 

 how little in need of rest birds are during their migration flight. 

 Large sections of the migratory streams of these birds which are 



