101 



journey at Heligoland. We must assume, therefore, that on 

 these occasions the migratory flocks are aware at the outset of 

 their journey of the difBculties they will meet with, and put forth 

 the necessary additional effort in order to travel the longer distance 

 within the given time. No doubt Herr Gatke had these possibili- 

 ties in his mind >vhen he remarks on p. 69—" there is hardly a 

 doubt but that the velocity of its migration flight may even 

 exceed this already remarkable figure," — i.e., 180 miles an hour. 



With regard to the statement that the Bluethroat does not 

 migrate by daylight, no account has been taken in the foregoing 

 argument that so late in the spring as May 30th, there is no such 

 thing as darkness from Central Scandinavia northwards. 



From a comparatively feeble species we now turn to one 

 whose powers of flight, along with that of its congeners, are well 

 known, viz., the Virginian Golden Plover. There will not be 

 any diffculty in believing that this bird is able to accomplish long 

 flights at a high rate of speed, when atmospheric conditions are 

 favourable. But there are probably few readers of Herr Gatke's 

 work who will be prepared for the statement that this Plover 

 accomplishes an unbroken flight of fifteen hours' duration over a 

 •distance of 3,200 geographical miles, or at the rate of 212 miles 

 an hour. This is, however, an indisputable fact according to the 

 ^assertions of the author. He has arrived at his conclusions from 

 the following evidence. He remarks (p. 68) — "Flocks consisting 

 of thousands of these birds have been met with at a distance of 

 400 . geographical miles and more east of Bermuda, flying in a 

 southerly direction on the way from their breeding places in 

 Labrador to Northern Brazil. The distance between the coasts 

 of the two countries amounts to 3,200 geographical miles, and 

 since there is along this whole stretch of route, not a single 

 point on which the travellers could aUght for rest, they ai:e 

 obliged to perform the whole length of this enormous journey 

 in one uninterrupted flight. We may probably assume fifteen 

 hours as the longest spell during which a bird is able to remain 

 on the wing without taking sustenance of any kind. On this 

 assumption, the velocity of flight of the above named birds 

 would amount to 212 geographical miles per hour." 



He further adds — " The case of the American Plover just 



