76 THE MIGRATION OF BIRDS. 



quarters, and never stay until they reach their 

 destinations, amounts practically to nothing, for 

 the instances of continued flight are exceedingly 

 rare. Birds travel by stages, staying here or there 

 on the way to feed or rest, so that it is an extremely 

 difficult matter to arrive at the rate of speed of the 

 actual migration flight. That some birds can fly 

 amazingly fast is unquestionable ; that they habitu- 

 ally do so on migration is not supported by facts. 

 The only stage of their journey which it is of vital 

 importance for them to get over quickly, is that 

 across the sea ; some birds, however, have no sea 

 to cross at all. Over land migrating birds appear to 

 fly at a moderate speed and with great persistency, 

 like a trained pedestrian who has set himself a long 

 task of endurance, plodding along in a steady but 

 continuous manner. We can only make the wildest 

 guesses at the time occupied by individual birds in 

 reaching their summer or winter quarters; conse- 

 quently it is equally impossible to give a time-log 

 of their route. Probably migrating birds do not 

 average more than 300 miles per day, during 

 their journey north or south ; but certainly birds 

 travel quicker north in spring than they do south 

 in autumn. Of course, this does not adequately 

 represent the velocity of their flight between the 

 stages. Some birds can fly amazingly quick ; 

 Swifts probably can and do attain a speed of nearly 

 200 miles per hour. There is, however, one 

 instance by which we can form some idea both 

 of the rapidity of flight and the briefness of 



