BANK-SWALLOWS. 249 



in Central America and the West Indies, or still farther 

 south. 



Their flight is rapid but unsteady, " with odd jerks and 

 vacillations not unlike the motions of a butterfly," as White 

 describes it; and continues: "Doubtless the flight of all 

 hirundines is influenced by and adapted to the peculiar sort 

 of insects which furnish their food. Hence it would be 

 worth inquiry to examine what particular genus of insects 

 affords the principal food of each respective species of swal- 

 low." They are constantly on the wing, skimming low 

 over land and loch, pausing not even to drink or bathe, but 

 simply dropping into some limpid lake as they sweep by 

 to sip a taste of water or cleanse their dirty coats. It seems 

 strange, then, that birds who sustain the unremitting exer- 

 tion of a flight scarcely less than one hundred miles an hour 

 in speed, during the whole of a long summer's day, should 

 not be thought capable of the transition from England to 

 Africa. However, at that time it was not well understood 

 what long-continued flight small birds actually do make, as, 

 for instance, from our coast to the Bahamas, or even across 

 to -Ireland, or from Egypt to Heligoland, one thousand two 

 hundred miles, which is passed over at a single flight, by a 

 certain tiny warbler, in every migration. 



The bank-swallow is not a musical bird, a faint, squeak- 



