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- 
