228 NATURAL HISTORY READER. 



White describes it ; and continues: "Doubtless the flight 

 of all hirundines is influenced by and adapted to the pecu- 

 liar 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 spe- 

 cies of swallow." They are constantly on the wing, skim- 

 ming 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 unremit- 

 ting exertion of a flight scarcely less than a hundred miles 

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

 should not be thought capable of a transition from England 

 to Africa. 



8. The secret of the local distribution of the bank-swal- 

 low is the presence or absence of vertical banks suitable for 

 them to penetrate for their burrows in which their nests 

 are placed. Firm sand, with no admixture of pebbles, is 

 preferred, and in such a bank, be it on sea-shore, river- 

 bank, sand-pit, or railroad-cutting, the face will be fairly 

 honey-combed with burrows, and here this charming and 

 graceful bird may be seen in hundreds and thousands. 

 Their domiciles are usually very close together, and the 

 wonder is how the birds can distinguish their own doors. 

 If mistakes do occur, I imagine they are very polite about 

 it, for I know of no more peaceable bird than they. 



9. In digging out their burrows they use their hard and 

 sharp beaks, like a pickaxe, to loosen the earth, after which 

 they remove it with their claws. Their burrows usually 

 sloj^e slightly upward, to avoid trouble from the rain, and 

 they extend back from two to ten feet, depending upon 

 the nature of the soil. The burrows will be placed high 

 or low upon the cliff, as the birds have to fear enemies from 

 above or below. The time employed to complete their 

 burrows is from four days to two weeks. 



