WILD LIFE OF ORCHARD AND FIELD 



another near the bottom, according as fancy dic- 

 tates or the birds have reason to fear this or that 

 enemy. English writers agree that occasionally 

 their bank-swallows do not dig holes, but lay in 

 the crannies of old walls and in hollows of trees. 

 This is never done, that I am aware of, in the United 

 States; but in California a closely allied species, 

 the rough-winged swallow, "sometimes resorts to 

 natural clefts in the banks or adobe buildings, and 

 occasionally to knot-holes." On the great plains, 

 however, our Cotyle burrows in the slight em- 

 bankments thrown up for a railway-bed, in lieu 

 of a better place; and at St. Paul, Minnesota, I 

 have seen them penetrating solid but soft sand- 

 rock. 



" How long does it take a bird to dig his cavern 

 under ordinary circumstances?" is a question which 

 it would seem hard to answer, considering the cryp- 

 tic character of his work. Mr. W. H. Dall says 

 four days suffice to excavate the nest. Mr. Morris, 

 a close observer of British birds, says, per contra, 

 a fortnight, and that the bird removes twenty 

 ounces of sand a day. 



When the female is sitting you may thrust your 

 arm in and grasp her, and, notwithstanding the 

 noise and violence attending the enlargement of 



287 



