BANK-SWALLOWS. 253 



or fowls is spread with little art for the reception of the 

 four to six white eggs. It may not be unimportant to re- 

 mark, also, that it always scrapes out with its feet the sand 

 detached by the bill ; but so carefully is this performed 

 that it never scratches up the unmined sand, or disturbs 

 the plane of the floor, which rather slopes upward, and of 

 course the lodgment of rain is thereby prevented." 



Sometimes the nest is carried to a far greater depth than 

 two or three feet, as in a case observed by Mr. Fowler, in 

 Beverly, Massachusetts, where, in order to get free of a 

 stony soil, where pebbles might be dislodged and crush the 

 eggs, the tunnel was carried in nine feet, while neighboring 

 birds in better soil only went a third as far. In one place 

 the burrows will be close to the top of the bluff; in another 

 near the bottom, according as fancy dictates, 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 embankments thrown up for a railway-bed, in 



