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 cut 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 lodgement 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 erush the 
egos, 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 
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