CIVILIZING. INFLUENCES. 191 
The natural breeding-place of all the three species I have 
mentioned is in caves and crevices of rock, the irregu- 
larities and hollows of limestone crags affording them the 
best chanees. ‘Swallows’ Cave,” at Nahant, is remember- 
ed as one of their hospices. I have seen all three species 
breeding together among the ragged ledges of Middle Park, 
Colorado; but considerable differences were noticeable be- 
tween the houses of these uncivilized builders and those 
of their educated brethren at the East, who now, perhaps, 
would find it rather hard to rough it as did their ancestors. 
Under the shelter of warm barns, and with such an abun- 
dance of food at hand that they have plenty of leisure be- 
tween meals to cultivate their tastes and give scope to their 
ingenuity, our barn and eave swallows have shown a won- 
drous improvement in architecture. The nests of the barn- 
swallows that I saw at the hot sulphur springs in Colorado 
consisted only of a loose bed of straw and feathers, for the 
hollow floors of the niches in which they were placed form- 
ed cavity and barrier for the safety of the eggs. Some 
nests, resting on more exposed ledges, had a rude founda- 
tion and rim of mud, but did not compare with the elab- 
orate half-bowls, lined with hay and feathers, that are plas- 
tered by the same species so firmly against the rafters of 
our barns, or with the large nest that is balanced on the 
