SWALLOWS. 331 
of Swallows are then at play in the air in Mexico, in the West Indies, and in Central 
America, just the same as at any other season of the year.” 
In speaking of the architecture of the Swallows, Dr. Coues writes: 
“Next after the migration, the nidification of Swallows is the best known point 
in their natural history. The nesting and the eggs of all the North American species 
haye become perfectly well known, such is the abundance of the birds, such their fami- 
liarity with man. Their buildings illustrate two striking propositions: 
“1. The versatility of architectural genius within the limits of a small and perfectly 
natural group of birds. 
“2. The influence of man in modifying the architectural customs of birds. 
“Every one of the North American species nests in a way peculiar to itself, even 
those which are most alike being distinguished by some circumstance, either of the nest. 
itself, or of the freight it bears; and all the species, with a single probable exception, 
have successively yielded to the modifying influences of the gradual settlement of the 
country by man. The Violet-green Swallow has held out the longest, and it is only 
very recently, in fact, that we have learned of its acceptance of the new order of things.. 
The time when the Barn Swallow forsook its primitive custom of building has passed 
out of mind; the modification is so profound, that this bird now very rarely nests 
elsewhere than in artificial resorts which man presents to its choice. In some cases, the 
change is complete in settled portions of the country, while elsewhere the same species 
retains its primitive habits. Thus the Cliff or Eave Swallow now nests habitually on 
buildings in the Eastern United States, though it still glues its curious mud fabrics to 
the faces of cliffs in the West; and the Purple Martin nests indifferently in boxes set up 
for its use, and in holes in trees. In the case of the Cliff Swallow, another curious 
result of the settlement of the country is seen in the gradual extension of the range of 
the species. Formerly restricted to regions abounding in natural nesting-sites, it has 
spread into populous distriéts, where the eaves of buildings afford a convenient substitute 
for the original breeding places. The Rough-winged Swallow originally nested, and 
generally still nests, like the Bank Swallow, in holes dug by itself in the ground; but it 
now often avails itself of the nooks afforded by bridges, piers, and other contrivances of 
man. I should not be surprised if this bird were an immigrant, into some parts at least 
of North America, of comparatively recent naturalization among us, attracted at length 
by conveniences for nesting. The Bank Swallow, the most cosmopolitan species of the 
whole family, seems to retain its wonted ways most sturdily of any—a fact perhaps 
explained by the highly exceptional character of its nidification. 
“To all this there is no parallel among our birds. Various species, indeed, now 
regularly accept the artificial nesting-places man provides, whether by design or other- 
wise. Such is notably the case with several kinds of Wrens, with at least one kind of 
Owl, with the Bluebird, the Pewit Flycatcher, and especially the House Sparrow. 
Various other birds occasionally avail themselves of like privileges, still retaining in the 
main their original habits. But in no other case than that of Swallows is the modi- 
fication of habit so profound, or so nearly without exception throughout an entire 
family. Next after the Swallows, the Wrens appear to yield the most readily, and all 
of our species will probably become modified in due time after the fashion of the House 
