418 Birds of Colorado 
Pueblo (Beckham), Springfield, Baca co. (Warren), Twin Lakes breeding 
(Scott), Fort Garland (Henshaw), Routt co. (Warren 08), Mesa co. 
(Rockwell), Fort Lewis and Cortez (Gilman). 
Habits.—The habits of the Barn-Swallow have been 
modified by civilized man. Formerly no doubt they 
bred in caves and crannies in cliff faces, as indeed is 
described by Dawson (“ Auk” XIV., p. 95), who found this 
species in its natural condition on the shores of Lake 
Chelan in Washington. Now they make use of buildings 
or bridges, to which they affix their nests; these are 
usually in the shape of a half-cup, and are built up of 
mud pellets, often held together with small sticks or 
straws, with an inside lining of feathers and hair. The 
eggs, usually four in number, are laid in June, and a 
second brood is raised later on in the middle of July 
or early in August. This Swallow is very constant to 
its chosen nesting-place ; Smith (93) related that a pair 
which he believed to be the same birds returned to his 
barn in Denver for fifteen successive years, and raised, 
when not disturbed, two broods each year. A clutch 
of four eggs taken by I. C. Hall on June Ist, near Greeley, 
are white, spotted fairly evenly but not very profusely 
with reddish-brown, and average ‘8 x 55. 
Genus IRIDOPROCNE. 
Swallows of moderate size, wing under 5-0—with rather slender 
bills and narrow, elongated nostrils overhung by an operculum ; tail 
rather short, less than half the wing and forked for about a quarter 
of its length ; lateral toes long, the claws reaching quite to the base 
of the middle claw. Sexes alike ; eggs white. 
This genus, ranging over the continental portions of temperate and 
tropical America, comprises five species, only one of which occurs in 
the United States. 
Tree-Swallow. Iridoprocne bicolor. 
A.O.U. Checklist no 614—Colorado Records—Allen 72, pp. 156, 
162; Henshaw 75, p. 217; Scott 79, p. 93; Drew 81, pp. 88, 115; 85, 
