416 Birds of Colorado 
Distribution.—Breeding in favourable situations throughout the 
greater part of North America as far north as the Yukon Valley, and 
south through north-west Mexico to Mazatlan ; south in winter as far 
as Honduras and perhaps to South America. 
The Cliff-Swallow is a common summer bird in Colorado, breeding 
locally from the plains to about 10,000 feet (colony at Fairplay in South 
Park, 9,800 feet, Allen 72). They reach Colorado from the south about. 
the beginning of May—Cajion City April 27th, Aiken (Henshaw 75), 
Pueblo May 8th (Lowe), but do not breed before June, and leave again 
early in September. They have been recorded from all over the State, 
from Weld co. (Markman), Limon (Aiken), and Baca co. (Warren 06) 
on the eastern plains ; from Estes Park (Kellogg), Twin Lakes (Scott), 
and Fort Garland (Henshaw), on the eastern slope ; and from Routt 
co. (Warren 08), Red-cliff (Keyser), and La Plata co. (Gilman) on the 
western slope of the Divide. 
Habits.—-The Cliff-Swallow breeds in colonies, either 
on. vertical or overhanging cliffs along rivers or, perhaps 
more frequently since the advent of man, on the walls 
or under the eaves of barns or outhouses. The nest 
is built up of pellets of mud partially no doubt moistened 
and softened by the saliva of the bird, and is usually 
in the shape of a squat bottle, with the opening in front, 
at other times like a retort, with an opening at the top 
of the nest, and a passage leading and opening down- 
wards ; the nest so formed is lined with feathers, straw, 
paper, leaves, or other soft material; four or five eggs 
are laid about June 5th in the plains, about a fortnight 
or three weeks later in the mountains. A set of three 
eggs, taken by I. C. Hall on June 15th, near Greeley, 
are rather long-ovals in shape ; they are white, moderately 
spotted with two shades of brown, and average ‘87 x ‘56. 
Like other Swallows, these birds feed entirely on the 
wing, chiefly on smaller insects, and are seldom seen 
on the ground, as their legs are very small and weak. 
Genus HIRUNDO. 
Moderate-sized Swallows—wing less than 5.0—with bill like that of 
Petrochelidon but slightly longer ; nostrils narrow, elongated, opening 
