256 LAND BIRDS 
=~ 
Notwithstanding the assertion sometimes made that 
young birds do not sing, I know positively that young 
Grosbeaks sing when eight weeks old, though, of course, 
their song is only a low warble as compared with the 
finished song of the adult. 
612. CLIFF SWALLOW. — Petrochelidon lunifrons. 
Famity: The Swallows. 
Length: 5.00-6.00. 
Adults: Forehead white or brown ; crown, back, and patch on chest 
glossy blue-black ; rump cinnamon-buff ; throat and collar chestnut ; 
sides and flanks brown ; remainder of under parts white. 
Young: Similar to adults, but colors duller and not sharply outlined ; 
chin and throat and often other parts of the head spotted with white ; 
tertials and tail-coverts margined with brown; chestnut of head 
partly or wholly wanting ; upper parts dull blackish. 
Geographical Distribution: Whole of North America; migrating in 
winter to Central and South America. 
California Breeding Range: Locally throughout the State. 
Breeding Season: June and July. 
Nest: Generally a round or retort-shaped structure, made of pellets of 
mud mixed with a few straws ; lined with feathers ; attached to cliffs 
or buildings. 
Eggs: 3 to 5; white, speckled or spotted with brown and lilac. Size 
0.82 X 0.56. 
CLIFF SWALLOWS present a curious example of the 
adaptation of a species to its environment. Formerly 
these little masons were all cliff-dwellers, their adobe 
nests being hung on the side of a cliff; but the advent 
of man into the wilderness has brought many changes, 
and now it is not unusual to find a colony snugly en- 
sconced beneath the eaves of the farmer’s barn. 
In 1902 these birds were nesting under the projecting 
tiles of the roofs covering one side of the quadrangle 
