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. 



Family : 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 



