The White-crowned Sparrow 



Taken in Inyo County 



Photo by the A uthor 



A DWARF WILLOW NESTING SITE 



Or, perhaps, and I propose this with the greatest diffidence, there 

 is a tendency toward homoplasy in song. A uniform environment 

 reacting upon diverse organisms tends to produce like results. Compare 

 the plumage and general appearance of the Pacific Fulmar and, say, 

 the California Gull. They look alike, but they hail from evolutionary 

 branches of early and vast divergence. Again, the climate of the Pacific 

 humid coastal region, as we know, makes for general suppression of 

 song, and especially of tonal quality. Per contra, the invigorating air of 

 the high Sierras may exert a uniformly stimulating influence upon two 

 sparrows so different as Zonotrichia and Passerella. Be that as it may, 

 these two are the authoritative interpreters of the Sierran wilderness. 



In nesting the White-crowned Sparrows usually crowd the season 

 at the upper levels. There is good need for this too, for occasionally the 

 season is so delayed by heavy snows that the osier patches are only 

 being released in July. At such a time the birds will erect a very sturdy 

 nest in the leafless branches of the willows, trusting to the belated bushes 

 to provide a leafy screen before the young have hatched. So rank is 

 this mountain growth, however, that if the season be a little more for- 



325 



