The Bell Sparrow 



in the chamisal associa- 

 tion. Two of these re- 

 cords were made in the 

 pure desert association of 

 the San Fernando Valley, 

 Opuntia bemardina, 

 Yucca whipplei, Sambu- 

 cus glanca, Rhus laurina, 

 and the rest. Both nests 

 were in "broom sage" 

 (A rtemisia dracuncu- 

 loides), as also were two 

 found in eastern San Luis 

 Obispo County, April 15, 

 1914, although the latter 

 may possibly have 

 marked a heretofore un- 

 recognized extension of 

 A. n. canescens. 



The remarkable sit- 

 uation as regards A. belli 

 and A . nevadensis invites 

 hypothesis. The undif- 

 ■ ferentiated members of 

 the original species, 

 Amphispiza preglacialis , 

 pushing northward and 

 westward from a distri- 

 bution center in Sonora, 

 invaded southern Cali- 

 fornia and the Great 

 Basin region. Later, 

 becoming isolated by the Sierro-San ice barrier, the form belli evolved, 

 while its counterpart and erstwhile brother was evicted from California 

 by the refrigeration of the eastern slopes of the Sierras and the White- 

 Mountains-Inyo-Desert system. In the reoccupation of this Owens 

 Valley country a new form, A. n. canescens, has evolved, and this form, 

 pushing its conquest westward, has stormed the Tehachipe and the bound- 

 ing barriers of the Mojave Desert, and has spilled over variously into the 

 Kings-Kern and San Joaquin regions. If this hypothesis be the correct 

 one, we may expect a steady advance on the part of A. n. canescens, and 

 a gradual retirement of the more strongly marked but weaker belli. 



280 



Photo by L. Huey and D. R. Dickey 

 - BELL SPARROW: ADULT WITH YOUNG 



