VOL* I.J Distribution of Land Birds. 299 



at about latitude 36^ and Its western at the confines of the Colorado 

 Desert. This definition of the range of GambeFs partridge applies 

 equally well in describing the bounderies of the Sonoran Area. It 

 is along the Colorado River that we find the maximum in the num- 

 ber and abundance of species characteristic of this area. The fol- 

 lowing IS a hst of the forms peculi^ir to the region : 



Callipepla gambeh. Icterus cucullatus nelsoni. 



Polioptila plumbea. Spizella atrigularis. 



Micropallas whitneyi. Amphispiza bilineata* 



Colaptes chrysoides, Melospiza fasciata fallax. 



Melanerpes uropygialis. Vireo vicinior. 



Chordelles texensis. Helminthophila Incise, 



Trochilus costse. Oroscoptes montanus. 



Pyrocephalusrubineusmexicanus. Harporhynchus lecontei. 

 Otocoris alpestris adusta. Harporhynchus crissalis. 



Agelaius phoeniceus. Campylorhynchus brunneicapillus 



Icterus parisorum. Auriparus flaviceps. 



Columbigallina passerina pallescens 



There is but one other Area represented in California— the Great 

 Basin Area. This is the Nevada fauna, which enters California 

 north of latitude 36^ and east of the Sierra Nevada Mountains. It 

 is essentially an Artemisia country, and has a fauna closely related 

 to that of the Sonoran Area, as shown by a number of forms which 



are common in both. 



iph 



bilineata and Oroscoptes montayius. The presence of the sage hen 

 ( Ceyitrocercus urophasianus) will generally serve to indicate the 

 Great Basin Area. It appears, also, that the thrush occurring on 

 the eastern slope of the Sierra Nevada is Tardus ustulatus swain- 

 soniy in which case we would have in this variety another mark of 

 the Area. This Area is, however, merely an incidental feature in 

 California, and the part which it plays in influencing our avifauna 



w 



is a small one. 



