131-tl GriniicU : 3Inm»tals and Birds of the Colorado Vnllfij 



65 



animal life within the region. Nor is there marked variation in atmos- 

 jiherie humidity, the entire area being swept by air currents of pre- 

 vailing dryness. To express the situation in a different way, zonal 

 and faunal conditions are remarkably uniform ; but associational con- 

 ditions are varied, as pointed out in the succeeding chapter. 



The zonal diagnosis, Lower Sonoran, is based in part upon the 

 presence of the following determinative genera: 



MAMMALS 

 Ammospermophilus 

 Sigmodon 

 Dipodomys 

 Peroguatluis 

 Pipistrelliis 

 Macrotus 



BREEDING BIRDS 



Melopelia 



Micropallas 



Geoeoccyx 



Centurus 



Calypte 



Pyrocephalus 



Guiraea 



Phainopepla 



Toxostoma 



Auriparus 



Polioptila 



The faunal diagnosis, Colorado Desert, is based in part upon the 

 presence of the following subspecies and species, selected from the 

 entire list as being particularly restricted: 



MAMMALS 

 Odocoileus hemionus eremicus 

 Citellus tereticaudus tereticaudus 

 Peromyscus eremicus eremicus 

 Reithrodontomys megalotis deserti 

 Xeotoma albigula venusta 

 Thomomys albatus 

 Dipodomys deserti deserti 

 Perognathus spinatus spinatus 

 Perognathus penicillatus penicillatus 

 Perognathus intermedius 

 Lepus californicus deserticola 

 Eelis oregonensis browni 

 Canis ochropus ester 

 Vulpes macrotis arsipus 

 Mephitis estor 

 Procyon pallidus 

 Myotis occultus 

 Myotis californicus pallidus 



The picked zonal and faunal "indicators" jast named are often 

 found in the same association with other elements seemingly less 

 sensitive to temperature and humidity. Some of the latter, however, 



BREEDING BIRDS 

 Lophortyx gambeli 

 Otus asio gilmani 

 Bubo virginianus pallescens 

 Dryobates scalaris cactophilus 

 Centurus uropygialis 

 C'olaptes chrysoides mearnsi 

 Agelaius phoeniceus sonoriensis 

 Melospiza melodia saltonis 

 Pipilo aberti 

 Piranga rubra eooperi 

 Vireo belli arizonae 

 Vermivora luciae 

 Dendroiea aestiva sonorana 

 Toxostoma crissale 

 Polioptila plumbea 



