1914] Grinnell: Mammals and Birds of flu Colorado Valley 



65 



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

 pheric 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 

 AmmospermopMlus 

 Sigmodon 

 Dipodomys 

 Perognathus 

 Pipistrellus 

 Macrotus 



BREEDING BIRDS 



Melopelia 



Mieropallas 



Geococeyx 



( ienturus 



• !al yjite 



Pyrocephalus 



Guiraca 



Phainopepla 



Toxostoma 



Auriparus 



Pol ioptila 



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 teretieaudus 

 I'eroniyscus eremicus eremicus 

 Reithrodontomys megalotis deserti 

 Neotoma albigula venusta 

 Thomomys albatus 

 Dipodomys deserti deserti 

 Perognathus spina tus spinatus 

 Perognathus penicillatus penicillatus 

 Perognathus intermedins 

 Lepus californicus deserticola 

 Felis oregonensis brown i 

 ( lanis ochropus est.or 

 Vulpes macrotis arsipus 

 Mephitis estor 

 Procyon pallidus 

 Myotis occultus 

 Myntis ealifornicus pallidus 



The picked zonal and faunal "indicators*' just named are often 

 found in the same association with other elements seemingly less 

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



BREEDING BIRDS 

 Lophortyx gambeli 

 Otus asio gilmani 

 Bubo virginianus pallescens 

 Dryobates scalaris cactophilus 

 Centurus uropygialis 

 Colaptes chrysoides mearnsi 

 Agelaius phoeniceus sonoriensis 

 Melospiza melodia saltonis 

 Pipilo aberti 

 Piranga rubra cooperi 

 Vireo belli arizonae 

 Vermivora luciae 

 Dendroica aestiva sonorana 

 Toxostoma crissale 

 Polioptila plumbea 



