43 



Natural History Observations from the Mexican 

 Portion of the Colorado Desert 



With a Note on the Lower Californian Pronghorn and a 



List of the Birds. 



By Robert Cushman Murphy 

 Brooklyn Museum. 



Contents. 



Page. 



Introduction 43 



Previous investigations 47 



Zonal, faunal, and associational status of the region 48 



Narrative of the trip 52 



On the Lower Californian Pronghorn 75 



Annotated list of the birds 80 



Literature cited 100 



Introduction. 

 The desert that lies west of the lower stretches of the 

 River Colorado, partly within the southeastern corner of the 

 State of Cahfornia and partly in Mexico, has been, since 

 Tertiary times, the driest section of the North American 

 Continent. This region, to which the name '^ Colorado 

 Desert" ^ was long ago applied, extends in the form of an 



1 The region is defined by Blake in MacDougal's ''Salton Sea," page 6: 

 "The name 'Colorado Desert' was given to this region by the writer in 

 1853. This was before the State of Colorado received its name. It was 

 deemed most appropriate to connect the name of the Colorado River with 

 the region, inasmuch as the desert owes its origin to the river by the 

 deposition of alluvions and the displacement of the sea-water. 



"A tendency is shown by some writers to extend the area known as 

 the Colorado Desert so as to include the arid regions north of it, especially 

 the mountainous region along the Colorado and the Mohave, partly known 

 to-day as the 'Mohave Desert.' This was not the intention or wish of 

 the author of the name. It was intended to apply it strictly to the typical 

 desert area of the lacustrine clays and alluvial deposits of the Colorado 

 where extreme characteristic desert conditions prevail, such as arid, 



