i''i *i Qrinnell: Mammals and Birds of the Colorado Valley 219 



There is a possibility that the bighorns on the Arizona side of 

 the Colorado differ slightly from those on the California side. The 

 latter unquestionably belong to the race nclsoni. Mearns (1907, p. 240) 

 describes a race (Ovis canadensis gaillardi) from the Gila Mountains, 

 Yuma County. Arizona. This locality is less than seventy-five miles 

 from the locality near Cibola where sheep are known to occur, and if 

 gaillardi is a really distinct form the sheep of Cibola are perhaps 

 referable to it rather than to nelsoni. 



Odocoileus hemionus eremicus (Mearns) 

 Burro Deer 



No trace of deer was found by us anywhere, nor had anyone we 

 talked with seen deer along the Colorado within four years. We were 

 told of their occurrence in numbers many years before, when they 

 were to be found both in the river bottom and back through certain 

 desert ranges, where there are springs which the deer could visit 

 regularly for water. 



In August, 1902, Mr. Frank Stephens saw two deer on the Cali- 

 fornia side of the river west of Cibola. The animals were jumped 

 from a wash among iron wood trees and made off across a wash. Sign 

 was fairly plentiful, and deer were said to be common at that time 

 on both sides of the river. 



Members of our party in 1910 looked over the same ground closely 

 without finding sign. The rapid settlement of the river bottom around 

 Palo Verde probably accounts for the disappearance of deer throughout 

 that section. At the Draper ranch twenty miles above Picacho a single 

 old buck had been seen "about" five years previously. 



Ammospermophilus harrisi harrisi (Audubon and Bachman) 

 Harris Ground Squirrel 



Twenty-six specimens secured, from localities all on the Arizona 

 side of the river, as follows : Mellen, 18 ; foot of The Needles, 1 ; above 

 Bill Williams River, 2; Ehrenberg, 3; 10 miles below Cibola, 2. None 

 was seen at any locality where not also taken, so that the species 

 appears not to occur near the river along its course below Cibola. Our 

 work shows, further, an extreme associational restriction, namely, to 

 rupestrine conditions as furnished in the rough hills and on those 

 parts of the desert mesa where the wind keeps the weathered detritus 



