MAMMALS OF YOSEMITE NATIONAL PARK 



73 



Photo by Author tbolo by Author 



Pocket gopher hole showing eccentric dirt pile. Pocket gopher mound. Note that it is lopsided. 



Pocket gophers make long series of 

 tunnels about half a foot below the sur- 

 face, with dirt piles thrown up at dif- 

 ferent spots above them. These are mainly 

 exploratory tunnels, thrown out in search 

 of food which consists of almost any 

 vegetable material, roots, stems and all. 

 Occasionally a side vent will be put up 

 to the surface so the animal may forage 

 near by, but never far from the safety 

 of his £ubway. Often a lower level of 

 tunnels contains nesting and storage 

 chambers. 



In wilderness country like Yosemite 

 National Park, pocket gophers have long 

 played an important part in the develop- 

 ment of the soil. They bring up a very 

 respectable amount of earth from below 

 — in one area, 1.64 pounds per square 

 yard, according to Grinnell and Storer. 

 Thus the weathering of the subsoil is 

 hastened by its being deposited on the 

 surface. The extensive tunnels permit 

 aeration and the introduction of water to 

 hasten the weathering of more subsoil. 

 These tunnels also, in time of rains or 

 melting snow, take up water, retard the 

 run-off and conserve water. 



Pocket gophers are prone to store far 

 more greenstuff underground than they 

 eat. The result is that more humus is 

 mixed with the soil. The population of 

 pocket gophers and other burrowing ani- 



mals in Yosemite appears heavy enough 

 so that the above factors are of real con- 

 sequence in the development of soils un- 

 der natural conditions and are a contri- 

 bution to the well-being of the natural 

 wild vegetation. 



The Allen pocket mouse was added 

 to the park list on July 9, 195 0, by 

 Ranger O. L. Wallis. He found a speci- 

 men that had been killed by a car one- 

 half mile above South Entrance on the 

 road to the Mariposa Grove. 



This subspecies is about 8 y /z inches long. 

 More than half this length is tail. The 

 upper parts are a shiny, grizzled, brown- 

 ish tan, with spiny hairs on the hips. The 

 feet and underparts, including the under- 

 side of the tail, are white. Along the 

 sides, between upper and lower parts, is 

 a streak of beautiful, reddish tan. It has 

 external cheek pockets, hence its name. 



.:-*§; 



From Knddtbrome by Anderson 



"Cores" of winter pocket gopher runs. 



