The Pocket Gopher. 117 



ings one exposes in digging along the tunnels are parts of one 

 animal's private labyrinth. A prairie-dog or a spermophile 

 digs a burrow very much like that of his neighbor ; but it must 

 be borne in mind that these animals are constructing homes, 

 not extending passageways in search of food. The gopher fol- 

 lows his own sweet will in mining. Here a chance for easier 

 digging turns him aside; there a promising lead of succulent 

 roots entices him the other way. Heading everywhere in gen- 

 eral and nowhere in particular, he may, in the course of a 

 year, explore the length and breadth of a field of many acres. 

 At irregular intervals he excavates a short lateral obliquely 

 upward to the surface of the ground. Through these the 

 loosened dirt is carried and thrust out in heaps. The presence 

 of a gopher is thus easily detected by the lines of mounds, 

 varying in size from a hatful to one or even several bushels 

 of dirt. A study of a fresh mound reveals the plan of con- 

 struction. The dirt is carried out of the opening and dis- 

 tributed radially, very much as miners dispose of the useless 

 shale from a coal-pit. Usually the dump extends only part 

 way around the opening, but sometimes the mound has the 

 shape of a cone with a crater at the top. Where surface vege- 

 tation hinders the work, the piles of dirt are more irregular. 



The Mound. In removing the excavated earth from the 

 burrow the gopher pushes his load before him in armfuls, so 

 to speak. At the exit it is thrown out with a quick flip of the 

 nose until the enlarging mound compels the animal to come 

 out and dump the material down the slopes. After these be- 

 come so steep that the material rolls back into the opening 

 much dirt still boils up from beneath under the pressure of a 

 powerful pair of shoulders. A wrinkled ring of earth on the 

 completed mound usually identifies the point of the last out- 

 thrusts. After scraping away a mound from the harder sur- 

 face of the ground, one may search in vain for the lateral 

 leading to the burrow. The miner has packed it so tightly 

 that the plug is as firm as the surrounding earth. Here and 

 there a gopher burrow enlarges into a chamber of moderate 

 size. Some of these are partly filled with dry grass; others 

 are used for food storage. Not infrequently one finds a pocket 

 extending upward, as though the animal had started to dig an 

 exit but had abandoned the task for some reason or other. 



Mole Runways. The ridges and mounds of earth thrown 



