116 ANIMAL COMPETITORS 



way. His movement in digging often seems as 

 rapid and automatic as that of a shuttle. 



Except in times of deep frost, the burrows 

 are seldom more than a foot underground, and 

 generally about six inches. At intervals, often 

 within a few feet, the gopher comes to the sur- 

 face to throw up a little hill of dirt; but the 

 opening which he makes is closed by being 



DIAGRAM OF A GOPHER'S BURROWING. 



packed so full of dirt that no trace of the tunnel 

 is visible except the little mound. 



The gopher goes on digging in winter as 

 well as in summer ; but if the frost prevents him 

 from coming to the surface, he uses a cross 

 section of his tunnel into which to pack the 

 earth which he has dug for his new excavations. 

 These tightly packed cylinders of earth are 

 often turned up by the plow. 



Pocket-gophers apparently breed only once a 



