1915.] 



INTEODUCTION". 



11 



and where potatoes are stored in the field they often enter the pits 

 to eat the tubers or carry them away. AH kinds of garden vegetables 

 and also most field crops are eagerly eaten, either below or above 

 the surface of the ground. Gophers sometimes burrow up into 

 pumpkins or squashes and eat out the insides without the mischief 

 being detected until the empty shells dry up. They will work all 

 summer in gram fields, cutting and eating the leaves, stems,, and 

 grain heads and covering with their hills of earth even more grain 

 than they eat. In alfalfa and clover fields and in grass meadows they 

 destroy both roots and tops and pile their mounds over much of the 

 crop, and in addition, by leaving their mounds full of smaU stones, 

 they dull and break the knives of mowing machines. Their mischief 

 is perhaps most exasperating in orchards and nurseries, as they 

 often injure or kill choice fruit trees by their underground operations. 

 They are very fond of the roots of apple, pear, and fig trees. 



In irrigation areas gophers have an annoying habit of burrowing 

 through the ditch banks and letting the water cut its way out, of 

 filling up the smaller ditches with their mounds, and of interfering 

 generally with the most efficient use of water. It is reported that 

 in the spring of 1915 their burrows caused two reservoir dams on 

 the Little Colorado River, near St. Johns, Ariz., to give way, causing 

 the death of eight persons by drowning, and damage to crops to the 

 extent of half a million dollars. 



WINTER HABITS. 



Apparently none of the pocket gophers hibernate, and in spring, 

 as the deep snows melt, their old burrow-molds are seen snakelike 

 over the surface of the ground as evidence of winter activity. They 

 work below the frost and instead of throwing out mounds they 

 tunnel under the snow along the surface of the ground, probably 

 gathering some green plants as they go, and then fill these snow 

 tunnels with earth from their burrows. This earth freezes and 

 hardens and often remains aU summer as earth casts of gopher 

 burrows in the snow. The long safe winter under protection of 

 the snow has probably done much to conserve the species and facil- 

 itate their wide dispersal and abundan_ce in high mountains and 

 northern areas. 



BREEDING HABITS. 



The little known of the breeding habits of Tliomomys barely 

 sufiices for a few general conclusions. In northern and more 

 elevated portions of the country female gophers usually contain 

 small embryos in June, and early in that month a male and female 

 are occasionally caught in the same burrow. This rarely happens 

 later in summer, and it is evident that onl}^ one litter of young 

 is regularly raised in a year. In warmer climates the young are 



