118 The Pocket Gopher. 



up by moles are often incorrectly supposed to be the work of 

 gophers. A little careful scrutiny will soon reveal the dif- 

 ference. The gopher piles up the dirt on the surface of the 

 ground, building a mound by the addition of load after load 

 on top of that already deposited. A mole simply heaves up 

 the dirt from beneath, forming piles which show radiating 

 cracks. Associated with these piles are the surface ridges 

 made by the animal when ranging in search of food. The 

 feeding runways of the gopher never show in surface ridges. 



Breeding. But little information along this line is obtain- 

 able in the literature accessible at this Station, and some of 

 the statements therein made are, in the light of our own in- 

 vestigations, found to be more or less erroneous. The pocket 

 gopher lives such a secluded life in its underground burrows 

 that direct observations of its breeding habits require con- 

 siderable painstaking effort. I have never been able to find a 

 litter of the young myself, although I have explored a great 

 many burrows in studying the animal. Occasionally, though, 

 I have run across a nest of soft, dry grass that had probably 

 been constructed for the purpose of rearing the young. 



As might be expected of animals living in such comparative 

 security, the pocket gopher is not a very prolific breeder. It 

 certainly rears but one litter a year in this locality, for I have 

 examined scores of specimens in all months of the year and 

 have found the embryos only in late winter and early spring. 

 The number of young in a litter varies from three to six and 

 averages a little more than four. Very rarely only two em- 

 bryos are found in the uteri. 



Quite early in the spring, before the snows are fairly gone, 

 the male gophers are said to roam about in search of mates. 

 As I have never encountered one on such amorous errands in- 

 tent I have not been able to verify the statement. It is en- 

 tirely probable, however, that for reasons of personal safety 

 such excursions are undertaken mainly after nightfall. If the 

 statements concerning the wanderings of the male are correct, 

 the period of gestation is short, for the young are nearly all 

 born, in this locality, in March and April. It seems more prob- 

 able, though, that mating takes place in late fall as well as in 

 early spring ; perhaps also during milder periods of the winter, 

 as fairly well developed embryos are found in the uteri from 

 January to May. The following table gives the results of some 



