1913] Bryant: Wandi rings of Poch l Gopht r 27 



gopher can he found picked clean around the mouth of the burrow, 

 showing that the food-getting has been limited largely to this circum- 

 scribed area. 



Another thing which it seems difficult to explain in connection with 

 the incident first noted is the fact that if gophers do travel about at 

 night they are certainly successful in finding their burrows again or 

 in digging new ones before daylighl appears. Their digging ability 

 would seem to be sufficiently effective to afford them plenty of chance 

 to conceal themselves again. Still, it is the common belief of observers 

 that each one of the complex systems of tunnels constitutes the per- 

 manent home of an individual gopher. 



If it be true that pocket gophers forage regularly above ground, 

 we have a partial explanation of how it became possible for gophers 

 to be entrapped in the oil. But why there should have been so many 

 on one particular night, or why they were apparently all traveling 

 in the same direction, remains unexplained. Such a migration seems 

 the more remarkable in that pocket gophers are supposed to lead a 

 solitary life. Bailey (loc. cit.) states that from the time the young are 

 half grown and bit;' enough to start burrows of their own each indi- 

 vidual lives entirely alone, except during the short mating season in 

 early spring. If each of the gophers caught in the oil had been living 

 by itself, it seems remarkable that so many should have come out of 

 their burrows on the same night and should have moved in the same 

 direction. 



The data at hand will not allow of the conclusion that this migra- 

 tion, if it can be called such, is exactly comparable with the sporadic 

 migrations of lemmings, or of meadow mice. It is certain, however, 

 that from some unknown cause large numbers of gophers left their 

 burrows on the night of May 1, 1913, in North Berkeley. That they 

 were either engaged in foraging or were seeking to improve their food 

 supply, when entrapped in the oil, seems probable. 



The accompanying photograph (fig. 1) shows four half-grown 

 pocket gophers, as seen by the writer on June 1, 1913, caught in oil 

 which had seeped down into the gutter in the same locality where 

 Mr. Light's observations were made. One was still breathing when 

 found. A meadow mouse {Mitral us californicus) and three other 

 gophers were similarly entrapped a few yards away the same night. 



The above incident further suggests crude oil as a possible method 

 of getting rid of gophers. If so many gophers were entrapped in a 

 strip of oil two feet wide in Berkeley, why would not a strip the same 



