690 THE MONTHLY BULLETIN. 



predators that dig, such as badgers and coyotes. The mouth of the 

 burrow is kept open, and is flush with the surface of the ground ; and 

 there is usually no trace of any mound. Sometimes there is a small 

 pile of fresh earth adjacent to a hole, but this is subject to quick 

 dissipation by the winds or the much more infrequent rains. The 

 mouth of the burrow is subtriangular in outline, the flattish base of the 

 triangle horizontal at the bottom. It is not often circular, as with 

 pocket gophers and kangaroo rats, and usually can be recognized accord- 

 ingly. There is evidence that these squirrels use the burrows of other 

 rodents, too, such as those of wood rats, kangaroo rats, and even badgers. 

 And in places where such retreats are afforded, individuals seem to 

 have their headquarters in the interstices of rock slides. Suffice it to 

 say that in the Antelope Ground Squirrel we do not find a good digger. 

 It takes a temperamentally phlegmatic animal to dig effectively. The 

 "Ammos" are too fidgety. 



This species does not live in colonies in the restricted sense in which 

 this term should be used, but the burrows are scattered out pretty evenly 

 over the general territory occupied. There is less of interdependence 

 between the individuals of this species than in most other ground 

 squirrels. 



In traveling through their domain one sees few of these ground 

 squirrels as compared with their real numbers. They are adepts at 

 dodging behind bushes, and at eluding observation by skipping off out 

 of sight considerably in advance of the intruder. For example, in a 

 census of animal life taken near Mohave, March 14, 1918, during a 

 three-hour walk, but two Antelope Squirrels were seen, whereas six 

 were found to have been caught in a line of rat-traps during the same 

 length of time. Then, too, the characteristic tracks in the sand on a 

 quiet day after it has been laid by a norther leave a graphic record of 

 the multitudinous peregrinations of these active rodents. They can 

 make more tracks in a given length of time than any other mammal with 

 which we are acquainted! 



Some notes made by the senior author the second week of March, 

 1918, near Mohave will help to give a clear idea of the characteristics 

 of the animal under discussion. Nearly all individuals seen would run 

 very fast across open spaces between the bushes, but would hesitate a 

 moment or so when passing through the bushes. When approaching 

 its burrow each animal would stop stock still just short of the mouth 

 of the burrow, and watch the intruder intently with head turned to one 

 side sufficiently so that it could look back past its rump. Meanwhile 

 the tail was vibrated intermittently as usual. Presently the animal 

 would dive down out of sight. One was seen to go down into a hole 

 situated in the side of a mound of sand accumulated about the base of 

 a very large creasote bush. This hole Avas one yard from the nearest 

 upright stem, but was directed downward diagonally toward the root- 

 system, and it was overshadowed by the radiating branches. The 

 diameter of this burrow at its mouth was just 40 millim^eters (about 

 one and three-fifths inches). The last that was seen of another squirrel 

 as he dived for his burrow, he had his tail over his back twitching as 

 violently as ever. He, too, had hesitated just an instant before the 

 final plunge. 



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