MAMMALS OF THE MEXICAN BOUNDARY, 305 



nunioroas holes by which to make its escape; but it oftener stops and 

 cliirrups saucily, stamping- with its fore paws. Its curiositj' is so great 

 that a few sharp chirrups with one's lips will often bring it to the 

 entrance of its burrow, or it may run directly up to within a few feet 

 of one. Then it stops, stamps, and jerks its tail, presently beating 

 an equally precipitate retreat and diving into its burrow with a loud 

 note of alarm. Its call-note is a quick, hollow whistle;, and it also 

 utters metallic chirrups and chipperings suggestive of its impulsive 

 nature. It very commonl}^ sits up perfectly erect upon its hind 

 feet, like the prairie-dog. The perpendicular carriage of its tail, 

 when running, is characteristic. In the vicinity of Fort Verde the 

 rutting- season is from the middle of January" to the middle of March, 

 during which time the genitals of the male are enormously enlarged 

 and the animal very active. A female killed on March 20 contained 

 six fetuses of about the size and shape of small grapes. B}^ the mid- 

 dle of July the young- are half grown. 



It inhabits the low banks and arroyos along- the Verde River. The 

 entrances of its l)urrows are numerous in these clay surfaces, and here 

 the g-round-squirrels frequently sit sunning themselves in cold weather. 

 It is also found in the rocky slopes bordering the valley, but not so 

 plentifully as in the rich river-bottom where its food is more abun- 

 dant; but it even ascends farther, across the lower mesas to the cedar 

 forests, where its range is abruptly limited by a high clitf or^-im rock, 

 bordering an elevated plateau. At the higher levels it feeds upon the 

 fruitage and seeds of the Spanish bayonet, which I have found in large 

 heaps under the stones, where it makes its home. There is snow occa- 

 sionally at this altitude, but these ground-squirrels were seen running 

 about more f reel}^ than those in the warm valley below. 



One year, when the crop of mesquite mast failed, the Harris ground- 

 squirrel migrated from the Verde Valley in large numbers, so that the 

 species was comparatively rare for a whole 3'ear. 



This ground-s(piirrel is to some extent carnivorous, as is well known 

 to be the case with the prairie-dog and the large ground-squirrel {Oto- 

 speriiiopJiiJ H.s <jrainiiiurui<) of this region. I have poisoned it upon the 

 carcass of a cougar, whose flesh was poisoned with str3^chnine. 



On the Mexican Boundary the Harris ground-squirrel was not 

 observed east of the Pajaritos Mountains, but was plentiful in rocky 

 country, thence west to the Colorado River, grading into the sub- 

 species saxicolus west of Quitobaquita. In 1884 it was noted about the 

 San Carlos Agency. In 1885 I traced it from Fort Verde through the 

 Agua Fria Valley, the Black Canyon, Desert Well, Phoenix, Casa 

 Grande, Sweet Water, and the Santa Cruz Valley. In 1893 and 1891- 

 the range of the typical form was traced through the Santa Cruz Val- 

 ley into Sonora, Mexico. In December, 1893, it was abundant in a 

 pass of the Pozo Verde Mountains, Sonora, near Monument No. Ill; 

 806.S9— No. 50—07 M 20 



