8 BULLETIX 1091, U. S. DEPARTMENT OF AGRICULTURE. { BuTl Na 1. 



invading the yellow pine Transition where the soil was dry and sandy 

 and the pine woods of open character. The same observer found it 

 common in grassy and weed-grown parks among the large junipers, 

 pinyons. and scattering yellow pines of the Bear Spring Mountains, 

 N. Mex. Bailey calls attention to the fact that the animal apparently 

 does not inhabit the lower half of the Lower Sonoran Zone, as it ex- 

 tends neither into the Eio Grande Valley of Texas nor the Gila 

 Valley of Arizona. In extreme western Texas it is common at the 

 upper edge of the arid Lower Sonoran Zone, and in this region does] 

 not enter the Upper Sonoran to any extent. 



In July. 1914. Goldman found this kangaroo rat common on thi 

 plain at 4.600 feet altitude, near Bonita. Graham County, Ariz., am 

 noted a few as high as 5,000 feet altitude on the warm southwesterii 

 slopes of the Graham Mountains, near Fort Grant. Apparently 

 spectaMlis reaches its upper altitude limit in the Burro Mountains. 

 X. Mex., where Bailey has found it sparingh- on warm slopes up to 

 5,700 feet, and at the western base of the Sandia Mountains, east of 

 Albuquerque. X. Mex.. where dens occur at approximately 6.000 

 feet. 



About Tucson it is undoubtedly more common in the somewhat 

 higher portions of the Lower Sonoran Zone, above the CovilJea asso- 

 ciation, than elsewhere (PI. IV. Figs. 1 and 2). A few scattered 

 dens are to be seen in the CovUleo^ belt, but as one rises to altitudes 

 of 3,500 to 4.000 feet, and the Gomllea is replaced by the cat's-claws 

 {Acacia sp. and Mimosa sp.) and scattered mescjuite (Prosopis) , with 

 the Opimtia becoming less abundant, kangaroo rat mounds come more 

 and more in evidence. Here is to be found the principal grass growth 

 supporting the grazing industry, and the presence of a more luxuriant 

 grass flora is probabh' an important factor m the greater abundance 

 of kangaroo rats, both spectaJjilis and meniaTni. In this generally 

 preferred environment the desert hackberry {CeltU pallida) is one of 

 the most conspicuous shrubs: clumps of this species are commonly 

 accompanied by kangaroo rat mounds. 



In order to ascertain whether the banner-tailed kangaroo rat has 

 any marked preference for building its mounds under Celtis or some 

 other particular plant, all the observable mounds were counted in a 

 strip about 20 rods wide and approximately 4 miles long, an area 

 of approximately 160 acres, particular note being taken of the kind 

 of shrub under which each mound was located. Of 300 mounds in 

 this area, 96 were under Prosopm, 95 under Acacia^ 65 under Celtis. 

 11 under Lycium, 31 in the open, 1 about a " choUa " cactus {Opvmtia 

 spi/iosior) ^ and 1 about a prickly pear {Opuntia sp.). There is ap-' 

 parently no strongW marked preference for any single species of 

 plant. AATiile both desert haclcberr}- and the cat's-claws afford a better 



