Life History of the Kangaroo Rat | Page 5

not inhabit the lower half of the Lower Sonoran Zone, as it extends
neither into the Rio 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 the plain at
4,600 feet altitude, near Bonita, Graham County, Ariz., and noted a few
as high as 5,000 feet altitude on the warm southwestern slopes of the
Graham Mountains, near Fort Grant. Apparently spectabilis reaches its

upper altitude limit in the Burro Mountains, N. Mex., where Bailey has
found it sparingly on warm slopes up to 5,700 feet, and at the western
base of the Sandia Mountains, east of Albuquerque, N. 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 Covillea association,
than elsewhere (Pl. IV, Figs. 1 and 2). A few scattered dens are to be
seen in the Covillea belt, but as one rises to altitudes of 3,500 to 4,000
feet, and the Covillea is replaced by the cat's-claws (Acacia sp. and
Mimosa sp.) and scattered mesquite (Prosopis), with the Opuntia
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
probably an important factor in the greater abundance of kangaroo rats,
both spectabilis and merriami. In this generally preferred environment
the desert hackberry (Celtis 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 Prosopis, 95 under Acacia, 65 under Celtis, 11
under Lycium, 31 in the open, 1 about a "cholla" cactus (_Opuntia
spinosior), and 1 about a prickly pear (Opuntia_ sp.). There is
apparently no strongly marked preference for any single species of
plant. While both desert hackberry and the cat's-claws afford a better
protection than mesquite--since cattle more often seek shade under the
latter, and in so doing frequently trample the mounds severely--it
appears that the general protection of a tree or shrub of some sort is
sought by kangaroo rats, rather than the specific protection of the
thickest or thorniest species.

The following records indicate particular habitat preferences of
spectabilis as noted at different points in its range:
Occurs on open bare knolls exposed to winds, also on gravelly places at
lower edge of foothills (Franklin Mountains, Tex., Gaut); here and
there over the barest and hardest of the gravelly mesas (Bailey, Tex.,
1905, 147); on open creosote-bush and giant-cactus desert (Tucson,
Ariz., Vorhies and Taylor); on firm, gravelly, or even rocky soil on the
grassy bajada land along the northwest base of the mountains, either in
the open or under Celtis, Prosopis, Lycium, Acacia greggii, or other
brush (Santa Rita Mountains, Ariz., Vorhies and Taylor); mounds
usually thrown up around a bunch of cactus or mesquite brush
(Magdalena, Sonora, Bailey); in heavy soil (Ajo, Ariz., A. B. Howell);
loamy soil (Gunsight, Ariz., A. B. Howell); in mesa where not too
stony (Magdalena, Sonora, Bailey); grassy plain (Gallego, Chihuahua,
Nelson); in open valley and high open plains (Santa Rosa, N. Mex.,
Bailey); in grassy and weed-grown parks among the larger junipers,
pinyons, and scattering yellow pines (Bear Spring Mountains, N. Mex.,
Hollister); on sand-dune strip (east side of Pecos River, 15 miles
northeast of Roswell, N. Mex., Bailey); among Ephedra patches (San
Juan Valley, N. Mex., Birdseye); in open sandy soil along dry wash
(Rio Alamosa, N. Mex., Goldman); on sides and crests of bare, stony
hills (Mesa Jumanes, N. Mex., Gaut); in open, arid part of the valley
and stony mesas (Carlsbad and Pecos Valley, N. Mex., Bailey); about
the edges of the plains of San Augustine and the foothills of the Datil
and Gallina Mountains, and in the Transition Zone yellow-pine forest
of the Gallina Mountains (Datil region, N. Mex., Hollister); on hard
limy ridges (Monahans, Tex., Cary).
A. Brazier Howell notes that spectabilis occurs in harder soil than does
deserti. This observation is confirmed by others, and seems to afford a
conspicuous habitat difference between the two, for deserti is typically
an animal of the shifting aeolian sands.
Usually, as