Xerospermophilus tereticaudus 371emergence. After a gestation of 26–35 days, a litter averaging
4.9–6.5 (range = 1–13) young is born within a burrow; this is
the only litter produced during the year. Multiple paternity
is common, and rises with an increase in litter size. Males
are capable of mating with multiple females, and in multiple
years. Reproduction is well timed to capitalize on the short
period of winter rains that occur in the Mohave and So-
noran deserts. Pregnant females can be found from March
to June. The young are weaned by 5–6 weeks, just one to
two weeks after emerging from the natal burrow. Natal dis-
persal is male biased, with a few females remaining in or
near their natal area after the June exodus of males. Sexual
maturity is reached by 10–11 months of age. Home ranges of
males and females do not diff er in size, averaging 0.30 ha.
Small burrow complexes are often evident. Individuals may
overwinter together in burrows, although in other seasons
nesting is rarely communal; this species does not form ma-
triarchal colonies. Burrows are relatively inconspicuous and
lack clear evidence of excavated soil or a mound; they are
located at the base of shrubs, in rocks, or along a wash. X. te-
reticaudus is incredibly heat tolerant, capable of foraging at
a temperature of 45°C. These animals use small patches of
shade and burrows for short periods of time. Round-tailed
ground squirrels forage on the ground and in the canopy
in search of buds, fl owers, leaves, and the fruits and seeds of
forbs, shrubs, trees, and cacti, often collecting them in mod-
est cheek pouches. Their principal predators are raptors,
snakes, and, to a lesser extent, canids, mustelids, and fe-
lids. Under threat, X. tereticaudus returns to the cover of its
burrow, often giving a high-pitched whistle or a series of
“chirps” for aerial predators, or using foot drumming in
the presence of snakes. Round-tailed ground squirrels are
primarily threatened by the conversion of deserts to urban
and agricultural lands, especially in the case of X. t. chlorus.
X. te reticaudus is not hunted or trapped, but it is occasionally
poisoned as a pest around human habitations and historic
structures, due to its burrowing habits.general references: Ball et al. 2005; Drabek 1973; Dun-
ford 1977a, 1977b, 1977c; Ernest and Mares 1987; Turkowski
1969; Wooden and Walsberg 2002.Xerospermophilus tereticaudus. Photo courtesy Randall D. Babb.