Squirrels of the World

Xerospermophilus perotensis 367

geographic variation: None.

conservation: IUCN status—vulnerable. Population
trend—decreasing.

habitat: Mojave ground squirrels inhabit deserts with
abundant annual herbaceous vegetation on sandy or gravelly
friable soils. Creosote bush (Larrea) associations are favored.

natural history: X. mohavensis is diurnal. Mohave ground
squirrels hibernate in burrows from midsummer (August) un-
til February (or as late as May in the north), during which
period fat stores provide their energy source. Males emerge
about two weeks prior to females and establish home ranges;
mating occurs in burrows soon after emergence from hiber-
nation, usually in February and March, and females locate
their nest burrows within their home range. After a gestation
of 29–30 days, a litter of four to nine young is born in the bur-
row during late March or early April, except in years of sig-
nifi cant drought, when no reproduction occurs. Burrows are
typically found on the edges of the home range (sometimes
more than 250 m from its center), and individuals use multiple
burrows for temporary cover, maternity, and hibernation.
Burrows are plugged each evening, probably to minimize
predator access. Mohave ground squirrels remain solitary
outside of the breeding season; aggression in the form of
chases occurs among individuals. Male home ranges (6.74 ha)
are much larger than those of females (0.73 ha), although sex-
ual size dimorphism does not exist. X. mohavensis is omnivo-
rous and feeds on the shoots, leaves, fl owers, and seeds of
green grasses, forbs, shrubs, cacti, and yucca; this species
also consumes considerable numbers of insects and other
animal matter as available. These items are collected in cheek

pouches and eaten with the squirrel sitting upright on its

haunches, often on a promontory. Populations fl uctuate

dramatically and are extirpated in marginal areas during ex-

tended droughts. Recolonization occurs from adjacent ar-

eas, and long-distance dispersal appears important for this

species’ persistence on the landscape, given local drought-

related extirpation. Juveniles are known to move as far as

6.2 km, with males (averaging 1.5 km) moving farther than

females (averaging 0.5 km). Their primary predators are rap-

tors, snakes, badgers (Taxidea taxus), coyotes (Canis latrans),

and bobcats (Lynx rufus). Individuals are extremely docile

and tolerate approach by humans. When threatened, Mo-

have ground squirrels rarely run to burrows, but rather

drop close to the ground and rely on camoufl age. Their

alarm call is a high-pitched “peep,” with a raspy quality.

Urban sprawl constitutes a threat to the persistence of X.

mohavensis, due to loss of habitat and the purposeful re-

moval of X. tereticaudus by poisoning.

general references: Best 1995i; Brooks and Matchett

2002; Gall and Zembal 1980; Hafner 1992; Hafner and Yates

1983; J. H. Harris and Leitner 2004, 2005; Laabs 1998.

Xerospermophilus perotensis

(Merriam, 1893)

Perote Ground Squirrel

description: Perote ground squirrels have a grizzled yel-

lowish brown dorsum, with a series of thin short incomplete

black lines appearing toward the posterior; faint buff fl ecks or

spots are visible in new pelage. Their white eyelids are dis-

tinctive. The feet, the lower limbs, and the venter are a pale

buff. The upper side of the tail is grizzled yellowish brown,

with black becoming prominent toward the tip; the underside

is ochraceous buff with a clear black line evident near the tip.

size: Both sexes—HB 250 mm (243–261 mm); T 71 mm (57–

78 mm).

distribution: This species is restricted to 2500 km^2 in Ve-

racruz and Puebla in central México.

geographic variation: None.

conservation: IUCN status—endangered. Population

trend—decreasing. X. perotensis is federally listed as threat-

ened in México.

Xerospermophilus mohavensis. Photo courtesy Philip Leitner.