Squirrels of the World

270 Ictidomys parvidens

I. parvidens is an omnivore that feeds heavily on the
leaves, shoots, fl owers, and seeds of grasses, forbs, shrubs,
and cacti, but it will consume signifi cant amounts of insects
and other animal matter when available. Adult survivorship
is high, with 53–63 percent of the adults remaining alive
during the year, whereas juvenile survival is only about
30 percent. Most small carnivores—including felids, canids
and mustelids, raptors, and snakes—prey on I. parvidens.
Their alarm call is a shrill whistle. Rio Grande ground squir-
rels are not hunted for food or pelts; however, they are shot
or poisoned as a local nuisance.

general references: Baudoin et al. 2004; Mandier and
Gouat 1996; Schwanz 2006; Yancey et al. 1993; Young and
Jones 1982.

Ictidomys tridecemlineatus (Mitchill, 1821)

Thirteen-Lined Ground Squirrel

description: The back of thirteen-lined ground squirrels
is marked with alternating light and dark longitudinal
stripes. Five cinnamon to sepia to black dark stripes are usu-
ally evident, with a series of white to buff spots or squares
along the middle of each stripe. Alternating between these
dark stripes are six light cream to buff stripes; sometimes
these light stripes are broken into spots. Several additional
lines or spots can be seen lower on the sides. The chin,
cheeks, eye rings, and sides of the nose are buff to cinnamon

buff. The venter is buff to cinnamon buff to pinkish buff.

The tail is fuscous black on the dorsal surface, suff used with

brown and frosted with buff ; the ventral side of the tail is

fuscous black throughout, with russet brown at the base

and cinnamon buff near the tip.

size: Both sexes—HB 170–310 mm; T 60–132 mm; Mass 110–

270 g.

distribution: This species is found in the Great Plains,

from southcentral Canada south through eastern Utah and

eastern Arizona to central Texas and east to Michigan and

Ohio (USA).

geographic variation: Ten subspecies are recognized.

I. t. tridecemlineatus—central USA and southcentral Canada.

See description above.

I. t. alleni—northwestern Wyoming (USA). This is a diminu-

tive and pale subspecies.

I. t. arenicola—eastern New Mexico, southwestern Colo-

rado, western Kansas, western Oklahoma, and north-

western Texas (USA). This is a small and pale form, with

light brownish dark stripes.

I. t. blanca—southcentral Colorado (USA). This is a small

pale subspecies.

I. t. hollisteri—central New Mexico (USA). This form has a

reddish tinge to the dark stripes and a strong buff tinge

to the light stripes.

I. t. monticola—eastcentral Arizona and westcentral New

Mexico (USA). It has a reddish tinge to the dorsum and

the underside of the tail.

I. t. olivaceus—northeastern Wyoming and westcentral

South Dakota (USA). This form is much darker on the

Ictidomys tridecemlineatus. Photo courtesy Phil Myers, Animal

Diversity Web, animaldiversity.org.

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