Squirrels of the World

Callospermophilus lateralis 255

soils with sandy or gravelly texture, or fi ne-grained soils
that are nearly brick hard when dry.

natural history: This squirrel is diurnal and active year-
round, but it may estivate during periods of extreme heat.
Nelson’s antelope squirrels are well adapted for desert life,
due to their pale color, which highly refl ects solar radiation;
and they are agile at climbing shrubs. A. nelsoni lives in shal-
low yet often complex burrows (usually excavated by kanga-
roo rats) that can have numerous openings and are often
associated with small gullies or shrubs. Nest chambers have
never been observed within the burrows. Breeding occurs

in late winter and spring, and a single litter of 6–11 (aver-

age = 8.9) is born 26 days later (in March) within the bur-

rows, where females nurse their young. Litters emerge at

weaning in April, when spring rains result in the major sea-

son for plant growth.

Nelson’s antelope squirrels feed heavily on green vegeta-

tion and on seeds, which they collect in their cheek pouches;

scavenged vertebrate fl esh and insects can also make up sig-

nifi cant portions of their diet. Densities are patchy in the

poor quality habitat often inhabited by A. nelsoni; however,

small colonies often form in suitable soil. Home ranges are

4.4 ha for each sex. Nelson’s antelope squirrels are less ener-

getic than other antelope squirrels, especially in extreme

heat and cold; they often take refuge in the shade of shrubs

or in burrows. A. nelsoni’s alarm vocalization is a short deep-

pitched trill (relative to other Ammospermophilus); this spe-

cies is extremely quiet, with soft calls. When running, Nel-

son’s antelope squirrels dart back and forth irregularly,

often with their tails curled over their backs, but these ani-

mals are more inclined to remain motionless unless startled

by sound. Mortality rates are high, with greater than 80 per-

cent unable to survive past 1 year of age. A. nelsoni is a prey

of badgers (Taxidea taxus), foxes, coyotes (Canis latrans), and

raptors. The major threats to conservation of this species

are conversion of their habitat to agriculture and the spread

of dense foliage from exotic species. The barren habitats in

which Nelson’s antelope squirrels live ensure that this spe-

cies is not an economic pest, nor is it harvested.

general references: Best, Titus, Lewis, et al. 1990; Cy-

pher 2001; Germano et al. 2001; U. S. Fish and Wildlife Ser-

vice 1998.

Ammospermophilus nelsoni. Photo courtesy Maggie Smith.

Callospermophilus (Merriam, 1897)

This genus has three species.

Callospermophilus lateralis (Say, 1823)

Golden-Mantled Ground Squirrel

description: C. lateralis is recognized by t he golden brown
mantle on the back of the head; two white stripes down the
back, each framed by two black stripes; and pale whitish or
yellow sides. Compared with Tamia s, the golden-mantled
ground squirrel does not have a median black line, and its
tail is smaller and less bushy. Compared with its sister spe-
cies, C. madrensis, found in México, C. lateralis has this dis-
tinctive mantle, more pronounced and more prominent

dorsal stripes, and shorter white stripes. Compared with C.

saturatus, found in the northern and northwestern portion

of its range, C. lateralis has a distinctive golden mantle and a

larger head.

size: Female—HB 176.5 mm; T 83.4 mm; Mass 159.7 g.

Male—HB 180.0 mm; T 87.2 mm; Mass 178.0 g.

Sex not stated—HB 174.0 mm; T 88.0 mm; Mass 245.7 g.

distribution: Golden-mantled ground squirrels are found

in mountainous areas of western North America, from cen-

tral British Columbia (Canada) to southern New Mexico (in

the Rocky Mountains), and from the Columbia River south