Marmota baibacina 271dorsum, with the light stripes and spots a pale yellowish
olivaceous.
I. t. pallidus—northern Great Plains (USA). This is another
small and pale form.
I. t. parvus—southcentral Wyoming, northeastern Utah, and
northwestern Colorado (USA). This diminutive form has
two of the medial light dorsal stripes broken into spots.
I. t. texensis—central Texas, Oklahoma, southeastern Kan-
sas, and southwestern Missouri (USA). This subspecies is
smallish, with a pale back and underside of the tail, and
a reddish tinge.
conservation: IUCN status—least concern. Population
trend—stable. I. t. monticola is a species of special concern in
Arizona (USA).
habitat: Thirteen-lined ground squirrels are restricted to
dry and sandy soils of open and very short grasslands,
meadows, shrublands, roadsides, cultivated fi elds, airfi elds,
golf courses, and suburban lawns.
natural history: This species is diurnal. Thirteen-lined
ground squirrels hibernate for fi ve to eight months in bur-
rows. Emergence begins in mid-March, with adult males
emerging through April or even May, which is when fe-
males appear aboveground. Mating occurs soon afterward.
Males range widely to fi nd fema les, a lt houg h t hey do defend
breeding territories. Male-male aggression is reduced at this
time, as males queue while waiting to mate with a female.
Copulation most frequently takes place aboveground, and
females mate with multiple males. After a gestation of 27–28
days, a litter of eight (range = 6–13) young is born within the
burrow; only a single litter is produced, except in the south-
ern portion of the range, where a second litter may be born.
Juveniles emerge at about 5 weeks and are weaned by 6–7
weeks of age; all juveniles disperse from their natal area and
reach adult size by 11 weeks. Adults begin to enter hiberna-
tion as early as late July, and young-of-the-year immerge by
October, after accumulating considerable fat stores that will
enable them to reach sexual maturity by their fi rst spring.
Burrows of at least two types are constructed: escape bur-
rows, which are short, dispersed, and inconspicuous tem-
porary shelters; and nesting burrows, which are up to 8 m
long and 0.5 m deep, with a grass-lined nest chamber. Bur-
row entrances are plugged each night. Although relatively
asocial, individuals do aggregate in areas of good-quality
habitat. They scent-mark with glands near the cheek that
are rubbed against objects. Territories are defended in at
least some populations, whereas in others interindividual
overlap is considerable. Male home ranges (5.0 ha) are larger
than those of females (0.5–0.8 ha). I. tridecemlineatus is more
omnivorous than many ground squirrels; this species eats
the shoots, leaves, fl owers, seeds, and fruits of grasses,
forbs, and trees, as well as considerable numbers of insects
(and even small vertebrates). Seeds are sometimes stored in
burrows over the winter. Their main predators include ca-
nids, mustelids, felids, raptors, and snakes. Their alarm call
is a soft whistled trill, often given in close proximity to the
burrow entrance. Calls are voiced primarily in response to
terrestrial predators, not aerial ones. Furthermore, females
with their young call most frequently, suggesting that the
function of the alarms is to warn their progeny. Thirteen-
lined ground squirrels are not hunted, but they are occa-
sionally trapped or poisoned for removal. I. tridecemlineatus
is a common species in the manicured grass landscapes
throughout much of its range, and it is tolerated by humans,
due to its low densities, small burrow structures, and in-
triguing appearance.general references: Arenz and Leger 1999; Cothran
1983; Cothran and Honeycutt 1984; Devenport et al. 2000;
Luna and Baird 2004; Schwagmeyer 1980, 1985.Marmota Blumenbach, 1779
The genus, comprising the marmots, consists of 15 species.
Marmota baibacina (Kastschenko, 1899)
Gray Marmot
description: Gray marmots are lightly grizzled brown to
charcoal, with a prominent suff usion of tan to buff to yellow
suggesting a gray color. The venter is tan to bright rust. The
snout is often dark brown with white to buff patches around
the nose or chin. The tail is a lighter color at the base, with
a dark brown to black tip.size: Both sexes—HB 460–650 mm; T 130–154 mm; Mass
4250–6500 g.distribution: This squirrel is found in the Altai and Tien
Shan Mountains in southwestern Siberia (Russia), south-
eastern Kazakhstan, Kyrgyzstan, Mongolia, and Xinjiang