MAMMALS OF MISSISSIPPI 6:1-6
Eastern chipmunk (Tamias striatus)
JEAN E. CHERVENAK
Department of Wildlife and Fisheries, Mississippi State University, Mississippi State, Mississippi, 39762, USA
Abstract—Tamias striatus (Linnaeus, 1758) is a sciurid commonly called the eastern chipmunk.
Tamias striatus is solitary, diurnal, omnivorous, and undergoes winter torpor. Individuals establish
solitary home ranges centered around extensive burrows. Diseases and parasites that affect T.
striatus include West Nile Virus, Cuterebrid bot flies, and Baylisascaris procyonis. Tamias striatus
is abundant throughout its range in eastern North America, inhabiting hardwood forests. It is 1 of
25 species within the genus Tamias, and the only member of subgenus Tamias. The species is
considered non-threatened, and is commonly seen throughout its range.
Published 5 December 2008 by the Department of Wildlife and Fisheries, Mississippi State University
Eastern chipmunk
Tamias striatus (Linnaeus, 1758)
CONTEXT AND CONTENT
Order Rodentia, suborder Sciuromorpha, family
Sciuridae, subfamily Xerinae, tribe Marmotini.
Tamias is not monotypic.
DISTRIBUTION
Tamias striatus is widely distributed throughout
its range in eastern North America (Rowe et
al. 2006). The northern extent of their range is
the southern tip of James Bay Canada, and the
southern limit is the Gulf of Mexico (Fig.2; Elliot
1978).
GENERAL CHARACTERS
Tamias striatus is a small rodent, weighing
between 73 and 136 g. Total body length is
205 to 299 mm. Tail length is 69 to 115 mm.
Dorsal pelage is reddish brown, with five dark
stripes alternated with two light buff stripes.
Stripes are also found on the sides of the head.
The tail is somewhat flattened and fully furred.
Ventral pelage is whitish; sometimes buff (Fig.
1; Sealander 1979). Tamias striatus is not
sexually dimorphic (Elliot 1978).
FORM AND FUNCTION
The skull of T. striatus is superiorly flattened
with a shallow brain case (Fig. 3). The
upper incisors are slightly recurved and
short, molars are low crowned with wide
Fig. 1. An adult Tamias striatus from northern New
Jersey. Used with permission of photographer .
Fig. 2. Geographic Distribution of Tamias striatus
(Wilson and Ruff 1999).
Females disperse approximately 85 m and
may overlap home ranges with their mothers
(Burke da Silva et al. 2002). Potential lifespan
of T. striatus may be as long as eight years;
however, longevity in the wild is generally 2 to 3
years (Sealander 1979).
Space use.—Tamias striatus is adapted
to mature deciduous forests with sparse
understory vegetation. Forest fragmentation is
not a large concern to the chipmunk, especially
if there are forested travel corridors. Individuals
have been documented crossing open fields
>220 m wide (Reunanen and Grubb 2005).
Fig. 3–Geographic distribution of Canis latrans. Adapted
from Jackson (1951), Hill et al. (1987), and Thornton et
al. (2004). Created using ArcGIS.
spaced cusps, and there may be subsidiary
cusplets between primary cusps (Howell 1938).
Dental formula is i 1/1, c 0/0, p 1/1, m 3/3, total
20 (Sealander 1979).
ONTOGENY AND REPRODUCTION
Tamias striatus reproduces in spring and
summer, though individual females may only
have one litter per year. Estrus lasts one
day, and most females within an area will go
into estrus within a few days of each other.
Both sexes mate multiple times with multiple
partners, copulating in cavities. Gestation
length is approximately 30 days (Elliot 1978).
Litter size ranges from 1 to 8, averaging 4 to
5 young. The neonates are altricial and are
reared in a nest chamber within the burrow
(Sealander 1979). Juveniles emerge from
the burrow at about 40 days of age and
disperse about 1 to 2 weeks later (Elliot 1978).
Females begin reproducing at one year of age
(Sealander 1979).
ECOLOGY
Population characteristics.—Dispersal of
juveniles varies between sexes, with males
dispersing up to 345 m from the natal burrow.
The eastern chipmunk establishes a solitary
home range of approximately 0.5 to 1 acre,
with a central home burrow maintained from
season to season. Home ranges may overlap
slightly, but only in the less used outer regions.
Individuals do not usually travel more than 45
m from their burrows. During breeding season
males will occasionally move from 60 to 90
m from their burrows in search of females in
estrus. A single female’s home range may be
visited by up to 12 different males while she is
in estrus (Elliot 1978).
Tamias striatus creates a burrow with a single
entrance; secondary entrances are plugged
with leaves and soil. Tunnels within the burrow
form a complex network around a nesting
cavity, with food hoards scattered throughout.
Burrows also contain a drainage system of
deep, tapered tunnels extending below the level
of the living tunnels. Because these burrows
are so complex, they are reused from season to
season (Elliot 1978).
Diet.—Although T. striatus is omnivorous, the
species feeds primarily on seeds, buds, and
berries (Reunanen and Grubb 2005). Other
components of the eastern chipmunk’s diet
include songbird eggs (Schmidt et al. 2001) and
invertebrates (Mahan and Yahner 1998).
Tamias striatus relies on food stores cached
in the fall to survive winter torpor. These food
stores consist primarily of acorns, beechnuts,
and sugar maple seeds (Humphries et al.
2003). Red oak acorns are the preferred food
for winter larders because of their higher lipid
content (Wood 2005).
Diseases and parasites.—The eastern
chipmunk is parasitized by Cuterebrid botflies
(also called warbles–Jaffe 2005). Bot flies
lay their eggs at the entrance to burrows; the
hatched larvae enter the host’s eyes, nose, or
mouth. The larvae then move beneath the skin
to the inguinal region where they mature and
burst through the skin of the host. Infection
of the lesion after the larvae leaves its host
can cause death if the infected individual was
heavily parasitized (Elliot 1978).
West Nile Virus is prevalent in T. striatus, and
is contracted from mosquitoes. The disease
can be passed both from mosquitoes to T.
striatus and vice versa. West Nile Virus causes
brain, kidney, and liver lesions; neurological
symptoms such as head tilting, lethargy, and
lack of coordination; and death in T. striatus
(Platt et al. 2007).
Tamias striatus is also parasitized by
Baylisascaris procyonis, a lower-intestine
dwelling nematode. Individuals are infected
when foraging in raccoon feces. The larval
cycle includes migration within the body, often
into the central nervous system. Baylisascaris
procyonis causes fatal or severe neurological
disease in over 50 species of mammals and
birds (Page et al. 2001).
BEHAVIOR
Grouping behavior.—Tamias striatus is
solitary, aggressive, and intolerant of other
individuals. No long-term social bonding
occurs. Social interactions between adults
outside of the breeding season consist primarily
of aggressive chases, usually when one
individual ventures too close to the center of
another’s home range. The greatest extent
of social cooperation in T. striatus is the use
of alarm calls to alert other individuals to the
presence of predators. (Elliot 1978).
Reproductive behavior.—Females stay
within their home range during estrus. Many
neighboring males will journey to her home
range in order to mate. Both males and
females mate multiple times with multiple
partners. There is no pair bonding between
males and females. Tamias striatus is
diestrous, with breeding seasons in spring
(February through April) and summer (June
through August). Juveniles stay in the burrow
for approximately 40 days, emerging in late
spring (April through June) or early fall (August
through October) depending on the breeding
season. Juveniles disperse between 1 to 2
weeks later (Elliot 1978).
Communication.—Tamias striatus uses three
distinctive alarm calls to alert other chipmunks
to the presence of predators: a chuck, a chip,
and a trill. A chuck is used when an individual
spots an aerial predator, a chip for terrestrial
predators, and trills when a predator is pursuing
an individual. Individual response to these
alarm calls varies depending on call rate and
number of individuals calling (Weary and
Kramer 1995).
Foraging.—Tamias striatus creates hoards
to store food. Scatter hoarding is much less
prevalent than larder hoarding since individuals
use their burrow hoards during winter torpor.
In the autumn, chipmunks use their expansive
cheek pouches to carry seeds and acorns
gathered both on the ground and in the crowns
of trees. (Elliot 1978).
During winter months, T. striatus uses burrow
hoards gathered in the fall as the primary
source of energy. Individuals create several
hoards within their burrows, storing surplus
food to last the entire winter. When T. striatus
emerges from hibernation in the spring,
overwintered seeds and acorns are the primary
source of food (Elliot 1978).
Tamias striatus raids songbird nests for eggs
(Schmidt et al. 2001). T. striatus also forages
for undigested berry seeds and corn in raccoon
feces (Page et al. 2001).
Winter Torpor.—Tamias striatus is a foodstoring hibernator. Rather than storing fat, T.
striatus creates a larder of various tree seeds in
its burrow. Individuals are solitary, and remain
in their burrows for 4 to 7 months (Humphries
et al. 2003). During bouts of torpor, individuals
rouse every 3 to 4 days to eat from their hoards
(Elliot 1978).
CONSERVATION
Tamias striatus is not endangered, and is
considered a species of least concern by the
International Union for Conservation of Nature
and Natural Resources Red List (IUCN 2007).
ACKNOWLEDGMENTS
I wish to thank my professor Dr. J. Belant for
his assistance and support throughout this
endeavor, as well as my fellow classmates
who served as editors. I also thank the staff of
the Mitchell Memorial Library and the College
of Forest Resources at Mississippi State
University for assistance in gaining access to
valuable information and materials.
LITERATURE CITED
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Contributing editor of this account was
Clinton Smith.