Fig. 1. Eastern chipmunk,
Prevention and Control Methods
construction will exclude chipmunks from structures.
Use 1/4-inch (0.6-cm)
mesh hardware cloth to exclude chipmunks from
gardens and flower beds.
Store food items, such
as bird seed and dog food, in rodent-proof
Ground covers, shrubs,
and wood piles should not be located adjacent to
Naphthalene (moth flakes or moth balls) may be
effective if liberally applied in confined places.
Repellents containing bitrex, thiram, or ammonium
soaps of higher fatty acids applied to flower bulbs,
seeds, and vegetation (not for human consumption)
may control feeding damage.
None are federally
registered. Check with local extension agents or a
USDA-APHIS-ADC personnel for possible Special Local
Needs 24(c) registrations.
Rat-sized snap traps.
Live (box or cage) traps. Glue boards.
Small gauge shotguns
or .22-caliber rifles.
Fifteen species of native
chipmunks of the genus Eutamias and one of the genus
Tamias are found in North America. The eastern chipmunk
(Tamias striatus) and the least chipmunk (Eutamias
minimas), discussed here, are the two most widely
distributed and notable species. Behavior and damage is
similar among all species of native chipmunks.
Therefore, damage control recommendations are similar
for all species.
The eastern chipmunk is a
small, brownish, ground-dwelling squirrel. It is
typically 5 to 6 inches (13 to 15 cm) long and weighs
about 3 ounces (90 g). It has two tan and five blackish
longitudinal stripes on its back, and two tan and two
brownish stripes on each side of its face. The
longitudinal stripes end at the reddish rump. The tail
is 3 to 4 inches (8 to 10 cm) long and hairy, but it is
not bushy (Fig. 1).
The least chipmunk is the
smallest of the chipmunks. It is typically 3 2/3 to 4
1/2 inches (9 to 11 cm) long and weighs 1 to 2 ounces
(35 to 70 g). The color varies from a faint yellowish
gray with tawny dark stripes (Badlands, South Dakota) to
a grayish tawny brown with black stripes (Wisconsin and
Michigan). The stripes, however, continue to the base of
the tail on all least chipmunks.
Chipmunks are often
confused with thirteen-lined ground squirrels (Spermophilus
tridecemlineatus), also called “striped gophers,” and
red squirrels (Tamiasciurus hudsonicus). The
thirteen-lined ground squirrel is yellowish, lacks the
facial stripes, and its tail is not as hairy as the
chipmunk’s. As this squirrel’s name implies, it has 13
stripes extending from the shoulder to the tail on each
side and on its back. When startled, a ground squirrel
carries its tail horizontally along the ground; the
chipmunk carries its tail upright. The thirteen-lined
ground squirrel’s call sounds like a high-pitched
squeak, whereas chipmunks have a rather sharp
“chuck-chuck-chuck” call. The red squirrel is very vocal
and has a high-pitched chatter. It is larger than the
chipmunk, has a bushier tail and lacks the longitudinal
stripes of the chipmunk. Red squirrels spend a great
deal of time in trees, while chipmunks spend most of
their time on the ground, although they can climb trees.
The eastern chipmunk’s
range includes most of the eastern United States. The
least chipmunk’s range includes most of Canada, the US
Rocky Mountains, the Great Basin, and parts of the upper
Midwest (Fig. 2).
and General Biology
typically inhabit mature woodlands and woodlot edges,
but they also inhabit areas in and around suburban and
rural homes. Chipmunks are generally solitary except
during courtship or when rearing young.
The least chipmunk
inhabits low sagebrush deserts, high mountain coniferous
forests, and northern mixed hardwood forests.
The home range of a
chipmunk may be up to 1/2 acre (0.2 ha), but the adult
only defends a territory about 50 feet (15.2 m) around
the burrow entrance. Chipmunks are most active during
the early morning and late afternoon. Chipmunk burrows
often are well-hidden near objects or buildings (for
example, stumps, wood piles or brush piles, basements,
and garages). The burrow entrance is usually about 2
inches (5 cm) in diameter. There are no obvious mounds
of dirt around the entrance because the chipmunk carries
the dirt in its cheek pouches and scatters it away from
the burrow, making the burrow entrance less conspicuous.
In most cases, the
chipmunk’s main tunnel is 20 to 30 feet (6 m to 9 m) in
length, but complex burrow systems occur where cover is
sparse. Burrow systems normally include a nesting
chamber, one or two food storage chambers, various side
pockets connected to the main tunnel, and separate
With the onset of cold
weather, chipmunks enter a restless hibernation and are
relatively inactive from late fall through the winter
months. Chipmunks do not enter a deep hibernation as do
ground squirrels, but rely on the cache of food they
have brought to their burrow. Some individuals become
active on warm, sunny days during the winter. Most
chipmunks emerge from hibernation in early March.
Eastern chipmunks mate two
times a year, during early spring and again during the
summer or early fall. There is a 31-day gestation
period. Two to 5 young are born in April to May and
again in August to October. The young are sexually
mature within 1 year. Adults may live up to 3 years.
Adult least chipmunks mate
over a period of 4 to 6 weeks from April to mid-July.
Least chipmunks produce 1 litter of 2 to 7 young in May
or June. Occasionally a second litter is produced in the
Chipmunk pups appear above
ground when they are 4 to 6 weeks old — 2/3 the size of
an adult. Young will leave the burrow at 6 to 8 weeks.
Population densities of
chipmunks are typically 2 to 4 animals per acre (5 to
10/ha). Eastern chipmunk population densities may be as
high as 10 animals per acre (24/ha), however, if
sufficient food and cover are available. Home ranges
often overlap among individuals.
The diet of chipmunks
consists primarily of grains, nuts, berries, seeds,
mushrooms, insects, and carrion. Although chipmunks are
mostly ground-dwelling rodents, they regularly climb
trees in the fall to gather nuts, fruits, and seeds.
Chipmunks cache food in their burrows throughout the
year. By storing and scattering seeds, they promote the
growth of various plants.
Chipmunks also prey on
young birds and bird eggs. Chipmunks themselves serve as
prey for several predators.
Damage and Damage Identification
Throughout their North
American range, chipmunks are considered minor
agricultural pests. Most conflicts with chipmunks are
nuisance problems. When chipmunks are present in large
numbers they can cause structural damage by burrowing
under patios, stairs, retention walls, or foundations.
They may also consume flower bulbs, seeds, or seedlings,
as well as bird seed, grass seed, and pet food that is
not stored in rodent-proof storage containers. In New
England, chipmunks and tree squirrels cause considerable
damage to maple sugar tubing systems by gnawing the
Chipmunks are not
protected by federal law, but state and local
regulations may apply. Most states allow landowners or
tenants to take chipmunks when they are causing or about
to cause damage. Some states, (for example, Georgia,
North Carolina, and Arkansas) require a permit to kill
nongame animals. Other states are currently developing
laws to protect all nongame species. Consult your local
conservation agency or USDA-APHIS-ADC personnel for the
legal status of chipmunks in your state.
Damage Prevention and Control
Chipmunks should be excluded from buildings wherever
possible. Use hardware cloth with 1/4-inch (0.6-cm)
mesh, caulking, or other appropriate materials to close
openings where they could gain entry.
Hardware cloth may also be
used to exclude chipmunks from flower beds. Seeds and
bulbs can be covered by 1/4-inch (0.6-cm) hardware cloth
and the cloth itself should be covered with soil. The
cloth should extend at least 1 foot (30 cm) past each
margin of the planting. Exclusion is less expensive in
the long run than trapping, where high populations of
Cultural Methods and
Landscaping features, such as ground cover, trees,
and shrubs, should not be planted in continuous fashion
connecting wooded areas with the foundations of homes.
They provide protection for chipmunks that may attempt
to gain access into the home. It is also difficult to
detect chipmunk burrows that are adjacent to foundations
when wood piles, debris, or plantings of ground cover
provide above-ground protection.
Place bird feeders at
least 15 to 30 feet (5 to 10 m) away from buildings so
spilled bird seed does not attract and support chipmunks
Naphthalene flakes (“moth flakes”) may repel
chipmunks from attics, summer cabins, and storage areas
when applied liberally (4 to 5 pounds of naphthalene
flakes per 2,000 square feet [1.0 to 1.2 kg/100 m2]).
Use caution, however, in occupied buildings, as the odor
may also be objectionable or irritating to people or
There are currently no
federally registered repellents for controlling rodent
damage to seeds, although some states have Special Local
Needs 24(c) registrations for this purpose. Taste
repellents containing bitrex, thiram, or ammonium soaps
of higher fatty acids can be used to protect flower
bulbs, seeds, and foliage not intended for human
consumption. Multiple applications of repellents are
required. Repellents can be expensive and usually do not
provide 100% reduction in damage to horticultural
There are no toxic baits registered for controlling
chipmunks. Baits that are used against rats and mice in
and around homes will also kill chipmunks although they
are not labeled for such use and cannot be recommended.
Moreover, chipmunks that die from consuming a toxic bait
inside structures may create an odor problem for several
days. Some states have Special Local Needs 24(c)
registrations for chipmunk control for site-specific
Consult a professional
pest control operator or USDA-APHIS-ADC biologist if
chipmunks are numerous or persistent.
Fumigants are generally ineffective because of the
difficulty in locating the openings to chipmunk burrows
and because of the complexity of burrows.
Aluminum phosphide is a
Restricted Use Pesticide that is registered in many
states for the control of burrowing rodents. It is
available in a tablet form, which when dropped into the
burrow reacts with the moisture in the soil and
generates toxic phosphine gas.
however, cannot be used in, under, or even near occupied
buildings because there is a danger of the fumigant
seeping into buildings.
Gas cartridges are
registered for the control of burrowing rodents and are
available from garden supply centers, hardware stores,
seed catalogs, or the USDA-APHIS-ADC program. Chipmunk
burrows may have to be enlarged to accommodate the
commercially or federally produced gas cartridges. Gas
cartridges should not be used under or around buildings
or near fire hazards since they burn with an open flame
and produce a tremendous amount of heat. Carbon monoxide
and carbon dioxide gases are produced while the
cartridges burn; thus, the rodents die from
Trapping is the most practical method of eliminating
chipmunks in most home situations. Live-catch wire-mesh
traps or common rat snap traps can be used to catch
chipmunks. Common live-trap models include the Tomahawk
(Nos. 102, 201) and Havahart (Nos. 0745, 1020, 1025)
traps. Check the Supplies and Materials section for
additional manufacturers of live-catch traps.
A variety of baits can be
used to lure chipmunks into live traps, including peanut
butter, nutmeats, pumpkin or sunflower seeds, raisins,
prune slices, or common breakfast cereal grains. Place
the trap along the pathways where chipmunks have been
seen frequently. The trap should be securely placed so
there is no movement of the trap prematurely when the
animal enters. Trap movement may prematurely set off the
trap and scare the chipmunk away. A helpful tip is to
“prebait” the trap for 2 to 3 days by wiring the trap
doors open. This will condition the chipmunk to
associate the new metal object in its territory with the
new free food source. Set the trap after the chipmunk is
actively feeding on the bait in and around the trap.
Live traps can be purchased from local hardware stores,
department stores, pest control companies, or rented
from local animal shelters.
Check traps frequently to
remove captured chipmunks and release any nontarget
animals caught in them. Avoid direct contact with
trapped chipmunks. Transport and release livetrapped
chipmunks several miles from the point of capture (in
areas where they will not bother someone else), or
euthanize by placing in a carbon dioxide chamber.
Common rat snap traps can
be used to kill chipmunks if these traps are isolated
from children, pets, or wildlife. They can be set in the
same manner as live traps but hard baits should be tied
to the trap trigger. Prebait snap traps by not setting
the trap until the animal has been conditioned to take
the bait without disturbance for 2 to 3 days. Small
amounts of extra bait may be placed around the traps to
make them more attractive. Set the snap traps
perpendicular to the chipmunk’s pathway or in pairs
along travel routes with the triggers facing away from
each other. Set the trigger arm so that the trigger is
sensitive and easily sprung.
To avoid killing songbirds
in rat snap traps, it is advisable to place the traps
under a small box with openings that allow only
chipmunks access to the baited trap. The box must allow
enough clearance so the trap operates properly. Conceal
snap traps that are set against structures by leaning
boards over them. Small amounts of bait can be placed at
the openings as an attractant.
Where shooting is legal, use a small-gauge shotgun
or a .22-caliber rifle with bird shot or C.B. cap loads.
Chipmunks are nervous and alert, so they make difficult
targets. The best time to attempt shooting is on bright
sunny days during the early morning.
Economics of Damage and Control
The majority of chipmunk
damage involves minimal economic loss (under $200).
Homeowners report that chipmunks are quite destructive
when it comes to their burrowing activities around
structures. This damage warrants an investment in
control to protect structural integrity of stairs,
patios, and foundations. Their consumption of seeds,
flower bulbs, fruit, and vegetables is often a nuisance.
We would like to thank all
the USDA-APHIS-ADC wildlife biologists who provided
information on chipmunks pertinent to their locality.
Kathleen LeMaster and Dee Anne Gillespie provided
Figure 1 from Schwartz and
Figure 2 from Burt and
Bennett, G. W., J. M.
Owens, and R. M. Corrigan. 1988. Truman’s scientific
guide to pest control operations. Purdue Univ./ Edgell
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Grossenheider. 1976. A field guide to the mammals.
Houghton Mifflin Co., Boston. 289 pp.
Corrigan, R. M., and D. E.
Williams. 1988. Chipmunks. ADC-2 leaflet, Coop. Ext.
Serv., Purdue Univ., West Lafayette, Indiana. in coop.
with the US Dept. Agric. 2 pp.
Dudderar, G. 1977.
Chipmunks and ground squirrels. Ext. Bull. E-867,
Michigan State Univ., Lansing, Michigan. 1 p.
Eadie, W. R. 1954. Animal
control in field, farm, and forest. The Macmillan Co.,
New York. 257 pp.
Gunderson, H. L., and J.
R. Beer. 1953. The mammals of Minnesota. Univ. Minnesota
Press. Minneapolis. 190 pp.
Hoffmeister, D. F., and C.
O. Mohr. 1957. A fieldbook of Illinois mammals. Nat.
Hist. Surv. Div. Urbana, Illinois. 233 pp.
Marsh, R. E., and W. E.
Howard. 1990. Vertebrate pests. Pages 771-831 in A.
Mallis ed., Handbook of pest control. 7th ed. Franzak
and Foster Co. Cleveland, Ohio.
Schwartz, C. W., and E. R.
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Missouri Press. Columbia. 356 pp.
Scott E. Hygnstrom; Robert
M. Timm; Gary E. Larson
PREVENTION AND CONTROL OF
WILDLIFE DAMAGE — 1994
Division Institute of Agriculture and Natural Resources
University of Nebraska -Lincoln
United States Department
of Agriculture Animal and Plant Health Inspection
Service Animal Damage Control
Great Plains Agricultural
Council Wildlife Committee
Williams State Director USDA-APHIS-Animal Damage Control
Lincoln, Nebraska 68501
Robert M. Corrigan Staff Specialist Vertebrate Pest
Management Purdue University West Lafayette, Indiana