Chipmunks
Lifespan/Lifestyle
A chipmunk can live up to seven years, but most don’t survive their first year in the wild. To communicate squirrels use body gestures with tail waving, their vocabulary is limited, but most communication happens with the body. Chipmunks live in woodlands, lawns, gardens, parks, and brushy areas. They burrow underground and their homes are normally blocked off by a large rock, tree stump, or post. The tunnels are normally two to three feet beneath the ground.
Sleep/Hibernation
Chipmunks are hibernating animals, but they do not get fat like others, every couple of days they wake-up to eat, and on warm, sunny, winter days, they may be seen above ground.
Diet
Chipmunks eat mostly plants, but they also eat small vertebrates, such as snails, or slugs. They will take handouts from humans; this can include a wide variety of items from pastries, to pizza.
Bruce’s Notes
Chipmunks are climbers they come in anywhere and they come in numbers from one to many. They can be controlled through poisons, exclusion, and trapping. Never poison inside of a building. Trapping is more advised on inside attics, crawl spaces, and wall cavities. They chew on wiring, cause wire damage, wall and attic fires. Also property value decreases with animal or rodent infestations. And you are responsible as a home owner to solve your animal damage problem, through animal control measures or poisons and exclusion or block out prior to the sell of your home. They leave an odor when they die and they leave fecal contamination.
Identification
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.
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 highpitched
squeak, whereas chipmunks
have a rather sharp “chuck-chuckchuck”
call. The red squirrel is very vocal
and has a high-pitched chatter. It is
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 wellhidden
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
escape tunnels.
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.
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.
Range
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
Habitat and General
Biology
Eastern chipmunks typically inhabit
mature woodlands and woodlot edges,
but they also inhabit areas in and
around suburban and rural homes.
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 fall.
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.
Food Habits
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 tubes.
Legal Status
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 USDAAPHIS-
ADC personnel for the legal
status of chipmunks in your state.
Damage Prevention and
Control
Exclusion
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 chipmunks exist.
Cultural Methods and Habitat
Modifications
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 near them.
Repellents
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 pets.
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 plantings.
Toxicants
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 use.
Consult a professional pest control
operator or USDA-APHIS-ADC biologist
if chipmunks are numerous or
persistent.
Fumigants
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.
Aluminum phosphide, 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
asphyxiation.
Trapping
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.
Shooting
Where shooting is legal, use a smallgauge
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.
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