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a

b

Fig. 2. Range of the eastern (a) and least chip-munk (b) in North America.

Identification

Fifteen species of native chipmunks ofthe genus Eutamias and one of thegenus Tamias are found in NorthAmerica. The eastern chipmunk(Tamias striatus) and the least chip-munk (Eutamias minimas), discussedhere, are the two most widely distrib-uted and notable species. Behavior anddamage is similar among all species ofnative chipmunks. Therefore, damagecontrol recommendations are similarfor all species.

The eastern chipmunk is a small,brownish, ground-dwelling squirrel. Itis typically 5 to 6 inches (13 to 15 cm)long and weighs about 3 ounces (90 g).It has two tan and five blackish longi-tudinal stripes on its back, and two tanand two brownish stripes on each sideof its face. The longitudinal stripes endat the reddish rump. The tail is 3 to 4inches (8 to 10 cm) long and hairy, butit is not bushy (Fig. 1).

The least chipmunk is the smallest ofthe chipmunks. It is typically 3 2/3 to4 1/2 inches (9 to 11 cm) long andweighs 1 to 2 ounces (35 to 70 g). Thecolor varies from a faint yellowish graywith tawny dark stripes (Badlands,South Dakota) to a grayish tawnybrown with black stripes (Wisconsinand Michigan). The stripes, however,continue to the base of the tail on allleast chipmunks.

Chipmunks are often confused withthirteen-lined ground squirrels(Spermophilus tridecemlineatus), alsocalled “striped gophers,” and redsquirrels (Tamiasciurus hudsonicus). Thethirteen-lined ground squirrel is yel-lowish, lacks the facial stripes, and itstail is not as hairy as the chipmunk’s.As this squirrel’s name implies, it has13 stripes extending from the shoulderto the tail on each side and on its back.When startled, a ground squirrel car-ries its tail horizontally along theground; the chipmunk carries its tailupright. The thirteen-lined groundsquirrel’s call sounds like a high-pitched squeak, whereas chipmunkshave a rather sharp “chuck-chuck-chuck” call. The red squirrel is very vo-cal and has a high-pitched chatter. It is

larger than the chipmunk, has abushier tail and lacks the longitudinalstripes of the chipmunk. Red squirrelsspend a great deal of time in trees,while chipmunks spend most of theirtime on the ground, although they canclimb trees.

Range

The eastern chipmunk’s range in-cludes most of the eastern UnitedStates. The least chipmunk’s rangeincludes most of Canada, the USRocky Mountains, the Great Basin, andparts of the upper Midwest (Fig. 2).

Habitat and GeneralBiology

Eastern chipmunks typically inhabitmature woodlands and woodlot edges,but they also inhabit areas in andaround suburban and rural homes.

Chipmunks are generally solitary ex-cept during courtship or when rearingyoung.

The least chipmunk inhabits low sage-brush deserts, high mountain conifer-ous forests, and northern mixedhardwood forests.

The home range of a chipmunk maybe up to 1/2 acre (0.2 ha), but the adultonly defends a territory about 50 feet(15.2 m) around the burrow entrance.Chipmunks are most active during theearly morning and late afternoon.

Chipmunk burrows often are well-hidden near objects or buildings (forexample, stumps, wood piles or brushpiles, basements, and garages). Theburrow entrance is usually about 2inches (5 cm) in diameter. There are noobvious mounds of dirt around the en-trance because the chipmunk carriesthe dirt in its cheek pouches and scat-ters it away from the burrow, makingthe burrow entrance less conspicuous.

In most cases, the chipmunk’s maintunnel is 20 to 30 feet (6 m to 9 m) inlength, but complex burrow systemsoccur where cover is sparse. Burrowsystems normally include a nestingchamber, one or two food storagechambers, various side pockets con-nected to the main tunnel, and sepa-rate escape tunnels.

With the onset of cold weather, chip-munks enter a restless hibernation andare relatively inactive from late fallthrough the winter months. Chip-munks do not enter a deep hibernationas do ground squirrels, but rely on thecache of food they have brought totheir burrow. Some individuals be-come active on warm, sunny days dur-ing the winter. Most chipmunksemerge from hibernation in earlyMarch.

Eastern chipmunks mate two times ayear, during early spring and againduring the summer or early fall. Thereis a 31-day gestation period. Two to 5young are born in April to May andagain in August to October. The youngare sexually mature within 1 year.Adults may live up to 3 years.

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Aluminum phosphide, however, can-not be used in, under, or even nearoccupied buildings because there is adanger of the fumigant seeping intobuildings.

Gas cartridges are registered for thecontrol of burrowing rodents and areavailable from garden supply centers,hardware stores, seed catalogs, or theUSDA-APHIS-ADC program. Chip-munk burrows may have to beenlarged to accommodate the com-mercially or federally produced gascartridges. Gas cartridges should notbe used under or around buildings ornear fire hazards since they burn withan open flame and produce a tremen-dous amount of heat. Carbon monox-ide and carbon dioxide gases areproduced while the cartridges burn;thus, the rodents die fromasphyxiation.

Trapping

Trapping is the most practical methodof eliminating chipmunks in mosthome situations. Live-catch wire-meshtraps or common rat snap traps can beused to catch chipmunks. Commonlive-trap models include the Toma-hawk (Nos. 102, 201) and Havahart(Nos. 0745, 1020, 1025) traps. Check theSupplies and Materials section foradditional manufacturers of live-catchtraps.

A variety of baits can be used to lurechipmunks into live traps, includingpeanut butter, nutmeats, pumpkin orsunflower seeds, raisins, prune slices,or common breakfast cereal grains.Place the trap along the pathwayswhere chipmunks have been seen fre-quently. The trap should be securelyplaced so there is no movement of thetrap prematurely when the animalenters. Trap movement may prema-turely set off the trap and scare thechipmunk away. A helpful tip is to“prebait” the trap for 2 to 3 days bywiring the trap doors open. This willcondition the chipmunk to associatethe new metal object in its territorywith the new free food source. Set thetrap after the chipmunk is activelyfeeding on the bait in and around thetrap. Live traps can be purchased fromlocal hardware stores, department

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stores, pest control companies, orrented from local animal shelters.

Check traps frequently to removecaptured chipmunks and release anynontarget animals caught in them.Avoid direct contact with trappedchipmunks. Transport and release live-trapped chipmunks several miles fromthe point of capture (in areas wherethey will not bother someone else), oreuthanize by placing in a carbon diox-ide chamber.

Common rat snap traps can be used tokill chipmunks if these traps are iso-lated from children, pets, or wildlife.They can be set in the same manner aslive traps but hard baits should be tiedto the trap trigger. Prebait snap trapsby not setting the trap until the animalhas been conditioned to take the baitwithout disturbance for 2 to 3 days.Small amounts of extra bait may beplaced around the traps to make themmore attractive. Set the snap traps per-pendicular to the chipmunk’s pathwayor in pairs along travel routes with thetriggers facing away from each other.Set the trigger arm so that the triggeris sensitive and easily sprung.

To avoid killing songbirds in rat snaptraps, it is advisable to place the trapsunder a small box with openings thatallow only chipmunks access to thebaited trap. The box must allowenough clearance so the trap operatesproperly. Conceal snap traps that areset against structures by leaningboards over them. Small amounts ofbait can be placed at the openings asan attractant.

Shooting

Where shooting is legal, use a small-gauge shotgun or a .22-caliber riflewith bird shot or C.B. cap loads. Chip-munks are nervous and alert, so theymake difficult targets. The best time toattempt shooting is on bright sunnydays during the early morning.

Economics of Damageand Control

The majority of chipmunk damage in-volves minimal economic loss (under$200). Homeowners report that chip-

munks are quite destructive when itcomes to their burrowing activitiesaround structures. This damage war-rants an investment in control to pro-tect structural integrity of stairs, patios,and foundations. Their consumptionof seeds, flower bulbs, fruit, and veg-etables is often a nuisance.

AcknowledgmentsWe would like to thank all the USDA-APHIS-ADC wildlife biologists who providedinformation on chipmunks pertinent to theirlocality. Kathleen LeMaster and Dee AnneGillespie provided technical assistance.

Figure 1 from Schwartz and Schwartz (1981).

Figure 2 from Burt and Grossenheider (1976).

For AdditionalInformationBennett, G. W., J. M. Owens, and R. M.

Corrigan. 1988. Truman’s scientific guide topest control operations. Purdue Univ./Edgell Commun. Duluth, Minnesota. 539pp.

Burt, W. H., and R. P. Grossenheider. 1976. Afield guide to the mammals. HoughtonMifflin Co., Boston. 289 pp.

Corrigan, R. M., and D. E. Williams. 1988.Chipmunks. ADC-2 leaflet, Coop. Ext. Serv.,Purdue Univ., West Lafayette, Indiana. incoop. with the US Dept. Agric. 2 pp.

Dudderar, G. 1977. Chipmunks and groundsquirrels. Ext. Bull. E-867, Michigan StateUniv., 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. Themammals of Minnesota. Univ. MinnesotaPress. Minneapolis. 190 pp.

Hoffmeister, D. F., and C. O. Mohr. 1957. Afieldbook 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. Mallised., Handbook of pest control. 7th ed.Franzak and Foster Co. Cleveland, Ohio.

Schwartz, C. W., and E. R. Schwartz. 1981. Thewild mammals of Missouri. The Univ.Missouri Press. Columbia. 356 pp.

EditorsScott E. HygnstromRobert M. TimmGary E. Larson