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David E. Williams State Director USDA-APHIS- Damage Control Lincoln, Nebraska 68501

Robert M. Corrigan Staff Specialist Vertebrate Pest Management Purdue University West Lafayette, Indiana 47907

Fig. 1. Eastern , striatus

Damage Prevention and Frightening Toxicants Control Methods Not effective. None are federally registered. Check with local extension agents or a Exclusion Repellents USDA-APHIS-ADC personnel for -proof construction will Area repellents. Naphthalene (moth possible Special Local Needs 24(c) exclude chipmunks from structures. flakes or moth balls) may be effec- registrations. tive if liberally applied in confined Fumigants Use 1/4-inch (0.6-cm) mesh hardware places. cloth to exclude chipmunks from Generally impractical. gardens and flower beds. Taste repellents. Repellents containing bitrex, thiram, or ammonium soaps Trapping Modification of higher fatty acids applied to -sized snap traps. Store food items, such as flower bulbs, , and vegetation and food, in rodent-proof (not for human consumption) may Live (box or cage) traps. control feeding damage. containers. Glue boards. Ground covers, shrubs, and wood piles Shooting should not be located adjacent to structure foundations. Small gauge shotguns or .22-caliber rifles.

PREVENTION AND CONTROL OF WILDLIFE DAMAGE — 1994 Cooperative Extension 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 B-13 Great Plains Agricultural Council Wildlife Committee a Chipmunks are generally solitary ex- Identification cept during courtship or when rearing Fifteen of native chipmunks of young. the and one of the The inhabits low sage- genus Tamias are found in North brush , high mountain conifer- America. The ous , and northern mixed (Tamias striatus) and the least chip- hardwood forests. munk (Eutamias minimas), discussed here, are the two most widely distrib- The home range of a chipmunk may uted and notable species. Behavior and be up to 1/2 acre (0.2 ha), but the adult damage is similar among all species of only defends a territory about 50 feet native chipmunks. Therefore, damage (15.2 m) around the entrance. control recommendations are similar Chipmunks are most active during the for all species. early morning and late afternoon. Chipmunk often are well- The eastern chipmunk is a small, b brownish, ground-dwelling . It hidden near objects or buildings (for is typically 5 to 6 inches (13 to 15 cm) example, stumps, wood piles or brush long and weighs about 3 ounces (90 g). piles, basements, and garages). The It has two tan and five blackish longi- burrow entrance is usually about 2 tudinal stripes on its back, and two tan inches (5 cm) in diameter. There are no and two brownish stripes on each side obvious mounds of dirt around the en- of its face. The longitudinal stripes end trance because the chipmunk carries at the reddish rump. The tail is 3 to 4 the dirt in its cheek pouches and scat- inches (8 to 10 cm) long and hairy, but ters it away from the burrow, making it is not bushy (Fig. 1). the burrow entrance less conspicuous. The least chipmunk is the smallest of In most cases, the chipmunk’s main the chipmunks. It is typically 3 2/3 to tunnel is 20 to 30 feet (6 m to 9 m) in 4 1/2 inches (9 to 11 cm) long and length, but complex burrow systems weighs 1 to 2 ounces (35 to 70 g). The occur where cover is sparse. Burrow systems normally include a nesting color varies from a faint yellowish gray Fig. 2. Range of the eastern (a) and least chip- with tawny dark stripes (Badlands, munk (b) in . chamber, one or two food storage ) to a grayish tawny chambers, various side pockets con- nected to the main tunnel, and sepa- brown with black stripes ( larger than the chipmunk, has a rate escape tunnels. and ). The stripes, however, bushier tail and lacks the longitudinal continue to the base of the tail on all stripes of the chipmunk. Red With the onset of cold weather, chip- least chipmunks. spend a great deal of time in trees, munks enter a restless and while chipmunks spend most of their Chipmunks are often confused with are relatively inactive from late fall time on the ground, although they can thirteen-lined ground squirrels through the winter months. Chip- climb trees. ( tridecemlineatus), also munks do not enter a deep hibernation called “striped ,” and red as do ground squirrels, but rely on the squirrels (Tamiasciurus hudsonicus). The Range cache of food they have brought to thirteen-lined is yel- their burrow. Some individuals be- lowish, lacks the facial stripes, and its The eastern chipmunk’s range in- come active on warm, sunny days dur- tail is not as hairy as the chipmunk’s. cludes most of the eastern United ing the winter. Most chipmunks As this squirrel’s name implies, it has States. The least chipmunk’s range emerge from hibernation in early 13 stripes extending from the shoulder includes most of Canada, the US March. to the tail on each side and on its back. Rocky Mountains, the Great Basin, and Eastern chipmunks mate two times a When startled, a ground squirrel car- parts of the upper Midwest (Fig. 2). year, during early spring and again ries its tail horizontally along the during the summer or early fall. There ground; the chipmunk carries its tail Habitat and General is a 31-day gestation period. Two to 5 upright. The thirteen-lined ground Biology young are born in April to May and squirrel’s call sounds like a high- again in August to October. The young pitched squeak, whereas chipmunks Eastern chipmunks typically inhabit are sexually mature within 1 year. have a rather sharp “chuck-chuck- mature woodlands and woodlot edges, Adults may live up to 3 years. chuck” call. The is very vo- but they also inhabit areas in and cal and has a high-pitched chatter. It is around suburban and rural homes.

B-14 Adult least chipmunks mate over a Legal Status Repellents period of 4 to 6 weeks from April to Naphthalene flakes (“moth flakes”) mid-July. Least chipmunks produce 1 Chipmunks are not protected by fed- may repel chipmunks from attics, litter of 2 to 7 young in May or June. eral law, but state and local regulations summer cabins, and storage areas Occasionally a second litter is pro- may apply. Most states allow land- when applied liberally (4 to 5 pounds duced in the fall. owners or tenants to take chipmunks when they are causing or about to of naphthalene flakes per 2,000 square 2 Chipmunk pups appear above ground cause damage. Some states, (for feet [1.0 to 1.2 kg/100 m ]). Use cau- when they are 4 to 6 weeks old — 2/3 example, Georgia, North Carolina, and tion, however, in occupied buildings, the size of an adult. Young will leave Arkansas) require a permit to kill as the odor may also be objectionable the burrow at 6 to 8 weeks. nongame . Other states are or irritating to people or pets. Population densities of chipmunks are currently developing laws to protect There are currently no federally regis- typically 2 to 4 animals per acre (5 to all nongame species. Consult your lo- tered repellents for controlling rodent 10/ha). Eastern chipmunk population cal conservation agency or USDA- damage to seeds, although some states densities may be as high as 10 animals APHIS-ADC personnel for the legal have Special Local Needs 24(c) regis- per acre (24/ha), however, if sufficient status of chipmunks in your state. trations for this purpose. Taste repel- food and cover are available. Home lents containing bitrex, thiram, or ranges often overlap among Damage Prevention and ammonium soaps of higher fatty acids individuals. Control can be used to protect flower bulbs, seeds, and foliage not intended for hu- Food Habits Exclusion man consumption. Multiple applica- tions of repellents are required. Chipmunks should be excluded from The diet of chipmunks consists prima- Repellents can be expensive and usu- buildings wherever possible. Use hard- rily of grains, nuts, berries, seeds, ally do not provide 100% reduction in ware cloth with 1/4-inch (0.6-cm) mushrooms, , and carrion. damage to horticultural plantings. mesh, caulking, or other appropriate Although chipmunks are mostly materials to close openings where they Toxicants ground-dwelling , they regu- could gain entry. larly climb trees in the fall to gather There are no toxic baits registered for nuts, , and seeds. Chipmunks Hardware cloth may also be used to controlling chipmunks. Baits that are cache food in their burrows through- exclude chipmunks from flower beds. used against and mice in and out the year. By storing and scattering Seeds and bulbs can be covered by around homes will also kill chipmunks seeds, they promote the growth of 1/4-inch (0.6-cm) hardware cloth and although they are not labeled for such various plants. the cloth itself should be covered with use and cannot be recommended. soil. The cloth should extend at least 1 Moreover, chipmunks that die from Chipmunks also prey on young foot (30 cm) past each margin of the consuming a toxic bait inside struc- and bird eggs. Chipmunks themselves planting. Exclusion is less expensive in tures may create an odor problem for serve as prey for several predators. the long run than trapping, where several days. Some states have Special high populations of chipmunks exist. Local Needs 24(c) registrations for Damage and Damage chipmunk control for site-specific use. Identification Cultural Methods and Habitat Modifications Consult a professional pest control operator or USDA-APHIS-ADC biolo- Throughout their North American Landscaping features, such as ground gist if chipmunks are numerous or range, chipmunks are considered mi- cover, trees, and shrubs, should not be persistent. nor agricultural pests. Most conflicts planted in continuous fashion connect- with chipmunks are nuisance prob- ing wooded areas with the founda- Fumigants lems. When chipmunks are present in tions of homes. They provide protec- Fumigants are generally ineffective large numbers they can cause struc- tion for chipmunks that may attempt because of the difficulty in locating the tural damage by burrowing under to gain access into the home. It is also openings to chipmunk burrows and patios, stairs, retention walls, or foun- difficult to detect chipmunk burrows because of the complexity of burrows. dations. They may also consume that are adjacent to foundations when flower bulbs, seeds, or seedlings, as wood piles, debris, or plantings of Aluminum phosphide is a Restricted well as bird seed, grass seed, and pet ground cover provide above-ground Use Pesticide that is registered in food that is not stored in rodent-proof protection. many states for the control of burrow- storage containers. In New England, ing rodents. It is available in a tablet Place bird feeders at least 15 to 30 feet chipmunks and tree squirrels cause form, which when dropped into the (5 to 10 m) away from buildings so considerable damage to maple sugar burrow reacts with the moisture in the spilled bird seed does not attract and tubing systems by gnawing the tubes. soil and generates toxic phosphine gas. support chipmunks near them.

B-15 Aluminum phosphide, however, can- stores, pest control companies, or munks are quite destructive when it not be used in, under, or even near rented from local animal shelters. comes to their burrowing activities occupied buildings because there is a around structures. This damage war- Check traps frequently to remove danger of the fumigant seeping into rants an investment in control to pro- captured chipmunks and release any buildings. tect structural integrity of stairs, patios, nontarget animals caught in them. and foundations. Their consumption Gas cartridges are registered for the Avoid direct contact with trapped of seeds, flower bulbs, , and veg- control of burrowing rodents and are chipmunks. Transport and release live- etables is often a nuisance. available from garden supply centers, trapped chipmunks several miles from hardware stores, seed catalogs, or the the point of capture (in areas where USDA-APHIS-ADC program. Chip- they will not bother someone else), or Acknowledgments munk burrows may have to be euthanize by placing in a carbon diox- We would like to thank all the USDA-APHIS- enlarged to accommodate the com- ide chamber. ADC wildlife biologists who provided mercially or federally produced gas information on chipmunks pertinent to their Common rat snap traps can be used to cartridges. Gas cartridges should not locality. Kathleen LeMaster and Dee Anne kill chipmunks if these traps are iso- Gillespie provided technical assistance. be used under or around buildings or lated from children, pets, or wildlife. near fire hazards since they burn with Figure 1 from Schwartz and Schwartz (1981). They can be set in the same manner as an open flame and produce a tremen- Figure 2 from Burt and Grossenheider (1976). live traps but hard baits should be tied dous amount of heat. Carbon monox- to the trap trigger. Prebait snap traps ide and carbon dioxide gases are by not setting the trap until the animal For Additional produced while the cartridges burn; has been conditioned to take the bait Information thus, the rodents die from without disturbance for 2 to 3 days. asphyxiation. Bennett, G. W., J. M. Owens, and R. M. Small amounts of extra bait may be Corrigan. 1988. Truman’s scientific guide to Trapping placed around the traps to make them pest control operations. Purdue Univ./ more attractive. Set the snap traps per- Edgell Commun. Duluth, . 539 Trapping is the most practical method pendicular to the chipmunk’s pathway pp. of eliminating chipmunks in most or in pairs along travel routes with the Burt, W. H., and R. P. Grossenheider. 1976. A home situations. Live-catch wire-mesh triggers facing away from each other. field guide to the . Houghton traps or common rat snap traps can be Set the trigger arm so that the trigger Mifflin Co., Boston. 289 pp. used to catch chipmunks. Common is sensitive and easily sprung. Corrigan, R. M., and D. E. Williams. 1988. live-trap models include the Toma- Chipmunks. ADC-2 leaflet, Coop. Ext. Serv., (Nos. 102, 201) and Havahart To avoid killing songbirds in rat snap Purdue Univ., West Lafayette, Indiana. in (Nos. 0745, 1020, 1025) traps. Check the traps, it is advisable to place the traps coop. with the US Dept. Agric. 2 pp. Supplies and Materials section for under a small box with openings that Dudderar, G. 1977. Chipmunks and ground additional manufacturers of live-catch allow only chipmunks access to the squirrels. Ext. Bull. E-867, Michigan State traps. baited trap. The box must allow Univ., Lansing, Michigan. 1 p. enough clearance so the trap operates Eadie, W. R. 1954. Animal control in field, farm, A variety of baits can be used to lure properly. Conceal snap traps that are and . The Macmillan Co., New York. chipmunks into live traps, including set against structures by leaning 257 pp. peanut butter, nutmeats, pumpkin or boards over them. Small amounts of Gunderson, H. L., and J. R. Beer. 1953. The sunflower seeds, raisins, prune slices, bait can be placed at the openings as mammals of Minnesota. Univ. Minnesota or common breakfast cereal grains. Press. Minneapolis. 190 pp. an attractant. Place the trap along the pathways Hoffmeister, D. F., and C. O. Mohr. 1957. A where chipmunks have been seen fre- Shooting fieldbook of Illinois mammals. Nat. Hist. quently. The trap should be securely Surv. Div. Urbana, Illinois. 233 pp. Where shooting is legal, use a small- placed so there is no movement of the gauge shotgun or a .22-caliber rifle Marsh, R. E., and W. E. Howard. 1990. trap prematurely when the animal with bird shot or C.B. cap loads. Chip- Vertebrate pests. Pages 771-831 in A. Mallis enters. Trap movement may prema- ed., Handbook of pest control. 7th ed. munks are nervous and alert, so they turely set off the trap and scare the Franzak and Foster Co. Cleveland, Ohio. make difficult targets. The best time to chipmunk away. A helpful tip is to Schwartz, C. W., and E. R. Schwartz. 1981. The attempt shooting is on bright sunny “prebait” the trap for 2 to 3 days by wild mammals of Missouri. The Univ. days during the early morning. wiring the trap doors open. This will Missouri Press. Columbia. 356 pp. condition the chipmunk to associate the new metal object in its territory Economics of Damage Editors with the new free food source. Set the and Control Scott E. Hygnstrom trap after the chipmunk is actively Robert M. Timm feeding on the bait in and around the The majority of chipmunk damage in- Gary E. Larson trap. Live traps can be purchased from volves minimal economic loss (under local hardware stores, department $200). Homeowners report that chip-

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