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The Handbook: Prevention and Control of Wildlife Damage Management, Internet Center Wildlife Damage for

July 1994

Thirteen-Lined Ground Squirrels

Edward C. Cleary USDA-APHIS-Animal Damage Control, Sandusky, OH

Scott R. Craven University of Wisconsin, Madison

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Cleary, Edward C. and Craven, Scott R., "Thirteen-Lined Ground Squirrels" (1994). The Handbook: Prevention and Control of Wildlife Damage. 24. https://digitalcommons.unl.edu/icwdmhandbook/24

This Article is brought to you for free and open access by the Wildlife Damage Management, Internet Center for at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in The Handbook: Prevention and Control of Wildlife Damage by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Edward C. Cleary Associate State Director USDA-APHIS- THIRTEEN-LINED Animal Damage Control Sandusky, Ohio 44870 GROUND SQUIRRELS Scott R. Craven Extension Wildlife Specialist Department of Wildlife Ecology University of Wisconsin, Madison Madison, Wisconsin 53706

Fig. 1. Thirteen-lined ground squirrel, Spermophilus tridecemlineatus (formerly Citellus spp.)

Damage Prevention and Toxicants Identification Control Method Zinc phosphide. The thirteen-lined ground squirrel Fumigants Exclusion (Fig. 1) is a slender rat-sized rodent Aluminum phosphide. weighing about 8 ounces (227 g) with a Buried galvanized hardware cloth is length of about 10 inches (25 cm) in- effective, but very expensive. Gas cartridges. cluding a tail of 3 inches (8 cm). As its Cultural Methods Trapping name implies, 13 stripes run the length of this ground squirrel’s body. Five of Destroy burrows and habitat by deep Live traps. the light-colored lines break up into a soil tillage. Glue boards. series of spots as they progress down Allow growth of tall rank vegetation. the back and over the rump. Five light Wooden-base rat-sized snap traps. and four dark stripes extend along the Plant as early as conditions permit Leghold and body-gripping traps. top of the head and end between the before squirrels emerge from animal’s eyes. The cheeks, sides of the hibernation. Snares. body, and legs are yellowish, tan, or Provide alternative foods in minimum- Shooting tan with an orange cast. The chest and belly are thinly covered with light tan tillage fields. Effective if persistent. fur. Each front foot has four toes with Repellents Other Methods long slender digging claws. There are five toes on each hind foot. None are registered. Burrow flooding.

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-165 Great Plains Agricultural Council Wildlife Committee Some of the common or colloquial includes seeds, green shoots, flower females. When they hibernate, their names for this species include heads, roots, vegetables, fruits, and body temperature is generally within “thirteen-liners,” “stripers,” “striped cereal grains. They rarely drink water, 3o C of the ambient air temperature. ground squirrels,” “striped gophers,” depending instead on water contained When active, their body temperature and “gophers.” in their food. They cache large quanti- can vary 8 to 10o C, without ill effect. ties of seeds and grass, but never meat. Mating activity begins within 2 weeks The cached food may be eaten during Range after the squirrels emerge from hiber- periods of bad weather or in the late nation. Both sexes are sexually active autumn and early spring when other The thirteen-lined ground squirrel is a for about 2 weeks. After a gestation food is scarce. grassland animal. Its original range period of 28 days, 3 to 14 (average 10) was limited to the prairies of the blind, naked, and toothless young are North American Great Plains. When General Biology, born. Only 1 litter is produced per Europeans arrived and started clearing Reproduction, and year. Young ground squirrels weigh forests and establishing pastures, the about 1/10 ounce (3 to 4 g) at birth. thirteen-lined ground squirrel was Behavior Their stripes begin to appear after quick to extend its range into the new about 12 days and their eyes open 28 habitat. Today, it ranges from central Thirteen-lined ground squirrels are to 30 days after birth. Young squirrels Alberta, Manitoba, and Saskatchewan strictly diurnal, coming above ground are weaned and on their own after 6 to in the north to Texas and New Mexico when the sun is high and the earth is 12 weeks. Thirteen-lined ground squir- in the south, and from central Ohio in warm, and returning to the warmth rels are sexually mature at 9 or 10 the east to Colorado in the west (Fig. and safety of their burrows long before months of age. 2). The forests of the Appalachian sundown. They rarely venture out of Highlands and the Rocky Mountains the burrow on damp, dark, or overcast have halted their east/west range days. When they venture out, they will Damage and Damage expansion. There are a few colonies in often stand upright, with front paws Identification Venango County, Pennsylvania, the held close to the chest, surveying their result of introductions made in 1919. domain. If danger threatens, they run, The thirteen-lined ground squirrel’s with tail held horizontally, to the near- preference for insects and field mice est burrow. The inconspicuous 2-inch may provide some benefit to the agri- (5-cm) diameter burrow opening is cultural community. Large concentra- often concealed by vegetation and tions of these ground squirrels in rarely has soil scattered in front of it pastures, fields, and gardens can, how- like a woodchuck’s burrow. The main ever, cause loss of forages and crops. entrance plunges down 6 inches (15 They dig up newly planted seeds, clip cm) or more before angling off into a emerging plant shoots, and pull complex system of galleries and side overripening wheat, barley and oats to entranceways. The nesting chamber, eat the grain. They will readily feed on about 9 inches (23 cm) in diameter and commonly grown home or truck gar- lined with fine dry grass, is located den vegetables, often damaging much somewhat deeper than the main bur- more than they consume. row system. The thirteen-lined ground squirrel’s natural enemies include just Thirteen-lined ground squirrels will about all predators, especially hawks, invade golf courses, parks, lawns, Fig. 2. Distribution map for thirteen-lined ground badgers, weasels, foxes, coyotes, bull athletic fields, cemeteries, and similar squirrels. They currently occur in all or part of 22 snakes, and black snakes. wide open grassy sites. Their burrow- states and 3 Canadian prairie provinces. ing and feeding activity can cause Thirteen-lined ground squirrels begin major economic and aesthetic damage Food Habits hibernation in September or early in such places. October and emerge between late March and early May in the northern Thirteen-lined ground squirrels are portions of their range. In southern Legal Status omnivorous. At least 50% of their diet Texas, they have been observed above is animal matter — grasshoppers, ground as late as October 27 and as Thirteen-lined ground squirrels are not wireworms, caterpillars, beetles, cut- early as January. Males usually begin protected by federal law. They are pro- worms, ants, insect eggs, mice, earth- hibernation earlier in the fall and tected by some state and provincial worms, small birds, and each other. emerge earlier in the spring than regulations (Table 1). The vegetative portion of the diet

B-166 Table 1. Status of the thirteen-lined ground squirrel in the United States and Pesticides Canada. Before using any pesticide, read and Alberta1 Nebraska1 follow all label directions. Many of the Arizona1 New Mexico1 pesticides used to control thirteen- Arkansas7 North Dakota1 lined ground squirrels are Restricted Colorado1 Ohio1 Use Pesticides that may only be sold to Illinois1 Oklahoma1 and used by certified pesticide applica- Indiana1 Pennsylvania3, 6 tors or persons working under their Iowa3 Saskatchewan1 direct supervision, and only for those Kansas1 South Dakota1 uses covered by the licensed applica- Manitoba1 Texas5 tor’s certification. Some of the pesti- Michigan4 Utah1 cides mentioned may not be registered Minnesota1 Wisconsin1 for every use in all states or provinces. Missouri3 Wyoming2 Contact your local cooperative exten- Montana1 sion agent, USDA-APHIS-ADC, state

1 or provincial pesticide regulatory No restriction on taking or possessing. agency, or state or provincial fish and 2Classed as wildlife, but no restriction on some or all methods of take. 3 wildlife department for information May be taken only with special state permit. regarding special permit requirements 4State permit needed for some methods of take such as poisoning, fumigation. 5 or endangered species restrictions. May be taken only when causing or about to cause damage. Specific use instructions can be found 6State threatened species. 7 on the individual product labels. Only Believed extinct in state. general use comments will be pre- sented here. Check the Pesticides sec- tion in this handbook for sample ground. It may be necessary to install a Damage Prevention and labels. Control cement threshold to keep squirrels from digging under the gate. Repellents Exclusion Cultural Methods None are registered. Exclusion is expensive and generally Activity in fields and gardens can be Toxicants practical only in situations where cost discouraged by deep soil cultivation, is not a primary concern. Thirteen- which destroys burrows and changes Zinc phosphide-treated baits can be lined ground squirrels are very good the habitat. Allow grassy areas to applied by hand in, or broadcast on at digging and climbing. They can be grow as tall and as dense as possible, noncrop areas such as rights-of-way, kept out of electrical substations or consistent with local land use prac- golf courses, ornamental plantings, similar installations with hardware tices. Such vegetation discourages nurseries, parks, lawns, field borders, cloth topped with sheet metal. Most ground squirrels but may encourage and ditch banks. Apply 1 teaspoon electrical substations or other secured population of other small mammals, (4 g) of untreated bait (clean oats or installations are enclosed by a chain such as voles (Microtus spp.). Plant other grains similar to the bait) around link fence that can be made ground crops as early as possible, before the each active burrow 2 to 3 days before squirrel-proof. Dig a trench 18 inches squirrels emerge from hibernation, to applying treated bait to ensure good (45 cm) wide and 18 inches (45 cm) reduce losses to seeds and seedlings. acceptance of toxicants. Apply prebait deep around the installation next to on a bright, warm, sunny day when the outside of the existing fence. Install Deter ground squirrels and other small the ground squirrels are most active. galvanized 0.5-inch (1.3-cm) or smaller mammals from feeding on crop seeds Allow material to fall through the mesh hardware cloth (6 foot [2 m] and seedlings by providing them with grass to the ground. Do not apply to wide) across the bottom and up the an alternative food source. At planting, bare ground and do not apply in piles. side of the trench nearest the existing broadcast 4 bushels of cracked corn Two to 4 days later, after the prebait 3 fence, continuing 3 feet (1 m) up the per acre (0.35m /ha) over the outside has been eaten, place 1 teaspoon (4 g) fence. Backfill the trench. Securely four to eight rows adjacent to ground of treated bait in the same locations. attach the hardware cloth to the chain- squirrel habitat. It also may be neces- Do not apply prebait or bait near link fence. Attach a piece of sheet sary to spot treat fields in areas where homes, where food or feed is grown, metal, 2 to 3 feet (61 to 90 cm) wide, to damage is expected or observed, over water, on roads, or other bare and above the hardware cloth. Adjust especially if conservation tillage is ground. Bury all carcasses found and all gates to fit within 0.5 inches (1.27 employed. any uneaten bait at the end of the cm) of the support post and the program.

B-167 For broadcast applications, apply 4 to cartridge, fuse end first, as far down without the trap being sprung, move 6 pounds of prebait per acre (4.5 to 6.7 the burrow as possible. Place the car- the trap to a new location. If the bait is kg/ha) in 20-foot (6.1-m) swaths using tridge, do not throw it. Immediately taken without the trap being sprung, hand- or ground-driven equipment. place the sod, grass side down, over try using mouse-sized snap traps. Two to 4 days later, apply an equal the opening and cover with soil to Young ground squirrels may not be amount of treated bait in the same make a tight seal. Close any other big enough to spring the rat-sized trap. location. Special care must be taken to openings from which smoke appears. Glue boards, either commercial or prevent application of treated bait over Gas cartridges come in different sizes. homemade, can be used to capture bare ground or in areas of scant veg- Therefore, make sure the cartridge will nuisance ground squirrels in residen- etation, where it can pose a direct fit into the burrow before lighting the tial areas. Place glue boards in areas threat to grain-eating birds. fuse. Some cartridges come with built- where activity or damage is occurring. Fumigants should never be used in or in fuses; others must have the fuse in- Bait them with the same type of mate- around buildings, or where there is serted by the operator. Check the rial used to bait snap traps. Place bait any danger that people, livestock, or specific product label for instructions in the center of the board. Once the other nontarget animals will come into and prepare the cartridge accordingly. animal becomes trapped, it can be contact with the gases. Treat and plug Avoid prolonged breathing of the killed and disposed of. Glue boards do all burrows, wait 24 to 48 hours, and smoke when using gas cartridges, and not work well in dusty, dirty environ- retreat any burrows that have been do not use them near buildings or ments. Care should be taken when reopened. Repeat this process until all other combustible material because of using glue boards outside because they burrows stay closed. Most burrow the fire hazard. can be attractive to children, pets, and fumigants work best when the soil nontarget wildlife. moisture is high and the air tempera- Trapping Live traps are commercially available ture is above 50o F (10o C). A few ground squirrels around a from a variety of manufacturers (see Aluminum phosphide tablets and pel- home garden or small row crop opera- Supplies and Materials at the end of lets can be used to treat thirteen-lined tion can be removed easily using this manual), or they can be home- ground squirrel burrows in agricul- wooden-base rat-sized snap traps, glue made. Use live traps that are 3 to 5 tural and noncropland areas. Label boards, or live traps. Snap traps and inches square and 18 to 20 inches long recommendations are to place 1 to 4 glue boards can kill animals caught in (8 to 13 cm square and 46 to 51 cm tablets or 5 to 20 pellets as far down them. If it is necessary to restrict access long). The 5 x 5 x 18-inch (13 x 13 x 46- into the burrow as possible. The lower to traps and glue boards by nontarget cm) chipmunk-sized trap works well. rates are recommended for smaller animals, place the traps under inverted Burrow-entrance live traps can be con- burrow systems under high moisture wooden boxes with a 2-inch (5-cm) structed using 0.5-inch (1.3-cm) hard- conditions, and the higher rates are hole cut in each end. This will, how- ware cloth (Fig. 3). The main body of recommended for larger burrow sys- ever, reduce trapping success. the trap is formed from a 12 x 20-inch tems when soil moisture is low. Seal Wooden-base rat-sized snap traps are (30 x 50-cm) piece bent to form a rect- the burrow entrance by packing the readily available and the easiest to use angular box 3 x 3 x 20 inches (8 x 8 x 51 opening with crumpled newspaper for most home gardeners. The biggest cm). The joining edges can be secured and then shoveling soil over the mistake most people make when try- with hog rings. Use hog rings to secure entrance. Be careful not to cover the ing to trap nuisance animals is not us- a 3-inch (8-cm) square piece of hard- tablets or pellets with soil when sealing ing enough traps. Set traps in the areas ware cloth to one end of the trap. The the burrow. Several states have placed where damage is occurring, next to ac- trap door is made from a piece of additional restrictions on the use of tive burrows, or on active runways. hardware cloth 2 3/4 x 8 inches (7 x 20 this material. Peanut butter is one of the most effec- cm). Attach one end of the door to the Gas cartridges that contain potassium tive baits and is difficult for the top of the trap with hog rings. Recess nitrate or sodium nitrate work simi- ground squirrel to remove without the point of attachment about 1 inch larly and therefore will be described springing the trap. Pieces of apple or (2.5 cm) to permit free movement of together. In the closed burrow system, other fruit, vegetable, or nut meat, can the door when the trap is placed in the a burning cartridge produces carbon also be used as bait. Securely attach burrow entrance. Bend the opposite monoxide (CO), carbon dioxide (CO ), end of the door so at least 2 inches (5 2 these baits to the trap trigger. You can and consumes oxygen. To use a gas increase the attractiveness of most cm) of the door are in contact with the cartridge, prepare it according to label baits by scattering about 1/2 teaspoon trap floor when the door is closed. A instructions. Cut a clump of sod of rolled oats on and around the trap. wire handle should be attached to the slightly larger than the burrow open- Cover the set, leaving enough room for top of the trap (Fig. 3). ing with a spade or other suitable tool. proper operation of the trap. Check the Before setting the trap, spend some Kneel at the burrow opening, light the traps every 24 hours and apply fresh time observing the squirrels to deter- fuse, and immediately place the bait. If more than 2 or 3 days go by mine which burrows are active. Set the

B-168 trap by wedging the door end firmly foundations or other underground The most effective method of control- into the entrance of an active burrow. structures that may be damaged by ling thirteen-lined ground squirrel The closed end should be pointing into water. damage will depend on the situation the air. Prop the trap in position with a and on the temperament of the people block of wood or other suitable object. Economics of Damage involved. Wooden-base rat-sized snap Gravity will hold the door closed until and Control traps, live traps, or gas cartridges may the squirrel pushes past it to leave its be the best methods for eliminating burrow and enters the trap. Dispose of one or two animals from a garden. The exact cost of damage caused by trapped animals in accordance with Burrow fumigation may be the best the thirteen-lined ground squirrel is local regulations. method in truck gardens, or in and difficult to quantify because much of it around parks, athletic fields, and cem- Snares made of 8 pound (3.6 kg) test probably goes unreported. For the eteries where the use of traps or poi- monofilament or wire fishing leader homeowner with one or two ground son could pose a hazard to people, are simple and effective. Leghold traps squirrels in the garden or a farmer pets, and nontarget wildlife. In (No. 0 longspring or coil-spring), and with a few ground squirrels in the orchards, vineyards and noncrop Conibear® traps (No. 110) can also be field, the animals may be more of a areas zinc phosphide treated baits used. However, the effort required to nuisance than a serious pest. However, may be most economical. set them, compared to snap traps, glue when large numbers are present, they boards, and burrow-entrance live can cause serious losses. Thirteen-lined traps, makes their use questionable. ground squirrels have established Acknowledgments colonies in and around borders of Shooting minimum tillage corn fields in Ne- We thank Richard Dolbeer and Tom Seamans, braska. Extension agents and farmers USDA-APHIS-Denver Wildlife Research Center; Shooting can provide control if the there have reported losses of 20 to 80 Douglas Andrews, USDA-APHIS-ADC; and landowner is willing to put in the nec- David Wolfert, USFWS for their editorial acres (8 to 32 ha) annually in fields assistance in the preparation of this manuscript. essary time and effort. All shooting during 1989 to 1992. should be carried out in a safe manner and in strict accordance with local Results of a survey of USDA-APHIS- For Additional regulations. ADC state offices, and of the Alberta, Manitoba, and Saskatchewan Provin- Information Other Methods cial Wildlife Services, indicate that the thirteen-lined ground squirrel is only a Burt, W. H., and R. P. Grossenheider. 1976. A Ground squirrels were often captured field guide to the mammals, 3d ed. minor pest in most suburban areas, Houghton Mifflin Co. Boston. 289 pp. by the Native Americans that lived on and a minor to moderate pest in most the central plains and the west coast by Davis, W. B. 1966. The mammals of Texas. Texas agricultural situations. Indiana ADC Parks Wildl. Dep. Bull. No. 41, Austin. 267 pouring water down the animal’s bur- considers them a major agricultural pp. row, thereby forcing the squirrel to the pest in no-till corn. As minimum till- surface. Similar methods of removing Doutt, J. K. 1967. The mammals of Pennsylvania. age farming increases, the potential for The Pennsylvania State Game Comm., ground squirrels still work. Flooding increased agricultural damage from Harrisburg. 281 pp. can enhance the effectiveness of trap- thirteen-lined ground squirrels may Gottschang, J. L. 1981. A guide to the mammals ping and snaring. Avoid flooding bur- increase. of Ohio. The Ohio State Univ. Press, rows that are adjacent to building Columbus. 176 pp. Hamilton, W. J. 1963. The mammals of eastern United States. Hafner Publ. Co., New York. 432 pp. Tomich, P. Q. 1982. Ground squirrels. Pages 192- 208 in J. A. Chapman and G. A. Feldhamer, eds. Wild mammals of North America: biology, management, and economics. The Johns Hopkins Univ. Press, Baltimore. Wobeser, G. A., and F. A. Leighton, 1979. A simple burrow entrance live trap for ground squirrels. J. Wildl. Manage. 43:571-572.

Fig. 3. Ground squirrels can be readily captured in this homemade live trap (Adapted from Wobeser Editors and Leighton 1979). Scott E. Hygnstrom Robert M. Timm Gary E. Larson

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