CHIPMUNK: (Tamias striatus)

The chipmunk is a small, ground-dwelling rodent that occurs throughout Missouri but is most common in the Ozarks. Their habit of digging for food and to excavate burrows can lead to conflicts with property owners.

 

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) is the most widely distributed and notable species in Missouri. 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.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-chuckchuck” 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.

 

Range

The eastern chipmunk’s range includes most of the eastern United States as far west as Minnesota, Iowa, Missouri, Arkansas and Louisiana. In Missouri they are the most common in the Ozarks.

 

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. Chipmunks are generally solitary except during courtship or when rearing young.The home range of a chipmunk may be up to ½ 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 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. 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.

 

Damage Prevention and Control

The Wildlife Code of Missouri specifies that you may shoot or trap damage-causing chipmunks to prevent further damage. Control methods can include exclusion, habitat modification, trapping and removal. Our technicians will help you determine the best options for your situation.

• Exclusion - Chipmunks occasionally enter homes. Prevent entry by closing holes in foundation walls and by screening windows, vents, and other ground-level openings. Chipmunks should be excluded from buildings as soon as possible. Hardware cloth with ¼-inch (0.6-cm) mesh, caulking, or other appropriate materials can be used 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 ¼-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. For active burrows, wait until the animals are out and away, fill the holes with soil, and cover them with rocks or other heavy objects.Exclusion is less expensive in the long run than trapping, where high populations of chipmunks exist.

• 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.

• Trapping - Trapping is the most practical method of eliminating chipmunks in most home situations. Cage-type traps are effective. Rat-sized snap traps are also effective but are indiscriminate and may kill non-target species. For best and quickest results, have an experienced professional perform trapping. There are many effective methods for trapping chipmunks, however, a great deal of experience is required to effectively trap chipmunks.

• Shooting - Shooting chipmunks is a possible control method. However, in most situations it is not a practical solution. Chipmunks are nervous and alert, so they make difficult targets. . Safety is a critical factor and in many circumstances may preclude the use of firearms (for example, local laws may prohibit shooting, or neighbors may be too close). Shooting is best left to professionals. In many urban areas, firearms may not be discharged, in most situations local authorities have regulations and restrictions regarding the use of firearms.

 

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.