Oregon City Chipmunks
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) are the two most widely distributed and notable species. Behavior and damage is similar among all species of native chipmunks, so damage control recommendations are similar for all species.
Eastern Chipmunk
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.
Least Chipmunk
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.
Habitat
The eastern chipmunk’s range includes most of the eastern United States. The least chipmunk’s range includes most of Canada, the United States Rocky Mountains, the Great Basin and parts of the upper Midwest.
Chipmonks often create burrows in well-hidden areas near objects or buildings. The burrow entrance is usually about 2 inches (5 cm) in diameter. The chipmunk carries the dirt in its cheek pouches and scatters it away from the burrow, making the burrow entrance less conspicuous.
Eastern chipmunks typically inhabit mature woodlands and woodlot edges, but they also inhabit areas in and around suburban and rural homes.
The least chipmunk inhabits low sagebrush deserts, high mountain coniferous forests, and northern mixed hardwood forests.
Fun Facts
Chipmunks are generally solitary except during courtship or when rearing young.
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.
Chipmunks enter a restless hibernation as winter approaches and are relatively inactive from late fall through winter months. They do not enter a deep hibernation but rely on the cache of food they have brought to their burrow. Some become active on warm, sunny days during the winter and 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 and two to five young are born in April–May and again in August–October. The young are sexually mature within 1 year. Adults may live up to 3 years.
Adult least chipmunks mate over a period of four to six weeks from April–mid-July. Least chipmunks produce 1 litter of two to seven young in May or June. A second litter is occasionally produced in the fall.
Chipmunk pups appear above ground when they are four to six weeks old — 2/3 the size of an adult. Young will leave the burrow at six to eight weeks of age.
Damage Identification
Chipmunks are considered minor agricultural pests throughout North America. 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, and 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 USDA-APHIS-ADC personnel for the legal status of chipmunks in your state.
Prevention and Control Methods
Exclusion
Rodent-proof construction will exclude chipmunks from structures. Use 1/4-inch (0.6-cm) mesh hardware cloth to exclude chipmunks from gardens and flower beds.
Habitat Modification
Store food items, such as bird seed and dog food, in rodent-proof containers. Ground covers, shrubs, and wood piles should not be located adjacent to structure foundations.
Frightening
Not effective.
Repellents
Area repellents. Naphthalene (moth flakes or moth balls) may be effective if liberally applied in confined places. Taste repellents. Repellents containing bitrex, thiram, or ammonium soaps of higher fatty acids applied to flower bulbs, seeds, and vegetation (not for human consumption) may control feeding damage.
Toxicants
None are federally registered. Check with local extension agents or a USDA-APHIS-ADC personnel for possible Special Local Needs 24(c) registrations.
Fumigants
Not usually effective.
Trapping
Rat-sized snap traps. Live (box or cage) traps. Glue boards.
Call Critter Control today at 1-800-CRITTER
ACKNOWLEDGEMENTS
The above information was adapted from PREVENTION AND CONTROL OF WILDLIFE DAMAGE with permission of the editors, Scott E. Hygnstrom, Robert M. Timm, and Gary E. Larson (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, Great Plains Agricultural Council Wildlife Committee).