Eastern chipmunks are widely distributed throughout the eastern United States and southeastern Canada. Their range extends from Nova Scotia, east to Saskatchewan and south to Oklahoma, where they occupy the eastern part of the state. Their range includes eastern Louisiana and the Florida Panhandle. This species does not occupy the peninsula of Florida or the coastal plains region, from Florida to North Carolina. They are not native to Newfoundland, but have been introduced. (Linzey, 2008; Snyder, 1982)
In the western portion of their range, eastern chipmunks inhabit wooded areas, river valleys and are interspersed in habitats distant from deciduous forests. This ground dwelling mammal inhabits open deciduous forests where cover is readily available in the form of stumps, logs or rocky outcrops. Their prime habitat is mature beech-maple forests, but they will occupy bushy areas and coniferous forests, however, swampy sites are avoided. (Da Silva, et al., 2002; Kurta, 1995; Linzey, 2008)
Eastern chipmunks are small rodents with grayish to reddish brown fur and a distinguishing yellowish to reddish patch on their rumps. Their pelage color and pattern varies by geography. Their underparts are white. Their sides and back have five dark stripes; the longest stripe occurs along their midline. Between their dark lateral stripes, there is a narrow white band. Light and dark stripes occur on their face around their eyes. Their tail is hairy, but not bushy and is somewhat flattened. Their rounded ears measure less than 20 mm. Their forefeet have four toes and their hindfeet have five. Eastern chipmunks have large cheek pouches located on either side of their mouth. The stripe along their body distinguishes them from all other rodents except least chipmunks. However, least chipmunks' stripes extend to the base of their tail, whereas, eastern chipmunks' stripes stop before their rump patch. Eastern chipmunks are noticeably larger than least chipmunks, which helps to distinguish between the two species. (Kurta, 1995; Snyder, 1982)
Eastern chipmunks are polygamous. During a brief estrous period, females mate with multiple males. Typically females in estrous stay within their home range and males come from outside areas to mate. On average, males travel 170 meters from their burrow to mate. (Da Silva, et al., 2002; Kurta, 1995; Saunders, 1988)
Eastern chipmunks produce two litters per year; one in early spring and one in midsummer. Their gestation period lasts 35 days. Litters consist of 2 to 5 altricial young, which are born blind and hairless in underground nests. Litter sizes are dependent on resource availability and the age of the mother. (Da Silva, et al., 2002; Kurta, 1995; Saunders, 1988)
At birth, young weigh just 3 grams. The neonates are weaned 40 days after birth. After weaning, females move to a new burrow, leaving their young in the natal burrow until they disperse. Young become independent two months after birth. Males disperse farther than females. Females stay close to their home burrow with their range sometimes overlapping. Most young do not breed until the spring following their birth. (Da Silva, et al., 2002; Kurta, 1995; Smith, 2005)
Most eastern chipmunks survive less than two years, but there are accounts of chipmunks living up to eight years. (Kurta, 1995)
Eastern chipmunks are diurnal and most active during mid-morning and mid-afternoon. They are solitary and territorial, especially close to their burrow. Foraging occurs mostly along the ground, but eastern chipmunks are proficient climbers. Eastern chipmunks cache food but do not have the fat stores to hibernate. Caches are marked with an olfactory cue to aid in relocation. This cue is dependent on the substrate and the moisture content of the seeds. Caching behavior is determined by the moisture content of the environment. Because olfactory cues are moisture dependent, scatter-hoarding in mesic climates are quickly pilfered. In more aggressive eastern chipmunks, larder hoarding is more beneficial because a single, large cache is easier to defend than several small caches. (Kurta, 1995; Penner and Devenport, 2011)
In a study of captive chipmunks, eastern chipmunks demonstrated less success than least chipmunks in cache pilfering behavior. However, cache defending behaviors were deterred in this study. Least chipmunks benefit from the larger caches of eastern chipmunks, which store up to four times as many seeds. Eastern chipmunks spend more time digging and searching for caches because least chipmunks hide seeds away from objects, which could be used as markers. Also, least chipmunks' olfactory cues are weak in comparison. It is less profitable for eastern chipmunks to rob the caches of least chipmunks. Both species showed signs of being very selective in choosing cache locations to prevent their caches from being robbed. (Kurta, 1995; Penner and Devenport, 2011)
Eastern chipmunks are somewhat tolerant of humans and will sometimes burrow under buildings. Their burrow is excavated less than one meter below the surface and has interconnected galleries up to 10 meters in length. Their burrow is typically in the center of a roughly circular home range, the primary use area has a radius of 15 to 25 meters from the entrance. One room is used as a nest site and the others are used for food storage. Their nest is made out of crushed leaves and measures 30 cm in diameter. The surface entrance to their burrow measures 5 cm across and does not contain excavated soil. Chipmunks distribute soil to the surrounding areas or use it to close an old entrance to the burrow. Winters are spent underground. Typical population density is 10 to 22 chipmunks per hectare. Home range size varies from 800 to 6,000 m2. In the early summer and early fall, their range is the largest. Breeding males have the largest home range. Eastern chipmunks defend their home ranges. Some dispersal, up to 0.9 km, will occur. Individuals that do not disperse have home range lengths of up to 0.5 km throughout their lifetime. (Da Silva, et al., 2002; Kurta, 1995; Linzey, 2008)
Eastern chipmunks are extremely vocal and produce a variety of chips, trills and calls to alert others to the presence of predators or for territory defense. Territorial calls lead to aggressive behavior when another individual is present. High intense chases establish hierarchies among groups of males competing for access to females, individuals display aggressive and submissive postures during these behaviors. Sniffing hindquarters and touching noses provides chemical signals during these interactions. Alarm calls can be costly and the benefits must outweigh the costs to justify such behavior. Eastern chipmunks give three distinct calls: chipping, chucking and trilling. Chipping and chucking are repeated calls lasting up to thirty minutes. Trills are shorter in duration and are given during pursuit by a predator. The other calls are typically given when a predator is spotted. (Baack and Switzer, 2000; Da Silva, et al., 2002; Saunders, 1988)
Eastern chipmunks react to alarm calls by altering their foraging behavior and becoming more alert. After an alarm call, they expend greater energy and spend more time exposed at feeding stations because they decrease the amount of food carried to caches after hearing the call. Eastern chipmunks increase vigilance, run shorter more direct distances and delay emergence from burrows after hearing an alarm call, which suggest that the calls directly affected behavior. Trill vocalizations are complicated and more difficult to understand than the other two types of calls. Adult females are most likely to trill when close (10 m from the burrow) to relatives. Females do not disperse as far as males and have more relatives living close to their burrows. Juvenile females trill at a lower rate than adults, this may indicate their higher predation risk or smaller fitness gain. Males trill farther from the burrow, 100 m or greater. This could be because males are uncertain of kinship and trilling would put an individual at higher risk. Trilling occurs in all active seasons, not just during juvenile emergence, which discounts the hypothesis that trilling is a mechanism of parental care. The primary function of trill calls is likely to warn nearby relatives of predators. This increases an individual’s overall fitness by helping related individuals. (Baack and Switzer, 2000; Da Silva, et al., 2002; Saunders, 1988)
Dietary staples include fruit, seeds and nuts. This is supplemented with insects, earthworms, slugs, bird’s eggs and mushrooms. Food is transported within cheek pouches located on either side of the mouth. Eastern chipmunks demonstrate food caching behavior throughout the year, but are particularly active in the early autumn to prepare for winter. Eastern chipmunks scatter-hoarder and will leave caches throughout their home range or in one of the rooms their burrow. They do not have the fat stores to hibernate, but instead enter periods of torpor. Chipmunks may arise frequently to feed and during mild winter weather they may forage above ground. (Kurta, 1995; Saunders, 1988)
Eastern chipmunks are primarily 'larder hoarders'. Seeds stored in this way cannot establish seedlings and are not beneficial to plant dispersal. However, their occasional scatter-hoarding behavior can be beneficial in seedling establishment. They also are important to spore dispersal for different kinds of fungi. Because of their abundance, chipmunks are a valuable prey item for a variety of species. (Vander Wall and Jenkins, 2011)
Eastern chipmunks are not significantly important to the economy. Eastern chipmunks eat insects and may be helpful in controlling the population of some pest species. They are also easily tamed and can make unique pets. (Kurta, 1995; Saunders, 1988)
Eastern chipmunks are listed as a species of Least Concern according to the IUCN Red List.
Michelle Kroll (author), Michigan Technological University, Joseph Bump (editor), Michigan Technological University, Leila Siciliano (editor), Animal Diversity Web Staff.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
uses sound to communicate
living in landscapes dominated by human agriculture.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
parental care is carried out by females
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
an animal that mainly eats seeds
An animal that eats mainly plants or parts of plants.
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
an animal that mainly eats all kinds of things, including plants and animals
the business of buying and selling animals for people to keep in their homes as pets.
having more than one female as a mate at one time
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
places a food item in a special place to be eaten later. Also called "hoarding"
living in residential areas on the outskirts of large cities or towns.
uses touch to communicate
living in cities and large towns, landscapes dominated by human structures and activity.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
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Da Silva, K., C. Mahan, J. Da Silva. 2002. The Trill of the Chase: Eastern Chipmunks Call to Warn Kin. Journal of Mammalogy, May 2002, Vol. 83, No. 2: 546-552.
Kurta, . 1995. Mammals of the Great Lakes Region. Ann Arbor, MI: University of Michigan Press.
Penner, J., L. Devenport. 2011. A comparative study of caching and pilfering behavior in two sympatric species, least chipmunks (Tamias minimus) and eastern chipmunks (Tamias striatus). Journal of Comparative Psychology, 125(4): 375-384.
Saunders, D. 1988. Adironack Animals. New York: Adirondack Wildlife Program, State University of New York, College of Environmental Science and Forestry, 1988.
Smith, J. 2005. "Small Mammals and Agriculture: A Study of Effects and Responses" (On-line). Accessed October 25, 2012 at http://www.stolaf.edu/depts/environmental-studies/courses/es-399%20home/es-399-05/Projects/Jared's%20Senior%20Seminar%20Research%20Page/.
Snyder, D. 1982. Tamias striatus. Mammalian Species, 168: 1-8.
Vander Wall, S., S. Jenkins. 2011. Plant-animal interactions and climate: Why do yellow pine chipmunks (Tamias amoenus) and eastern chipmunks (Tamias striatus) have such different effects on plants?. Ecoscience, 18(2): 130-137.