Tamias striatuseastern chipmunk

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Geographic Range

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)

Habitat

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)

Physical Description

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)

  • Range mass
    66 to 115 g
    2.33 to 4.05 oz
  • Range length
    255 to 266 mm
    10.04 to 10.47 in
  • Average basal metabolic rate
    0.813 W
    AnAge

Reproduction

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)

  • Breeding interval
    Eastern chipmunks have 2 breeding seasons.
  • Breeding season
    One of their breeding seasons begins in February and lasts until April and the second begins in June and ends in August.
  • Range number of offspring
    2 to 5
  • Average number of offspring
    5
    AnAge
  • Average gestation period
    35 days
  • Average gestation period
    31 days
    AnAge
  • Average weaning age
    40 days
  • Average time to independence
    2 months
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    187 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    1 years
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    228 days
    AnAge

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)

Lifespan/Longevity

Most eastern chipmunks survive less than two years, but there are accounts of chipmunks living up to eight years. (Kurta, 1995)

Behavior

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)

  • Range territory size
    800 to 6,000 m^2

Home Range

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)

Communication and Perception

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)

Food Habits

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)

  • Animal Foods
  • eggs
  • insects
  • terrestrial worms
  • Plant Foods
  • seeds, grains, and nuts
  • fruit
  • Other Foods
  • fungus

Predation

Eastern chipmunks are prey for most diurnal predators including weasels, felids and domestic dogs and cats. Large raptors including red-tailed hawks and goshawks also prey on chipmunks. (Kurta, 1995)

Ecosystem Roles

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)

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

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)

  • Positive Impacts
  • pet trade
  • controls pest population

Economic Importance for Humans: Negative

Some Sciurids cause destruction to crops in gardens, fields and in food storage areas. Eastern chipmunks are not noted for causing this type of damage. (Smith, 2005)

  • Negative Impacts
  • crop pest

Conservation Status

Eastern chipmunks are listed as a species of Least Concern according to the IUCN Red List.

Contributors

Michelle Kroll (author), Michigan Technological University, Joseph Bump (editor), Michigan Technological University, Leila Siciliano Martina (editor), Animal Diversity Web Staff.

Glossary

Nearctic

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.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

bilateral symmetry

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.

chemical

uses smells or other chemicals to communicate

endothermic

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.

female parental care

parental care is carried out by females

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

introduced

referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.

iteroparous

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).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

polygynous

having more than one female as a mate at one time

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

urban

living in cities and large towns, landscapes dominated by human structures and activity.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

2001. "How the Chipmunk Got His Stripes" (On-line). Canku Ota. Accessed November 11, 2012 at http://www.turtletrack.org/Issues01/Co01132001/CO_01132001_Chipmunkstripes.htm.

Baack, J., P. Switzer. 2000. Alarm Calls Affect Foraging Behavior in Eastern Chipmunks (Tamias striatus, Rodentia: Sciuridae). Ethology, 106: 1057–1066.

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.

Linzey, A. 2008. "Tamias striatus. IUCN 2012" (On-line). IUCN Red List of Threatened Species. Accessed October 31, 2012 at www.iucnredlist.org.

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.