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Tamias minimusleast chipmunk

By Kurt Schlimme

Geographic Range

Least chipmunks, Tamias minimus, are found throughout North America, occupying much of the Rocky Mountain region and the western Great Plains of the United States. In addition, they are found throughout central and western Canada and in parts of Wisconsin, Minnesota and Michigan. (Bergstom, 1999; Kurta, 1995)

Habitat

Least chipmunks are found throughout the boreal and temperate forests of North America. However, least chipmunks prefer more open areas such as forest edges and openings. They are also commonly found near rock cliffs, river bluffs, and open jack pine stands. (Hamilton and Whitaker, 1979)

Physical Description

Least chipmunks are the smallest of all chipmunks. Body length ranges from 185 to 222 mm (Burt, 1946). Individuals weigh between 42 and 53 g. Females are larger than males in some populations (Berstrom, 1999) There are three dark and two light stripes on the face and five dark and four light stripes along their sides. The middle stripe runs to the end of the tail (Burt, 1946). Dorsal background fur is orangish-brown, and ventral coloration is grayish-white (Kurta, 1995). The tail is bushy and long, ranging from 81 to 95 mm, and is pale brown in color (Hamilton and Whitaker, 1979). (Bergstom, 1999; Burt, 1946; Hamilton and Whitaker, 1979; Kurta, 1995)

Because they hibernate, these chipmunks are heterothermic. However, their body temperature remains relatively constant over short spans of time. There is a lower body temperature when the animal is torpid than when it is active. (Bergstom, 1999)

  • Sexual Dimorphism
  • female larger
  • Range mass
    42 to 53 g
    1.48 to 1.87 oz
  • Range length
    185 to 222 mm
    7.28 to 8.74 in
  • Average basal metabolic rate
    0.349 W
    AnAge

Reproduction

The mating system of these animals has not been well described. Males emerge from hibernation earlier than females, and apparently engage in some level of competition for mates. It is likely, therefore, that the species is either polygynous or polygynandrous. (Baker, 1983)

Individuals become sexually mature at 10 months of age (Kurta, 1995). Most mating occurs in April when females first emerge from hibernation. Gestation lasts approximately 30 days (Hamilton and Whitaker, 1979). Litter size varies from 2 to 6 young. There is normally a single litter during the breeding season, although females may produce a second litter if their first litter is lost (Burt, 1946). Newborns are naked and pink in color, measuring 50 mm in length and weighing an average of 2.25 g (Banfield, 1974). Eyes open at 28 days and fur is fully grown in by 40 days (Baker, 1983). Lactation lasts approximately 60 days and offspring remain with the mother for six weeks or longer (Kurta, 1995). (Baker, 1983; Banfield, 1974; Burt, 1946; Hamilton and Whitaker, 1979; Kurta, 1995)

  • Breeding interval
    These chipmunks usually breed once per year.
  • Breeding season
    Breeding occurs in early April when these chipmunks awake from hibernation.
  • Range number of offspring
    2 to 6
  • Average number of offspring
    4.9
    AnAge
  • Average gestation period
    30 days
  • Average gestation period
    30 days
    AnAge
  • Average weaning age
    60 days
  • Average time to independence
    60 days
  • Average age at sexual or reproductive maturity (female)
    10 months
  • Average age at sexual or reproductive maturity (male)
    10 months

Parental care in least chipmunks is extensive. Young are altricial, and are not even fully furred until they reach about 40 days of age.

Females chose nursery nests while they are pregnant. These nests are located in stumps, under logs, in brush piles, or rock piles. They are generally connected to chambers filled with cached food supplies. A female positions her nursery nest so that it is protected from rainfall and runoff, to ensure the comfort and health of her offspring when they arrive. Nests are often lines with grass.

Mothers take care of their young until they are weaned, sometime after 60 days of age. They provide food, shelter, grooming, and other care for the pups.

The role of males in the care of offspring is not certain. There are some indications that males may help to defend the home range of female's whose young they have sired. They may even help to maintain the nursery nest, and bring food to the young. (Baker, 1983; Bergstom, 1999; Burt, 1946)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female
    • protecting
      • male
      • female

Lifespan/Longevity

The lifespan of these animals has not been reported. They are reported to have shorter lives than Eastern chipmunks, which can live as long as 11 years. (Baker, 1983)

  • Range lifespan
    Status: captivity
    10 (high) years
    AnAge

Behavior

Least chipmunks are adept climbers. Some individuals construct nests high above the ground. Chipmunks climb trees in order to warm themselves in the sun during periods of cool weather (Hamilton and Whitaker, 1979).

Least chipmunks are most active between April and October. Nests are built seasonally, with summer homes being constructed from leaves and bark in rotting logs and tree cavities. Winter nests are located in underground burrows that consist of dried grass, bark, fur, feathers and soft vegetation (Kurta, 1995). With the onset of cold weather, chipmunks retire to these burrows, where they enter torpor and live off stored food until spring (Kurta, 1995). Hibernation in these animals is not as deep as it is in ground squirrels, and they awake frequently to snack on stored food during the winter months (Bergstom, 1999). Least chipmunks are territorial and will defend their nests from invaders.

Least chipmunks are diurnal. In general, they are not social, except for mating and rearing young. However, when provisioned by humans, they are remarkably tollerant of conspecifics (Bergstrom, 1999). (Baker, 1983; Bergstom, 1999; Hamilton and Whitaker, 1979; Kurta, 1995)

Home Range

Home ranges have been estimated at 1/4 of an acre. Some areas have up to 6 individuals per acre. (Banfield, 1974)

Communication and Perception

Like other diurnal sciurids, vision is an important part of commmunication. Visual signals, such as body posture, convey important information to conspecifics.

In addition to visual communication, these animals use a variety of auditory signals to communicate. They use calls to advertize their ownership of a territory, to find mates, and when they feel threatened.

Tactile communication is important between mothers and their offspring, as well as between mates and rivals.

The role of olfactory cues in this species have not been described, but scents are often important in individual recognition. It is likley that there are some chemical cues used by these chipmunks in communication. (Baker, 1983; Bergstom, 1999)

Food Habits

Least chipmunks eat a wide variety of foods. Their diet including nuts, berries, fruits, grasses, fungi, snails, insects, and possibly some small birds and mammals. From April through October, much of a chipmunk's time is spent foraging. Least chipmunks forage both on the ground and in trees at heights up to 9 m (Kurta, 1995). Cheek pouches allow individuals to carry multiple food items back to their burrows, where they are either eaten or stored for future use. (Baker, 1983; Bergstom, 1999; Kurta, 1995)

  • Animal Foods
  • birds
  • mammals
  • carrion
  • insects
  • terrestrial non-insect arthropods
  • mollusks
  • terrestrial worms
  • Plant Foods
  • leaves
  • roots and tubers
  • seeds, grains, and nuts
  • fruit
  • flowers
  • Other Foods
  • fungus

Predation

Major threats to these animals include weasels, goshawks, Cooper's hawks, snakes, mink, red fox, bobcats, and martens, as well as domestic dogs and cats. (Baker, 1983; Bergstom, 1999)

Ecosystem Roles

As animals that carry nuts and seeds from one place to another, least chipmunks are probably very important in seed dispersal. They also play and important role as a food source to their predators. They also provide habitat for a number of parasites. (Baker, 1983)

  • Ecosystem Impact
  • disperses seeds
  • creates habitat
Commensal/Parasitic Species
  • fleas
  • ticks
  • lice
  • mites
  • nematode worms

Economic Importance for Humans: Positive

Least chipmunks are predators of pest insects and may play a role in seed or pollen dispersal.

Economic Importance for Humans: Negative

Least chipmunks have no significant negative impacts on humans, though they may occasionally be a nuisance to campers (Hamilton and Whitaker, 1979). (Hamilton and Whitaker, 1979)

Conservation Status

The primary threat to least chipmunks is habitat loss caused by the encroachment of humans. Hunting or trapping may also pose a small threat. Currently least chipmunk populations are steady.

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Kurt Schlimme (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

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

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

arboreal

Referring to an animal that lives in trees; tree-climbing.

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.

carrion

flesh of dead animals.

chemical

uses smells or other chemicals to communicate

diurnal
  1. active during the day, 2. lasting for one day.
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.

fertilization

union of egg and spermatozoan

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.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

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.

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

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

solitary

lives alone

stores or caches food

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

tactile

uses touch to communicate

taiga

Coniferous or boreal forest, located in a band across northern North America, Europe, and Asia. This terrestrial biome also occurs at high elevations. Long, cold winters and short, wet summers. Few species of trees are present; these are primarily conifers that grow in dense stands with little undergrowth. Some deciduous trees also may be present.

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

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

1999. "USGS: Northern Prairie Wildlife Research Center" (On-line). Accessed (Date Unknown) at http;//www.npwrc.usgs.gov/resrouce/DISTR/MAMMALS/Mammals/least.htm.

Baker, R. 1983. Michigan Mammals. East Lansing, MI: Michigan State University Press.

Banfield, A. 1974. The Mammals of Canada. Toronto: University of Toronto Press.

Bergstom, B. 1999. Least Chipmunk| Tamias minimus . Pp. 366-369 in D Wilson, S Ruff, eds. Smithsonian Book of North American Mammals. Washington, D.C.: Smithsonian Institution Press in Association with the American Society of Mammalogists.

Burt, W. 1946. The Mammals of Michigan. Ann Arbor: The University of Michigan Press.

Hamilton, W., J. Whitaker. 1979. Mammals of the Eastern United States. Ithaca and London: Comstock Publishing Associates.

Kurta, A. 1995. Mammals of the Great Lakes Region. Ann Arbor: The University of Michigan Press.

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