Tamias minimus

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.

• Biogeographic Regions
• nearctic nearctic
  • native native

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.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• taiga taiga
• forest forest
• scrub forest scrub forest

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).

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.

• Other Physical Features
• endothermic endothermic
• heterothermic heterothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger

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.

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).

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
• viviparous viviparous

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.

• Parental Investment
• altricial 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.

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).

• Key Behaviors
• arboreal arboreal
• terricolous
• diurnal diurnal
• motile motile
• sedentary sedentary
• hibernation hibernation
• solitary solitary

Home Range

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

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.

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

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.

• Primary Diet
• herbivore herbivore
  • granivore granivore

• Animal Foods
• birds
• mammals
• carrion carrion
• insects
• terrestrial non-insect arthropods
• mollusks
• terrestrial worms

• Plant Foods
• leaves
• roots and tubers
• seeds, grains, and nuts
• fruit
• flowers

• Other Foods
• fungus

• Foraging Behavior
• stores or caches food stores or caches food

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.

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.

• Ecosystem Impact
• disperses seeds
• creates habitat

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).

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.

Additional Links

Encyclopedia of Life

BioKIDS Critter Catalog

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.

References

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 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.

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