Least chipmunks are the smallest of all chipmunks. They are between 185 and 222 mm long, and weigh between 42 and 53 g. Females are sometimes larger than males. They have three dark and two light stripes on the face. Their sides are also striped, with and five dark and four light stripes. The rest of the fur on the back is orangish-brown, and the belly is grayish-white. The pale brown tail is bushy and long. (Burt, 1946; Hamilton and Whitaker, 1979; Kurta, 1995)
These chipmunks hibernate in winter. When they hibernate, their body temperature is lower than it is when they are active. Because their body temperature varies, they are called heterothermic. But, since they maintain a constant body temperature when active and when hibernating, they are also considered homeothermic. (Bergstom, 1999)
Least chipmunks live in North America. They are found in the Rocky Mountain region and the western Great Plains of the United States. Populations also live in central and western Canada, as well as in parts of Wisconsin, Minnesota and Michigan. (Bergstom, 1999; Kurta, 1995)
Least chipmunks sometimes live in forests, but prefer more open areas such as forest edges and openings. They are often found near rock cliffs, river bluffs, and open jack pine stands. (Hamilton and Whitaker, 1979)
The mating system of these animals is not known with certainty. Males seem to compete for mates, and come out of hibernation before females do. Female least chipmunks probably mate with only one or a few males, whereas it is likely that males mate with as many females as they can. (Baker, 1983)
Least chipmunks are not able to breed until they are 10 months old. These animals breed when females first emerge from hibernation in the spring. Pregnancy lasts about 30 days. Females give birth to a single litter of 2 to 6 young in May or June. Some females may produce a second litter if their first litter is lost.
Newborn least chipmunks are pink and have no fur. Theyr eyes don't open until they are about 28 days old, and their hair is grown in completely by the time they are 40 days old. At birth, least chipmunks are only 50 mm long, ans weigh only 2.25 g. Mothers provvide milk for their babies until they are 60 days old. Young chipmunks leave their mother shortly after weaning. (Baker, 1983; Banfield, 1974; Burt, 1946; Hamilton and Whitaker, 1979; Kurta, 1995)
Parental care in least chipmunks is extensive. Young are helpless at birth, and are not even fully furred until they are 40 days old.
Females chose nursery nests while they are pregnant. These nests are in stumps, under logs, in brush piles, or rock piles. The female usually has a food supply close by. Nursery nests are lined with grass, and are sheltered so that they do not get wet from rain or water on the ground. This helps the offspring stay healthy when they arrive.
Mothers take care of their young. They feed the young milk until they are 60 days old. Mothers also give their pups shelter and grooming. Fathers may also play a role in protecting the young by helping to defend the mother's territory. They may also bring some food to the young, and help to keep the nest in good repair. (Baker, 1983; Bergstom, 1999; Burt, 1946; Kurta, 1995)
Least chipmunks are good climbers. Some individuals build nests high above the ground in the trees. Chipmunks sometimes climb trees to find sunlit branches on which to warm themselves when the weather is cool.
Least chipmunks are most active between April and October. Nests are built seasonally. Summer homes are made from leaves and bark in rotting logs and tree cavities. Winter nests are built in underground burrows, and are made of dried grass, bark, fur, feathers and soft vegetation. When the weather turns cold chipmunks go into these burrows, where they hibernate until spring. During hibernation, they wake up often to snack on stored food. Least chipmunks are territorial and defend their nests from invaders.
Least chipmunks are active during the day, and sleep at night. They are not social, and prefer to spend their time alone. Still, when humans are around to feed them peanuts and other goodies, they are often seen with other least chipmunks. (Baker, 1983; Bergstom, 1999; Hamilton and Whitaker, 1979; Kurta, 1995)
Home ranges have been estimated at 1/4 of an acre. Some areas have up to 6 individuals per acre. (Banfield, 1974)
Like other squirrels that are active during the day, vision is an important part of commmunication. Visual signals, such as body posture and tail movement, deliver important information to other chipm.
Sounds are also used in the communication of these animals. Least chipmunks use calls to advertize their ownership of a territory, to find mates, and when they feel threatened.
Touching lets some chipmunks communicate. This is especially important between mothers and their offspring. It is also important for mates and rivals.
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)
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)
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)
Least chipmunks are predators of pest insects and may play a role in seed or pollen dispersal.
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.
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.
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.