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 (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: Central Yukon south through the Sierra Nevada and southern New Mexico, east to Michigan and western Quebec (Hoffmann et al., in Wilson and Reeder 1993). See Sullivan (1985) for biogeographic information.

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.

Range mass: 42 to 53 g.

Range length: 185 to 222 mm.

Other Physical Features: endothermic ; heterothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: female larger

Average basal metabolic rate: 0.349 W.

Length: 23 cm

Weight: 70 grams

• Terrestrial

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 ; terrestrial

Terrestrial Biomes: taiga ; forest ; scrub forest

Comments: Found in various habitats. Common in coniferous forests but also uses clearcuts, deciduous woods, sagebrush, riparian zones, and in western regions may even occur in alpine tundra. Winter nest up to 1 m below ground surface. Summer dens typically are in hollow logs or stumps, in rock piles, or under debris, evacuated burrows. Also nests in tree cavities above ground.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

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.

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

Foraging Behavior: stores or caches food

Primary Diet: herbivore (Granivore )

Comments: Feeds mostly on seeds, nuts, fruits, and acorns.

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

Commensal/Parasitic Species:

• fleas
• ticks
• lice
• mites
• nematode worms

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.

Known Predators:

• weasels
• goshawks
• Cooper's hawks
• snakes
• mink
• red fox
• bobcats
• martens
• domestic dogs
• domestic cat

Highly favorable habitats may contain 30 or more per acre, though average densities typically range from 5 to 15 per acre (Jackson 1961). Home range varies from less than an acre to 4 acres (Banfield 1974).

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 ; acoustic

Comments: May be active throughout the day, but prefers the sunny midday hours. Begins semihibernation in late October. Fully active by mid-March. May be active on warm winter days.

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.

Range lifespan

Status: captivity: 10 (high) years.

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).

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 gestation period: 30 days.

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.

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

Average birth mass: 2.3 g.

Average gestation period: 30 days.

Average number of offspring: 4.9.

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 ; 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)

Breeds in early spring. Gestation lasts 31 days. Litter size is 2-7 (average 5-6). Only one litter per year. Second litter may be produced if first fails. Sexually mature in first spring.

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.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

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

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

Comments: Formerly included in genus Eutamias, which recently was included in the genus Tamias (Levenson et al. 1985; Jones et al. 1992, Hoffmann et al., in Wilson and Reeder 1993). Based on patterns of variation in ectoparasites (Jameson 1999) and molecular phylogenetics (Piaggio and Spicer 2001), the North American mammal checklist by Baker et al. (2003) placed all North American chipmunks (except Tamias striatus) in the genus Neotamias. Thorington and Hoffmann (in Wilson and Reeder 2005) noted that chipmunks could be legitimately allocated to one (Tamias), two (Neotamias, Tamias), or three (Tamias, Neotamias, Eutamias) genera; they chose to adopt the single-genus (Tamias) arrangement.