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Tamias rufusHopi chipmunk

By Jessica Morris

Geographic Range

Hopi chipmunks are found only in western North America from north-central Arizona to Monument Valley as well as into eastern Utah, eastern Idaho, western Colorado (restricted to Yampa River southward), and into the Rocky Mountain Range towards Canada. (Burt and Best, 1994; Good, et al., 2003; Saldaña-DeLeon and Jones, 1998)

Habitat

Hopi chipmunks prefer bare or vegetated rocky substrate that contains juniper and pinyon pine. In western Colorado, they occupy two microhabitats: sage patches and juniper/pine patches. Hopi chipmunks live at elevations of 1,290 to 2,700 meters. (Burt and Best, 1994; Root, et al., 2001)

  • Range elevation
    1,290 to 2,700 m
    to ft

Physical Description

Hopi chipmunks are small, monotypic chipmunks in the subgenus Neotamias. They weigh 47.9 to 59.3 grams depending on the season. Their external length measures 197 to 235 mm. Females are generally slightly larger than males but have no other distinct differences in morphology. The coloring is buffy and gray patchwork. Upperparts have black stripes highlighted with tones of orange-red running in an anterior to posterior direction down its back. Hopi chipmunks also have pale facial white and "rufous" facial stripes with the lower stripe extending under the ears. The tail is mixed black and chestnut dorsally and chestnut with faint black stripes ventrally. There are two annual molts: one in the spring and one in early autumn. The dental formula is I 1/1, C 0/0, P 2/1, M 3/3, totaling 22 teeth. The skull has a long and narrow braincase, short nasals, a narrow interorbital region, and rather large auditory bullae. (Burt and Best, 1994; Hall, 1981; Hoffmeister and Ellis, 1979; Levenson, et al., 1985; Nowak, 1999; Saldaña-DeLeon and Jones, 1998; Wilson and Reeder, 2005)

  • Sexual Dimorphism
  • female larger
  • Range mass
    47.9 to 59.3 g
    1.69 to 2.09 oz
  • Range length
    197 to 235 mm
    7.76 to 9.25 in

Reproduction

The mating behavior of Hopi chipmunks is unknown. In other Neotamias species such as Merriam's chipmunks (Tamias merriami), several males congregate in areas where there are many females. Males run around if an estrous female is nearby. It is unknown if males chase the female until one corners her for copulation (such as in the Eastern chipmunk) or if males perform a display. When a male approaches a female, he rubs his body and face against hers. This may be a form of scent-marking, and precedes copulation. Pre-copulation vocals and mating calls have been noted in other Neotamias chipmunks and are most likely utilized by Hopi chipmunks. (Compton and Callahan, 1995; Nowak, 1999; Yahner, 1978)

The breeding season of Hopi chimpunks is from February until mid-April. Males prepare for the breeding season by becoming sexually active through enlargement of testes about a week after emerging from their winter dens. Females are prepared for mating immediately after exiting their winter dens. Females give birth to one litter after a gestation period of 30 to 33 days. Young chipmunks weigh an average of 3 grams at birth. The heads of the young are larger than bodies and they have no hair. The young are cold to the touch until they are a week old. They have a fairly uniform growth rate and gain 0.50 g per day on average. By 2 weeks, the color of the adult facial patterns becomes visible, the incisors have erupted, the toes have begun to separate, and the young can drag themselves using their front legs. By 3 weeks, the hair becomes smooth and more adult-like, the toes are fully separated, and the young can move more efficiently. At 5 weeks, the young become active outside and the cheek-teeth have erupted. At 6 weeks, they are consuming solid foods. Weaning is a slow process and usually occurs when the young are 6 to 7 weeks old and by then are fully independent. Sexual maturity usually occurs at 10 to 12 months with most females having their first litter in their first year. (Burt and Best, 1994; Hoffmeister and Ellis, 1979; Nowak, 1999; Root, et al., 2001)

  • Breeding interval
    Hopi chipmunks breed once a year between February and April.
  • Breeding season
    Breeding season of Hopi chipmunks runs from February to April.
  • Range number of offspring
    4 to 7
  • Average number of offspring
    5
  • Range gestation period
    30 to 33 days
  • Average gestation period
    31 days
  • Range weaning age
    6 to 7 weeks
  • Average weaning age
    6 weeks
  • Range time to independence
    6 to 7 weeks
  • Average time to independence
    6 weeks
  • Range age at sexual or reproductive maturity (female)
    10 to 12 months
  • Average age at sexual or reproductive maturity (female)
    10 months
  • Range age at sexual or reproductive maturity (male)
    10 to 12 months
  • Average age at sexual or reproductive maturity (male)
    10 months

The mother cares for the young extensively until they are capable of being independent. Weaning is a gradual process. Males contribute no parental care towards the young. (Burt and Best, 1994)

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

Lifespan/Longevity

Exact lifespan of Hopi chimpmunks is unknown. The maximum lifespan of other Tamias chipmunks in captivity is roughly 9.5 years, but their lifestyle tends to lower their life expectancy considerably. The longest expected lifespan in the wild is 8 years, but most individuals survive only 2 to 3 years, and only 10% of individuals survive their first 64 months of life. (Bergstrom and Hoffmann, 1991; Gorbunova, et al., 2008; Nowak, 1999)

  • Range lifespan
    Status: wild
    8 (high) years
  • Range lifespan
    Status: captivity
    5 to 9.5 years
  • Typical lifespan
    Status: wild
    2 to 8 years
  • Average lifespan
    Status: wild
    2-3 years

Behavior

Hopi chipmunks are diurnal and active during the early morning hours, especially following rainstorms or thundershowers. They are also hibernators, usually decreasing activity just before the breeding season from November to April. Hopi chipmunks do not hibernate for great lengths of time, especially since the species can be active until late November and periodically leave their dens during the winter. Hopi chipmunks often interact with other species of chipmunks in western North America, creating a very distinct ecological community that is based on their environmental preference. This creates a mosaic of different microhabitats in which the Hopi chipmunks occupy higher elevations while species such as yellow-pine chipmunks (Tamias amoenus) occupy the lower regions. This suggests that Hopi chipmunk interactions with other Tamias species are limited by habitat preference and geological isolation and do not include hybridization between species. Knowledge of interactions between species is limited, but comparing with other Tamias species, it can be assumed that Hopi chipmunks share similar characteristics of solitary living and tend to display dominance and solitary behavior when other chipmunks enter their territory. (Burt and Best, 1994; Good, et al., 2003; Nowak, 1999; Yahner, 1978)

  • Range territory size
    0.005 to 0.0128 km^2

Home Range

Home range is hard to calculate in a two-dimensional space because Hopi chipmunks are avid climbers whose home range may include trees and sandstone cliffs. Projected territory size varies among males, females, and juveniles. Territory size is 1.28 ha for adult males and 1.04 ha for adult females. Territory size of juveniles is no larger than 0.50 ha. (Burt and Best, 1994)

Communication and Perception

Communication and perception strategies of Hopi chipmunks are likely similar to other Neotamias species. These animals produce two main categories of calls: alarm calls and agonistic (courtship) sounds. Alarms calls vary and may include a chip, chuck, or "chippering" sound. Trills and whistles have also been recorded. Courtship sounds were similar, but tended to be much harsher. (Nowak, 1999)

Food Habits

The diet of Hopi chipmunks consists largely of the berries and seeds of its local region. The variety and type available for consumption is affected by the season and geographical range. In Utah, Hopi chipmunks feed primarily on the berries of the one-seeded juniper (Juniperus monosperma). In other areas, individuals feed on cliff rose, squawberry (Rhus trilobata), mountain mahogany, and seeds and nuts from Russian thistle, pinyon pine, and the Gambel and waxy leaf oaks. In late spring and summer, Hopi chipmunks feed on green vegetation. In the fall, their diet changes to favor nuts as they become available. The species also has been seen caching food in rocky ledges and utilizes its large cheek pouches to carry food to caches. Hopi chipmunks do not typically eat leaves or stems in the wild although in captivity, they are known to eat parts of dandelions. They need constant access to water, and can die of thirst if deprived of water for only 2 days. (Burt and Best, 1994; Nowak, 1999)

  • Plant Foods
  • leaves
  • roots and tubers
  • wood, bark, or stems
  • seeds, grains, and nuts
  • flowers

Predation

Hopi chipmunks are eaten by snakes, birds, and possibly mammals. Bullsnakes (Pituophis catenifer sayi) have been known to eat juvenile chipmunks. Other predators include coyotes (Canis latrans), Swainson's hawks (Buteo swainsoni), and long-tailed weasels (Mustela frenata). The exact mortality of the chipmunks by these predators is not known. (Burt and Best, 1994)

Ecosystem Roles

Mites and fleas are common parasites that infect Hopi chipmunks. In one case, botfly larva (likely Cuterebra) was found under the skin of an individual, but it is not known whether this larvae typically uses the Hopi chipmunk as a host. Hopi chipmunks displays caching behavior, so it can be assumed that it may also disperse seeds. The species also interacts with a large number of western chipmunks in North America, but due to its habitat preference, it is thought that there are not a lot of interspecific interactions in the ecosystem. (Burt and Best, 1994; Nowak, 1999)

  • Ecosystem Impact
  • disperses seeds
Commensal/Parasitic Species

Economic Importance for Humans: Positive

The positive impact of the Hopi chipmunk on humans is unknown, but most likely minimal. Some chipmunks of the subgenus Neotamias are killed for their skins in the fur trade, although it is not certain if Hopi chipmunks are included in this trade. (Nowak, 1999)

  • Positive Impacts
  • body parts are source of valuable material

Economic Importance for Humans: Negative

There have been suggestions that Hopi chipmunks damage crops (as some Neotamias live close to agricultural areas) but the species rarely occurs in large enough concentrations to cause much damage. (Nowak, 1999)

  • Negative Impacts
  • crop pest

Conservation Status

Hopi chipmunks are considered stable and not endangered. There has been some concern that habitat loss due to agricultural and urban expansion may adversely affect Neotamias species in the future. (Nowak, 1999; Wilson and Reeder, 2005)

Other Comments

The species has been called by different names, which include the 1905 classification of Eutamias hopiensis. The species has also been called Eutamias quadrivittatus rufus, suggesting it to be a subspecies of Colorado chipmunks (Eutamias quadrivittatus), but there has been considerable debate concerning the arrangement of Neotamias and Eutamias and where Tamias falls under as a subgenus. Studies such as the size of the skull and baculum, as well as body shape and coloring, have sought to see if T. quadrivittatus and T. rufus are subspecies or separate species. As of now, Hopi chipmunks are classified as Tamias rufus, separate from Eutamias quadrivittatus. (Hoffmeister and Ellis, 1979; Nowak, 1999; Patterson, 1984; Wilson and Reeder, 2005)

Contributors

Jessica Morris (author), University of Alaska Fairbanks, Laura Prugh (editor), University of Washington.

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.

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

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

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.

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

folivore

an animal that mainly eats leaves.

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

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.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

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

polygynous

having more than one female as a mate at one time

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

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.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

visual

uses sight to communicate

References

Bergstrom, B., R. Hoffmann. 1991. Distribution and Diagnosis of Three Species of Chipmunks (Tamias) in the Front Range of Colorado. The Southwestern Naturalist, 36: 14-28.

Burt, S., T. Best. 1994. Mammalian Species: Tamias Rufus. The American Society of Mammalogists, 460: 1-6.

Compton, S., J. Callahan. 1995. REPRODUCTIVE BEHAVIOR IN MERRIAM'S CHIPMUNK ( TAMIAS MERRIAMI ). Great Basin Naturalist, 55: 89-91.

Good, J., J. Demboski, D. Nagorsen, J. Sullivan. 2003. PHYLOGEOGRAPHY AND INTROGRESSIVE HYBRIDIZATION: CHIPMUNKS (GENUS TAMIAS) IN THE NORTHERN ROCKY MOUNTAINS. Evolution, 57: 1900-1916.

Gorbunova, V., M. Bozzella, A. Seluanov. 2008. Rodents for comparative aging studies: from mice to beavers. AGE, 30: 111-119.

Hall, E. 1981. Mammals of North America Volume 1. New York: John Wiley & Sons.

Hoffmeister, D., L. Ellis. 1979. Geographic Variation in Eutamias quadrivittatus with Comments on the Taxonomy of Other Arizonan Chipmunks. The Southwestern Naturalist, 24: 655-665.

Levenson, H., R. Hoffman, C. Nadler, L. Deutsch, S. Freeman. 1985. SYSTEMATICS OF THE HOLARCTIC CHIPMUNKS (TAMIAS). Journal of Mammalogy, 66: 219-242.

Nowak, R. 1999. Walker's Mammals of the World 6th Edition Volume II. Baltimore and London: The John Hopkins University Press.

Patterson, B. 1984. Geographic Variation and Taxonomy of Colorado and Hopi Chipmunks (Genus Eutamias). Journal of Mammalogy, 65: 442-456.

Root, J., C. Calisher, B. Beaty. 2001. MICROHABITAT PARTITIONING BY TWO CHIPMUNK SPECIES (TAMIAS) IN WESTERN COLORADO. Western North American Naturalist, 61: 114-118.

Saldaña-DeLeon, J., C. Jones. 1998. Annotated checklist of the recent mammals of Colorado. Museum of Texas Tech University: 1-16.

Wilson, D., D. Reeder. 2005. Mammal Species of the World Volume II. Baltimore and London: The John Hopkins University Press.

Yahner, R. 1978. The Adaptive Nature of the Social System and Behavior in the Eastern Chipmunk, Tamias striatus. Behavioral and Sociobiology, 3: 397-427.

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