Tamias rufus

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.

• Biogeographic Regions
• nearctic nearctic
  • native native

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.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• desert or dune desert or dune
• mountains mountains

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.

• Other Physical Features
• endothermic endothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger

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.

• Mating System
• polygynous polygynous

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.

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

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.

• Parental Investment
• altricial altricial
• female parental care 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.

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.

• Key Behaviors
• scansorial
• terricolous
• diurnal diurnal
• motile motile
• sedentary sedentary
• hibernation hibernation
• solitary solitary
• territorial territorial

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.

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.

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic

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

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.

• Primary Diet
• herbivore herbivore
  • folivore folivore
  • granivore granivore
  • lignivore

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

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

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.

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.

• Ecosystem Impact
• disperses seeds

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.

• 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.

• 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.

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 E. quadrivittatus and T. rufus are subspecies or separate species. As of now, Hopi chipmunks are classified as Tamias rufus , separate from Eutamias quadrivittatus .

Additional Links

Encyclopedia of Life

BioKIDS Critter Catalog

Contributors

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

References

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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.

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

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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.

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