Tamias dorsalis

Geographic Range

Tamias dorsalis is found mainly in the southwestern United States of America. Its range inludes the states of Nevada, Utah, Arizona, and New Mexico as well as the northern portion of Mexico.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

Cliff chipmunks spend much of their time near cliffs. Dens, particularly winter dens, are in rocky outcroppings. In summer, chipmunks will stay overnight in cliffs, but much of their diurnal activity is away from the den area. Tamias dorsalis generally inhabits elevations of 1500 to 3700 m with scrub-type habitat. The tendency is toward occupying patches of juniper ( Juniperus spp. ), but T. dorsalis is also found in areas with oaks ( Quercus spp. ), maples ( Acer spp. ), Piñon pine ( Pinus monophylla ), and Ponderosa Pine ( P. ponderosa ). Cliff chipmunks have been found in lava fields and deserts at lower elevations.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• scrub forest scrub forest

Physical Description

Tamias dorsalis is a smoky-gray chipmunk with dark stripes on its back. These dark stripes are more distinct on the summer fur than on the winter fur. It lacks the white stripes often found in the pelage of this genus. The flanks are light brown in color, and the undeparts are creamy-white. The tail is bushy with black on top and cinnamon brown underneath. The feet have a hint of yellow. The molt in May and June from winter to summer pelage occurs from anterior to posterior. Females tend to molt into their summer pelage in June and July, later than males, due to the engergy requirements of pregnancy and lactation.

Adults of this species average 70 g. Females are larger than males, weighing between 70 and 74 g. The smaller males weigh between 61 and 64.5 g.

The total length of T. dorsalis ranges between 217 and 249 mm, with the hind foot measuring between 34 and 37 mm. They have 22 teeth. Eight mammae are present on the females.

There are several subspecies reported, and these subspecies are reported to have clinal variation which intergrades them phenotypically. The subspecies may be defined mainly by differences in body and skull dimensions, pelage characters, dental characeters, and differences in the baculum.

Tamias dorsalis is sympatric with several other species of chipmunks, including T. canipes , T. cinereicollis , T. minimus , T. quadrivittatus , and T. umbrinus. However, all of these species have well defined white stripes on their fur, making it easy to distinguish them from T. dorsalis at a glance.

The species is diagnosed by its baculum. This has a thin shaft, ranging in length from 2.64 to 3.69 mm. The distal half of the shaft is somewhat laterally compressed. The keel, which is 20% of the length of the tip, is low. The tip of the baculum is between 20% and 40% the length of the shaft, and forms an angle of 140 degrees with the shaft.

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

• Sexual Dimorphism
• female larger

Reproduction

Details on the reproductive system of this species are scant. However, one estrus female was the center of attention of as many as 14 males, indicating that there is probably some competition among males for access to these females. It is not known whether the female in this report mated with more than one of the males.

Males are reproductively active from January through June although most breeding occurs in March. A study of T. dorsalis in the mountains of Arizona suggests that copulation does not occur until May with birth in late June and early July. These discrepancies can be attributed to the duration of winter and the quantity of food available. Tamias dorsalis does not gain weight before winter, but will loose some over the winter. February through April are lean months and may play a crucial role in the copulation and breeding success of T. dorsalis .

Cliff chipmunks have only one litter per year, with an approximate size of 4 to 6 young. Parturition normally occurs in the months of April to July with the young emerging from burrows about a month later.

Although details on the development of this species are lacking, cliff chipmunks are probably like other members of their genus. Tamias cinereicollis young are reported to nurse for 41 to 45 days. They are capable of eating solid foods at 36 to 40 days of age.

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

The young spend their early days in the den of their mother, and are presumed to be altricial. As mammals, females of this species provide their young with milk, grooming, and protection. Mature females in Arizona have been recorded in transport of half-grown young which are carried in the mouth. Males are not reported to be involved in the care of the young.

• Parental Investment
• no parental involvement
• altricial altricial
• pre-fertilization
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • protecting
    • female

Lifespan/Longevity

The longevity of this species has not been reported.

Behavior

Tamias dorsalis has been described as shy. Generally, cliff chipmunks are diurnal with activity mainly in the mornings and then again from the late afternoon until dusk.

In northern Utah, T. dorsalis was recorded to have 57% of its activity foraging and 3% as grooming behavior. Tamias dorsalis takes dust baths by lowering its belly into a dry, powdery soil and alternately writhing its head or tail end. It then flips over and throws its hindquarters around in the soil also. Tamias dorsalis grooms its head with the forepaws and will groom its tail end as well by biting into the fur.

Tamias dorsalis can be territorial and will chase others if the minimum individual distance has been violated. However, these territorial encounters apparently occur mainly in the area around dens. Away from dens, most encounters result in mutual nosings or chases. Females can be somewhat gregarious, and form feeding aggregations during the morning feeding. As many as 10 chipmunks may gather at a food source, and slowly travel together through the food sources, keeping a distance of 3 to 10 meters betwen individuals. Individuals in these aggregations may vocalize to identify themselves, or to maintain spacing.

Tamias dorsalis is typically found close to refugia. Although it may take cover in trees, the species is most likely to climb steep rocks when it is alarmed.

Cliff chipmunks usually make their dens and nests in rocky bluffs and cliffs. Sometimes underground burrows and tree nests are used. There may be different use of habitat in summer versus winter, with different nesting sites used in different seasons. Also, seasonal migrations may occur, and if they do, they appear to be related to availability of food sources.

• Key Behaviors
• terricolous
• fossorial fossorial
• diurnal diurnal
• motile motile
• migratory migratory
• sedentary sedentary
• territorial territorial

Home Range

Home ranges have been reported to range between 0.4 and 2 hectares. Individuals of this species are reported to typically maintain home ranges with a greatest dimension of about 100 m.

Communication and Perception

Tamias dorsalis has three different calls that characterize different meanings. A bark emitted during standing, resting, or squatting suggests normal activity. A sharp "whsst" or "psst" chirp from an upright, alert position and tail twitching indicates excitement. A mixture of high-pitched sounds represents being surprised or threatened.

In addition to its vocal communications, it is likely that this diurnal species uses other visual signals to communicate with conspecifics. For example, body posture may indicate friendly or hostile intentions when two individuals come together.

Tactile communication is undoubtedly important between mates as well as rivals, and also occurs between a mother and her young. Although specific scent based communication has not been reported for this species, it may occur.

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

• Perception Channels
• visual visual
• infrared/heat infrared/heat
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Tamias dorsalis forages for juniper berries, pine seeds, and acorns. These make up a large portion of the diet of this species. Tamias dorsalis is an opportunistic forager and will eat available plant material. Seeds are gathered during prime availability and are carried in cheek pouches and are transported to temporary caches. Seeds and vegetation are generally cached within 100 m of the home cliff, with many of these caches being retrieved later. Use of plants as food sources seems to influence both daily and seasonal movements. Females have been noted to spend more time foraging than males. Tamias dorsalis is mainly herbivorous although these chipmunks have been noted to eat a wide variety of insects, herps, birds, and eggs in Utah.

• Primary Diet
• herbivore herbivore
  • granivore granivore

• Animal Foods
• amphibians
• reptiles
• eggs
• insects
• terrestrial non-insect arthropods

• Plant Foods
• seeds, grains, and nuts
• fruit

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

Predation

Tamias dorsalis remains close to the cliff faces and rocks for easily available cover. The indistinctness of their stripes is also supposed to serve as an anti-predator adaptation. Potential predators in different regions include Cooper's hawks ( Accipiter cooperii ), Sharp-shinned hawks ( Accipiter jamaicensis ), American kestrels ( Falco sparverius ), coyotes ( Canis latrans ), badgers ( Taxidea taxus ), long-tailed weasels ( Mustela frenata ), and prairie rattlesnakes ( Crotalus viridis ). Domestic cats may also prey on T. dorsalis.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Cliff chipmunks are food for a variety of carnivores and raptors. They also cache seeds, and so may be an important means of seed dispersal. They compete with other species of chipmunks and ground squirrels for seeds. Bot-fly larva ( Cuterebra ), fleas, lice and white chiggers ( Trombiculi allredi ) have been found on T. dorsalis . Necropsies of T. dorsalis in other regions have not found any endoparasites.

• Ecosystem Impact
• disperses seeds

Economic Importance for Humans: Positive

These animals are not reported to have any positive economic impact on humans. However, as a prey species, they do provide food for some of the larger predatory species that humans enjoy watching. Also, because they are themselves sort of cute, they may provide entertainment for tourists in natural areas.

Economic Importance for Humans: Negative

If agricultural areas are within or near the range of T. dorsalis , the possibility of crop damage is present although it has not been documented.

• Negative Impacts
• crop pest

Conservation Status

Cliff chipmunks are not listed by CITES or IUCN.

Other Comments

Tamias dorsalis has kidney specializations that are adaptive to dry habitats. A number of subspecies exist and contribute to the differences noted in each category. Differences between subspecies also contributes to the reported shyness or lack of shyness in different regions. Synonym: Eutamias dorsalis .

Additional Links

Encyclopedia of Life

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Louise Venne (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor, instructor), University of Wisconsin-Stevens Point.

References

Best, T. 1999. Gray-collared chipmunk ( Tamias cinereicollis ). Pp. 362-363 in The Smithsonian Book of North American Mammals . Washington and London: The Smithsonian Institution Press.

Broadbrooks, H. 1999. Cliff Chipmunk ( Tamias dorsalis ). Pp. 363-365 in The Smithsonian Book of North American Mammals . Washington and London: The Smithsonian Institution Press.

Dunford, C. 1974. Annual Cycle of Cliff Chipmunks in the Santa Catalina Mountains, Arizona. Journal of Mammalogy , 55(2): 401-416.

Hart, E. 1976. Life History Notes on the Cliff Chipmunk, Eutamias dorsalis, in Utah. Southwestern Naturalist , 21(2): 243-246.

Hart, E. 1992. Tamias dorsalis. Mammalian Species , No. 399: 1-6. Accessed 12/05/02 at http://www.science.smith.edu/departments/Biology/VHAYSSEN/msi/pdf/i0076-3519-399-01-0001.pdf .

CITES. 2002. "CITES appendices" (On-line ). Accessed 12/05/02 at http://www.cites.org/eng/append/index.shtml .

National Wildlife Federation. "Cliff Chipmunk, enature.com" (On-line ). enature.com. Accessed 12/08/02 at http://www.enature.com/fieldguide/showSpeciesGS.asp?sort=1&curGroupID=99&display=1&area=99&searchText=cliff+chipmunk&curPageNum=1&recnum=MA0186 .

U.S. Fish & Wildlife Service. 2002. "Endangered Species Information, U.S. Fish and Wildlife Service" (On-line ). Accessed 12/05/02 at http://endangered.fws.gov/wildlife.html .

University of New Mexico. 1998. "Sevilleta LTER Data" (On-line ). Accessed 12/06/02 at http://sevilleta.unm.edu/data/species/mammal/profile/cliff-chipmunk.html .

IUCN. 2002. "The IUCN Red List of Threatened Species" (On-line ). Accessed 12/05/02 at http://www.redlist.org/ .