Tamias townsendiiTownsend's chipmunk

Geographic Range

Townsend's chipmunks are found in the northwestern United States. Their distribution ranges from the the Rogue River in southern Oregon to southwestern British Columbia along the Pacific coast. Thus they are found in an oceanic, or marine west coast climate. ("Tamias townsendii", 2012; Sutton, 1993)

Habitat

Townsend's chipmunks are mainly found in dense hardwood forests and dense coniferous forests. They tend to live in riparian areas within the forests, or in areas with dense shrub cover which influence their behavior. They can sometimes reach more open areas, like clear-cut forests, especially several years after the cut when the secondary forest is growing. This provides shrub cover and an abundant source of food. Their home range extends from the coast to the sub-alpine areas of the Cascade Range in Oregon. For nesting, they look for talus slope with lose rocks that provide a shelter. (Headley and Sells, 2005; Linzey and Hammerson, 2008; Sutton, 1993)

  • Range elevation
    0 (low) m
    0.00 (low) ft

Physical Description

Townsend's chipmunks have dark brown and striped backs. There are five dark stripes alternating with four lighter stripes; the middle one is usually darker. Unlike squirrels, chipmunks have striped faces. Townsend's chipmunks have two gray and three brown stripes on their faces. Other anterior stripes might also be observed, but they are mostly obsolete. Underparts are creamy white to gray. Ears are black in front and gray behind. The bushy tail is dark brown to dark tipped with gray above, and brown below. The tail is held erect while running. Townsend's chipmunks tend to be brighter during the summer, and undergo two molts annually in May and August. Juvenile pelage is similar to adults. (Edelman and Koprowski, 2006; Headley and Sells, 2005; Levenson and Hoffman, 1984; Smithsonian Institution, 2012; Sutton, 1993; Thorington and Ferrell, 2006)

Townsend's chipmunks are considered fairly large among chipmunks. Their size range from 22 to 38 cm, and averages 25.5 cm. This includes a tail of 7 to 17 cm. Their weight ranges from 60 to 118 g, and averages 75 g. Females are 2% to 6% larger than males, which leads to a female dominance in the population. (Edelman and Koprowski, 2006; Headley and Sells, 2005; Levenson and Hoffman, 1984; Smithsonian Institution, 2012; Sutton, 1993; Thorington and Ferrell, 2006)

Their dental formula is: 1/1 0/0 2/1 3/3 =22, with a small vestigial upper premolar that all western North American chipmunks possess and eastern North American do not. (Edelman and Koprowski, 2006; Headley and Sells, 2005; Levenson and Hoffman, 1984; Smithsonian Institution, 2012; Sutton, 1993; Thorington and Ferrell, 2006)

  • Sexual Dimorphism
  • female larger
  • Range mass
    60 to 118 g
    2.11 to 4.16 oz
  • Average mass
    75 g
    2.64 oz
  • Range length
    22 to 38 cm
    8.66 to 14.96 in
  • Average length
    25.5 cm
    10.04 in

Reproduction

There is little documentation regarding mating systems of Townsend's chipmunks. Mating is seasonal and occurs for 2 weeks in spring. Like most chipmunks, they are likely not promiscuous, nor do they form a pair bond. (Edelman and Koprowski, 2006; Thorington and Ferrell, 2006)

Townsend's chipmunks only breed once a year for a period of 2 weeks right after hibernation. This is so that all reproduction activities can occur between late spring and early summer, when food availability and climate are more favorable. In this way, young can mature during summer and prepare for winter. ("AnAge entry for Tamias townsendii", 2005; Sutton, 1993)

Townsend's chipmunks are viviparous. Gestation lasts 28 days and parturation occurs from May to June. Females give birth to 3 to 6 young in their burrows. At birth the young have no hair or teeth. Their eyes are closed, ears folded, feet webbed, and skin translucent. They weigh around 3.5 g. At 10 days, dorsal hairs have begun to grow on their back, and their eyes are still closed. They are not totally helpless, but are able to use their forelimbs to move by pulling and pushing. By 20 days, they have fur, incisors, and are more active. They appear above ground in July, when food and climate conditions are favorable. At the end of the 50-day weaning period, they weigh around 35 g. At 90 days, they are considered adults. Adults reach sexual maturity at 353 days, and Townsend's chipmunks can reproduce the following summer. ("AnAge entry for Tamias townsendii", 2005; Sutton, 1993)

  • Breeding interval
    Townsend's chipmunks breed once a year.
  • Breeding season
    Townsend's chipmunks breed for 2 weeks in spring, usually in late April.
  • Range number of offspring
    3 to 6
  • Average gestation period
    28 days
  • Average weaning age
    50 days
  • Average time to independence
    90 days
  • Average age at sexual or reproductive maturity (female)
    353 days
  • Average age at sexual or reproductive maturity (male)
    353 days

Pups are altricial at birth, so the mother provides protection and sustenance. She primarily keeps them in the burrow, and feeds them milk until they transition to an omnivorous diet. The mother nurses the young until they leave the burrow and become independent. (Headley and Sells, 2005)

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

Lifespan/Longevity

In captivity, an individual Townsend's chimpunk lived to 9.3 years. Another specimen has been said to have lived up to 10.2 years, but this was inadequately documented. In the wild, Townsend's chipmunks live 2 to 7 years, with an expected lifespan of 5 years. Food availability may be a limiting factor in populations, and might reduce survival and reproduction. ("AnAge entry for Tamias townsendii", 2005; Headley and Sells, 2005; Sutton, 1993; Weigl, 2005)

  • Range lifespan
    Status: wild
    2 to 7 years
  • Range lifespan
    Status: captivity
    10.2 (high) years
  • Typical lifespan
    Status: wild
    7 (high) years
  • Average lifespan
    Status: wild
    5 years
  • Average lifespan
    Status: captivity
    7 hours

Behavior

Townsend's chipmunks are solitary and demonstrate fairly aggressive behavior toward conspecifics or other chipmunks. They are said to be territorial. An individual lives in a single burrow that can reach up to 10 m in length. They are active during the day, mostly in the late morning and early afternoon. Their general behavior varies with the season, and they are more active from March to late November. They are the most active during the warm period. Their activity consists mainly of feeding, but also gathering food that they cache in their burrow as reserves for the winter. During winter, they can display different behavior depending on the area where they live: at higher elevation, where snow occurs, Townsend's chipmunks tend to hibernate, whereas in warmer areas along the coast, they tend to stay active even during the cold period. ("Tamias townsendii", 2012; Edelman and Koprowski, 2006; Encyclopedia of life, 2012; Fuller and Blaustein, 1990; Harestad, 1991; Sutton, 1993; Thorington and Ferrell, 2006; Waldien, et al., 2006)

Townsend's chipmunks have to make some tradeoffs between energy and nutrient demands, and the cost of foraging. When foraging, they expose themselves to predators. Therefore, they usually prefer paths with cover so they can stay hidden from predators. They can also climb trees or use their burrows as a refuge to escape from them. ("Tamias townsendii", 2012; Edelman and Koprowski, 2006; Encyclopedia of life, 2012; Fuller and Blaustein, 1990; Harestad, 1991; Sutton, 1993; Thorington and Ferrell, 2006; Waldien, et al., 2006)

  • Range territory size
    0.8 (high) km^2
  • Average territory size
    0.5 km^2

Home Range

Home ranges can reach up to 0.5 ha, but the core area only is defended actively, which is 9 to 12 m from the burrow. Home range size may be influenced by body size, population density, food distribution. The female-biased sexual size dimorphism leads to the dominance of females in the population. Since they are bigger, they tend to have larger territories. (Edelman and Koprowski, 2006)

Communication and Perception

Townsend's chipmunks perceive their environment through sight, hearing, and smell, but communicate using vocalizations, threat displays, and touch. Their most important method of communication is vocalizations, primarily alarm calls made by males, females, adults, and juveniles. This is an interesting behavior, because even if the Tonwsend's chipmunks tend to be solitary, they give alarm calls to warn their conspecifics, compromising their own survival. This can be considered as altruism. This phenomenon seems to be more important when the chipmunks are genetically related. This involve kin selection: they are able to recognize individuals to which they are more related. This is mainly accomplished by familiarization when they are young, such as sniffing and grooming. (Fuller and Duszynski, 1997)

Food Habits

Townsend's chipmunks have a fairly diverse diet. Underground fungi (truffes) emit a strong odor and seem to be the favorite food of the Townsend's chipmunks, especially during winter. Thus they are primarily mycophagous, but tend to diversify they diet depending upon the availability of the different resources. During the summer, they feed mainly on berries including blackberries (Rubus fruticosus), salal berries (Gaultheria shallon), and thimble-berries (Rubus parviflorus). In the fall, their diet tends to switch to seeds: maple (Acer pseudoplatanus) seeds, thistle (Cynareae) seeds, grain seeds, conifer seeds, but also acorns (Quercus), huckleberries (Vaccinium and Gaylussacia), grass and roots. Townsend's chipmunks forage mainly on the ground, but may also climb in trees. They use their cheek pouches to carry food from their foraging areas to their burrow. (Encyclopedia of life, 2012; Headley and Sells, 2005; Sheppard, 1989; Sutton, 1993)

  • Animal Foods
  • insects
  • Plant Foods
  • roots and tubers
  • seeds, grains, and nuts
  • fruit
  • Other Foods
  • fungus

Predation

Townsend's chipmunks use alarm calls to warn other individuals, especially their relatives. Their small size and color of fur also make them cryptic, which is an advantage for a prey. They also display some behavioral adaptations like the preference for covered areas. Townsend's chipmunks are preyed upon by weasels (Mustela), minks (Neovison vison), bobcats (Lynx rufus), house cats (Felix catus), foxes (Vulpes), martens (Martes), skunks (Mephitidae), hawks (Accipitrinae), owls (Strigiformes), and snakes (Serpentes). (Encyclopedia of life, 2012; Harestad, 1991; Waldien, et al., 2006)

Ecosystem Roles

Townsend's chipmunks are mainly primary consumers (though they do not feed exclusively on plants), enabling energy flows from primary producers to secondary consumers. Townsend's chipmunks are potential seed dispersers. They partially feed on seeds which may end up in their feces because of their low digestibility. Moreover, they store seeds in their burrows, and even if they consume these during winter, some might remain at the beginning of the spring and germinate. They may also participate in fungi dispersal. They spread the spores by carrying them on their feet, and by eating fungi, can also disperse them in their feces. Townsend's chipmunks can be host for some parasites like coccidain parasites (Eimeria) and contribute to their propagation in the ecosystem. (Edelman and Koprowski, 2006; Fuller and Blaustein, 1990; Headley and Sells, 2005)

  • Ecosystem Impact
  • disperses seeds
Commensal/Parasitic Species
  • protozoans (Eimeria)

Economic Importance for Humans: Positive

Townsend's chipmunks rely partially on a mycophagous diet, so they can potentially play a role in forest ecology. They can disperse fungi that contribute to create enriched soils, resulting in a global enhancement of soil quality in the forest. Thus it might be an advantage in commercial forestry. (Headley and Sells, 2005; Sutton, 1993)

Economic Importance for Humans: Negative

Townsend's chipmunks are potential fungus dispersers, which mean they can also be an agent in the dissemination of harmful fungus, especially for conifer seeds. Thus they can cause problems in commercial forestry, though on a limited scale. (Headley and Sells, 2005; Sutton, 1993)

Conservation Status

Townsend's chipmunk populations are quite stable. They are not threatened and are considered quite common. Herbicide treatment of Douglas-fir plantations caused a decline in a coastal population in British Columbia in the 1980's, but only temporarily. Their density ranges from 0.6 to 1.1 individuals per hectare in a mature forest, but may be 2 to 4 times higher in clear-cuts (3 to 10 years after the cut). (Sullivan, 1990)

Other Comments

Sciuridae fossils have been found worldwide, however their biogeography (dispersal over evolutionary time) is still obscure. No fossil from the Pleistocene era has been found of Townsend's chipmunks.

Contributors

Anne-Claire Acquisto (author), University of Alaska Fairbanks, Laura Prugh (editor), University of Alaska Fairbanks, Catherine Kent (editor), Special Projects.

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.

aposematic

having coloration that serves a protective function for the animal, usually used to refer to animals with colors that warn predators of their toxicity. For example: animals with bright red or yellow coloration are often toxic or distasteful.

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

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

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

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

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.

mycophage

an animal that mainly eats fungus

native range

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

omnivore

an animal that mainly eats all kinds of things, including plants and animals

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

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

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

2005. "AnAge entry for Tamias townsendii" (On-line). AnAge : the Animal Ageing and Longevity Database. Accessed November 16, 2012 at http://genomics.senescence.info/species/entry.php?species=Tamias_townsendii.

2012. "Tamias townsendii" (On-line). USA National Phenology Network. Accessed December 09, 2012 at http://www.usanpn.org/Tamias_townsendii.

Edelman, A., J. Koprowski. 2006. Influence of female-biased sexual size dimorphism on dominance of female Townsend's chipmunks. Canadan Journal of Zoology, 84: 1859-1863. Accessed November 16, 2012 at http://ag.arizona.edu/~squirrel/CJZ%20dimorph%20in%20Chips%2007.pdf.

Encyclopedia of life, 2012. "Facts about Tamias townsendii" (On-line). Encyclopedia of Life. Accessed November 16, 2012 at http://eol.org/pages/4466570/details.

Fuller, C., A. Blaustein. 1990. An investigation of sibling recognition in a solitary sciurid, Townsend's Chipmunk, Tmaias townsendii. Behaviour, 112/No1/2: 36-52. Accessed November 16, 2012 at http://www.jstor.org/stable/10.2307/4534827.

Fuller, C., D. Duszynski. 1997. Eimeria (Protozoa : Eimeriidae) from North American Sciurids, Glaucomys sabrinus and Tamias townsendii : with a description of a new species. The Journal of Parasitology, 83/3: 467-470. Accessed November 16, 2012 at http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1176&context=parasitologyfacpubs.

Harestad, A. 1991. Spatial behaviour of Townsend's chipmunks and habitat structure. Acta theoriologica, 36: 247-254. Accessed November 15, 2012 at http://rcin.org.pl/Content/11759/BI002_26813_Cz-40-2_Acta-T36-nr21-247-254_o.pdf.

Headley, S., S. Sells. 2005. "Townsend's Chipmunk" (On-line). Accessed December 06, 2012 at http://extension.oregonstate.edu/catalog/pdf/ec/ec1580.pdf.

Levenson, H., R. Hoffman. 1984. Systematic relationships among taxa in the Townsend Chipmunk group. The southwestern Naturalist, 29/2: 157-168. Accessed November 16, 2012 at http://www.jstor.org/stable/10.2307/3671022.

Linzey, A., G. Hammerson. 2008. "Tamias townsendii (Townsend's chipmunk)" (On-line). The IUCN Red List of Threatened Species. Accessed November 16, 2012 at http://www.iucnredlist.org/details/42584/0.

Robertson, S. "How do Chipmunks communicate?" (On-line). eHow. Accessed November 16, 2012 at http://www.ehow.com/info_10069070_chipmunks-communicate.html.

Sheppard, D. 1989. "Les suisses et les tamias" (On-line). Faune et flore du pays. Accessed November 16, 2012 at http://www.hww.ca/fr/especes/mammiferes/les-suisse-et-les-tamias.html.

Smithsonian Institution, 2012. "North American Mammals - Townsend's Chipmunk" (On-line). Smithsonian National Museum of Natural History. Accessed November 16, 2012 at www.mnh.si.edu/mna/image_info.cfm?species_id=391.

Sullivan, T. 1990. Demographic responses of small mammal populations to a herbicide application in coastal coniferous forest: population density and resiliency. Canadian Journal of Zoology, 68: 874-883. Accessed December 09, 2012 at http://www.nrcresearchpress.com/doi/pdf/10.1139/z90-127.

Sutton, D. 1993. Tamias Townsendii. The American Society of Mammalogists, 432: 1-6.

Thorington, R., K. Ferrell. 2006. Squirrels : the animal answerguide. Baltimore, MD, USA: Johns Hopkins University Press.

Waldien, D., J. Hayseb, M. Husob. 2006. Use of downed wood by Tonsend's Chipmunks (Tamias townsendii) in Western Oregon. Journal of Mammalogy, 87/3: 454-460. Accessed December 06, 2012 at http://www.bioone.org/doi/pdf/10.1644/05-MAMM-A-136R1.1.

Weigl, R. 2005. Longevity of Mammals in Captivity; from the Living Collections of the World.. Stuttgart: E. Schweizerbart'sche.