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)
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)
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)
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)
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)
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)
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)
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)
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)
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)
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)
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)
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)
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)
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)
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.
Anne-Claire Acquisto (author), University of Alaska Fairbanks, Laura Prugh (editor), University of Alaska Fairbanks, Catherine Kent (editor), Special Projects.
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.
uses sound to communicate
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.
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.
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.
uses smells or other chemicals to communicate
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.
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.
parental care is carried out by females
union of egg and spermatozoan
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
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.
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).
having the capacity to move from one place to another.
an animal that mainly eats fungus
the area in which the animal is naturally found, the region in which it is endemic.
an animal that mainly eats all kinds of things, including plants and animals
chemicals released into air or water that are detected by and responded to by other animals of the same species
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
places a food item in a special place to be eaten later. Also called "hoarding"
uses touch to communicate
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).
Living on the ground.
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
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.
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.
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.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
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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.
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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.
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Thorington, R., K. Ferrell. 2006. Squirrels : the animal answerguide. Baltimore, MD, USA: Johns Hopkins University Press.
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