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Townsend's ground squirrel

Spermophilus townsendii

What do they look like?

Townsend's ground squirrels are pale and dark gray on top, and creamy white underneath. Their fur is also slightly pink and tan on both their backs and bellies. Subspecies are slightly different colors. Subspecies in the Escalate desert in southern Utah are redder than squirrels in the north. In western Nevada, some are very pale. Townsend's ground squirrels are usually 167 to 271 mm long and weigh 82 to 325 g. Their skulls have a wide opening for their brain, wide cheek arches, a long ear canal, and teeth with high crowns. (Rickart, 1987)

  • Sexual Dimorphism
  • male larger
  • Range mass
    82 to 325 g
    2.89 to 11.45 oz
  • Range length
    167 to 271 mm
    6.57 to 10.67 in
  • Range basal metabolic rate
    .62 to 1.10 cm3.O2/g/hr
  • Average basal metabolic rate
    .86 cm3.O2/g/hr

Where do they live?

Right now, Townsend's ground squirrels live in a small part of Washington including the Yakima River Valley, the Horse Heaven Hills, and West of the Yakima River. This area is only about 7,000 square kilometers. Townsend's ground squirrels once lived throughout Nevada, eastern Oregon, southern Idaho, south-central Washington, and far eastern California. However, they were separated by rivers and geography into 7 different subspecies. Their overall numbers declined and their separation into different species also caused their range to shrink to the area where they currently live. (Baker, et al., 2003; Hafner, et al., 1998; Rickart, 1987)

What kind of habitat do they need?

Townsend's ground squirrels live between 1,000 meters and 2,100 meters in elevation. They are found in dry deserts around plants like sagebrush, greasewood, and shadescale. They like soils where the water drains well, like farms that aren't used anymore, canals, and along the side of roads. They compete with closely related squirrels like Belding's ground squirrels and Uinta ground squirrels. When they have this competition, they usually end up in the driest areas. (Rickart, 1987)

  • Range elevation
    1000 to 2100 m
    3280.84 to 6889.76 ft
  • Average depth
    1.46 m
    4.79 ft

How do they reproduce?

Townsend's ground squirrels have one set of young per year. Males mate with more than one female. (Johnson, 2000)

Townsend's ground squirrels reproduce once a year in late winter, right after females wake up from hibernation. Older females reproduce more than the youngest ones. The young develop inside the bodies of the females for 23 days and they give birth between February and April. They usually have 7 to 10 offspring at a time, and they weigh 2.2 to 4.9 g when they are born. They drink their mother's milk for 35 days and then are able to be independent one year after they are born. Females are able to mate when they are 1 year old, but males can take 2 years to be able to mate. Sometimes, Townsend's ground squirrels kill their own young that are still drinking milk from their mother. (Hall, 1946; Johnson, 2000; Rickart, 1987)

  • How often does reproduction occur?
    Townsend's ground squirrels produce one litter per year, soon after they awaken in late winter.
  • Breeding season
    The breeding season for Townsend's ground squirrels is late winter through early spring, or January to March.
  • Range number of offspring
    7 to 10
  • Average gestation period
    23 days
  • Average weaning age
    35 days
  • Average time to independence
    1 years
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Range age at sexual or reproductive maturity (male)
    1 to 2 years

Female Townsend's ground squirrels do most of the caring for their young until they are one year old and able to be independent. They nurse their offspring and provide them with food.

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

How long do they live?

Townsend's ground squirrels probably have a lifespan similar to Piute ground squirrels. They live in similar places and scientists used to think they were a subspecies of Townsend's ground squirrels. The longest they live is 5 years, and the oldest ones are more likely to be females. Males usually don't live longer than 3 years. (Rickart, 1988)

  • Range lifespan
    Status: wild
    5 (high) years
  • Average lifespan
    Status: wild
    3 years

How do they behave?

Townsend's ground squirrels are mostly active during the day, especially in early morning. They avoid being active for a long time when its very hot or windy. Their activities include climbing up to look around, searching for food, and crossing rivers. They live together in large groups, and each squirrel has its own burrow. The longer the squirrel lives there, the more tunnels, nests, and entrances it builds in its burrow. Males often leave the group they were born in and join a new one. The squirrels hibernate in groups in the winter. Males wake up in late January, a little before females. However, females are more likely to survive the winter. Their numbers drop in dry years, and are lowest in years after a drought. (Rickart, 1987; Smith and Johnson, 1985)

  • Average territory size
    .01 km^2

Home Range

Groups of Townsend's ground squirrels live in a territory that can be up to a hectare. Groups have adults that stay and males and females that come and go. (Hafner, et al., 1998; Smith and Johnson, 1985)

How do they communicate with each other?

Townsend's ground squirrels use calls with different tones and sounds to communicate with each other. Some have one note and others have more than one. When they are underground, they make higher-pitched calls. Scientists aren't sure exactly what the calls are for, though they are probably used to confuse predators. Ground squirrels also make different kinds of alarm calls. (Rickart, 1987)

What do they eat?

Townsend's ground squirrels eat mostly plants such as Sandberg's bluegrass, winterfat, big sagebrush, Russian thistle, tansymustard, and cheatgrass. They eat slightly different things depending on their habitat and age. Sandberg's bluegrass is common in most places, and they are more likely to eat winterfat when it's more common. Townsend's ground squirrels also eat small amounts of insects. (Smith and Johnson, 1985; Van Horne, et al., 1998)

  • Animal Foods
  • insects
  • Plant Foods
  • leaves
  • roots and tubers
  • wood, bark, or stems

What eats them and how do they avoid being eaten?

Townsend's ground squirrels avoid predators by using camouflage, burrows, and warning signals. They are hunted by badgers, coyotes, long-tailed weasels, prairie falcons, red-tailed hawks, rough-legged buzzards, ferruginous hawks, Swainson's hawks, ravens, prairie rattlesnakes, and northern pine snakes. They are also eaten by Piute Indians. (Mateo, 2007)

What roles do they have in the ecosystem?

Townsend's ground squirrels get many kinds of parasites, mostly ones that live in their intestines. Fleas that live on them are called Meringis shannoni, Opisthocrosis washingtonensis, and Thrassis petiolatus. Parasites that live in their intestines are called: Eimeria adaensis, Eimeria beecheyi, Eimeria bilamellata, Eimeria callospermophili, Eimeria lateralis, Eimeria morainensis, Eimeria pseudospermophili. Worm parasites living in their intestines are called Hymenolepis citelli, Pterygodermatites colaradensis, Spirura infundibuliformes, and Syphacia citelli. (Bossard, 2006; Wilber and Shapiro, 1997)

  • Ecosystem Impact
  • disperses seeds
Commensal or parasitic species (or larger taxonomic groups) that use this species as a host
  • eimerians (Eimeria adaensis)
  • eimerians (Eimeria beecheyi)
  • eimerians (Eimeria bilamellata)
  • eimerians (Eimeria callospermophili)
  • eimerians (Eimeria lateralis)
  • eimerians (Eimeria morainensis)
  • eimerians (Eimeria pseudospermophili)
  • helminths (Hymenolepis citelli)
  • helminths (Pterygodermatites colaradensis)
  • helminths (Spirura infundibuliformes)
  • helminths (Syphacia citelli)
  • fleas (Meringis shannoni)
  • fleas (Opisthocrosis washingtonensis)
  • fleas (Thrassis petiolatus)

Do they cause problems?

Townsend's ground squirrels damage crops grown by farmers, so humans have tried to reduce their numbers. (Rickart, 1987)

  • Ways that these animals might be a problem for humans
  • crop pest

How do they interact with us?

Piute Indians eat Townsend's ground squirrels. They may have even brought them to the place where they currently live. (Rickart, 1987)

  • Ways that people benefit from these animals:
  • food

Are they endangered?

Townsend's ground squirrels are listed as vulnerable by the IUCN Red List of Threatened Species. This is because less than 10 percent of their habitat is left and they only live in small area. Their habitat is shrinking and becoming more difficult for them to inhabit. Groups of them are separated from each other, and they are also targeted by humans because they damage crops. (Yensen and Hammerson, 2008)

Contributors

Ethan Fifield (author), University of Alaska Fairbanks, Laura Prugh (editor), University of Alaska Fairbanks, Catherine Kent (editor), Special Projects.

References

Baker, R., L. Bradley, R. Bradley, J. Dragoo, M. Engstrom, R. Hoffman, C. Jones, F. Reid, D. Rice, C. Jones. 2003. Revised Checklist of North American Mammals North of Mexico, 2003. Occasional Papers: Museum of Texas Tech University, 229: 23. Accessed December 11, 2012 at http://www.nsrl.ttu.edu/publications/opapers/ops/op229.pdf.

Bossard, R. 2006. Mammal and Flea Relationships in the Great Basin Desert: from H. J. Egoscue's Collections. Journal of Parasitology, 9 (2): 260-266.

Hafner, D., E. Yensen, G. Kirkland, Jr.. 1998. "Status Survey and Conservation Action Plan: North American Rodents" (On-line pdf). IUCN Red List of Threatened Species. Accessed December 11, 2012 at http://data.iucn.org/dbtw-wpd/edocs/1998-039.pdf.

Hall, E. 1946. Mammals of Nevada. Berkeley, CA: University of California Press.

Johnson, V. 2000. "Townsend’s Ground Squirrel" (On-line). California Wildlife Habitat Relationships System. Accessed December 08, 2012 at http://www.sibr.com/mammals/M069.html.

Mateo, J. 2007. Ecological and hormonal correlates of antipredator behavior in adult Belding’s ground squirrels (Spermophilus beldingi). Behavioral Ecology and Sociobiology, 62 (1): 37-49.

Rickart, E. 1988. Population Structure of the Piute Ground Squirrel (Spermophilus mollis). The Southwestern Naturalist, 33 (1): 91-96.

Rickart, E. 1987. "Spermophilus townsendi. Mammalian Species No. 268" (On-line pdf). Accessed December 11, 2012 at http://www.science.smith.edu/msi/pdf/i0076-3519-268-01-0001.pdf.

Smith, G., D. Johnson. 1985. Demography of a Townsend Ground Squirrel Population in Southwestern Idaho. Journal of Ecology, 66 (1): 171-178.

Van Horne, B., R. Schooley, P. Sharpe. 1998. Influence of Habitat, Sex, Age, and Drought on the Diet of Townsend’s Ground Squirrels. Journal of Mammology, 79 (2): 521-537.

Wilber, P., H. Shapiro. 1997. An artificial life approach to host-parasite interactions. Journal of Ecological Modeling, 101 (1): 113-122.

Yensen, E., G. Hammerson. 2008. "Spermophilus townsendii (Townsend's Ground Squirrel)" (On-line). IUCN Red List of Threatened Species. Accessed December 11, 2012 at http://www.iucnredlist.org/details/20476/0.

 
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Fifield, E. 2013. "Spermophilus townsendii" (On-line), Animal Diversity Web. Accessed October 16, 2018 at http://www.biokids.umich.edu/accounts/Spermophilus_townsendii/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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