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Tundra shrews, Sorex tundrensis, were once considered to be a subspecies of S. arcticus (MacDonald 2003). More recent literature, however, has treated S. tundrensis as a distinct Nearctic species. When specimens of S. arcticus from Edmonton, Alberta were compared with specimens of S. tundrensis from the Northwest Territories they were found to differ substantially in all external measurements except for except for hind foot length and nearly all cranial measurements. In addition to differences in size, the two species also differ in the morphology of their auditory ossicles (Youngman 1975). Moreover, George (1988) found that S. tundrensis was a genetically distinct species from S. arcticus based on a molecular study of 26 allozyme loci. Sorex tundrensis is a Beringian species, unlike S. arcticus, suggesting that the ancestor of tundra shrews entered North America from Asia when Alaska and Siberia were still connected at the Bering Strait (van Zyll de Jong 1983).

Sorex tundrensis is a member of the Sorex araneus group, which has trivalent sex chromosomes (X, Y1, and Y2) in males (Lukacova, et al. 1996). Other species belonging to this group are European common shrews (Sorex araneus) and Arctic shrews (Sorex arcticus) (van Zyll de Jong 1983). Interestingly, Palearctic populations of S. tundrensis have a karyotype that is considered most primitive in Sorex araneus group (Lukacova et al. 1996). For this reason, Volobouev (1989) has suggested that tundra shrews are the oldest lineage of extant species in the araneus group.

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Yuke, C. 2007. "Sorex tundrensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sorex_tundrensis.html
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Cherish Yuke, University of Alaska Fairbanks
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Link Olson, University of Alaska Fairbanks
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Tanya Dewey, Animal Diversity Web
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Behavior

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Little is known about the communication in S. tundrensis. However, other Sorex species use well-developed olfactory, tactile, and auditory senses. Shrews use their long snouts, covered with vibrissae, for locating prey. The tip of the snout is a highly sensitive glandular pad or rhinarium. Olfaction is also used socially in shrews. There are many scent glands that are scattered in the skin that cover most of the body. These scent glands are probably used in communicating sexual state and marking territories.

Shrew species communicate with different types of calls as well, for example, chirps are sometimes used in courtship.

Communication Channels: tactile ; acoustic ; chemical

Other Communication Modes: scent marks

Perception Channels: visual ; tactile ; acoustic ; chemical

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Yuke, C. 2007. "Sorex tundrensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sorex_tundrensis.html
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Cherish Yuke, University of Alaska Fairbanks
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Link Olson, University of Alaska Fairbanks
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Tanya Dewey, Animal Diversity Web
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Conservation Status

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Sorex tundrensis is of least concern on the IUCN list. It is not listed on CITES appendices or the United States Endangered Species Act.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

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Yuke, C. 2007. "Sorex tundrensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sorex_tundrensis.html
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Cherish Yuke, University of Alaska Fairbanks
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Link Olson, University of Alaska Fairbanks
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Tanya Dewey, Animal Diversity Web
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Benefits

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There are no known adverse affects of S. tundrensis on humans. Other shrews have been known to prey on Douglas fir seeds, which could have an effect on the regeneration of Douglas firs.

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Yuke, C. 2007. "Sorex tundrensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sorex_tundrensis.html
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Cherish Yuke, University of Alaska Fairbanks
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Link Olson, University of Alaska Fairbanks
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Tanya Dewey, Animal Diversity Web
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Benefits

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Shrews are voracious predators of insect larvae and play an important part in regulating pest species.

Positive Impacts: controls pest population

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Yuke, C. 2007. "Sorex tundrensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sorex_tundrensis.html
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Cherish Yuke, University of Alaska Fairbanks
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Link Olson, University of Alaska Fairbanks
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Tanya Dewey, Animal Diversity Web
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Associations

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Little is known about the ecosystem roles of S. tundrensis. Other shrews in the genus Sorex are very important in regulating invertebrate prey populations.

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Yuke, C. 2007. "Sorex tundrensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sorex_tundrensis.html
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Cherish Yuke, University of Alaska Fairbanks
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Link Olson, University of Alaska Fairbanks
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Tanya Dewey, Animal Diversity Web
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Trophic Strategy

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Little is known about the food habits of S. tundrensis. In Alaska they were found to eat insects, larvae, earthworms, and floral parts of small grasses (van Zyll de Jong 1983). Tundra shrews, like other shrews, must forage almost continually to fuel their high metabolic rates.

Animal Foods: insects; terrestrial worms

Plant Foods: flowers

Primary Diet: carnivore (Insectivore , Vermivore)

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Yuke, C. 2007. "Sorex tundrensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sorex_tundrensis.html
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Cherish Yuke, University of Alaska Fairbanks
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Link Olson, University of Alaska Fairbanks
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Tanya Dewey, Animal Diversity Web
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Distribution

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Sorex tundrensis is a Nearctic species. It ranges through most of Alaska, including Kodiak Island and across the Bering Strait into northeastern Siberia, where it is proposed that the closest relatives of S. tundrensis are found (van Zyll de Jong 1983). In Canada, its range includes northern Yukon Territory, the Mackenzie Delta region of the Northwest Territories, and the extreme northwestern part of British Columbia (van Zyll de Jong 1983). Sorex tundrensis has a limited distribution in British Columbia, being confined to the Haines Triangle region (Nagorsen 1996).

Biogeographic Regions: nearctic (Native )

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Yuke, C. 2007. "Sorex tundrensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sorex_tundrensis.html
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Cherish Yuke, University of Alaska Fairbanks
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Link Olson, University of Alaska Fairbanks
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Tanya Dewey, Animal Diversity Web
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Habitat

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Sorex tundrensis inhabits a variety of alpine and arctic habitats as well as forests, shrublands, and meadows. Habitats include a variety of dwarf trees and shrubs, including Betula, Salix, and Ledum species (van Zyll de Jong 1983). They are found in mossy bog habitats but seem to prefer habitats that are more dry than do sympatric species of shrews, such as barren ground shrews, Sorex ugyanak (MacDonald 2003).

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: tundra ; taiga

Wetlands: bog

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Yuke, C. 2007. "Sorex tundrensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sorex_tundrensis.html
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Cherish Yuke, University of Alaska Fairbanks
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Link Olson, University of Alaska Fairbanks
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Tanya Dewey, Animal Diversity Web
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Life Expectancy

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Longevity ranges from 12 to 18 months and maturity is probably the spring following birth (Forsyth 1999). Nothing is known about the longevity of S. tundrensis in captivity. However, in other soricids, life expectancy varies from season to season, and susceptibility to death is believed to be highest during the juvenile stage and the breeding period (Churchfield 1990).

Typical lifespan
Status: wild:
12 to 18 months.

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Yuke, C. 2007. "Sorex tundrensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sorex_tundrensis.html
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Cherish Yuke, University of Alaska Fairbanks
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Link Olson, University of Alaska Fairbanks
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Tanya Dewey, Animal Diversity Web
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Morphology

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Tundra shrews are medium-sized, stocky shrews. In Canada mass ranges from 4.9 to 10.0 g (average 6.8 g). Head and body length is between 84 and 115 mm (average 97 mm) and tail length ranges from 25 to 37 mm (average 31 mm). In Alaska, the mass ranges from 3.8 to 10.0 g (average 6.6 g). Head and body length is between 83 to 120 mm (average 95 mm) and tail length ranges from 20 to 36 mm (average 29 mm).

Sorex tundrensis has a distinct pelage that varies seasonally and with age. In summer adults have a tricolor pelage, with a dark brown back, pale brown sides, and a pale gray belly (Keys and Wilson 2002). The difference between back and belly pelage is less distinct in juveniles and subadults. In winter pelage is bicolored, consisting of a brown back and grayish sides and belly. Pelage is also longer in winter than in summer (van Zyll de Jong 1983). The tail is bicolored, with the top notably more brownish than the bottom and darker towards the tip. The winter molt begins in April and May and continues into June. In August and September, the winter fur begins to grow and the fall molt is completed in November (van Zyll de Jong 1999).

Sorex tundrensis and its close relative, S. arcticus, are similarly patterned, but the latter has a longer tail with a much darker back. Sorex tundrensis is larger than S. ugyunak, as well as having a shorter tail.

The dental formula is 3/1, 1/1, 3/1, 3/3 = 32 teeth.

Range mass: 3.8 to 10 g.

Range length: 83 to 120 mm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: sexes alike

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Yuke, C. 2007. "Sorex tundrensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sorex_tundrensis.html
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Cherish Yuke, University of Alaska Fairbanks
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Link Olson, University of Alaska Fairbanks
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Tanya Dewey, Animal Diversity Web
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Associations

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Tundra shrews are preyed on by owls, hawks, snakes, and small mammalian carnivores, such as weasels. It is suggested that their foul odor deters some predators, such as domestic cats.

Known Predators:

  • owls (Strigiformes)
  • hawks (Accipitridae)
  • snakes (Serpentes)
  • weasels (Mustela)
  • domestic cats (Felis silvestris)

Anti-predator Adaptations: cryptic

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Yuke, C. 2007. "Sorex tundrensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sorex_tundrensis.html
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Cherish Yuke, University of Alaska Fairbanks
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Link Olson, University of Alaska Fairbanks
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Tanya Dewey, Animal Diversity Web
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Reproduction

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Males become sexually active in the summer, but reproductive activity decreases as autumn approaches (van Zyll de Jong 1983). Churchfield (1990) found that the flank glands in soricids are prominent in adult males and may act in attracting females for breeding. There is little specific information on reproduction in S. tundrensis.

There is not a lot of information on the breeding biology of this species. However, pregnant females have been recorded in June, July, and September. Numbers of embryos range from 8 to 12, with an average of 10 (van Zyll de Jong 1983). Females probably produce several litters in a season and are capable of breeding in their first summer (Nagorsen 1996). Gestation is poorly understood, but has been suggested to range from 13 to 28 days, with number of offspring ranging from 8 to 12 (Forsyth 1999). Tundra shrews breed in the spring following their birth.

Breeding interval: Tundra shrews breed several times during the breeding season.

Breeding season: Tundra shrews breed during the warm season each year.

Range number of offspring: 8 to 12.

Range gestation period: 13 to 28 days.

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

Females nurse and protect their young in a nest until they become independent.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)

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Yuke, C. 2007. "Sorex tundrensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sorex_tundrensis.html
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Cherish Yuke, University of Alaska Fairbanks
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Link Olson, University of Alaska Fairbanks
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Tanya Dewey, Animal Diversity Web
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Tundra shrew

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The tundra shrew (Sorex tundrensis) is a small shrew found in Alaska, the northern Yukon Territory, the MacKenzie Delta region of the Northwest Territories, extreme northwestern British Columbia[3] and eastern Russia. At one time, this animal was considered to be a subspecies of the Arctic shrew (Sorex arcticus).

It is dark brown on its back with pale brown sides and grey underparts. Its tail is brown on top and lighter brown below. Its fur grows longer for winter. Its body is about 12 centimetres (4.7 in) in length including a 4 centimetres (1.6 in) long tail. It weighs about 11 grams (0.39 oz).

This animal is found on hillsides with shrubs or grassy vegetation or dry ridges near marshes or bogs. It eats insects, worms and grasses. Predators include hawks and owls. This animal is active day and night year-round, burrowing through the snow in winter. It mates during the spring. 4 to 8 young are born in a nest under a log or in a crevice.

References

  1. ^ Hutterer, R. (2005). Wilson, D.E.; Reeder, D.M. (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. p. 298. ISBN 978-0-8018-8221-0. OCLC 62265494.
  2. ^ Tsytsulina, K.; Formozov, N.; Sheftel, B.; Stubbe, M.; Samiya, R.; Ariunbold, J. & Buuveibaatar, V. (2008). "Sorex tundrensis". IUCN Red List of Threatened Species. 2008. Retrieved 9 February 2010.old-form url
  3. ^ Nagorsen, D. 1996. Opossums, shrews and moles of British Columbia. Royal British Columbia Museum Handbook. ISBN 0-7748-0563-3.
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Tundra shrew: Brief Summary

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The tundra shrew (Sorex tundrensis) is a small shrew found in Alaska, the northern Yukon Territory, the MacKenzie Delta region of the Northwest Territories, extreme northwestern British Columbia and eastern Russia. At one time, this animal was considered to be a subspecies of the Arctic shrew (Sorex arcticus).

It is dark brown on its back with pale brown sides and grey underparts. Its tail is brown on top and lighter brown below. Its fur grows longer for winter. Its body is about 12 centimetres (4.7 in) in length including a 4 centimetres (1.6 in) long tail. It weighs about 11 grams (0.39 oz).

This animal is found on hillsides with shrubs or grassy vegetation or dry ridges near marshes or bogs. It eats insects, worms and grasses. Predators include hawks and owls. This animal is active day and night year-round, burrowing through the snow in winter. It mates during the spring. 4 to 8 young are born in a nest under a log or in a crevice.

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