American Water Shrew (sorex Palustris):
Physical characteristics: The American water shrew ranges from 2.5 to 3.2 inches (6.3 to 8.1 centimeters) in head and body length with a similar-sized tail, and weighs 0.3 to 0.6 ounces (8 to 18 grams). They have dark brownish gray backs and whitish bellies, a likewise two-toned tail, red-tinged front teeth, and hind feet that are larger than the forefeet. Like many other water-loving shrews, they have stiff, fringed hairs on their feet that aid in swimming.
Geographic range: United States and Canada.
Habitat: Usually found in or near water, these shrews prefer damp, forested areas with many places on land where they can hide, such as fallen logs, a thick understory, and/or rock piles. They readily take to the water, where they can make good use of their specially designed feet and swim underwater or run across the water surface like some water insects do.
Diet: Active mainly at night, they eat caterpillars, grubs, worms, and an occasional fish. Unlike many shrews that have to eat their body weight in food every day, this species can survive on just a tenth of its body weight or less in food per day. Compared to humans, however, that is still a considerable amount.
Behavior and reproduction: A variety of land animals find the American water shrew to be a tasty treat, but the shrews are quite adept at escaping into the water. Unfortunately, they must also be wary of several fish species, including trout, which also eat shrews. The shrews float well, so they must paddle with their hindfeet furiously to stay underwater. This species also makes chirping noises that may be used to find food through echolocation. Adults keep to themselves most of the time and will fight other adults that come too close. Mating occurs in the spring and summer. Pregnancies last about three weeks, and mothers retreat to tunnel nests to have their young. She may have two or three litters each year with three to ten babies at a time. Although the babies are helpless when they are born, they grow quickly and leave their mothers in about a month. The young can start their own families a few months later. Those that survive to adulthood usually only live to be about eighteen months old.
American water shrews and people: Other than a fleeting glimpse, people rarely have any contact with this shrew.
Conservation status: American water shrews are not considered threatened. ∎
FOR MORE INFORMATION
Nowak, Ronald M. Walker's Mammals of the World, 6th ed. Baltimore: Johns Hopkins University Press, 1999.
Stone, David, and the IUCN/SSC Insectivore, Tree Shrew and Elephant Shrew Specialist Group. Eurasian Insectivores and Tree Shrews-Status Survey and Conservation Action Plan. Gland, Switzerland: IUCN, 1995.
Wilson, D. E., and S. Ruff, eds. The Smithsonian Book of North American Mammals. Washington, DC: Smithsonian Institution Press, 1999.
Matsuzaki O. "The Force Driving Mating Behavior in the House Musk Shrew (Suncus murinus)." Zoological Sciences 19, no. 8 (2002): 851–69.
"American Water Shrew." BBC. http://www.bbc.co.uk/nature/wildfacts/factfiles/642.shtml (accessed July 1, 2004).
Endangered Species Program, U.S. Fish & Wildlife Service. http://endangered.fws.gov/ (accessed on July 1, 2004).
IUCN Red List of Threatened Species—Species Information. http://www.redlist.org (accessed on July 1, 2004).
"Least Shrew." All Taxa Biodiversity Inventory. http://www.dlia.org/atbi/species/animals/vertebrates/mammals/soricidae/Cryptotis_parva. html (accessed July 1, 2004).
"Savi's pygmy shrew, Etruscan shrew." America Zoo. http://www.americazoo.com/goto/index/mammals/48.htm (accessed July 1, 2004).
"Soricidae—Shrews." All Taxa Biodiversity Inventory. http://www.dlia.org/atbi/species/animals/vertebrates/mammals/soricidae/ (accessed July 1, 2004).
"Water Shrew." All Taxa Biodiversity Inventory. http://www.dlia.org/atbi/species/animals/vertebrates/mammals/soricidae/Sorex_palustris.html (accessed July 1, 2004).
- Shrews: Soricidae - American Least Shrew (cryptotis Parva): Species Accounts
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