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Notiosorex crawfordidesert shrew

By David Allen

Geographic Range

Notiosorex crawfordi ranges from southern California east through eastern Arizona and from southern Colorado to the western edges of Texas and Arkansas. The shrew also ranges into the northern deserts of Central America.

Habitat

Desert shrews are found in arid areas but are not restricted to any particular habitat. Specimens have been taken in cattail marshes, in beehives, wood rat nests, among yuccas, under piles of cornstalks, and beneath piles of refuse and brush left by people. The shrew lives in elevations as high as 6,300 ft. At lower elevations the shrew will be found in humid microclimates such as in burrows or under rocks.

Physical Description

Notiosorex crawfordi is a small shrew averaging 81 mm in length. The tail is greater than twice the lenth of the hind feet. The body has gray fur with some highlights of brown above. The underside is pale and gray. Sometimes this shrew can be pale and ashy in color. The tail is long and the ears are more noticable than on other shrews. The dental formula of the desert shrew is I 3/2, C 1/0, Pm 1/1, M 3/3. This is the only shrew in North America with 3 cheek teeth that have only one cusp on each tooth.

  • Range mass
    4.5 to 8 g
    0.16 to 0.28 oz

Reproduction

Notiosorex crawfordi can reach sexual maturity in two months of age. They are capable of having more than one litter a year if conditions are favorable. The female shrew makes a crude nest of fine grasses and other vegetation with some hair in a secluded area such as under a plant or board. The litter consists of 3 to 5 in a brood. These infants are born without hair and are blind. The young mature rapidly and may accompany the mother for a short time before venturing off on their own.

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual

Behavior

The shrew is an aggressive hunter and very active. Notiosorex crawfordi is hunted by owls and tends to remain in areas that can provide some form of cover or escape. This species attempts to avoid large organisms if possible. Unlike other shrews, the desert shew does not burrow though it will use the burrows of other animals.

Desert shrews are capable of entering a state of totpor. By doing this they are able to save energy and are capable of lowering their quantity of food needed to survive.

Communication and Perception

Food Habits

Due to a fast metabolic rate the shrew is an aggressive hunter and very active. A captive shrew eats about 75% of its body weight each day. In the desert shrews consume large quantities of invertebrates including worms, spiders, insects and possibly small mammals, lizards, or birds whenever able to catch them. For the most part this shrew feeds on insect larve and adults. Notiosorex crawfordi is common near water and is known to drink, but it is also capable of obtaining water from its prey.

Economic Importance for Humans: Positive

Shrew help control some of the invertebrates that are considered to be pests in agriculture and to people in general.

Conservation Status

Notiosorex crawfordi live in a habitat that has become a place for human recreation. Off-road vehicles, camping, along with other activities and the refuse that individuals leave behind have an impact on the shrew. The degregation of the habitat may cause these animals to become threatened. Mexico has listed this species as threatened.

Contributors

David Allen (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

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

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.

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

chemical

uses smells or other chemicals to communicate

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

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.

motile

having the capacity to move from one place to another.

native range

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

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

References

October 20, 1997. "Species: Crawford's Desert Shrew (Notiosorex crawfordi crawfordi (NM))" (On-line). Accessed December 13, 1999 at http://www.fw.vt.edu/fishex/nmex_main/species/050690.htm.

December 24, 1997. "The Mammals of Texas - Online Edition" (On-line). Accessed December 13, 1999 at http://www.nsrl.ttu.edu/tmot1/noticraw.htm.

Findley, J. S., H., Jones C.. 1975.. Mammals of New Mexico.. Albuquerque.: University of New Mexico Press..

Findley, J. 1987.. The Natural History of New Mexican Mammals.. Albuquerque.: University of New Mexico Press..

MacMahon, J. 1985.. The Audubon Society Nature Guides: Deserts.. New York.: Alfred A. Knopf..

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