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Overview
Brief Summary
Description
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Mammal Species of the World
Click here for The American Society of Mammalogists species account
- Original description: Coues, E., 1877. Precursory notes on American insectivorous mammals, with descriptions of new species, p. 651. Bulletin of the U.S. Geological and Geographical Survey of the Territories, 3:631-653.
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Distribution
Range Description
It ranges up to 2,600 m asl in Arizona, and 2,317 in Zacatecas in Mexico.
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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.
Biogeographic Regions: nearctic (Native )
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National Distribution
United States
Origin: Native
Regularity: Regularly occurring
Currently: Present
Confidence: Confident
Type of Residency: Year-round
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Global Range: Southwestern U.S. and northern Mexico. From Baja California and central mainland of Mexico north to southern Colorado, and from central Texas and western Arkansas to southern California.
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Physical Description
Morphology
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.
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Size
Size in North America
Average: 87.6 mm
Range: 77-98 mm
Weight:
Average: 4.3 g
Range: 2.9-6.3 g
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Diagnostic Description
See Carraway (1995) for a key to western North American soricids based primarily on dentaries.
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Type Information
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Mammals
Sex/Stage: Unknown;
Preparation: Skull; Remainder in Fluid
Collector(s): S. Crawford
Locality: El Paso, 2 Mi Above, Near Old Fort Bliss, El Paso County, Texas, United States, North America
- Type: Coues, E. 1877 May 15. Bull. U.S. Geol. And Geogr. Surv. Terr. 3: 646.
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Ecology
Habitat
Habitat and Ecology
The diet in the wild has not been studied in detail. Foods accepted by captives have includes mealworms, cutworms, cock-roaches, crickets, earwigs, sowbugs, months, beetles, centipedes, and carrion of mammals, birds, and lizards. Its reproductive cycle is unknown; some pregnant females have been recorded from April to November. The gestation period is unknown; a typical litter is 3 to 5 young (Wilson and Ruff, 1999).
In California and Baja California it can be found in chaparral (John Matson pers. comm.).
Systems
- Terrestrial
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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.
Terrestrial Biomes: desert or dune ; chaparral
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Comments: Found in arid areas having adequate cover for resting and nesting; deserts, semiarid grassland with scattered cactus and yucca, chaparral slopes, alluvial fans, sagebrush, gullies, juniper woodland, riparian associations, village dumps. In Oklahoma, many were collected from stick houses of Neotoma micropus (Caire et al. 1989). Ranges up to meadows in ponderosa pine forest (2438-2618) in southeastern Arizona (Davis and Sidner 1989).
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Migration
Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
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Trophic Strategy
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.
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Comments: Feeds primarily on insects, spiders, and centipedes, which also serve as a source of water (Ingles 1965). May paralyze and store insects for later use (Hoffmeister 1986).
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General Ecology
Frequently preyed upon by owls (great horned, barn, long-eared, burrowing, etc.).
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Life History and Behavior
Cyclicity
Comments: Active throughout the year, at any hour (Armstrong 1982). Periodically becomes torpid (Hoffmeister 1986).
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Reproduction
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.
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Reproduction appears to occur throughout the warmer months; probably throughout the year in the southern part of the range. Length of gestation unknown, probably a little less than 3 weeks. Up to 6 young per litter; apparently at least 2 litters/year. Young altricial. (Hoffmeister 1986).
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Conservation
Conservation Status
IUCN Red List Assessment
Red List Category
Red List Criteria
Version
Year Assessed
Assessor/s
Reviewer/s
Justification
History
- 1996Lower Risk/least concern
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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.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
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National NatureServe Conservation Status
United States
Rounded National Status Rank: N5 - Secure
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NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
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Trends
Population
Population Trend
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Threats
Threats
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Management
Conservation Actions
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Relevance to Humans and Ecosystems
Benefits
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.
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Wikipedia
Crawford's Gray Shrew
Crawford's Gray Shrew, Notiosorex crawfordi, also known as the Desert Shrew, is a small shrew that can be found in the southwestern United States and northern Mexico. It is a member of the order Soricomorpha and the family Soricidae. It is was the only known member of the genus Notiosorex until 2 species N. villai distributed in Tamaulipas, Mexico, and N. evotis distributed along the northwest coast of Mexico were named.[3] A fourth distinct species, N. cockrumi, was discovered in Arizona and named in 2004.[4]
Crawford's Gray Shrew is one of the smallest desert mammals and one of the world's smallest homeotherms. When fully grown it will only grow to a size of about 1.5 to 2 inches (3.8 to 5.1 cm) long, half of which is the tail and it will only grow to a weight of about 3 to 5 grams (0.11 to 0.18 oz). It is a gray-brown with light gray under parts. The long tail is gray with it being lighter underneath. It has small, but relatively prominent ears.
A Crawford's Gray Shrew is born during the summer months to a litter size of three to six. When born, Crawford's Gray Shrew is naked, pink and is about the same size as a honeybee. It grows rapidly and reaches its adult size in about four to five weeks. As a baby, its diet consists of milk that the mother produces without the aid of water. After two to three weeks, the diet is changed into food that is brought back to the nest and then regurgitated into the juvenile's mouth. By the time fall rolls around, Crawford's Gray Shrew is out of the nest and is on its own. As an adult, the diet changes from the regurgitation of food to real food that it kills itself. Crawford's Gray Shrew will eat lizards, small mice, and scorpions. The main food source for Crawford's Gray Shrew, though, is a wide variety of arthropods. Since Crawford's Gray Shrew has a very high rate of metabolism, it will eat up to 75 percent of its body weight every day. A few rare occurrences have been known where it will eat its full body weight in a single day; this can be dangerous since it can overheat the animal. The amount of heat produced by the high rate of metabolism and the heat gained from its surrounding environment will give a high risk of overheating.
Crawford's Gray Shrew, unlike most shrews, does not have access to an abundant water supply. To conserve the little water that shrews do absorb is to find shelter that will protect them from the harsh external temperatures. Crawford's Gray Shrew does not construct its own burrow or use the ones made by other animals. Instead, it builds small nests that can be found in pack rat houses or under dead agaves.
Another way Crawford's Gray Shrew will conserve its precious water is by doing most of its activities at night. This is also an odd behavior among shrews, since most will hunt day and night since it does not take long for a shrew to starve to death. Crawford's Gray Shrew has poor vision, so it uses its highly-sensitive ears and long nose to hunt down its prey. It will also use a tactic similar to that of a bat and use echolocation with high-pitched squeaks to hunt down prey. It will then compile a large amount of food during the night so it will not have to go out during the day. To keep from losing any water from its victims, Crawford's Gray Shrew will bite off the legs and then crush the prey's head so as not to kill it but to keep it fresh and unable to move.
Since water loss is a huge problem for Crawford's Gray Shrew, it has adapted by reducing two major paths of water loss. One of these ways is through respiration. While breathing, Crawford's Gray Shrew will inhale air that will be warmed to body temperature and will absorb water vapor from the nasal walls. Exhaled air is cooled and so as the air is exiting the water vapor from the air clings to the nasal passage. This keeps in more water vapor than if the air was exhaled at body temperature. Water loss is reduced even more through respiration because Crawford's Gray Shrew takes fewer breaths than other shrews and it has the lowest resting metabolic rate of all shrew species.
The other form of reducing water loss is through the form of urine. Crawford's Gray Shrew has to expel a large amount of nitrogenous waste from its body. This is a potential for a large loss of water when urinating. Fortunately, Crawford's Gray Shrew is able to reduce the amount of water loss during this action as well. It does this by concentrating a large amount of urea in their urine. When urea is being concentrated it uses basically the same principle as conserving water while breathing. The end result of all this concentration is urine that is four times more concentrated than that of a human. Since it takes only a few drops of urine to expel all the waste from a Crawford's Gray Shrew in one day, this saves a huge amount of water.
Even with all of these adaptations to help Crawford's Gray Shrew to survive in the harsh environment of the desert, it still only lives for a relatively short time. Since it hunts at night, Crawford's Gray Shrew is susceptible to nocturnal hunters such as snakes and owls. Although it can emit a musky odor that makes it seem less appetizing to mammalian predators it still lives for only about a year or so in the wild.
References
- ^ Hutterer, Rainer (16 November 2005). Wilson, Don E., and Reeder, DeeAnn M.. ed. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press, 2 vols. (2142 pp.). pp. 281. ISBN 978-0-8018-8221-0. OCLC 62265494. http://www.bucknell.edu/msw3.
- ^ Timm, R., Matson, J., Woodman, N. & Castro-Arellano, I. (2008). "Notiosorex crawfordi". IUCN Red List of Threatened Species. Version 2009.2. International Union for Conservation of Nature. http://www.iucnredlist.org/apps/redlist/details/41456. Retrieved 08 February 2010.
- ^ Carraway, L. N., and R. M. Timm (2000). "Revision of the extant taxa of the genus Notiosorex (Mammalia: Insectivora: Soricidae)". Proceedings of the Biological Society of Washington 113: 302–318.
- ^ "New Species Of Desert Shrew Found In Southern Arizona". Science News (ScienceDaily). 2004-01-30. http://www.sciencedaily.com/releases/2004/01/040130074738.htm. Retrieved 2006-05-14.
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Names and Taxonomy
Taxonomy
Comments: Baker et al. (2003) examined DNA variation in Notiosorex and described a new species (Notiosorex cockrumi) from southern Arizona and Sonora, Mexico; they also concluded that Notiosorex in northern Baja California may represent another undescribed species. However, because DNA data are available from so few individuals from throughout the range of N. crawfordi, the ranges of the proposed new taxa cannot be fully characterized. Moreover, the two taxa exhibit no known morphological differences; the only known difference between them is genetic (Baker et al. 2003). Hutterer (in Wilson and Reeder 2005) listed N. cockrumi and N. crawfordi as distinct species.
Two Mexican forms formerly included in this species (N. evotis and N. villai) are now considered distinct species (Carraway and Timmm 2000).
Hall (1981) included Megasorex gigas in this genus, but most other authors have regarded Megasorex and Notiosorex as distinct genera (see Hutterer, in Wilson and Reeder 2005).
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