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Sorex merriami

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA MAMMALIA EULIPOTYPHLA SORICIDAE

Scientific Name: Sorex merriami
Species Authority: Dobson, 1890
Common Name(s):
English Merriam's Shrew

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2008
Date Assessed: 2008-06-30
Assessor(s): NatureServe (Hammerson, G. & Cannings, S.)
Reviewer(s): Amori, G. (Small Nonvolant Mammal Red List Authority) & Chanson, J. (Global Mammal Assessment Team)
Justification:
Listed as Least Concern because it is very widespread, although uncommon, and the population does not appear to be in decline.

Geographic Range [top]

Range Description: This species occurs in the western United States (Verts and Carraway 1998) and extreme southern British Columbia, Canada (D. Nagorsen pers. comm.). It occurs in the Great Basin, Columbia Plateau, northern Great Plains and southern Rocky Mountains. It ranges between elevations of 650 to 9,500 ft asl (Armstrong and Jones 1971). George (1990) provided information on range extensions in New Mexico. Benedict et al. (1999) discussed new collections in northwestern Nebraska.
Countries:
Native:
Canada; United States (Arizona, California, Colorado, Idaho, Montana, Nebraska, Nevada, New Mexico, Oregon, South Dakota, Utah, Washington, Wyoming)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: There is no information about population densities for this species. It is thought to be nowhere abundant; at known sites, several hundred trap-nights are needed to capture one animal (Verts and Carraway 1998). It is sparse and uncommon, but its range is large (much of southwestern North America) and conservation status is secure on a global basis.
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: Habitats include various grasslands, including grasses in sagebrush scrub and pinyon-juniper woodland, as well as mountain mahogany shrublands and mixed woodlands (Clark and Stromberg 1987, Benedict et al. 1999). Merriam's shrew has been recorded also in spruce-aspen habitat in New Mexico (George 1990). It seems to prefer drier habitats than those used by other shrews. It may utilize the burrows and runways of other animals (Armstrong, in Wilson and Ruff 1999).

In Washington, pregnant females have been captured from April to July, and nursing females in March, July and October. Three litters ranged from five to seven (Johnson and Clanton 1954, cited in Verts and Carraway 1998). In Washington and Wyoming, this species was frequently found in association with Lagurus curtatus. Owls are the only known predators. Merriam's shrew feeds primarily on lepidopteran caterpillars, beetles, cave crickets, ichneumon wasps, and spiders, as well as other arthropods (Johnson and Clanton 1954, cited in Verts and Carraway 1998; Clark and Stromberg 1987). It has the highest relative bite force of all western shrews studied, indicating that it is adapted to forage on relatively large, hard-bodied prey (Verts and Carraway 1998).
Systems: Terrestrial

Threats [top]

Major Threat(s): There are no major threats to this widespread species. Grassland and shrub steppe is being lost to agriculture and other development and the species' tolerance of grazing is unknown, but this is not a major threat at present (Verts and Carraway 1998).

Conservation Actions [top]

Conservation Actions: It presumably occurs in protected areas throughout its range.

Citation: NatureServe (Hammerson, G. & Cannings, S.) 2008. Sorex merriami. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 02 August 2014.
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