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Sorex obscurus

Merriam, 1895

a dusky shrew

G5Secure Found in 2 roadless areas NatureServe Explorer →
G5SecureGlobal Rank
LowThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.1111666
Element CodeAMABA01430
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVertebrate Animal
KingdomAnimalia
PhylumCraniata
ClassMammalia
OrderEulipotyphla
FamilySoricidae
GenusSorex
Concept Reference
Woodman, N. 2018. American Recent Eulipotyphla: Nesophontids, Solenodons, Moles, and Shrews in the New World. Smithsonian Contributions to Zoology, No. 650. 107 pp.
Taxonomic Comments
Based on Woodman (2018), phylogenetic analysis of the mitochondrial cytochrome b gene indicated that S. monticola, as conceived by Alexander (1996), is not monophyletic but comprises three genetically divergent species-level clades for which the oldest available names are (Demboski and Cook 2001; Shafer and Stewart 2007) S. monticola for their "southern continental clade," S. obscurus for the "northern continental clade," and S. pacificus for the "coastal clade." The subspecies of S. obscurus recognized by Woodman (2018) are based primarily on Alexander's (1996) review of S. monticola and include alascensis, obscurus, shumaginensis, and soperi.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2022-07-26
Change Date2022-07-26
Edition Date2022-07-26
Edition AuthorsHunting, K. (2022)
Threat ImpactLow
Range Extent>2,500,000 square km (greater than 1,000,000 square miles)
Number of OccurrencesUnknown
Rank Reasons
This species is widespread in Alaska and non-coastal western and central Canada occupying a variety of habitat types. It is likely less abundant in the northern tier U.S. states but likely not threatened. There are no documented threats to this species; however local or regional distributions may be impacted by habitat loss and fragmentation below the population effect level.
Range Extent Comments
The range extent of this species includes the taiga biome in Alaska, south through western Yukon Territory and coniferous forests east through non-coastal British Columbia, Alberta, Saskatchewan, and extreme western Manitoba (Canada) south into non-coastal Washington and northern Oregon, east through Idaho and Montana, and northern Wyoming, USA. Based on a concave hull analysis of recent location data (GBIF 2022) and descriptions of the species range (Woodman 2018), the range extent of this species is about 5,245,000 km2.
Occurrences Comments
The number of occurrences of this species is unknown.
Threat Impact Comments
There are no known population-level threats to this species.
Ecology & Habitat

Description

The size of this species is relatively small with the tail about equal to the body length. Upper parts are uniform dull sepia brown with the underparts ashy. The tail is bicolor with the upper side concolor with black upper over white under tail.

Diagnostic Characteristics

Distinguished morphologically from sympatric conspecifics primarily by ear size, cranial measurements, palate breadth, and unicuspidate teeth breadth. See Alexander (1996) and Woodman (2018) for a discussion of distinguishing genetic characteristics.

Habitat

Similar to conspecifics S. monticola and S. eximis. This species occurs in a variety of vegetative communities and habitats but generally is found in grassy or otherwise relatively mesic openings in coniferous (mainly boreal) forests (Alaska) and similar but more moist openings in forests in Canada. In the U.S. it occurs in sub-alpine and alpine forests in openings with moist soils or transition areas between more mesic and wet habitats
Terrestrial Habitats
Forest - ConiferForest EdgeWoodland - ConiferWoodland - MixedGrassland/herbaceous
Other Nations (2)
United StatesNNR
ProvinceRankNative
MontanaS5Yes
WashingtonS4Yes
OregonS4Yes
IdahoS4Yes
WyomingSNRYes
AlaskaS4Yes
CanadaN5
ProvinceRankNative
Yukon TerritoryS5Yes
ManitobaS3Yes
Northwest TerritoriesS5Yes
SaskatchewanSUYes
AlbertaS5Yes
British ColumbiaS5Yes
Threat Assessments
ThreatScopeSeverityTiming
No known threats———

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Roadless Areas (2)
Utah (2)
AreaForestAcres
Beehive PeakFishlake National Forest59,137
North PavantFishlake National Forest53,262
References (7)
  1. Alexander, L. F. 1996. A morphometric analysis of geographic variation within <i>Sorex monticolus</i> (Insectivora: Soricidae). University of Kansas Natural History Museum Miscellaneous Publication No. 88.
  2. American Society of Mammalogists (ASM). 2025. Mammal Diversity Database (Version 1.13) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.10595931. Online. Available: https://www.mammaldiversity.org/
  3. Demboski, J. R., and J. A. Cook. 2001. Phylogeography of the Dusky Shrew, <i>Sorex monticolus</i> (Insectivora, Soricidae): insight into deep and shallow history in Northwestern North America. Molecular Ecology 10:1227–1240.
  4. GBIF. 2022. GBIF.org (16 June 2022) GBIF Occurrence Download for <i>Sorex monticola obscurus</i> (includes data for the Woodman 2018 <i>S. m. obscurus</i> and <i>S. m. pacificus</i>) https://doi.org/10.15468/dl.dmjasx
  5. Merriam, C.H. 1895. Revision of the shrews of the American genera <i>Blarina </i>and <i>Notiosorex</i>. North American Fauna 10(72). https://www.biodiversitylibrary.org/page/45540214
  6. Shafer, A. B. A., and D. T. Stewart. 2007. Phylogenetic relationships among Nearctic shrews of the genus <i>Sorex </i>(Insectivora, Soricidae) inferred from combined cytochrome b and Inter-SINE fingerprint data using Bayesian analysis. Molecular Phylogenetics and Evolution 44:192–203.
  7. Woodman, N. 2018. American Recent Eulipotyphla: Nesophontids, Solenodons, Moles, and Shrews in the New World. Smithsonian Contributions to Zoology, No. 650. 107 pp.