Sorex fumeus
| Smoky Shrew
(Sorex fumeus) | |
|---|---|
| Range | |
 | |
| Taxonomic classification | |
| Order: | Eulipotyphla |
| Suborder: | Erinaceota |
| Family: | Soricidae |
| Subfamily: | Soricinae |
| Tribe: | Soricini |
| Genus: | Sorex |
| Subgenus: | Otisorex |
| Species group: | Sorex oreopolus group |
| Binomial details | |
| Sorex fumeus G. S. Miller, 1895 | |
| Other resources | |
| Full taxonomic details at MDD | |
Identification
From Owen (1984): "In winter, the pelage is nearly concolor in general aspect; color of the dorsum may vary from slaty to deep gray or almost blackish; the venter may be a little paler and somewhat silvery. The summer pelage is dull brown dorsally and slightly paler ventrally. The tail is bicolored throughout the year; its upperparts are fuscus, below it is paler and washed with light yellow."
From Naughton (2012): "Pelage of this shrew varies seasonally and is brownish in summer and dark grey to almost black in winter. The underside is often slightly lighter than are the upper parts, being brownish yellow in summer and grey to silver grey in winter. The feet are similar in coloration to the underside. The tail is bicoloured, dark above and yellowish buff below. Both sexes possess side glands, but these are only evident on immature males and on adults of both sexes. The side glands become enlarged during the breeding season, and those of adult males produce an odoriferous secretion. The tail of both sexes may swell when they are in reproductive condition, sometimes to the extent that a noticeable constriction forms at the base of the tail."
From Best & Hunt (2020): "This is a relatively large shrew. Color of the back may be slate gray to blackish to dark brown, depending upon the season. Underside of the body is paler than the back. The tail is bicolored and is dark on top and pale on the underside."
External measurements
Length measurements are in millimeters (mm) and weight measurements are in grams (g), unless stated otherwise. If available, the sample size (n=) is provided. If a range is not provided and n= is not given, then the listed measurement represents an average.
| Part of range | Reference | Total length | Tail length | Hindfoot length | Ear length | Mass |
|---|---|---|---|---|---|---|
| Canada | Naughton (2012) | 104–125 | 42–54 | 12–15 | 5.8–8.0 | |
| Carolinas, Virginia, Maryland | Webster et al. (1985) | 104–120 | 40–51 | |||
| Great Lakes Region | Kurta (2017) | 110–126 | 42–52 | 12–15 | 6–11 | |
| New York (Ithaca) | Whitaker Jr. & Hamilton Jr. (1998) | 110–125 (n=50) | 37–47 (n=50) | 12.3–14 (n=50) | 6.1–11 (n=50) | |
| not reported | Best & Dusi (2014) | 111 (101–122) | 44 (41–48) | 13 (12–14) | males: 8.9 (n=29); females: 7.4 (n=24) | |
| rangewide | Wilson & Ruff (editors, 1999) | 110–127 | 37–49 | 6–11 | ||
| Virginia | Linzey (1998) | 100–125 | 37–50 | 5.5–9.2 |
Color variation
This section shows some of the color variation present in Sorex fumeus. The location is provided for reference only. The individual shown does not necessarily represent the only color variant within the local population. From van Zyll de Jong (1983): "S. fumeus is a rather uniform species showing little marked geographic variation."
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New Hampshire, Carroll County (month: June) -
New Hampshire, Carroll County (month: August) -
New Hampshire, Carroll County (month: August) -
Tennessee, Sevier County (month: June) -
Virginia, Giles County (month: September) -
Virginia, Giles County (month: September) -
Virginia, Warren County (month: May) -
Virginia, Warren County (month: April) -
Virginia, Warren County (month: September)
Skull
| Sorex fumeus skull characters | |
|---|---|
| units in mm | |
| Skull | |
| Condylobasal length: | 17.4–18.5 (Owen, 1984) |
| Postmandibular canal: | Absent; occasionally present on one side |
| Shape: | Braincase flattened, sometimes extremely; posterior border of the infraorbital foramen ahead of the space between the M1 and M2; mental foramen approximately level with the protoconid of m1 |
| Dental | |
| Upper unicuspids: | 5 |
| Unicuspid notes: | U3>U4 |
| Tines present: | Yes |
| Tine size: | Small |
| Tine position: | Just below the upper limit of pigment on upper incisors |
| Shape upper incisors: | Strongly curved and diverging |
| Dental characters: | Width of unicuspids exceeds length |
From Owen (1984): "Skull large; third unicuspid larger than fourth; width of unicuspids exceeds length; medial pigmented ridge, extending from apices of unicuspids to nearly one-half distance to cingulum, often lacking; small post-mandibular foramen may be present on at least one mandible; palate broad (Hall, 1981; Junge and Hoffmann, 1981). The cranium often is flattened, sometimes extremely so (Junge and Hoffmann, 1981)."
From Naughton (2012): "There are five readily apparent upper unicuspids, and the third is larger than the fourth."
From Best & Hunt (2020): "The third unicuspid is larger than the fourth, and unicuspids are wider than long."
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Lateral view of the skull of Sorex fumeus. The lower jaw is not shown. Long scale bar represents 1 cm; short scale bar represents 1 mm. -
Unicuspids of Sorex fumeus, scale is 1 mm. -
Upper incisors of Sorex fumeus, scale is 1 mm.
Subspecies
From van Zyll de Jong (1983): "S. fumeus is a rather uniform species showing little marked geographic variation. The two indistinct subspecies recognized are said to be somewhat different in size and colour."
From Woodman (2018): " The validity of the two recognized subspecies warrants investigation as they may simply represent samples from either end of a latitudinal size cline, as seen in Sorex dispar, or some form of local variation. Sorex fumeus umbrosus was originally differentiated by its having grayer winter pelage and averaging slightly larger than S. f. fumeus. Huggins and Kennedy (1989) reported a more complex pattern of size variation, however, with larger individuals generally in the central portion of the species’ distribution (southern Pennsylvania, Maryland, West Virginia, and northern Virginia) and smaller individuals to the north and to the south."
Similar species
From Best & Hunt (2020): "The tail is shorter than that of the long-tailed shrew [Sorex dispar], and the smoky shrew is much larger than the American pygmy shrew [Sorex hoyi] or cinereus shrew [Sorex cinereus]."
Sorex fumeus 
Masked Shrew (Sorex cinereus) 
Eastern Pygmy Shrew (Sorex hoyi)
If only the skull is available, S. fumeus can be differentiated from S. cinereus by the length of the skull (>17 mm in S. fumeus and <17 in S. cinereus; van Zyll de Jong, 1983) and the shape of the upper incisors (curved in S. fumeus and straight in S. cinereus). S. fumeus can be separated from S. dispar by the location of the posterior border of the infraorbital foramen relative to the space between the first and second upper molars (space between M1 and M2; van Zyll de Jong, 1983; Naughton, 2012; Diersing, 2019). Comparison of the skulls of Sorex dispar, S. cinereus and S. fumeus below.
The anterior margin of the zygomatic plate in Sorex fumeus is located over posterior end of the first molar (M1). Based on Naughton (2012). 
In the Rock Shrew (Sorex dispar), the anterior margin of the zygomatic plate is located over the anterior end of the second molar (M2). Based on Naughton (2012) and Diersing (2019). 
The anterior margin of the zygomatic plate in the Masked Shrew (Sorex cinereus) is located over posterior end of the first molar (M1). Based on Diersing (2019).
References
Best TL, Dusi JL. 2014. Mammals of Alabama (Vol. 4). Tuscaloosa (AL, USA): University Alabama Press.
Best TL, Hunt JL. 2020. Mammals of the southeastern United States. Tuscaloosa (AL, USA): University Alabama Press.
Diersing VE. 2019. Taxonomic revision of the long-tailed shrew, Sorex dispar Batchelder, 1911, from the Appalachian Region of North America, with the description of a new subspecies. Journal of Mammalogy 100(6): 1837-1846.
Hall ER. 1981. The mammals of North America. Second edition. John Wiley & Sons, New York.
Huggins JA, Kennedy ML. 1989. Morphologic variation in the masked shrew (Sorex cinereus) and the smoky shrew (S. fumeus). American Midland Naturalist, pp.11-25.
Junge JA, Hoffman RS. 1981. An annotated key to the long-tailed shrews (Genus Sorex) of the United States and Canada with notes on middle American Sorex. Occasional Papers of the Museum of Natural History, The University of Kansas, Lawrence Kansas. Number 94; Pages 1-48.
Kurta A. 2017. Mammals of the Great Lakes region. Ann Arbor (MI, USA): University of Michigan Press.
Linzey DW. 1998. The mammals of Virginia. McDonald & Woodward Publishing.
Miller GS Jr. 1895-12-31. The long-tailed shrews of the eastern United States. North American Fauna 10:35-56.
Naughton D. 2012. The natural history of Canadian mammals. Toronto (ON, CA): University of Toronto Press.
Owen JG. 1984. Sorex fumeus. Mammalian species (215): 1-8.
van Zyll de Jong CG. 1983. Handbook of Canadian mammals-marsupials and insectivores. National Museums of Canada, Ottawa, 1:1-210.
Webster WD, Parnell JF, Biggs WC. 1985. Mammals of the Carolinas, Virginia, and Maryland. Chapel Hill (NC, USA): University of North Carolina Press.
Wilson DE, Ruff S, editors. 1999. The Smithsonian Book of North American Mammals. Washington D.C. (USA): Smithsonian Institution Scholarly Press.
Woodman N. 2018. American Recent Eulipotyphla: Nesophontids, Solenodons, Moles, and Shrews in the New World. Smithsonian Institution Scholarly Press. Book. https://doi.org/10.5479/si.1943-6696.650