Sorex vagrans
| Vagrant Shrew
(Sorex vagrans) | |
|---|---|
| Range | |
 | |
| Taxonomic classification | |
| Order: | Eulipotyphla |
| Suborder: | Erinaceota |
| Family: | Soricidae |
| Subfamily: | Soricinae |
| Tribe: | Soricini |
| Genus: | Sorex |
| Subgenus: | Otisorex |
| Species group: | Sorex vagrans group |
| Binomial details | |
| Sorex vagrans S. F. Baird, 1857 | |
Description
Nagorsen and Panter (2009) provide the following diagnostic qualitative traits for identifying Sorex vagrans from the lower Fraser River basin of British Columbia: "The dorsal coloration is brown in the summer and grey in the winter. The tail is not strongly bicolored. There are 4 or less paired toe pads on the 3rd 4th digits of the hind foot. The third unicuspid is much shorter than the fourth unicuspid. The medial edges of the upper incisors are straight. The medial tines on the upper incisors are medium-large and positioned at or above the upper edge of pigment."
From Clothier (1955): "Sorex vagrans has at least two well defined molts each year, one in spring and one in the fall, and two pelages, the summer and the winter. The winter pelage is darker than the summer pelage, and the two can be distinguished without difficulty."
From Gillihan & Foresman (2004): "Dorsal pelage is gray to dark brown in interior populations, nearly black in some coastal populations. Ventral pelage is white to brown or gray. Tail of juveniles is distinctly bicolored, dark brown above and white below. Tail of adults is indistinctly bicolored, light to medium brown above and white below (Carraway 1990; Nagorsen 1996)."
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 |
|---|---|---|---|---|---|---|
| British Columbia (southwestern) | Nagorsen and Panter (2009) | 92–112 (n=42) | 35–46 (n=42) | 11–13 (n=44) | 2.9–5.8 (n=44) | |
| California | Jameson & Peeters (2004) | 90–120 | 34–42 | 11–12 | 6–8 | 5–7 |
| Canada | Naughton (2012) | 85–126 | 32–58 | 9–15 | 4–10 | 4–10 (avg 5–8) |
| Oregon | Woodman and Fisher (2016) | 84–120 (n=127) | 31–55 (n=127) | 10–14 (n=127) | ||
| Oregon (east of Cascade Range) | Verts & Carraway (1998) | 85–110 | 33–44 | 9–13 | 2.1–6.3 | |
| Oregon (west of Cascade Range) | Verts & Carraway (1998) | 83–112 | 31–44 | 10–13 | 3.4–7.8 | |
| rangewide | Wilson & Ruff (editors, 1999) | 100–115 | 38–48 | 3–8 |
Color variation
This section shows some of the color variation present in Sorex vagrans. The location is provided for reference only. The individual shown does not necessarily represent the only color variant within the local population.
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Washington, Skamania, subadult -
Washington, Clark County, molt is almost complete
Skull
| Sorex vagrans skull characters | |
|---|---|
| units in mm | |
| Skull | |
| Condylobasal length: | 15.5–17.5 (Gillihan & Foresman, 2004) |
| Postmandibular canal: | Absent; occasionally present on one side |
| Shape: | Braincase is rounded |
| Dental | |
| Upper unicuspids: | 5 |
| Unicuspid notes: | U3<U4 |
| Tines present: | Yes |
| Tine size: | Small |
| Tine position: | At or above the upper edge of pigment; commonly there is a white or pale-colored area between the tine and body of the tooth |
| Shape upper incisors: | Diverging |
Jameson & Peeters (2004): "Inner side of lower jaw without postmandibular canal; inner (median) surface of unicuspid teeth with pigmented ridge; third upper unicuspid smaller than fourth; first and second unicuspids equal or nearly equal; upper incisor with median tine or lobe; pigment on anterior surface of upper incisors not extending dorsally to median tine or lobe."
Carraway (1989): "The body of the first upper incisors is straight and only slightly divergent (Carraway, 1987). Cranially, Sorex vagrans can be distinguished from all other taxa considered herein by the presence on the anteriomedial edge of the first upper incisors of a small tine with pigment that does not occur above the dorsal level of the tine; commonly there is a white or pale-colored area between the tine and the body of the tooth. The foramen on the zygomatic plate in 95.6 percent of individuals examined is either immediately posterior to, or directly in line with, the metacone of M1."
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Lateral view of the skull of Sorex vagrans. Long scale bar represents 1 cm; short scale bar represents 1 mm. -
Unicuspids of Sorex vagrans, scale is 1 mm. -
Upper incisors of Sorex vagrans, scale is 1 mm.
Similar species
From Gillihan & Foresman (2004): "Sorex vagrans is separated from other North American Sorex species by the combination of condylobasal length usually 15.5-17.5 mm and the 3rd unicuspid noticeably smaller than the 4th, apparent in lateral view. The latter characteristic is shared with S. longirostris, S. monticolus [and S. obscurus], and S. trowbridgii. The presence of a post-mandibular canal on each side of the lower mandible will distinguish S. trowbridgii and S. rohweri from S. vagrans. The ranges of S. longirostris and S. vagrans do not overlap.
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Arrow points to the location of the post-mandibular canal. Modified from Junge and Hoffman (1981).
Comparison with Sorex monticolus and Sorex obscurus
The following descriptions below for Sorex monticolus hold true for Sorex obscurus as well. A phylogentic analysis by Demboski & Cook (2001), split Sorex monticolus with the "northern continental clade" belonging to the Northern Montane Shrew (Sorex obscurus) and the "southern continental clade" belonging to the Southern Montane Shrew (Sorex monticolus). Further studies will be needed to fully understand the new species boundaries for S. monticolus and S. obscurus.
From Smith & Belk (1996): "Sorex monticolus differs from S. vagrans in structure and pigmentation of the upper incisor teeth, cranial dimensions, and by the number of digital callosities on the feet. In S. monticolus, the medial tines of the upper incisors typically are large and situated well below the upper limit of the red pigment of the incisors. In S. vagrans, typically the tines are small, and located above the upper limit of the pigment (Hennings and Hoffmann, 1977; Junge and Hoffmann, 1981)."
From Gillihan & Foresman (2004): "Compared to S. monticolus, S. vagrans is generally smaller, with a shorter tail and smaller skull and teeth (van Zyll de Jong 1983). Pigmentation on 11 of S. vagrans extends no further than to dorsal limit of medial accessory cuspules, whereas pigmentation of S. monticolus extends above cuspules (Junge and Hoffmann 1981). Digits 2 through 4 on hind feet of S. vagrans possess 4 or less paired friction pads, whereas those of S. monticolus possess 5 or more pairs (van Zyll de Jong 1982), although this character may not be usable on dried specimens."
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Sorex vagrans -
Southern Montane Shrew (Sorex monticolus) -
Northern Montane Shrew (Sorex obscurus) -
Upper unicuspids of Sorex vagrans -
Upper unicuspids of the Southern Montane Shrew (Sorex monticolus) -
Upper unicuspids of the Northern Montane Shrew (Sorex obscurus) -
Upper incisors (I1s) of Sorex vagrans -
Upper incisors (I1s) of the Southern Montane Shrew (Sorex monticolus) -
Upper incisors (I1s) of the Northern Montane Shrew (Sorex obscurus)
References
Baird SF. 1857. Mammals. In Reports of Explorations and Surveys to Ascertain the Most Practicable and Economical Route for a Railroad from the Mississippi River to the Pacific Ocean. Part 1. General Report upon the Zoology of the Several Pacific Railroad Routes, Volume 8, bk. 1. Washington, D.C.
Carraway LN. 1987. Analysis of characters for distinguishing Sorex trowbridgii from sympatric S. vagrans. Murrelet 68:29-30.
Carraway LN. 1989. A morphologic and morphometric analysis of the "Sorex vagrans species complex" in the Pacific Coast region. Dissertation. Oregon State University.
Clothier RR. 1955. Contribution to the life history of Sorex vagrans in Montana. Journal of Mammalogy 36(2): 214-221.
Gillihan SW, Foresman KR. 2004. Sorex vagrans. Mammalian species 744(1): 1–5.
Hennings D. 1970. Systematics of the Sorex vagrans-obscurus complex revisited. Graduate Student Theses, Dissertations, & Professional Papers. 6564.
Hennings D, Hoffmann RS. 1977. A review of the taxonomy of the Sorex vagrans species complex from western North America. Occasional Papers of the Museum of Natural History, The University of Kansas 68:1-3.
Jameson EW, Peeters HJ. 2004. Mammals of California (No. 66). Berkeley (CA, USA): University of California Press.
Junge JA, Hoffmann 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 94:1-48.
Nagorsen DW, Panter N. 2009. Identification and status of the Olympic shrew (Sorex rohweri) in British Columbia. Northwestern Naturalist 90(2): 117-129.
Naughton D. 2012. The natural history of Canadian mammals. Toronto (ON, CA): University of Toronto Press.
Smith ME, Belk MC. 1996. Sorex monticolus. Mammalian Species (528): 1-5.
van Zyll de Jong CG. 1982. An additional morphological character useful in distinguishing two similar shrews Sorex monticolus and Sorex vagrans. The Canadian Field-Naturalist, 96:349-350.
van Zyll de Jong CG. 1983. Handbook of Canadian mammals-marsupials and insectivores. National Museums of Canada, Ottawa, 1:1- 210.
Verts BJ, Carraway LN. 1998. Land mammals of Oregon. Berkeley (CA, USA): University of California Press.
Wilson DE, Ruff S, editors. 1999. The Smithsonian Book of North American Mammals. Washington D.C. (USA): Smithsonian Institution Scholarly Press.
Woodman N, Fisher RD. 2016. Identification and distribution of the Olympic Shrew (Eulipotyphla: Soricidae), Sorex rohweri Rausch et al., 2007 in Oregon and Washington, based on USNM specimens. Proceedings of the Biological Society of Washington, 129(1), pp.84-102.