BC Conservation Data Centre: Conservation Status Report
Spilogale gracilis
Western Spotted Skunk
| Scientific Name: | Spilogale gracilis |
|---|---|
| English Name: | Western Spotted Skunk |
| Provincial Status Summary | |
| Status: | S2S3 |
| Date Status Assigned: | April 18, 2023 |
| Date Last Reviewed: | April 18, 2023 |
| Reasons: | Western Spotted Skunk extends from the US border from Ross Lake to Chilliwack, along the foothills of the Coast Mountain range north to Pemberton and west along the Sunshine Coast to at least Sechelt. There are only 14 occurrences known; however, inventory for this species is lacking. Urban development, forestry and impacts from Striped Skunk (e.g. competition) and Barred Owls (predation and prey reduction) are the most significant threats to this species. |
| Range | |
| Range Extent: | E = 5,000-20,000 square km |
| Range Extent Estimate (km2): | 10,000 |
| Range Extent Comments: | In BC, the distribution of the Western Spotted Skunk extends from the international border, in peri-urban and wilderness areas from Ross Lake to Chilliwack (under current conditions), along the foothills of the Coast Mountain range north to Pemberton and west along the Sunshine Coast to at least Sechelt. Given the paucity of recent records the exact current distribution is poorly (or inaccurately) defined but the species likely persists in the CWHdm, ds1, ms1, xm and IDFww BEC zones (typically in mature forested habitats; based on recent observations), up to elevations of at least 500m (and up to 880 m) in BC (the northern extent of the species global distribution) (J. Hobbs, pers. comm. 2023). |
| Area of Occupancy (km2): | EF = 26-500 |
| Area of Occupancy Comments: | Western Spotted Skunk is documented to occupy suitable habitat (e.g., mixed woodlands, farmlands, and (under current conditions in BC) mature (>80yrs) coniferous forests with structural heterogeneity; including areas with extensive understory or deciduous component. Based on known occurrences, there are only 14 4km2 grid cells but, given the paucity of available inventory information this likely grossly underestimates the area of occupancy (J. Hobbs, pers. comm. 2023). |
| Occurrences & Population | |
| Number of Occurrences: | C = 21 - 80 |
| Comments: | There are 14 known occurrences based on reliable data (i.e., QEP or photographic evidence). There are an additional 12 historic records shown in E-fauna, including records on the lower mainland (n=9), the Sunshine Coast (n=2), and a single record near Pemberton (Klinkenberg ND; accessed March 27, 2023). Given a 10km separation distance for suitable and unsuitable habitat (NatureServe ND; accessed April 14, 2023) and the lack of inventory information, the known number of occurrences is an underestimate. |
| Number of Occurrences with Good Viability / Ecological Integrity: | U = Unknown |
| Comments: | Two of the the 14 occurrences known are likely no longer viable (J. Hobbs pers. comm. 2023). |
| Number of Occurrences Appropriately Protected & Managed: | Rank Factor not assessed |
| Population Size: | U = Unknown |
| Comments: | There is not enough data to determine population size. |
| Threats (to population, occurrences, or area affected) | |
| Degree of Threat: | BC = High - medium |
| Comments: |
At least one threat has changed since 2014, resulting in a higher threat score than Medium-low, which was the final score in 2014. For example, category 8 threat (Invasive & other problematic species, genes & diseases) has increased from unknown to "high" in scope, severity and timing (J. Hobbs, pers. comm. 2023): The evolutionarily recent invasion of Barred Owls into forests of the Pacific Northwest likely has both direct and indirect (negative) effects upon Western Spotted Skunk. Given slow reproductive cycle of Western Spotted Skunk (1 litter (of 2-5 kits)/year) barred owls have potential to alter food-web dynamics by displacing native predators (e.g. Spotted Owl) and reducing native prey populations utilized by Western Spotted Skunk. In consideration of direct effects: in Tosa et al. (2022) barred owl depredation (of Western Spotted Skunk) accounted for 36.3% of mortalities and evidence of interaction and depredation was deemed high; in contrast, Tosa et al (2022) cited depredation of Western Spotted Skunks as very low (1 out of 22,421 pellets; Forsman and others 2004) as reported by Livezey 2007. In consideration of indirect effect Tosa et al. (2022) point out that invasive predators place relatively high stress on native species as invasive predators typically reach higher population densities in novel environments and typically have a more diverse diet relative to native predators (Livezey et al. 2007). |
| Trend (in population, range, area occupied, and/or condition of occurrences) | |
| Short-Term Trend: | U = Unknown |
| Comments: | Short-term trend has not been assessed; however, indirect and direct impacts from Barred Owls are likely causing a decline (J. Hobbs, pers. comm. 2023). |
| Long-Term Trend: | DE = Decline of 30-70% |
| Comments: | Cowan (1930) historically described the species as ?the most abundant representative of the weasel family? but observations, and suspected abundance, have since declined dramatically. This species has likely been extirpated from Vancouver (SPEC (2010), Cowan (1930), Merilees (1988), as cited in Page 2012). |
| Other Factors | |
| Intrinsic Vulnerability: | AB=Highly to moderately vulnerable. |
| Comments: | High, slow to reproduce (i.e., annual reproductive cycle, small number of offspring, and likely reduced survivorship of young in non-pristine, and even pristine, habitats as the species is likely very sensitive to non-native predators, particularly barred owl (Tosa et al. 2022). |
| Environmental Specificity: | C=Moderate. Generalist or community with some key requirements scarce. |
| Comments: | Western Spotted Skunk is a generalist but limited availability of mature and old-growth forested within the species? range support assignation of ?C? for this field. This is further supported by a (potential) predilection for talus or rock outcrops and, at upper elevation limits, for riparian habitats. |
| Other Rank Considerations: | |
| Information Gaps | |
| Research Needs: | |
| Inventory Needs: | |
| Stewardship | |
| Protection: | |
| Management: | |
| Version | |
| Author: | Hobbs, J. |
| Date: | April 18, 2023 |
| References | |
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Happe, P.J., K.F. Beirne, C.E. Cantway, et al.. 2005. Forest carnivore inventory, Olympic National Park. Olympic National Park, Port Angeles, WA. NPS/PWR-NCCN/INV-2005/001. NPS D-380. 62 pp |
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Hobbs, J. and Stefanison. S. 2014. Recent Spotted Skunk Observations in the Lower Mainland. Prepared for L. Ramsay, CDC. 13pp |
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Page, N. 2012. Mammals of Vancouver and Point Grey. Summary of Historical and Current Occurrence Records. Raincoast Applied Ecology. |
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Boulerice, J. T., and B. M. Zinke. 2017. Winter Habitat Associations for Spotted Skunks (Spilogale spp) in South-Central Wyoming. The American Midland Naturalist 178:17?28.
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Carey, A. B., and J. E. Kershner. 1996. Spilogale gracilis in Upland Forests of Western Washington and Oregon. Northwestern Naturalist 77:29?34.
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Christophersen R.G., R. C. Kuntz II, and J.F. McLaughlin 2005. A Survey of Forest Carnivore Species Composition and Distribution in North Cascades National Park Service Complex, Washington. USDI National Park Service. Sedro Woolley, WA. NPS/PWR-NCCN/INV-2005/01. NPS D-271. 48 pp.
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Doty, J. B., and R. C. Dowler. 2006. Denning ecology in sympatric populations of skunks (Spilogale gracilis and Mephitis mephitis) in west-central Texas. Journal of Mammalogy 87:131-138.
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Klinkenberg, Brian (Editor). ND. E-Fauna BC: Electronic Atlas of the Fauna of British Columbia [www.efauna.bc.ca]. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver.
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Livezey, K. B., M.F. Elderkin, P.A. Cott, et al.. 2007. Barred owls eating worms and slugs; the advantage in not being picky eaters. Northwestern Naturalist 89: 185-190.
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Mead, R. A. 1968. Reproduction in Western Forms of the Spotted Skunk (Genus Spilogale). Journal of Mammalogy 49:373?390.
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Reid, M., J. Petterson, and J. Schaberl. 2010. A survey of forest carnivores in Mount Rainier National Park, Washington: National Park Service, North Coast and Cascades Network. Natural Resource Technical Report NPS/NCCN/NRTR?2010/412. National Park Service, Fort Collins, Colorado.
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Verts, B. J., L. N. Carraway, and A. Kinlaw. 2001. Spilogale gracilis. Mammalian Species 2001:1?10.
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Please visit the website Conservation Status Ranks for information on how the CDC determines conservation status ranks. For global conservation status reports and ranks, please visit the NatureServe website http://www.natureserve.org/.
Suggested Citation:
B.C. Conservation Data Centre. 2023. Conservation Status Report: Spilogale gracilis. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 7, 2026).