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Spilogale putorius 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Carnivora Mephitidae

Scientific Name: Spilogale putorius
Species Authority: (Linnaeus, 1758)
Common Name(s):
English Eastern Spotted Skunk, Plains Spotted Skunk, Allegheny Spotted Skunk, Appalachian Spotted Skunk, Spotted Skunk
Spanish Zorillo Manchado
Synonym(s):
Viverra putorius Linnaeus, 1758
Taxonomic Notes:

Based on patterns of mitochndrial DNA variation in Mustelidae (sensu lato), Dragoo and Honeycut (1997) recommended that skunks Mephitis, Conepatus, Spilogale and the Oriental stink badgers Mydaus be separated as a distinct family, Mephitidae. Subsequent mitochondrial DNA work by Marmi et al. (2004) and multi-gene work by Eizirik et al. (2010) supported the family-level recognition of the Mephitidae.

Although Spilogale gracilis has been included in S. putorius by some authors (e.g. Van Gelder 1959, Hall 1981, Wozencraft 1993), Mead (1968) argued that S. gracilis and S. putorius have distinct reproductive strategies (the former shows delayed implantation while the later does not) and therefore should be considered distinct species. Dragoo et al. (1993) assessed allozyme and mitochondrial DNA data and found that the level of genetic divergence between these two forms of Spilogale was similar to that observed between other well-recognised species of skunks. Jones et al. (1992), Baker et al. (2003) and Wozencraft (2005) both recognised S. gracilis and S. putorius as separate species. Similarly, Owen et al. (1996) examined the karyotypes of two each of S. putorius interrupta and S. putorius tropicalis, the results of which Wozencraft (2005) stated supported the recognition of S. angustifrons (containing tropicalis) as a species distinct from S. putorius (containing interrupta).

In the residual S. putorius, three subspecies are recognized (Kinlaw 1995): the plains or prairie spotted skunk S. p. interrupta, the Allegheny or Appalachian spotted skunk S. p. putorius, and the Florida spotted skunk S. p. ambarvalis. These subspecies are found, respectively, in the central USA west of the Mississippi River, in the south-eastern USA including the southern Appalachian Mountains, and in peninsular Florida. To date, there have been no detailed intraspecies phylogenetic or phylogeographic examinations of S. putorius genetic variability.

Assessment Information [top]

Red List Category & Criteria: Vulnerable A2abc+3bc+4abc ver 3.1
Year Published: 2016
Date Assessed: 2015-10-06
Assessor(s): Gompper, M. & Jachowski, D.
Reviewer(s): Schipper, J. & Duckworth, J.W.
Contributor(s): Helgen, K. & Reid, F.
Justification:
Results of ongoing surveys show that this species is continuing to decline across its range, and is likely to continue to do so at a similar rate so long as threats continue to reduce populations of this once common small carnivore. Although the species has a relatively large geographic range, it has been extirpated from broad areas of its historical (pre-fur-trapping) range. The cessation of harvest in the later 20th century means that quantification of the subsequent decline rates is not possible, but these are assumed to have continued at a rate resembling those during the mid 20th century - observed and estimated to be at least 30% over the last three generations (13-14 years) and which are considered likely to continue for the next three generations. Further, multi-decadal trends in the number of individuals captured purposely or incidentally by fur trappers suggest the population is in broad decline across many portions of its range (Wires and Baker 1994, Landholdt and Genoways 2000, Gompper and Hackett 2005, Sasse and Gompper 2006, Nilz and Finck 2008, Leberg and Davis 2012).
Previously published Red List assessments:

Geographic Range [top]

Range Description:The Eastern Spotted Skunk Spilogale putorius is found from as far north as Minnesota, USA (and marginally into southeastern Manitoba and southwestern Ontario, Canada) to as far south as Tamaulipas, Mexico. In the eastern portion of its range it occurs in south-central Pennsylvania, USA, and south in the Appalachian Mountain chain to Florida, USA, and its western historical range extends to eastern Colorado and Wyoming, USA (Hall 1981, Kinlaw 1995). The geographic limits of its range are poorly described. Range expansion is reported to have occurred in the western USA during the late 1800s and early 1900s, and has been attributed to anthropogenic landscape change which facilitated population expansion in states such as Iowa, South Dakota, and Colorado (van Gelder 1959, Choate et al. 1974).
Countries occurrence:
Native:
Canada; Mexico; United States
Additional data:
Upper elevation limit (metres):2600
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:

This species is widely distributed and was once common and harvested for pelts in many areas. Harvest data are available for many US states, and these data reveal large geographic variation in the numbers of individuals harvested within any given year in the mid 1900s as well as massive declines in the numbers harvested over time (Gompper and Hackett 2005, Sasse and Gompper 2006). These declines are not attributable to decline in the number of trappers attempting to harvest furbearers. For instance, harvested animals declined from between 30,000 and 90,000 per year in Iowa between the 1920s and mid 1940s, to fewer than 100 per year when harvest of the species ended in the 1970s. Similar patterns are noted elsewhere; across the Great Plains, and beginning in about 1940, harvests dramatically declined, such that by the early 1950s total harvests in all states were below 10% of pre-crash harvest, and by the 1980s harvests were below 1% of those during pre-decline. In northern, southern and eastern states, the historical harvest was lower, but similar patterns of population declines are observed (Gompper and Hackett 2005, Sasse and Gompper 2006). The species is now considered very rare or even absent from several states within its historical range (e.g., Minnesota DNR, n.d.).

Few reports of population density for Spilogale putorius are available. Crabb (1948) calculated estimates in an agricultural area of Iowa of between one per 11.4 ha and one per 5.0 ha, depending on the method of calculation. The work in Iowa occurred when the species was still common in the state (it is now almost absent). Data collected in 1973–1974 on a barrier island in Canaveral National Seashore, Florida, revealed an extremely high density of 40/km² (Kinlaw et al. 1995).

Current Population Trend:Decreasing
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:The three subspecies of Eastern Spotted Skunk occur in separate physiographic regions and their habitat preferences vary accordingly, with a consistent theme being the need for dense cover.  The most well studied subspecies is Midwestern Spilogale p. interrupta, for which a radio-tracking study revealed that it selected forested areas with dense understorey (Lesmeister et al. 2009).  Survivorship analyses further revealed that a majority of moralities occurred when the subspecies entered or occupied more open forest habitats (Lesmeister et al. 2010).

Based on historical records and ongoing research, the subspecies known as the Appalachian Eastern Spotted Skunk (S. p. putorius) is primarily found in higher elevation forested habitats in the Appalachian region. Historical records of S. p. putorius extend down into the piedmont and coastal plain of Virginia and the Carolinas. However, no detections have been made in those regions for at least the past 30 years. Because of a general lack of structured monitoring, it is still unclear if S. p. putorius is rare or just cryptic within the mountains of Appalachia. However, limited evidences suggest that, similar to S. p. interrupta, it prefers forested habitats with dense understorey (Reed and Kennedy 2000) with many of the most dense and frequent sightings occurring at high elevation (Diggins et al. 2015). 

The Florida race (S. p. abarvalis) is the least studied, but most frequently encountered, subspecies.  Multiple anecdotal reports suggest that in contrast to the other subspecies, S. p. abarvalis is often encountered in and near human habitation, making dens in backyards and human structures.  Observations in more rural areas suggest a strong association with Gopher Tortoise Gopherus polyphemus burrows (Frank and Lips 1989).

All three subspecies are known to be fairly opportunistic omnivores. Although the only intensive studies of feeding habits are from decades ago and from agricultural settings (Selko 1936, Crabb 1941), it is generally reported that the species is primarily insectivorous, and when insects are unavailable, it preys on small mammals or birds (Boppel and Long 1994, Kinlaw 1995). However, no detailed diet studies have been conducted in forested habitats. The species is primarily nocturnal and produces one litter per year, typically in the late spring or early summer (Kinlaw 1995).
Systems:Terrestrial
Generation Length (years):3.4

Use and Trade [top]

Use and Trade: This species is widely distributed and was once common and harvested for pelts in many regions.

Threats [top]

Major Threat(s):

While each subspecies varies somewhat in specific suite of threats, a number of patterns have emerged that require further investigation. First, while Eastern Spotted Skunk is currently reported as infrequent, incidental captures by fur trappers and the historical overharvest could have contributed to population declines (Gompper and Hackett 2005). Second, the timing of declines in the mid 20th century coincides with the first wide-scale use of synthetic pesticides, suggesting a possible link between synthetic pesticide use and spotted skunk declines. Third, landscape change associated with modern row-crop agriculture, mesophitication of eastern forests, or other large-scale habitat alterations have negatively affected the availability of early successional forest habitat and shrub cover prefered by the species. Interestingly, this has been most recently been observed in attempts to conserve Red-cockaded Woodpecker Leuconotopicus borealis, where pine stands managed with an open understorey for conservation of the endangered woodpecker conflict with management strategies for this skunk, which requires dense understory (Lesmeister et al. 2013). Fourth, predator communities have similarly changed over the past century, potentially leading to altered competition dynamics. Fifth, a number of diseases could be linked to spotted skunk decline, including parvoviruses, distemper virus, and rabies (Gompper in revision). Overall, it is likely that simultaneously several of these threats influenced, and continue to influence, Eastern Spotted Skunk populations, and that threats could differ somewhat between subspecies. Further research is urgently needed in this area to explain the species's decline and its current distribution.

Conservation Actions [top]

Conservation Actions: Based on historical trapping records, a range-wide decline of at least >90%  is likely to have occurred since the 1950s (Gompper and Hackett 2005). The plains subspecies (S. p. interrupta) is likely to be the race most in need of conservation action, and is included in a current Federal petition for listing as 'endangered' under the U.S. Endangered Species Act. Most states throughout the range of the species now list it as either 'endangered', 'threatened', or a species of 'conservation concern'.

Overall, given the lack of knowledge regarding primary threats (see Threats) and causes of decline, research is urgently needed to guide conservation action. Fortunately, researchers from multiple states and universities currently have ongoing research projects on the species, and in 2015 the Eastern Spotted Skunk Cooperative Study Group was formed to help inform managers of research priorities and potential conservation actions.




Citation: Gompper, M. & Jachowski, D. 2016. Spilogale putorius. The IUCN Red List of Threatened Species 2016: e.T41636A45211474. . Downloaded on 25 February 2017.
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