Mammal Species of the World
- Original description: Merriam, C.H., 1890. Results of a biological survey of the San Francisco Mountain region and desert of the Little Colorado in Arizona. North American Fauna,, 3:1-136.
S. gracilis inhabits the western half of the United States. Some taxonomists call the western spotted skunk a subspecies of S. gracilis and others consider it a separate species.(Whitaker 1980)
Biogeographic Regions: nearctic (Native )
occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Year-round
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: Range extends from southern British Columbia, Montana, and northern Wyoming southward through most of the western United States and into Mexico and Central America (south to Costa Rica). Range barely enters the Great Plains.
The western spotted skunk looks much like the eastern spotted skunk except that the white areas are more extensive. Both are relatively small and slender. They are black with a white spot on their forehead and in front of each ear. They have a pair of dorsolateral white stripes on the anterior portion of their bodies beginning at the back of their head, a pair of lateral stripes confluent with the spots in front of the skunk's ears, and a ventrolateral pair which begins just behind the forelegs. These cut off at mid-body and the posterior portion of the skunk's body has two interrupted white bands, a white spot on each side of the rump and two more at the base of the tail. The underside of the tail is white for nearly half its length and the tip is extensively white. The ears are short and low on the sides of the head. They have five toes on each foot but the claws on the front feet are more than twice as long as those on the back feet, sharp, and recurved. Males average 423mm in length (134 of that being tail) and 565 g in weight. Females average 360 mm (129 tail) and 368 g (Davis and Schmidley 1994).
Length: 450 cm
Weight: 630 grams
Size in North America
Average: 425 mm males; 383 mm females
Range: 350-581 mm males; 320-470 mm females
Average: 700 g males; 400 g females
Range: 500-900 gm males; 200-600 gm females
Habitat and Ecology
The western spotted skunk prefers rocky bluffs and brush-bordered canyon stream beds. They make dens in rocky outcrops or hollow logs in the wild; however, they often live in close association with people, frequently nesting in rock fences or even attics (Davis and Schmidley 1994).
Comments: Brushy canyons, rocky outcrops (rimrock) on hillsides and walls of canyons. In semi-arid brushlands in U.S., in wet tropical forests in Mexico. When inactive or bearing young, occupies den in rocks, burrow, hollow log, brush pile, or under building.
Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Skunks are omnivores. They enjoy eggs (wild or domestic, especially turkey eggs), young rabbits (Davis and Schmidley 1994), fruit and berries (Skunks), mice, voles, roots, and even arthropods such as grasshoppers (Savage 1999), and scorpions (Davis and Schmidley 1994).
Comments: Insects, rodents, small birds, and possibly bird eggs constitute most of diet (Ingles 1965). Reptiles and amphibian s also taken (Leopold 1959), as are many types of fruits and berries.
Adults are essentially solitary.
Life History and Behavior
Comments: More nocturnal than is striped skunk, rarely seen abroad during daylight hours. Active throughout the year.
The testes of adult and young males begin enlarging in March, producing sperm in May, and reach their peak by September. Females come into heat around in September and breeding begins. Most are bred by October when the formation of sperm is halted and the testes begin to regress again. The blastula stage of the embryo is free floating in the uterus for the first 180-200 days before implanting. Gestation usually lasts 210-230 days and litters ranging from 2-5 young are born in late April or May (Davis and Schmidley 1994). Baby skunks are called kits (Savage 1999). Young females become sexually mature at about 4 or 5 months of age and the cycle begins again (Davis and Schmidley 1994).
Females breed during late September-October. Implantation is delayed, total gestation period lasts 210-230 days. Litter size is 4-6. Young leave nest about 1 month after birth, follow mother until almost full grown. Sexually mature in 4-5 months.
IUCN Red List Assessment
Red List Category
Red List Criteria
Recently described as a separate species from the eastern spotted skunk because of differences in color pattern, cranial features, reproductive physiology, and breeding season; the western spotted skunk is neither endangered nor threatened. It is adapting readily to the new sources of food and habitats provided by civilization (Davis and Schmidley 1994).
US Federal List: no special status
IUCN Red List of Threatened Species: least concern
National NatureServe Conservation Status
Rounded National Status Rank: N4 - Apparently Secure
Rounded National Status Rank: N5 - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Relevance to Humans and Ecosystems
Economic Importance for Humans: Negative
The skunk in general may be seen as a pest because of its affinity for making dens in human property combined with the foul smell it is capable of emitting. The fear that skunks carry rabies has shown to be no more worrisome than any other wild animal (Savage 1999). It is also known to nest in attics and steal turkey eggs from farmers (Davis and Schmidley 1994).
Economic Importance for Humans: Positive
Skunks help keep down populations of animals such as rodents and grasshoppers which can be harmful to a farmer's crops (Savage 1999). They also eat scorpions, which may be useful to people by keeping down the population of this poisonous arthropod, especially since these skunk prefers to live near developed areas (Davis and Schmidley 1994). People have also begun descenting skunks and keeping them as pets because they are quite friendly and can be kitty litter trained (Skunks).
Western spotted skunk
With a total length of 35–55 centimetres (14–22 in), the western spotted skunk is smaller than the striped skunk (Mephitis mephitis). The adult is boldly striped black and creamy white, mainly longitudinally, with a white spot on the head between the eyes, and a white patch below each ear. The ears are short and rounded. The animal has a conspicuously large, long haired black and white tail.
Distribution and habitat
Their habitat is mixed woodlands, open areas, and farmlands. They display deimatic (threat) behavior, raising their hind parts in the air and showing their conspicuous warning coloration to scare off predators. They spray by standing on their forelegs and raising their hindlegs and tail in the air.
Taxonomy and etymology
The western spotted skunk was first described by Clinton Hart Merriam in 1890; its specific name, gracilis, is derived from the Latin for "slender". Although it was thought for years to be conspecific with the eastern spotted skunk (S. putorius), the presence of delayed implantation in the western spotted skunk clearly sets it apart.
Seven subspecies are generally recognized:
- S. g. amphiala (=amphialus) Dickey, 1929 - Channel Islands spotted skunk (Channel Islands of California)
- S. g. gracilis Merriam, 1890
- S. g. latifrons Merriam, 1890
- S. g. leucoparia Merriam, 1890
- S. g. lucasana Merriam, 1890
- S. g. martirensis Elliot, 1903
- S. g. phenax Merriam, 1890
- Wozencraft, W. C. (2005). "Order Carnivora". In Wilson, D. E.; Reeder, D. M. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. pp. 623. ISBN 978-0-8018-8221-0. OCLC 62265494. http://www.bucknell.edu/msw3.
- Cuarón, A.D., Reid, F. & Helgen, K. (2008). Spilogale gracilis. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 27 January 2009.
- ITIS Report. "ITIS Standard Report: Spilogale gracilis". http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=552466. Retrieved December 8, 2007.
- Verts, Carraway & Kinlaw. (2001) Mammalian Species: Spilogale gracilis. American Society of Mammalogists, 674: 1-10.
- Smithsonian: National Museum of Natural History. "North American Mammals: Spilogale gracilis". http://www.mnh.si.edu/mna/image_info.cfm?species_id=359. Retrieved December 8, 2007.
Names and Taxonomy
Comments: This species has been included in S. putorius by some authors (e.g., Wozencraft, in Wilson and Reeder 1993). Mead (1968) argued that gracilis and possibly leucoparia, both of which were included in S. putorius by Van Gelder (1959) and Hall (1981), are reproductively isolated from eastern populations and therefore should be considered distinct species. Jones et al. (1992), Baker et al. (2003), and Wozencraft (in Wilson and Reeder 2005) recognized S. gracilis and S. putorius as separate species.
Based on patterns of mtDNA variation in Mustelidae, Dragoo and Honeycut (1997) recommended that skunks (Mephitis, Conepatus, Spilogale) and the stink badgers (Mydaus) be separated as a distinct family (Mephitidae). Wozencraft (in Wilson and Reder 2005) recognized Mephitidae.