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Mephitidaeskunks and stink badgers

By Matthew Wund

Diversity

The family Mephitidae, which includes the skunks and stink badgers, is comprised of four extant genera (Mephitis, Conepatus, Spilogale and Mydaus) and 13 species. While many authors have traditionally considered skunks a subfamily (Mephitinae) within Mustelidae, recent molecular evidence indicates that skunks do not lie within the mustelid group and should be recognized as a single family, Mephitidae, a systematic understanding that is accepted here. Stink badgers (Mydaus) have only recently been considered part of the skunk clade (Dragoo and Honeycutt, 1997; Flynn et al., 2005). (Dragoo and Honeycutt, 1997; Flynn, et al., 2005; Nowak, 1991; Sato, et al., 2004; Vaughan, et al., 2000; Whitaker and Hamilton, 1998)

Three of the four genera of skunks inhabit the New World, collectively ranging from Canada to central South America; the exception are stink badgers (Mydaus), which occur on islands in Indonesia and the Philippines. Skunks are distinguishable by their conspicuous patterns of black and white stripes or spots, which serve as aposematic signals to would-be predators. Skunks have extremely well-developed anal scent glands with which they produce noxious odors to deter threats. Spotted skunks (Spilogale) are the smallest members of this family, weighing between 200 g and 1 kg. Hog-nosed skunks (Conepatus) reach the largest sizes (up to 4.5 kg). Mephitids have relatively long rostra (although not so pronounced in Spilogale), broad, squat bodies, and often a thickly-furred tail. They have short limbs and robust claws that are well-suited for digging. (Nowak, 1991; Vaughan, et al., 2000; Whitaker and Hamilton, 1998)

Mephitids are mainly omnivorous. They often eat vegetation, insects and other small invertebrates, and smaller vertebrates such as snakes, birds and rodents. Mephitids are nocturnal, and inhabit a range of habitats that includes woodlands, deserts, grasslands, and rocky montane areas. They typically do not occur in dense forest. Skunks and stink badgers are adept diggers, which allows them to find food in the soil as well as to help excavate their dens. Some species can climb trees, either to seek shelter or to find food. (Kruska, 1990; Nowak, 1991)

Geographic Range

Three genera of Mephitidae occur solely in the New World. Mephitis ranges from southern Canada to Costa Rica, Conepatus ranges from the Southern United States to Argentina, and Spilogale ranges from Southern British Coumbia in the west, and Pennsylvania in the east, south to Costa Rica. Mydaus is restricted to Indonesia and the Philippines in Southeast Asia. (Kruska, 1990; Nowak, 1991; Whitaker and Hamilton, 1998)

Habitat

Members of the family Mephitidae can be found in a variety of habitats, including relatively open forests, grasslands, agricultural areas, meadows, open fields, and rocky montane areas. Stink badgers may even spend some of their time in caves. Mephitids generally do not occur in very dense forests or in wetlands. During the day, skunks and stink badgers seek shelter in burrows or under the cover of rocks or logs. They can dig the burrows themselves, or may use the dens of other species, such as marmots or badgers. At night, skunks and stink badgers come out from their dens and forage. Some skunks are agile climbers (e.g., Spilogale) and can be found in trees in search of food or to avoid predators. (Kruska, 1990; Nowak, 1991)

Physical Description

Skunks and stink badgers can be recognized by their striking color patters. They are generally black (or sometimes brown) with a prominent, contrasting pattern of white fur on their faces, backs, and/or their tails. Generally, they have either white spots, or a white stripe running from their head, down their back to their tail. Patterns vary within and among species. For example, spotted skunks, as the name implies, have many white spots on a black background. Striped skunks have white dorsal stripes of varying thickness and length that may or may not run through the tail or extend onto the head. Coloration in skunks and stink badgers serves as an aposematic signal to would-be predators. All mephitids have extremely well-developed anal scent glands with which they produce noxious odors to deter threats. The product of the scent glands is secreted through nipples near the anus, and can be projected between 1 and 6 meters towards a threatening animal. (Kruska, 1990; Nowak, 1991; Vaughan, et al., 2000; Whitaker and Hamilton, 1998)

Mephitids have a relatively long rostrum (although it is not so large in Spilogale), broad, squat bodies, and often a thickly-furred tail. They have short limbs and robust claws that are well-suited for digging. Spotted skunks (Spilogale) are the smallest members of this family, weighing between 200 g and 1 kg. Hog-nosed skunks (Conepatus) reach the largest sizes (up to 4.5 kg). (Kruska, 1990; Nowak, 1991)

  • Sexual Dimorphism
  • sexes alike

Reproduction

Generally, skunks are not territorial, and individuals of many species regularly den with conspecifics. During the mating season, males of some species may monopolize several females (e.g. Mephitis mephitis), chasing other males away when they approach. Even when males do not actively defend a group of females, male home ranges often overlap with those of females indicating that individual males may mate with several females in a season. (Nowak, 1991; Whitaker and Hamilton, 1998)

Little is known about the breeding biology of stink badgers.

Skunks are seasonal breeders; typically, the breeding season lasts two to three months, but the time of the breeding season varies among species, and within species according to geographic location. (Kruska, 1990; Nowak, 1991; Whitaker and Hamilton, 1998)

Skunks' gestation period varies among species. In Mephitis and Conepatus, gestation lasts 2 to 3 months. Spilogale gracilis undergoes delayed implantation, in which the fertilized egg does not implant into the uterine wall for a prolonged period of time. Spilogale putorius also exhibits delayed implantation, but only in the northern part of its range. Gestation times (including delayed implantation) in these species can last 250 days or more. Delayed implantation is more typical of species and or populations that live in seasonal climates. (Kruska, 1990; Thom, et al., 2004)

Skunks generally give birth to 2-10 altricial young per year in a single litter. The young are weaned after about two months and become sexually mature late in their first year of life. (Kruska, 1990)

Little is known about parental care in stink badgers. Being mammals, females must invest some care before the young are weaned.

Skunks are born in an altricial state, without fur and with their eyes closed. Although the stink glands are full at birth, young cannot use them in defense until after the first week of life, and thus rely on the mother for full protection from predators. The young are weaned after about two months and can begin foraging on their own. Young will share a den with their mothers, and perhaps other conspecifics. Den sharing is especially important during the winter in northern areas to increase survival. (Kruska, 1990; Nowak, 1991)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • post-independence association with parents

Lifespan/Longevity

First-year skunks suffer high mortality (~ 50% - 70%) as a result of predation and disease. Those that survive can live up to 7 years in the wild, although 5 to 6 years is more typical, and up to 10 years in captivity. Humans are a significant threat to skunks, either killing them deliberately to control the spread of rabies, or killing them accidentally while skunks make their way onto roads and highways. (Kruska, 1990; Nowak, 1991; Whitaker and Hamilton, 1998)

Behavior

Members of the family Mephitidae are perhaps most familiar to people because of their conspicuous antipredator behavior. All mephitids can project a sticky, foul-smelling secretion from their anal scent glands in order to deter a potential threat. Stink badgers can spray over one meter, whereas some skunks (e.g. Mephitis mephitis) can spray an attacker at distances over 6 meters. When confronted with a presumed threat, skunks first face the threat, raise their tails with hair standing on end, and might also stomp on the ground. Skunks may even stand on their forepaws in a "handstand" as they face their attacker. If sufficiently provoked, they will bend their bodies in a U-shape, aiming their hindquarters at the threat and spraying fluid. Typically, skunks aim for a predator's eyes, which are especially sensitive to the fluid. In addition to spraying attackers, some skunks (e.g., Spilogale putorius) climb trees to avoid danger. (Kruska, 1990; Nowak, 1991; Whitaker and Hamilton, 1998)

Skunks and stink badgers are nocturnal. They spend the daytime hours in burrows or hollow logs, and forage in the evenings for vegetation, insects, worms, and small vertebrates. In seasonal climates, skunks remain in their dens during the winter months. While they do not enter deep hibernation, they do subsist mainly on fat reserves. Communal dens help skunks conserve energy in the winter. (Kruska, 1990; Nowak, 1991)

Skunks are not typically aggressive towards each other, or to heterospecifics. Home ranges typically overlap, and males of some species only actively defend females during the mating season. Although skunks generally forage alone, they may den in groups of several individuals, or even with other species. In many cases, adult males den by themselves or only with females. (Kruska, 1990; Nowak, 1991)

Communication and Perception

Skunks are generally not vocal, but sometimes communicate with grunts, growls, and hisses. Olfaction is probably an important part of communication, especially during the mating season. Skunks are not territorial, so do not need to mark territories. Skunks have elaborate visual displays to ward off potential predators, which include holding the tail and body erect, standing on the forepaws, and stomping the ground. (Kruska, 1990; Nowak, 1991; Whitaker and Hamilton, 1998)

Food Habits

Members of the family Mephitidae are omnivorous, but a large proportion of their diet consists of animal material. Skunks and stink badgers eat a variety of invertebrates such as worms and insects. They also eat small vertebrates such as rodents, lizards, snakes, birds and eggs. Mephitids forage nocturnally, rooting for and digging up prey as they wander through their home range. In northern areas, skunks greatly increase their fat reserves during the fall. During the winter months these skunks spend most of their time sleeping in dens, but will emerge to forage on warmer days. (Kruska, 1990; Nowak, 1991)

Predation

Although their scent gland secretions are a potent deterrent to predators, mephitids are at risk of predation. This is especially true for young skunks. When they are out of their burrows, skunks remain relatively conspicuous and depend on their warning coloration to deter attackers. Known predators of skunks and stink badgers are larger carnivores such as coyotes, foxes, pumas, civets, American badgers, and lynx. Birds of prey, having less well-developed olfaction than mammals, are less susceptible to the skunks' odor, although being sprayed in the eyes is a risk. Avian predators may include eagles and owls. Great horned owls (Bubo virginianus) are known to prey on skunks. (Kruska, 1990; Nowak, 1991; Whitaker and Hamilton, 1998)

Ecosystem Roles

As omnivores, mephitids potentially impact a variety of plant and animal populations in their respective communities. In particular, many species consume large quantities of insects and rodents. Although skunks have many potential predators, they are not the staple in the diet of any other species. Following one encounter with a skunk, predators often learn not to pursue them. Skunks also harbor and transmit several parasites and diseases such as distemper and histoplasmosis. Rabies is a significant problem for skunks. In the midwestern United States, striped skunks have recently overtaken domestic dogs as the species most commonly afflicted with rabies. (Nowak, 1991; Whitaker and Hamilton, 1998)

Commensal/Parasitic Species

Economic Importance for Humans: Positive

Skunks and stink badgers are generally beneficial to humans because they eat a variety of insect and rodent pests. The pelts of skunks are sometimes traded, although they are currently not in high demand. The fur of Spilogale is considered to be the finest among skunks, although no skunk pelts are considered highly valuable. Occasionally, people eat stink badgers (after removing the stink glands) or use a mixture of their skin and water in an attempt to cure rheumatism or fevers. (Nowak, 1991; Whitaker and Hamilton, 1998)

Economic Importance for Humans: Negative

By far, humans are skunks' largest threat. Humans often consider skunks to be pests due to their smell and their occasional predation on domestic poultry and eggs. As significant vectors of rabies, skunks are often poisoned, shot, or otherwise killed in an effort to control the spread of this disease. (Kruska, 1990; Nowak, 1991; Whitaker and Hamilton, 1998)

Conservation Status

Skunks are generally abundant, but some populations are considered rare or possibly threatened due to demand for their fur. Big Thicket hog-nosed skunks , Conepatus mesoleucus telmalestes, known only from the Big Thicket region of Texas, are considered extinct. Conepatus chinga rex, Molina's hog-nosed skunks from northern Chile seems to have become rare as a result of hunting pressures. The Palawan stink badger is currently listed as vulnerable on the IUCN redlist, due to human induced habitat degradation and fragmentation. (IUCN 2004, 2004; Kruska, 1990; Whitaker and Hamilton, 1998)

  • IUCN Red List [Link]
    Not Evaluated

Other Comments

The common name "skunk" has its origins in Algonquin dialects. (Kruska, 1990)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Matthew Wund (author), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

aposematic

having coloration that serves a protective function for the animal, usually used to refer to animals with colors that warn predators of their toxicity. For example: animals with bright red or yellow coloration are often toxic or distasteful.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

causes disease in humans

an animal which directly causes disease in humans. For example, diseases caused by infection of filarial nematodes (elephantiasis and river blindness).

causes or carries domestic animal disease

either directly causes, or indirectly transmits, a disease to a domestic animal

chemical

uses smells or other chemicals to communicate

delayed implantation

in mammals, a condition in which a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months.

drug

a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

fertilization

union of egg and spermatozoan

food

A substance that provides both nutrients and energy to a living thing.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

fossorial

Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

internal fertilization

fertilization takes place within the female's body

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

polygynous

having more than one female as a mate at one time

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Amstislavsky, S., Y. Ternovskaya. 2000. Reproduction in Mustelids. Animal Reproduction Science, 60-61: 571-581.

Dragoo, J., R. Honeycutt. 1997. Systematics of mustelid-like carnivores. Journal of Mammalogy, 78/2: 426-443.

Flynn, J., J. Finarelli, S. Zehr, J. Hsu, M. Nedbal. 2005. Molecular phylogeny of the Carnivora (Mammalia): assessing the impact of increased sampling on resolving enigmatic relationships. Systematic Biology, 54/2: 317-337.

IUCN 2004, 2004. "2004 IUCN Redlist of Threatened Species" (On-line). Accessed July 26, 2005 at http://www.iucnredlist.org/.

Koepfli, K., R. Wayne. 2003. Type I Sts markers are more informative than cytochrome b in phylogenetic reconstruction of the Mustelidae (Mammalia: Carnivora). Systematic Biology, 52/5: 571-593.

Kruska, D. 1990. Mustelidae. Pp. 388-449 in B Grzimek, ed. Grzimek's Encyclopedia of Mammals, Vol. 3, 1 Edition. New York: McGraw-Hill.

Marmi, J., J. Lopez-Giraldez, X. Domingo-Roura. 2004. Phylogeny, evolutionary history and taxonomy of the Mustelidae based on sequences of the cytochrome b gene and a complex repetitive flanking region. Zoologica Scripta, 33/6: 481-499.

Nowak, R. 1991. Carnivora: family Mustelidae. Pp. 1104-1143 in Walker's Mammals of the World, Vol. 2, 5th Edition. Baltimore: Johns Hopkins University Press.

Sato, J., T. Hosada, M. Wolsan, H. Suzuki. 2004. Molecular phylogeny of arctoids (Mammalia: Carnivora) with emphasis on phylogenetic and taxonomic positions of the ferret-badgers and skunks. Zoologial Science, 21: 111-118.

Thom, M., D. Johnson, D. Macdonald. 2004. The Evolution andThe evolution and maintenance of delayed implantation in the Mustelidae (Mammalia: Carnivora). Evolution, 58/1: 175-183.

Vaughan, T., J. Ryan, N. Czaplewski. 2000. Mammalogy, 4th Edition. Toronto: Brooks Cole.

Whitaker, J., W. Hamilton. 1998. Mammals of the Eastern United States. Ithaca: Comstock Publishing.

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