Mephitidae

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).

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.

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.

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.

• Biogeographic Regions
• nearctic nearctic
  • native native
• oriental oriental
• neotropical neotropical
  • native native

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.

• Habitat Regions
• temperate temperate
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland
• forest forest
• scrub forest scrub forest
• mountains mountains

• Other Habitat Features
• suburban suburban
• agricultural agricultural

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.

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).

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• 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.

• Mating System
• polygynous polygynous

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.

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.

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.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • internal internal
• viviparous viviparous
• delayed implantation delayed implantation

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.

• Parental Investment
• altricial 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.

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.

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.

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.

• Key Behaviors
• terricolous
• fossorial fossorial
• nocturnal nocturnal
• motile motile
• hibernation hibernation

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.

• Communication Channels
• visual visual
• acoustic acoustic
• chemical chemical

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

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.

• Primary Diet
• omnivore omnivore

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.

• Anti-predator Adaptations
• aposematic aposematic

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.

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.

• Positive Impacts
• food food
• body parts are source of valuable material
• source of medicine or drug source of medicine or drug
• controls pest population

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.

• Negative Impacts
• injures humans
  • causes disease in humans causes disease in humans
• causes or carries domestic animal disease causes or carries domestic animal disease

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.

Other Comments

The common name "skunk" has its origins in Algonquin dialects.

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (editor), Animal Diversity Web.

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

References

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

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