Common names for Plestiodon obsoletus include Great Plains skinks and Sonoran skinks.
Great Plains skinks are preyed on by venomous snakes, birds of prey, and small mammals. Snakes find and trap the skinks in their burrows. Small, fossorial mammals also find skink burrows and prey on them. Most adult Great Plains skinks have scars from predators but they will aggressively defend themselves. They use hard wriggling bites that cause lacerations and defecation as a defense mechanism. When a Great Plains skink bites, it uses its powerful jaws to grab a small piece of skin. It will then thrash around until it leaves a painful laceration. Great Plains skinks are also relatively cryptically colored in their native environment.
Known Predators:
Anti-predator Adaptations: cryptic
Great Plains skinks are larger than other species of skinks with a relatively thick torso and neck. The neck is muscular and equals the body in diameter. They have long, curved claws and their toes and feet are covered in scales. Great Plains skinks do not have the traditional striped pattern of most skinks, and their scale patterns have changed to an oblique pattern rather than the normal parallel pattern. The coloring is a mottled light grey, dark brown, and black. Males also have a patch of orange on either side of their head.
Range mass: 14 to 40 g.
Range length: 100 to 140 mm.
Sexual Dimorphism: male larger; sexes colored or patterned differently; male more colorful
Great Plains skinks can live up to 8 years in the wild. The population has a sharp decrease in frequency of skinks that survive from age 1 to 2 and there are large drops in the frequency of older skinks that levels off around year 5.
Range lifespan
Status: wild: 8 (high) years.
Average lifespan
Status: wild: 3 years.
Average lifespan
Status: wild: 3 years.
Great Plains skinks are found in wide and diverse habitats including mixed woodland, prairies, forests, mountain slopes, canyons, open hillsides and deserts. In the southwest, they are confined to rugged rocky terrain. Areas that have short, thick grass or other ground vegetation, and flat rocks for shelter are optimal habitats for Great Plains skinks and they are found in dense low vegetation near rock outcroppings, or beneath trash and rocks. If rocks or other surface cover are absent they will burrow in the open or use small mammal burrows for shelter
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: savanna or grassland ; forest ; mountains
The biogeographic range of Plestiodon obsoletus (Great Plains skinks) begins in western Missouri and northwest Arkansas and extends to eastern Arizona. It reaches as far north as the southern portions of Nebraska and ends in northern Mexico. They are found in Nebraska, Colorado, Arizona, New Mexico, Texas, Oklahoma, Kansas, Missouri, and Arkansas. They are only found in the Nearctic region and specifically in the southern half of the North American Grassland Biome. Plestiodon obsoletus are most abundant in Kansas. Scattered populations are found in more northern portions of Nebraska, Iowa, and Missouri but are not connected to the main distribution. Lack of rocks coupled with a decrease of mean daily temperatures has limited distribution around these isolated populations.
Biogeographic Regions: nearctic (Native )
In the wild, Great Plains skinks consume only invertebrates. Their diet consists of insects, arachnids, arthropods, and gastropods. There have rarely been remains of other skinks in the stomachs of Great Plains skinks, but it is believed that this is mostly due to accidents. Most frequently, the remains of gryllid crickets, short-horned grasshoppers, scarabaeid beetles, lepidopteran larvae, and carabid beetles are found in their stomachs. Most prey is found in the sheltered areas near the burrow and many prey species can be found underground. They rely on their sense of smell to find prey and to avoid venomous species. Invertebrate prey generally not consumed include earthworms, centipedes, ants, and cockroaches. Their diet changes seasonally with available arthropod prey.
Animal Foods: insects; terrestrial non-insect arthropods
Primary Diet: carnivore (Insectivore , Eats non-insect arthropods)
Great Plains skinks are a food source for their predators and help control insect and other invertebrate populations in their environment. Parasitic species that use Plestiodon obsoletus as a host include four species of chigger. Compared with other species of skinks, Plestiodon obsoletus carries a larger number of chiggers. Plestiodon obsoletus is one of the principle carriers of chiggers out of all species that live Great Plains grasslands.
Commensal/Parasitic Species:
Great Plains skinks prey on insects and arachnids that could be considered pests to humans.
Positive Impacts: controls pest population
Great Plains skinks carry a large number of chiggers, which can be transmitted to humans.
After eggs are laid they take about 40 days to hatch. Hatching occurs in late summer and first hibernation begins in October of the same year. Juvenile Plestiodon obsoletus are black with a vibrant blue tail. They do not display the mottled, tri-color pattern until adulthood. Because of this trait, scientists considered juveniles a different species for many years: Eumeces guttulatus. By the time the skinks reach one full year of age, they are nearing adult size, coloring, and reproductive maturity. They can live for up to eight years.
Distribution of Great Plains skinks is large but has areas of isolated colonies. These small populations are isolated because they are surrounded by inhospitable habitats with little cover and lower daily temperatures than are necessary for survival of the species.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
Great Plains skinks use visual cues and their sense of smell to discriminate the sex of other skinks at a distance. After contact is made, communication is through touch and smell.
Communication Channels: visual ; tactile ; chemical
Other Communication Modes: pheromones
Perception Channels: visual ; tactile ; chemical
Mating pairs may be found under rocks during breeding season, but they are a polygynandrous species. Sexual activity is limited to a period of a few weeks in late spring and the mating pattern followed is similar to other species of Eumeces. The male recognizes the female due to her scent and lack of orange markings on the head. The male chases the female, nips at her tail, and catches her by her neck skin. The male loops underneath the female to begin copulating. Copulation lasts around 6 minutes.
Mating System: polygynandrous (promiscuous)
Mating occurs in late April and early May, eggs are laid in early June and hatch in about 40 days. Great Plains skinks produce large clutches of 7 to 24 eggs. Only 8% of lizard species have larger average broods than this Great Plains skinks. Large clutches compensate for the long amount of time required to incubate the eggs and because they may not reproduce every year. The mother guards the eggs for a 1 to 2 month incubation period. No more than 1 clutch per year is possible and some females do not breed every year. Older females are more productive than young ones (as in many other species of lizard). Environmental factors may also influence clutch size. If the weather is dry females will change nesting sites. If eggs are already laid, she will dig up the soil around them to increase humidity. Females are known to release water from the bladder to moisten the nest cavity if necessary. When the eggs hatch, the mother smells around the eggs to locate eggs that are not yet hatched. She passes her head over babies left to right and rouses the recently hatched skinks. She grooms babies for ten days after birth by licking their cloacal vent around 5 times for about half a second. Hatching occurs in the late half of the summer and mortality of young is high. By the time the skinks reach one full year they are nearing adult size.
Breeding interval: Breeding can occur as often as once yearly, although individuals often breed less frequently.
Breeding season: Mating occurs in late April and early May
Range number of offspring: 7 to 24.
Average number of offspring: 12.
Average gestation period: 40 days.
Average time to independence: 1 years.
Average age at sexual or reproductive maturity (female): 1 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; sexual ; oviparous
The mother spends the entire summer sheltering and guarding her eggs before they hatch. Following birth, the mother cares for the young and is extremely tolerant of them. Males give no care to young.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)
The Great Plains skink (Plestiodon obsoletus)[1] is a species of lizard endemic to North America.
The Great Plains skink, together with the broad-headed skink, is the largest skink of the genus Plestiodon. It reaches a length of 9 to 13 cm from snout to vent (SVL) or up to nearly 34 cm total length (including the tail).
This lizard is light gray or beige in color; its dorsal scales have black or dark brown edges. The scales on the sides run diagonally. The belly is yellow. Juveniles are black with white sports on the lips and the head and have a blue or bluish tail.[2]
The Great Plains skink is very common on the Great Plains, ranging from southeastern Wyoming and Nebraska (and also Fremont County, Iowa) southward to eastern Arizona, New Mexico, Texas, and into Mexico.[2]
This skink lives in open plains habitat or the eastern foothills of the Rocky Mountains, in areas near water, e.g. irrigation ditches. In southeastern Colorado, it occurs in elevation up to about 1900 m (7200 ft); in northern Colorado, only at elevations below about 1400 m (4500 ft).[2]
The mating season of the Great Plains skink is in April or May. The female lays between 5 and 32 eggs (on the average about 12) in early summer, which she guards until they hatch in late summer.[2]
The Great Plains skink (Plestiodon obsoletus) is a species of lizard endemic to North America.
