Plestiodon fasciatus (Linnaeus, 1758)
Common Five-lined Skink
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Plestiodon fasciatus, Eumeces fasciatus
Basis for Listing
The common five-lined skink, also known as the blue-tailed skink, is widely distributed throughout the eastern United States and into southeastern Ontario. There are disjunct populations in Minnesota, northeastern Iowa, and southeastern Wisconsin (Harding 1997). In Minnesota, the common five-lined skink was formerly known from only five scattered locations in three counties along the Minnesota River Valley near Granite Falls, and it was classified as a state endangered species in 1984. Since then, populations have been found in two additional counties in southeastern Minnesota and in one east-central county. The species' status was subsequently downgraded to special concern in 1996. The primary threats facing the common five-lined skink are habitat destruction and degradation.
The common five-lined skink is a shiny-scaled lizard which gets its name from the 5 distinct yellowish stripes which run along its sides, back, and tail. These stripes may fade in adult males (Harding 1997). The stripe down the center of the back splits at the neck and forms a "V" on the top of the head. The background color is variable with age and sex, with the young being black and older adults being gray or light brown. The tail is bright blue in the young, blue gray in adult females, and gray in adult males. Because of this, people also call this lizard the blue-tailed skink. The face and throat of adult males is orange-red. The average total length of adults is 12.5-21.5 cm (5-8.5 in.) (Oldfield and Moriarty 1994). Common five-lined skinks may be confused with the more common northern prairie skink (Plestiodon septentrionalis septentrionalis), which has dark brown lines along its sides and 3 wide tan stripes separated by 2 narrow dark stripes along its back.
The common five-lined skink inhabits rocky bluffs, forest edges, oak savannas, and dry northern hardwood forests. In Minnesota, it is found in or near granite outcrops in the Minnesota River Valley (Lang 1982), and in exposed limestone and sandstone outcrops and bluff prairies in the eastern part of the state (Oldfield and Moriarty 1994). The areas inhabited by skinks generally have abundant cover and basking areas, including natural features such as rocks, stumps and logs, and human-made items such as sheet metal or tar paper. The presence of rocks or bedrock outcrops is a very important habitat component for this species (Lang 1982; Howes and Lougheed 2004).
Biology / Life History
The common five-lined skink is a permanent resident, which hibernates from early October to late April or early May in mammal burrows, crevices in rock formations, or rotting stumps or logs (Lang 1982; Harding 1997). In Minnesota, breeding takes place in late May. Within about a month, the female digs a small chamber under a rock or in a decaying log or stump, and lays 5-18 eggs (Lang 1982; Oldfield and Moriarty 1994). She will stay with the eggs for 24-60 days until they hatch, guarding against predators (Oldfield and Moriarty 1994; Harding 1997). She will also eat any spoiled eggs during this time. The young are precocial and will leave the nest within 1-2 days after hatching. Food consists of crickets, locusts, grasshoppers, beetles, insect larvae, caterpillars, spiders, moths, and snails (Oldfield and Moriarty 1994; Harding 1997). In Minnesota, roaches and spiders may be the most common food item (Lang 1982). The common five-lined skink is a solitary species and males will defend their territories against intruders during the breeding season. Their home territory has a diameter of 9-27.4 m (30-90 ft.)(Fitch 1954). While normally found on the ground, this lizard may climb into low shrubs to bask or forage for food (Harding 1997). A common five-lined skink will readily release its tail when attacked by a predator. The tail will continue to wiggle on the ground, distracting the predator while the skink makes its escape. The tail will re-grow, but the new tail is generally not as long or colorful as the original.
Conservation / Management
The common five-lined skink is harmless to humans (Harding 1997). The primary threats to its survival are habitat destruction and degradation. Threats from the pet trade are minimal (Lang 1982). Since the common five-lined skink exists in small, somewhat isolated populations in Minnesota, even small-scale habitat disruption could lead to local elimination of the species (Harding 1997). Hard rock and aggregate mining along the Minnesota River corridor may be a threat to this species. Also, red cedar (Juniperus virginiana) encroachment on the rock outcrops in the Minnesota River Valley has substantially reduced available open habitat for this species (Lang 1982, 2003). Selective cutting and burning is necessary to restore the open areas that common five-lined skinks need to survive. While fire is beneficial to maintaining open habitats, fires over several consecutive years may have a negative impact on skink populations by killing individuals or eliminating fallen logs, which skinks use as nesting areas (Klemens 1993). General prescribed burning guidelines have been developed for amphibians and reptiles in the Midwest, although land managers conducting burns in areas with known rare reptile or amphibian species or high concentrations of reptiles and/or amphibians may wish to contact their Regional Nongame Wildlife Specialist for input on burn planning, including timing of burns, so as to minimize impacts on these species. At a minimum, management units should be designed to avoid burning all the occupied habitat on a site in a given year.
Conservation Efforts in Minnesota
The Minnesota DNR has funded several surveys for this species in the state, including a survey in the Granite Falls area in 1979, a survey of the distribution and abundance of the common five-lined skink in 1982 (Lang 1982), and ongoing work by the Minnesota Biological Survey (MBS). MBS targeted this species during their surveys of the Minnesota River Valley in 1982, the southeastern part of the range in 1984, and the Granite Falls area in 1998 and 1999. A 2002-2003 re-survey of the Granite Falls area indicated that five-lined skink populations had declined on public lands (Lang 2003). MBS focused on documenting common five-lined skinks in new counties in the southwestern portion of the state in 2006. The DNR Nongame Wildlife Program provides technical guidance relating to common five-line skinks as part of environmental review and regional habitat conservation planning prcoesses, as well as to local land managers and private landowners.