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Six-lined Racerunner

Overview:

Scientific Name: Aspidoscelis sexlineatus

Size: 6 – 10.5” (total length)

Status: One colony exists in east-central Michigan which is most likely a natural relict population. The Great Lakes region is the edge of the range for this species but can be locally abundant in isolated colonies. 

Michigan State Status: Threatened

Federal Status: Threatened

MDNR Wildlife Action Plan Status: Species of Greatest Conservation Need

Habitat:

In Michigan, it is found in dry, fallow fields with adjacent dry forested habitat. In other parts of its range, it is found in habitats with sandy soils found in prairies, fallow fields, riverbanks and savannas.  

Conservation:

The six-lined racerunner is only known to exist in one population in east-central Michigan. Although still in debate, it is likely that this isolated colony is a natural relic population that has persisted since the glacial retreat. Activities that cause an increase in shade and ground cover as well as the application of pesticides pose a serious threat to the already state threatened six-lined racerunner. 

Best Management:

Identify and protect quality six-lined racerunner habitat containing extant populations. Ensure open, sparsely vegetated habitat is maintained by conducting tree harvest during late fall to early winter. Consider utilizing a technique that removes the canopy as well as understory to create large, open areas. Implement alternative strategies to prevent the need for pesticide application or consider utilizing alternative, low-toxicity substances and biocontrols. Mowing may be conducted to eliminate ground cover but should adhere to strict protocols to prevent incidental mortality. Mow infrequent and during the hottest times of the year and set the mower deck high (>6”). Create basking and cover structures by implementing woody debris, stones, logs, burrows, and leaf litter within these specific sites. Also provide nesting sites by including burrows as well as hibernacula consisting of logs and rocks. This species benefits from prescribed burns.

Adult Coloration:

Its body is black, grey, brown, or olive in color with six yellowish-green, white, or grey stripes running down the back and sides with an indistinct brownish stripe down the middle of the back. In males the neck and front of the body may be green or bluish-green, older males the stripes are less distinct. 

Adult Characteristics:

Slim bodied with a very long tail. The scales are granular on the body while the scales on the head are large and platelike, the belly scales are flat, rectangular, and arranged in straight rows. Males have a more robust head and a wider vent than females. The tail is encircled by rings of rough scales. 

Typical lifespan in wild: 2-6 years  

Breeding interval: twice annually  

Breeding season: May- July 

Range number of offspring: 1-8 

Average number of offspring: 4 

Range gestation period: 36-40 days 

Average age at sexual/reproductive maturity (female): 1 

Average age at sexual/reproductive maturity (male): 1 

Diet: Grasshoppers, cicadas, beetle larvae, spiders, and ants 

Predators: Fire Ants 

Juvenile Characteristics:

Has distinct light stripes on the darkened body with bluish or bluish-green tails. 1.2” body length (snout to vent) at hatching.  

Species Confused With:

All other lizards in the state have smooth, shiny, scales.

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