July 20, 2020

Lizards in Minnesota? We have three species that are found in the state: Prairie Skink (Plestiodon septentrionalis) across all of MN except northeast and north central, Common Five-lined Skink (Plestiodon fasciatus) found in extreme southeast MN and along the MN River Valley, and my target for the day—Six-lined Racerunner (Aspidoscelis sexlineata), which is almost exclusively found in the southeast counties bordering the Mississippi River.

Six-lined Racerunner? Yes, this lizard is incredibly speedy (it can run up to 18MPH!) and it has six greenish-yellow stripes…three running down each side of its body (with a darker middle stripe…so it could technically be called the “Seven-lined Racerunner” but nobody asked me).

And this lizard needs that kind of speed to ambush grasshoppers, crickets, spiders, flies and other insects who can be quite quick to take wing at the first hint of danger.

Range of Six-lined Racerunner in the U.S (from NatureServe.org)

Thanks to a tip from a herpetologist friend I searched this spot along the Mississippi River in Houston County, Minnesota (the southeastern most county in MN). He said to only go on a sunny and very warm day since these guys are only active in the heat of midday. In fact, their ideal air temperature for activity is 93 degrees F! (Fitch, 1958). They won’t even come out of burrows on cool days (below 72?). Mid May is when they emerge and they go back underground for the winter in late August.

Check out the unique scales on the Six-lined Racerunner’s tail. They can “drop” their tail if in danger, or if a predator grabs them by the tail, but it is much more unusual than with the skinks.

My first “sighting” was just a line of grass moving as an unseen lizard raced away from me. The site was sandy with a surprising amount of forb cover. I would have thought I’d find them in more open sandy country. A line of jumbled rocks is where they would scurry to for cover.

After about two hours, and about six lizards speeding away from me to the shelter of the rocks, I finally found a Racerunner that wasn’t racing. I was able to sloooowly creep towards him (see below on how I knew his gender) and get a few shots through the grasses.

The blue throat/chin and lime green face tells me that this is a male who is still in breeding “plumage.”

Much of this information about the natural history of Minnesota’s herps was gleaned from Moriarty and Hall’s excellent Amphibians & Reptiles of Minnesota (University of Minnesota Press, 2014). You can buy it here. Or purchase from Amazon here.

In this Blog Post from summer 2019, I searched for the Five-lined Skink along the rocky landscape of the Minnesota River Valley, but instead found a juvenile Prairie Skink.