A brief introduction to the Eastern fence lizard

 

(photo by Michael Carlo)

The Eastern fence lizard (Sceloporus undulatus) is a North American spiny lizard that can be found ranging along the east coast of the United States from central Florida, up into New Jersey and Pennsylvania, and west to the Mississippi River (there have been recent sightings in northern Pennsylvania and southern New York, suggesting the range is expanding further north). It is a member of a group of sceloporine lizard species that stretches from coast to coast across the United States and south into northern Mexico.

 

(modified from Leache 2009)

Fence lizards get their common name from the basking behavior they exhibit. During the day, they like to bask in sunny spots on trees (standing or fallen) and other vantage points such as fence posts. Those spots allow them to warm in the sunlight while keeping an eye out for prey to catch or predators to avoid. Lizards are easy to spot when basking on high fence posts, so they were named after the place where people often spotted them (other names sometimes used include “fence swift” and “pine lizard”).

 

(photo by Michael Carlo)

 

(photo by Michael Carlo)

The scientific name, Sceloporus undulatus, has its own origins. The genus name, Sceloporus, is derived from a Greek word for “leg” and a Latin word for “hole,” which refers to enlarged pores found in the femurs of sceloporine lizards. The specific epithet, undulatus, comes from the Latin word for “wave,” and is used to describe this species because of the dark, wavy cross-pattern on the backs of Eastern fence lizards.

Eastern fence lizards are sexually dimorphic, meaning females and males exhibit different characteristics such as color/marking, size, shape, and behavior. There are a few major differences between female and male Eastern fence lizards, including the coloration pattern mentioned above, that can simplify identifying the sex of a lizard in the field. Females typically have much more prominent dark, wavy lines on their backs with coloration ranging from black/grey to brown/tan. Males tend to have less distinct markings to the point that they often appear solid brown in coloration. Temperate does affect their coloration. If you capture a fence lizard when its body temperature is relatively cool, it will appear very dark and its markings will be less distinct. If the lizard is nice and warm, its markings will become much more distinct, and its coloration will become generally lighter.

 

(photo by Michael Carlo; top is female, bottom is male)

During the breeding season, which lasts from April to about mid-August in South Carolina, another coloration difference becomes very prominent — males have deep blue patches on their throats and bellies. While some females do develop lightly colored blue patches, they are nothing in comparison to the brilliant blue coloration of a male fence lizard trying to attract a mate. Females do tend to grow larger than males, though that’s not an easy criterion to use when you find them in the wild since that would require you to determine the lizard’s age.

 

(photo by Michael Carlo; top is female, bottom is male)

 

(photo by Buck Snelson)

Where we study Eastern fence lizards in South Carolina, they are commonly found in primarily pine forests. They like stands with lots of fallen trees that provide a nice heterogeneous habitat structure and plenty of insects to eat. So, you’re more likely to find them in older sections of forest, and less likely in some of the more newly cut/burned and heavily managed areas. The small part of Sumter National Forest where we are tracking fence lizards is not heavily managed, so a relatively large population of lizards has proliferated through the forest.

 

(photo by Michael Carlo)

 

(photo by Michael Carlo)

That’s all for now! I wanted to give you all a brief introduction to the lizards to show you what they look like, where we find them, and few facts about the species. Soon, I will post a lab note talking about how we manage to catch the lizards when we locate them.