[3] The species is found along forest edges, rock piles, and rotting logs or stumps in the eastern United States.
The specific name, undulatus, is Latin for "wave", referring to the transverse dark crossbars on the backs of these lizards.
[9] The following cladogram is based on Leaché and Reeder, 2002:[8] S. cowlesi S. cautus S. tristichus S. consobrinus S. woodi S. undulatus S. virgatus S. occidentalis The eastern fence lizard can grow from 4.0 to 7.5 inches (10 to 19 cm) in total length (including tail).
[10] It is typically colored in shades of gray or brown, and has keeled scales, with a dark line running along the rear of the thigh.
The male is usually brown, and during the summer, has a more greenish-blue and black coloration on the sides of the belly and throat than the female.
[11] The lizards mostly inhabit sparsely wooded areas with ample sunlight, such as pine barrens with sandy or loose soil.
They can be found basking atop of both natural and artificial structures including coarse woody debris, tree stumps, rock piles, sandy hills, dead logs, and fence posts.
They seek refuge under structures such as woodpiles, logs, and rocks for coverage and protection when it gets too hot and at night.
"[14] This sexual dichromatism is correlated to and somewhat regulated by plasma levels of testosterone in juveniles and adult females.
[14] Male eastern fence lizards can also experience short-term color changes on their dorsal side and badge after exposure to temperature changes.
In 1942, Carl Kauffeld released 29 of the lizards near Rossville where they still persist today in post oak-blackjack oak barrens.
[21][22] There have also been sightings of the fence lizards in northern Pennsylvania and southern New York (in the Hudson Valley and Long Island), suggesting that their range may be expanding north.
[23] Despite its broad geographic distribution, these lizards tend to prefer temperatures that optimize their digestive performance.
[24] The eastern fence lizard has several adaptations to better survive in colder regions of its distribution, including larger eggs, more efficient embryonic development, and shorter incubation times.
[26] When climate conditions are stable, fence lizards prefer to sleep in the same site over short periods of time.
Eastern fence lizards run faster uphill than downhill at a fixed degree of incline or decline.
[35] Studies have shown that eastern fence lizards display an ontogenetic shift in consumption of native and invasive prey.
[38] The female finds a suitable location to lay her eggs, usually in a rotting log or similarly damp area, and deposits them without any further parental care.
[42] After the eggs are laid by a female, the development of the embryo and yolk within differ from that of birds, which has long been assumed to be identical.
Fire ants also compete with eastern fence lizards for their nesting habitats and predate on their eggs.
However, exposure to fire ants did not increase the percentage of lizards that demonstrated escape behavior.
[46] Given the incubation period of the eggs, one study suggests that 61% of nests may be at risk of predation by these invasive fire ants.
Nest choice and distance to the nearest fire ant mound did not significantly impact predation; thus, because there is little that eastern fence lizards can do to resist such predation on their eggs, there is conservation efforts toward stopping invasive species such as this fire ant.