By Ethan Hatchett
The eastern fence lizard is one of the more unique reptiles in Georgia. Reaching 4 to 7 inches long, this native lizard is found throughout the state wherever there are dry, open forests. Fence lizards are most often seen basking in the sun on logs, rocks and buildings. Common names for the species include “wood lizard” and “pine swift,” respective nods to the reptile’s preferred habitat and speed.
Colored light gray to brown or black with spiky, rough scales, the fence lizard looks like no other lizard in Georgia. Wavy crossbands on its back mimic tree bark and help the lizard blend in. Males also sport a bright blue patch under their chin and on their belly.
During the breeding season, male fence lizards establish territories and closely guard them. When approached, a male will flash the blue patch under its chin, do “push-ups” and bob its head. If the threatening display doesn’t work, he will fight the intruder. To attract females, males rely on their bright blue coloring and perform a sort of mating dance similar to their aggressive display of push-ups.
Females create nests in moist soil and rotten logs, laying about three to 16 eggs in a clutch. Younger females will lay one clutch in a season, while older females can lay up to four. The female leaves the nest after laying the eggs. When they hatch, the juvenile lizards are on their own.
Eastern fence lizards are sit-and-wait predators, relying heavily on camouflage and ambushing prey spotted from their high perches. The lizards primarily feed on various insects but show a strong preference for ants. It’s ironic, then, that fire ants have proved a challenge for younger fence lizards.
Evidence suggests fence lizard nests are vulnerable to these South American ants that spread into Georgia decades ago. However, in areas where fire ants are prevalent, the lizards have developed fascinating new behaviors and even changed physically, according to some researchers.
The accidental importation of fire ants into the seaport at Mobile, Ala., in the early 1900s undercut the fence lizard’s patient strategy for finding prey. The stinging ants would easily overwhelm lizards with their paralyzing and deadly venom . Yet within only 80 years – or about 40 generations of eastern fence lizards – the behavior, shape and physiology of eastern fence lizards in fire-ant infested regions changed.
A study found that fence lizards in these areas had longer hindlegs, more helpful in removing fire ants and fleeing. Instead of their traditional tactic of still-hunting, the lizards also twitched and were quicker to run. Researchers documented physiological changes, as well, such as the fence lizards producing more stress hormone, which would be beneficial in dealing with fire ant attacks.
The long-term consequences of the adaptations to introduced hazards are not known. The changes may help deter fatal encounters with fire ants but they could make the lizards more vulnerable to other predators that find them by sight.
Eastern fence lizards are a commonly seen across Georgia. Fast, flashy and full of a charm, these small reptiles are an integral part of the state’s landscapes. And their coloration and spiky features make them easy to identify and a joy to encounter.
Ethan Hatchett is a communications assistant in DNR’s Wildlife Conservation Section.