Reptiles, especially lizards, are popular pets in American households, with over four million households owning at least one. Among the diverse species of lizards, the Eastern Fence Lizard (Sceloporus undulatus) stands out. While not ideal as a pet, understanding their diet and behavior is fascinating.
Eastern Fence Lizard: An Overview
Eastern fence lizards are medium-sized reptiles commonly found in the eastern United States. They are also referred to as the prairie lizard, fence swift, gray lizard, gravid lizard, northern fence lizard or pine lizard. Colloquially, they are sometimes called horn-billed lizards. These lizards are often spotted basking on wooden fences, hence their name. Agile and quick, they are also known as fence swifts or pine swifts. The scientific name Sceloporus undulatus comes from the lizard’s femoral pores and the dark, rippling lines on its back.
Physical Characteristics
Eastern fence lizards typically grow to be around 4 to 7 inches long. Size can vary depending on location, with those in New York and Maryland being smaller than their counterparts in southern states like Virginia and Florida. They have spiny, rough scales lining their backs, and their dorsal colors range from gray and brown to bronze, featuring narrow, wavy, dark crossbands more prominent in adult females and young lizards.
Males are more colorful than females, especially during mating seasons, with patches on their stomachs and throats. These patches, used to show dominance, turn green during colder months. Females, on the other hand, have black horizontal stripes on their backs.
Habitat and Behavior
These lizards prefer dry, open woodlands of pines and hardwoods, avoiding overly wet or shaded areas. They dwell in trees or wooded structures like stumps, buildings, and rock piles. Diurnal creatures, they are active during the day and sleep at night, enjoying basking in the sun. When disturbed, they quickly dash up trees or seek shelter under debris.
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Male eastern fence lizards are territorial and defend their territory aggressively, especially against competing males, by displaying their blue underside and performing "pushups." They mate between April and August, with females laying 5 to 15 eggs in rotted logs, soil, or debris from June to early August. These eggs hatch around late August. After mating, males and females no longer associate. Older females may lay 2 to 4 clutches per year. After being laid, eggs double in size during embryonic development. Upon hatching, individuals are about half the size of adults.
Diet of the Eastern Fence Lizard
Eastern fence lizard diet mainly includes insects and arthropods. They are carnivores (insectivores); their diet consists of ants, beetles, spiders, moths, grasshoppers, lady bugs and stink bugs. To have enough energy for laying eggs, female lizards tend to consume more insects during spring than in other months. Eastern fence lizards typically forage twice a day all year round.
Hunting Strategy
To catch their prey, eastern fence lizards employ a "sit and wait" strategy. They find a hidden spot to observe their prey and attack at the opportune moment. They rely on their sight to locate prey, recognizing only living and moving targets.
Supplemental Foods
Occasionally, eastern fence lizards may also consume snails and plant matter, like needlegrass.
Lifespan and Threats
The average lifespan of an eastern fence lizard is thought to be more than five years, possibly averaging ages of 4 years. However, this can be shortened by predators like snakes, birds, and other mammals. To avoid predators, eastern fence lizards use camouflage, play dead, and can break off their tails to escape capture. They are quick, which helps them evade predators, potentially leading to a longer lifespan.
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Besides predators, parasites like botflies also pose a threat. While the eastern fence lizard population is currently stable, increased flooding frequency could threaten hatchling populations.
Conservation Status and Threats
According to IUCN, the Eastern fence lizard is locally common and widespread throughout its range but no overall population estimate is available. Eastern fence lizards feed only on various insects and thus control their populations. The species is listed as Threatened by New York State, indicating it is likely to become Endangered in the foreseeable future. Taking, importing, transporting, or possessing these lizards is prohibited without a license or permit. Standardized survey protocols are needed to monitor their populations effectively.
Habitat and Range
Naturally occurring fence lizard populations are confined to the Hudson Highlands region of the state. All extant, naturally occurring, locations are found in the Hudson Highlands along a narrow corridor in two counties along the east side of the Hudson River. Their range extends primarily from southern New Jersey to central Georgia and west to Louisiana, eastern Kansas, and eastern Texas. Isolated colonies exist in southeastern New York and northeastern Pennsylvania, with a single record from Missouri.
These areas feature steep slopes with open rocky areas surrounded by mixed-deciduous, oak-dominated forests. They prefer hardwood forests on well-drained sites, typically on ridgetops, upper slopes, or south- and west-facing slopes with loamy or sandy loamy soils.
Ecological Role
Eastern fence lizards play a crucial role in controlling insect populations, contributing to the balance of their ecosystems.
Read also: Eating Habits: Eastern Coral Snake
Interesting Facts
- Fence lizards are named for their habit of basking on rail fences.
- Five extant, naturally occurring populations are known, with one introduced population on Staten Island persisting since 1942.
- Males with larger blue patches are more likely to be preyed on by birds.
- They are generally active from late April until early October and may be inactive during the hottest part of the day in the summer.
- Five-lined skinks often share habitats with fence lizards in the Hudson River Valley sites.