The Western Fence Lizard is a common sight across western North America, often encountered in various habitats from backyards to natural landscapes. Its widespread presence frequently leads people to wonder about its nature and if it poses any risks. Understanding this reptile’s characteristics helps in appreciating its role in local ecosystems.
Poisonous Versus Venomous
The terms “poisonous” and “venomous” describe distinct biological mechanisms for delivering harmful substances. An animal is poisonous if it contains toxins that cause harm when ingested, inhaled, or absorbed through external contact, such as the skin secretions of poison dart frogs.
In contrast, a venomous animal actively injects toxins into another organism, typically through a bite or sting. This mechanism is seen in snakes, spiders, and scorpions, which possess fangs or stingers. The key difference lies in the method of exposure: poisonous organisms are harmful when touched or consumed, while venomous ones inject their harmful substances.
Western Fence Lizards: Harmless to Humans
Western Fence Lizards (Sceloporus occidentalis), recognized by their blue bellies, are neither poisonous nor venomous to humans. While they might bite if threatened or handled, their bite is not toxic and is generally harmless, causing only a slight pinch.
These lizards exhibit defensive behaviors when confronted. Their first instinct is to run away and hide. If cornered, male lizards may perform “push-ups” to display their bright blue undersides, making them appear larger and more intimidating to potential threats. Like many animals, Western Fence Lizards can carry bacteria such as Salmonella on their skin, but this is a general hygiene concern, not related to them being poisonous.
Safe Encounters with Western Fence Lizards
Observing Western Fence Lizards from a distance is the best approach for human and animal safety. Handling these reptiles can cause them stress, and while their bite is not dangerous, it could lead to the transfer of common surface bacteria. Always wash hands thoroughly after any contact with wild animals to mitigate bacterial transfer.
These lizards play a beneficial role in their ecosystems, primarily by controlling insect populations. Their diet includes beetles, ants, flies, caterpillars, and spiders. They also consume ticks, and their blood contains a protein that can kill the bacteria responsible for Lyme disease, potentially reducing its spread in their habitat. Their presence contributes to a balanced environment, and understanding their docile nature helps foster coexistence.