Urban Field Guide: Western Fence Lizard (Sceloporus occidentalis)

Photo by Connor Long. Accessed via Wikimedia Commons.

Basking in the warm sun atop stone and asphalt, the Western Fence Lizard is a common sight in many cities on the West Coast. These little reptiles live in a wide variety of habitats, using their skillful climbing and ability to run with short bursts of speed to track down tasty arthropods like flies, beetles, and spiders. There are five known subspecies of Western Fence Lizard, each with unique colorations, but they can all be identified by their characteristic bright blue underbellies.

Notable Features:

  • A Tail for the Ages: Predators like snakes and hawks will sometimes go after this species. Like many lizards, Western Fence Lizards can detach their tails when a predator is near, creating a still-moving distraction and letting them slip away. Don’t worry! The tail grows back within a few weeks. 
  • Lizard Duels: Male Western Fence lizards compete for territory during the mating season in the spring. To impress females and ward off opponents, they will bob their heads and raise their tails in the air. Females lay clutches averaging around eight eggs, which hatch in the summertime. 
  • City Legs, City Scales: Researchers have discovered that Western Fence Lizards are undergoing astounding evolutionary changes to help adjust to life in cities. Fence lizards in regions like Los Angeles have both shorter legs and fewer but larger scales than their non-urban cousins. Why? Scientists believe that these shorter legs help the lizards navigate more smoothly on human-built surfaces like concrete (Putman et al. 2019). Meanwhile, larger scales might help them cope with increased temperatures in cities due to the Urban Heat Island Effect – where cities tend to get hotter than less-urbanized spaces. The larger scales help hold in moisture, helping Western Fence Lizards beat the city heat!

Western Fence Lizards also have the wild ability to neutralize Lyme disease through special chemicals in their blood. When ticks bite them, Western Fence Lizard blood removes lyme disease from the tick, preventing them from infecting future hosts. Just another reason to keep these metropolitan reptiles close!

When these lizards bob their heads at me, I respectfully back away. It’s nice to give them a win. -A.J.

Works Cited: 

  1. Stebbins, Robert C. “A Field Guide to Western Reptiles and Amphibians.” 3rd ed. Peterson Field Guides, 2003
  2. Putman BJ, Gasca M, Blumstein DT, Pauly GB. Downsizing for downtown: Limb lengths, toe lengths, and scale counts decrease with urbanization in western fence lizards (Sceloporus occidentalis). Urban Ecosyst. 2019 Dec;22(6):1071-1081. doi: 10.1007/s11252-019-00889-z.
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