Western Fence Lizards are Superheroes who keep Lyme Disease at Bay

When warmer weather brings us back to the trails and swimming holes of the Yuba River watershed, it also brings tick season. While most of us know to check for ticks after a day outdoors, fewer people know about the remarkable creature helping to keep Lyme disease at bay in California: the western fence lizard.

Understanding Ticks in the Yuba Watershed

The most common tick in our region is the western blacklegged tick (Ixodes pacificus). These small arachnids change their habitat preferences depending on their life stage. Young ticks, called nymphs, live in dense woodlands with abundant leaf litter. Adult ticks prefer areas with shorter vegetation like grasslands, where they climb onto plants and wait for a host—whether a small mammal, bird, deer, or occasionally a human or pet—to brush past.

Western blacklegged ticks are known transmission vectors for Borrelia burgdorferi, the bacteria that causes Lyme disease. Ticks do not inherently carry this bacteria. Instead, they acquire it by feeding on an infected animal, then transfer it to the next host. Early symptoms of Lyme disease include a distinctive bullseye rash, fever, headache, and fatigue. Without treatment, the infection can progress to more serious conditions including facial nerve paralysis, joint pain, and heart problems.

Meet the Western Fence Lizard

Western fence lizards (Sceloporus occidentalis) are the most common lizard species throughout much of California. You have probably seen them basking on rocks, fences, or warm surfaces around the Yuba watershed. Colloquially called “blue bellies” for the bright blue markings on their abdomens, these small reptiles have darker, keeled scales on their backs and legs that help them blend into their surroundings.

Most people do not think much about the lizard sunning itself on their porch. But western fence lizards play an extraordinarily important role in disease control—one that scientists are still working to fully understand.

How Lizards Fight Lyme Disease

Here is where the story gets fascinating. Young western blacklegged ticks preferentially seek out western fence lizards as hosts. With most animals, a tick carrying Lyme disease bacteria would infect its host within 24 hours of biting. But in 1998, scientists discovered something remarkable: western fence lizard blood contains a protein that kills B. burgdorferi bacteria.

Not only does the lizard avoid infection, but the tick feeding on it is actually cured of the bacteria it was carrying.

This natural defense mechanism is thought to help reduce Lyme disease incidence across California. However, recent research led by Dr. Andrea Swei has revealed an even more complex story. Studies show that removing western fence lizards from an environment dramatically reduces the number of ticks carrying Lyme disease—not just because the lizards cure infected ticks, but because fewer young ticks survive to adulthood without their preferred hosts. Without enough ticks reaching maturity, the cycle of disease transmission is interrupted.

These findings demonstrate how much we still have to learn about the ecology of Lyme disease in California and the intricate relationships between species in our local ecosystems.

Protecting Yourself and Your Pets

While having western fence lizards around helps decrease Lyme disease risk, ticks can still transmit other diseases. Here are science-based steps to stay safe during tick season:

For People:

• Avoid walking through tall grass or areas with abundant leaf litter
• Use 0.5% permethrin on clothing and EPA-approved insect repellent on exposed skin
• Examine all clothing and gear for ticks after coming indoors
• Shower within two hours of outdoor activities to conduct a thorough tick check
• If a tick attaches, carefully remove it and all mouthparts with fine-tipped tweezers as soon as you notice it

For Pets:

• Consult your veterinarian about effective tick preventatives for your animals
• Conduct thorough tick checks after pets have been in potential tick habitat
• Remove any ticks promptly

For Your Yard:

• Keep grass and brush around your home well-groomed
• Stack firewood away from living areas
• Create a three-foot barrier of gravel or mulch between brush and recreational spaces
• Remove large debris that could provide hiding places for ticks

Why Biodiversity Matters

The story of western fence lizards and Lyme disease illustrates a fundamental truth about healthy ecosystems: biodiversity protects us. When we maintain habitat for native species like western fence lizards, we are not just preserving wildlife for its own sake—we are supporting complex ecological relationships that benefit human health and well-being.

This principle extends throughout the Yuba River watershed. Native fish need cold, clean water and connected habitat. Birds need riparian vegetation for nesting. Pollinators need diverse wildflowers. And yes, we need western fence lizards to help control disease-carrying ticks.

Protecting watershed health means protecting these interconnected relationships. It means maintaining the forests, meadows, and riparian areas where these species thrive. It means understanding that human health and environmental health are inseparable.

Join the Movement Protecting the Yuba Watershed

Every time you see a western fence lizard basking on a rock along the Yuba River, remember: you are looking at a small but mighty defender of public health, working within an ecosystem that has evolved these relationships over millennia.

The South Yuba River Citizens League works to protect and restore the habitats that support these complex ecological relationships. Through science-based advocacy, hands-on restoration, water quality monitoring, and community engagement, we ensure that the Yuba watershed remains healthy and resilient—supporting everything from native lizards to thriving human communities.

When you become a SYRCL member, you are investing in the science that helps us understand these connections, the restoration work that protects habitat, and the advocacy that ensures our watershed policies are based on sound ecology. You are supporting an organization that recognizes that protecting nature means protecting ourselves.

Become a SYRCL member today and join the community working to protect the intricate, interconnected web of life in the Yuba River watershed—from the smallest blue-bellied lizard to the mightiest free-flowing river.

Together, we can ensure the Yuba watershed continues to support the biodiversity that keeps our ecosystems—and our communities—healthy and thriving.