Pictured here is a close up of a Western Fence Lizard (Sceloporus occidentalis). Photo courtesy of Tuleyome

WOODLAND, CA (MPG) - You have probably seen hundreds of them in your life, the unassuming Western Fence Lizard (Sceloporus occidentalis). During summer months, they can be seen scampering about in our gardens, skittering along hiking trails and sunbathing on rocks or fences, as their name implies.

The Western Fence Lizard has been at the center of a scientific debate in recent years related to their connection with black legged deer ticks that carry the bacterium that causes Lyme’s disease. A study done by UC Berkeley Etymologist Robert Lane in 1998 found that a protein in their blood kills the bacterium that causes Lyme’s disease. When a tick infected with this bacterium feeds on a Western Fence Lizard, this protein kills the bacterium inside the tick, after which the tick can no longer spread the disease.

A Western Fence Lizard (Sceloporus occidentalis) sunbathes on a branch. Photo courtesy of Tuleyome

Based on this finding, it was assumed that these lizards help reduce the risk of Lyme infections in areas where they are present. Since learning this I have seen them as tiny little superheroes, running around in plain clothes as superheroes are wont to do in their free time. However, as I sat down to write about their heroics, I found that a later study conducted by graduate students at UC Berkeley, including Andrea Swei, a lead author of the study, showed that the relationship between ticks and these lizards is much more complex than initially assumed.

In 2010 researchers removed a number of Western Fence Lizards from two areas in Marin County with the hypothesis that this reduction in the lizard population would increase the prevalence of infected ticks. Surprisingly, their findings showed that the decrease in lizard numbers actually had the impact of decreasing tick populations as not all ticks were able to find another suitable host. These conflicting findings remind us that there is still much we have to learn about the complexities of our ecosystems, and the delicate balance that each species helps maintain.

So, whether they are regional heroes that help protect us from Lyme’s, or just a regular Joe that has to weather more than their fair share of tick bites, they are cool neighbors that do some pretty interesting things and are fun to watch in the summer months.

Western Fence Lizards sustain themselves on a diet of mostly insects, including spiders, flies, caterpillars, and mosquitos. They are most commonly found in California, but their range stretches north to Washington, east to Arizona and Utah and as far south as Northern Mexico. Throughout their range, they can live in most climates, except harsh deserts.

Measuring between 3.9 and 8.4 inches in length, their backs and limbs are covered with matte spiny scales in brown, gray, tan, black and beige. Their undersides are smooth, in shades of white and yellow, and they have characteristic vibrant cerulean to navy blue patches that give them their nickname, Blue-bellies.

The mating displays of males in spring can provide some delightful nature watching. Sceloporus occidentalis are territorial, and they will show their dominance and reproductive prowess by repeatedly raising themselves up in a “push-up” motion, revealing their blue underbellies. At night females dig small underground pits in damp soil, where they lay clutches of 3-17 eggs. They can have up to three clutches in a year, with juveniles hatching in July and August.

As temperatures cool, between October and March, they go into a hibernation-like state called brumation, where their body systems slow down, conserving energy. During brumation they are vulnerable to predation, thus hide under tree bark, rocks, and in small crevices or underground burrows. They have evolved to sleep with one eye open, which scientists believe allows them to rest one side of their brain while maintaining awareness with the other.

Sceloporus occidentalis can live 5-7 years in the wild. A preferred prey of many birds, they are also predated upon by snakes, coyotes, racoons, and domestic cats. They have a defensive strategy called caudal autotomy, for getting away from would-be predators. When grasped, the tail self-amputates and flops around to distract the predator, allowing time to escape. During the 3-5 weeks that it takes to regrow their tail, they are at greater risk of predation as they lack the ability to protect themselves in this critical way. Additionally, lizards with regrown tails are less attractive to future mates, and can be prone to increased parasite infestation, making losing their tail a very costly injury.

There are many ways to support Western Fence Lizards. Spaying and neutering cats, and keeping domestic cats indoors decreases non-native predation of these native lizards.  Avoiding pesticide usage in our yards has positive impacts on lizards that rely upon insects for sustenance. Lizards need safe cover from predators, and simply adding a few well-placed rocks or logs to outdoor landscapes can provide needed refuge. Planting native plants draws beneficial insects which lizards need to thrive. Lastly, as tempting as it may be to a child (or curious adult) to pick up a lizard, they are likely to lose their tail in defense, and this puts them in danger even after you have let them go. With lizards, like other wildlife, it is best to look and not touch.

So, while I love the story that they have Lyme protective superpowers that help humans, it may be that their superpower is merely a self-protective adaptation that we happen to sometimes benefit from. Nevertheless, they are interesting neighbors that we can protect and enjoy watching from a distance.

Diana Drips is a Certified California Naturalist. Tuleyome is a 501(c)(3) nonprofit conservation organization based in Woodland, CA. For more information go to www.tuleyome.org.