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Thursday, May 01 2014 10:23 AM

Bluebellies: lizards that both entertain and fight Lyme disease

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A male Western Fence Lizard basking on a fallen tree limb.

Now that the temperatures have risen once again, I see Western Fence Lizards on a daily basis: basking on boulders and wood piles, scurrying along the walls of old buildings, rustling in dry leaves and grass as they race to conceal themselves when they hear the sound of my approaching footsteps. These are easily the most frequently seen reptiles in the Tehachapi Mountains, and their re-emergence as the days warm up is one of my favorite signs of spring.

Field guides refer to them as Western Fence Lizards (Sceloporous occidentalis), but most people call them simply "Bluebellies" because of the sky blue markings on the underside of the males' belly and throat. The males may also have bluish or turquoise markings on their backs, especially during the breeding season, which is now. Females and juveniles lack the coloring on their backs, and have only faint blue on their bellies or none at all. When first basking in the sun, Fence Lizards are sometimes very dark, almost black, until they warm up and then they gradually lighten to reflect rather than absorb sunlight.

These very common lizards make life more interesting with their attractive colors and vigorous antics, and they also consume lots of invertebrates, including beetles, termites, crickets and other insects of all kinds, spiders, scorpions and more. But they also do something else that makes the area safer for people -- they combat Lyme disease.

Bluebellies eat ticks, which reduces the numbers of these parasites, but they also do something more extraordinary: a protein in the blood of Western Fence Lizards kills the Lyme disease bacterium in ticks that feed on the lizards. In California, Western Black-legged Ticks, also known as "deer ticks," are the primary vector for Lyme disease, especially the tiny nymphal ticks. When these ticks attach themselves to Bluebellies, a helpful protein in the lizards' blood kills the Lyme disease, so that after feeding on the lizard, the tick no longer carries Lyme disease.

Some have hypothesized that the large number of Western Fence Lizards statewide may be the reason that Lyme disease is less common in California than it is in some Northeastern states, where Lyme disease is epidemic. I've loved Bluebellies since I was a little kid, and the fact that they also reduce the chance of getting Lyme disease is one more reason to be fond of them.

While Fence Lizards eat a wide range of invertebrates, they themselves are on the menu of many different predators, including kestrels and shrikes, snakes, weasels, foxes, feral cats and more, so they must be constantly vigilant. These fairly small but robust lizards are always ready race up a tree or along a wall, hurl themselves off a boulder into dense vegetation or dive into a rock crevice to escape a perceived threat.

Young Bluebellies are miniature and especially susceptible to predation, even by larger lizards or big spiders. Fence Lizards easily detach their tails when seized, and the separated tail bends and twists reflexively, distracting a would-be predator while the lizard escapes. A lizard will eventually re-grow a new tail, but it isn't a speedy process and stub-tailed Bluebellies are not an uncommon sight.

Fence Lizards, called "Wo-go-sin-az" by the local Nüwa (Kawaiisu or Paiute) Indian people, are well-known for doing pushups more often than Jack Lalanne. This is mostly a male territorial display when one lizard encroaches on another, but females do it as well and they sometimes remain in the "pushed-up" position, so I have to conclude that they do like the improved view that it offers. If you want to see what a difference it can make, lay flat on the floor and see how well you can see, and then do a pushup and see how much better the view is.

Western Fence Lizards are one of the most frequently-encountered creatures you'll see when outside in the Tehachapi Mountains during daylight hours. We have two different subspecies -- both the San Joaquin and Great Basin versions of Western Fence Lizards -- and their entertaining, energetic behavior and suppression of Lyme disease are reasons enough to cherish them.

Jon Hammond has written for the Tehachapi News for over 30 years. Send email to: tehachapimtnlover@gmail.com

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