Focus on Nature

FOCUS NATURE DIMINUTIVE AND CUTE, THAT'S OUR GECKO LIZARD

While 750 varieties of geckos can be found around the world, Arizona is home to but two species of these shy saurians. One is the native variety, and the other is a relative newcomer whose population is growing. Although seldom seen, the western banded gecko is one of the most common animals in Arizona, says John Gunn, an Arizona Game and Fish Department wildlife specialist. These diminutive critters hide underrocks or debris during the heat of the day, venturing out at night to forage for such soft-bodied invertebrates as crickets.

This native gecko will live almost anywhere in the Sonoran Desert where city life has not encroached too heavily, according to Bryan Starrett, herpetologist gamekeeper at the Phoenix Zoo.

"Drive down a desert road at night, especially along a canyon or a streambed, and chances are you will find geckos," says Starrett.

It is not surprising that many of us are not aware we share the desert with this common little animal because its pale skin blends with the hues of the rocky desert floor, and its size and shape camouflage it well. Arizona's geckos stretch out to a mere four inches, and they are at their stoutest at less than an inch around. Their tiny offspring could easily be mistaken for scorpions, says Gunn.

Western banded geckos have straw-colored, almost translucent, smooth skin with darker-colored bands from their necks to their tails. They walk in an "elevated posture," almost as if they were standing on tiptoe.

Like many of the desert plants that store water to get them through dry periods, these native geckos store fat in their tail tissues from which they draw nourishment to sustain them during dry weather and months of hibernation each year. When it stalks its prey, the gecko's tail curves and turns in a fashion similar to a prowling cat's tail. When the animal is threatened, its tail may drop off at the slightest touch but continue to move for a while, perhaps diverting the predator's attention from the rest of the animal.

Within cities, Arizona residents are more apt to spy the Mediterranean gecko, which recently appeared in the Sonoran Desert, Gunn says. These European imports They threaten are insects.

probably hitched a ride into the country hiding on plant-nursery stock and building materials and since have thrived in microhabitats produced by humans.

In winter these newcomers most often are found seeking shelter in gutters, foundation cracks, behind swamp coolers, and in light fixtures. Luckily, they have filled a biological niche in our environment without displacing any other species. The only animals they Mediterranean geckos range in color from pinkish to gray with brown or gray blotches on their backs that become bands on their tails. Their skin is rougher than the western banded gecko's, and, on average, they are slightly smaller than their native cousin.

Like most other geckos, Gunn says, the Mediterranean has villi, "a microscopic form of Velcro," on the pads of its feet that enable it to walk up the sides of walls or even upside down on ceilings. If you see a gecko on a wall, it most likely is a Mediterranean, and if you see it on the ground, it probably is a western banded gecko.

The Mediterranean population is expanding. So far they can be found in Tucson, Phoenix, Tempe, and parts of Mesa. The public buildings in Chandler are covered with them, says Gunn. He has seen up to 15 geckos surrounding a security light high on the side of a building, waiting for flying bugs.

Like their Hawaiian counterparts, Gunn says these little lizards possess "endearing qualities," especially to those who study them. They have velvety bodies topped with big eyes. And "They seem to have a permanent grin fixed on their faces," Gunn says. "At times they look like a crocodile from the front."

And then there is the gecko's voice. Crocodilians are the only other reptiles that have a voice box, Gunn says. When frightened, geckos will squeak loudly, a sound almost like the bark of a small dog. But perhaps the most endearing quality geckos possess except to pest-control companies - is their voracious appetite for bugs.