Creature Feature: Texas Banded Gecko
Big Bend National Park is remote and dry – not exactly a place that most people think of right away when they plan a vacation. But the desert is full of interesting things, some of them so small that they might escape notice. Take, for example, the ghostly Texas Banded Gecko. This little fella is endemic to northeastern Mexico, the Rio Grande area of South and West Texas, and some locales in New Mexico. Big Bend National Park is a good place to look for them.
First reported to science in 1893, the Texas Banded Gecko (Coleonyx brevis) is the smallest of the six gecko species that call the Lower 48 home. Indeed, it is the smallest of all the North American geckos. A fully grown adult weighs barely two grams and is only four or five inches long. Females are generally a bit larger than males, but both sexes have delicate, slender bodies equipped with tails that account for about half of their total length.
Scientists named this reptile for the alternating bands of dark brown and pale yellow that run across the pale pinkish brown body of the young gecko. As the animal grows older, its appearance becomes more mottled. The blotches, patches, and spots of light and dark colors help the adult animal blend into its surroundings. Like many small lizards, the Texas banded gecko has small scales that resemble sandpaper. It is silent most of the time, but will squeak when frightened, breeding, or announcing its territorial claims.
This little gecko doesn't have sticky pads on the bottom on its feet, so it isn't a particularly good climber. It spends most of its life on the ground and under rocks, rarely moving any higher, as it patrols the cracks and crevices of rocky canyons and gullies, feeding on spiders, insects, and other small creepy-crawlies. Geckos are considered welcome guests in homeowners' yards because they will eat termites, cicadas, and other pests.
The gecko’s large eyes are a tremendous asset when looking for food and watching for predators. The vertical pupils and moveable eyelids that add to its distinctive appearance help the gecko both spot its prey and avoid becoming a meal for a larger predator.
Nocturnal by nature, the Texas Banded Gecko is most active from dusk to midnight. It flicks its tongue while hunting, using chemoreceptors as well as its sight to find its meal. Once it finds a tasty morsel, the gecko will arch its body over the prey and strike downward, reminiscent of a snake.
The gecko’s reproductive cycle hasn’t been thoroughly studied yet. The breeding season is in late spring and is thought to last for several months. Females lay one or two eggs in an underground nest. Eggs hatch in two months, and the mini-sized adults quickly mature. As the eggs are forming, the female uses fat stored in her tail to increase the size of the egg yolk. This extra energy the egg receives helps ensure that the hatchlings develop properly and grow quickly.
Geckos reportedly can live up to 25 years, but it’s unlikely that a wild hatchling will live to that ripe old age. The animal's natural predators run the gamut from birds to snakes to bigger lizards, and the Texas Night Snake in particular is one of the gecko's biggest menaces.
One of the gecko's most fascinating behaviors can be seen only when it is threatened. When it feels that it is about to be attacked, the gecko will point its tail towards the predator and move it up and down like a scorpion. If the predator continues to advance, the gecko will detach its tail from its body and dart off – hopefully escaping while the predator gobbles down the severed tail. A new tail replaces the discarded one in four or five weeks, restoring the gecko’s unusual defense mechanism.
Females seem to detach their tails more often than males, leading scientists to believe that the female’s larger size makes it more vulnerable. This seems logical enough, since predators find it easier to spot bigger animals. In a 1978 article published in the Journal of Hertology, Benjamin Dial reported that 80 percent of the female geckos he studied had detached tails, compared with only 68 percent of the males.
The Texas Banded Gecko is relatively common and is not deemed to need any special protection. Of course, habitat degradation and other factors may cause population declines in particular locales. If you have a hankering to see the Texas banded gecko on its home turf, the best time is after sunset.
Motorists often see geckos in their headlights, since the little predators find roadways good places to search for insects and other food. People sometimes describe geckos as “ghoulish-looking.” Geckos don’t bite, however, and are considered quite harmless. When you see one, just leave it alone and enjoy watching this quirky little west Texas resident do its thing.