Photograph by Joel Sartore, National Geographic
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A tokay gecko mugs for the camera at the Sunset Zoo in Manhattan, Kansas.

Photograph by Joel Sartore, National Geographic

Are Lizards as Silent as They Seem?

Geckos are the noisiest, but other lizards also make sounds.

Where I live in Florida, I can’t open the door without causing a gecko or another lizard to skitter away. They’ve never complained.

But maybe I haven’t been listening.

Elizabeth St. John asked Saturday’s Weird Animal Question of the Week via Facebook, “Do lizards make any sounds?” So I queried some experts about lizard locution. Lizards, I discovered, are not silent actors in the animal world.

Right From the Gecko

“While it is true that most lizards are mute, many make sounds of various kinds,” Robert Espinoza, a biologist at California State University, Northridge, explains via email.

Geckos are the gabbiest, and some produce “a variety of chirps, clicks, and squeaks, some inaudible to humans,” Espinoza says.

“The chirping, sometimes called ‘barking,’ of geckos is either a territorial or courtship display,” to ward off other males or attract females, Peter Zani, a biologist at the University of Wisconsin–Stevens Point, says via email.

Some noteworthy noisemakers, Zani says, are Mediterranean house geckos, which squeak during fights and flirtatiously click to draw females. The turnip-tailed gecko of Central and South America makes territory-marking clicks thought to mimic insects. And the New Caledonian gecko, the largest gecko at 14 inches (36 centimeters), has a growl that earned it the local nickname of “the devil in the trees.”

The sound of one gecko is even embedded in its name: Male tokay geckos, from Asia, make a loud, persistent mating call, “tokay-tokay!” (Watch video: “Gregarious Geckos”)

Lizard Language

They may not be as chatty as geckos, but other lizards can also communicate audibly.

One sound in the reptile repertoire is hissing, which is normally a defensive display used to warn off potential predators, Zani says.

Lizards achieve this sound “by forcing air out of the lungs across the glottis,” Espinoza explains. It’s a warning that “is typically accompanied by an open-mouth gape to inform the would-be predator that the the lizard can back up the audible signal with a painful bite.”

This is certainly the case with the gila monster, a native of the American southwest that injects a neurotoxin into bite wounds through grooves in its teeth. Their hissing is audible in this video of a gila monster fight.

Other hissing lizards include the Australian blue-tongued skink and the goanna, an Australian monitor lizard that inflates flaps of skin around the throat to make its warning sound.

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The threat display of an eastern blue-tongued skink involves flashing their tongue.

Larger lizards are usually the ones that hiss, Espinoza explains, most likely “because such a threat from a smaller animal wouldn’t be, well, threatening.”

Vocal lizards are “scattered throughout the lizard tree,” he says, “indicating that this ability has independently evolved in many lineages, perhaps for similar reasons.”

The lizards’ closest living relative, the tuatara from New Zealand, is also a noisemaker. Tuataras produce a croaking sound when attacked and are known to “emit softer vocalizations through courtship,” Espinoza says. (Find out how dinosaurs might have made sound with their feathers.)

As for those geckos I accidentally scare? Espinoza says they might be responsible for the chirping I hear at night in spring and summer.

Sorry, little guys, I can hear you now.

Weird Animal Question of the Week answers your questions every Saturday. If you have a question about the weird and wild animal world, tweet me, leave me a note or photo in the comments below, or find me on Facebook.

Weird Defense. When confronted with a predator … the Regal Horned Lizard shoots blood from his eye into the face of the predator.