An all-female lizard species that reproduces asexually stress-eats to cope with the deafening racket of jets at a nearby military base

The Colorado checkered whiptail lizard.

Getty Images

• A rare lizard species in Colorado reacts to stress-inducing loud noises by eating, a study found.
• Researchers studied the Colorado checkered whiptail, an all-female lizard species, in 2021.
• Noise pollution from aircraft flyovers at Fort Carson in Colorado piqued the reptiles' anxiety.

The urge to chow down during moments of high stress apparently transcends species.

A study published late last month found that Colorado checkered whiptails respond to loud noises and related anxieties by eating copiously.

"We show that noise disturbance does have measurable physiological impacts on Colorado checkered whiptails," co-author Megan Kepas, a doctoral student at Utah State University said in a statement published by EurekAlert. "We also show that they are somewhat resilient and may compensate for this to some degree by alter[ing] their feeding and movement behaviors."

The rare, all-female species, which reproduce asexually, live exclusively in Colorado and boast long, thin tails, giving them their name. Researchers zeroed in on a collection of the reptiles located near Colorado Springs at the Fort Carson US military installation.

The Army base is the site of frequent helicopter flyovers, as well as transport aircraft and fighter jets that soar just above the lizards' habitat, polluting the airspace with their deafening roars.

That noise disturbance, it turns out, has a measurable effect on the lizards below. 

Multiple populations of whiptails, which are classified as "at risk" by the US Army and of "special concern" by Colorado Parks and Wildlife, reside in the 212 square mile radius of Fort Carson, including within the base's training area, where large aircraft frequently fly less than 20,000 feet above the ground. 

The authors of the study, which appeared in the journal Frontiers in Amphibian and Reptile Science, worked together with pilots at Fort Carson to research how the military-industrial complex is impacting the reptiles below.

In June 2021, researchers asked Army pilots to fly over the Fort Carson training area at specific times and then abstain from flying in the area in order to compare and contrast the lizards' responses.

Noise readings during the study period ranged from 33.9 decibels to 112.2 decibels — reaching levels equivalent to that of a power saw and which exceed the average pain threshold for most people. On non-flying days, the noise was akin to that of a humming fridge.

A Javelin missile fired by soldiers with the 2nd Stryker Brigade Combat Team heads toward a target during a live-fire training exercise on April 28, 2022 in Fort Carson, Colorado.

Photo by Michael Ciaglo/Getty Images

Researchers each day collected as many lizards as they could — 82 in total — observing their behavior for three minutes before the capture. Study participants weighed and measured the lizards, took their blood, and used a portable machine to conduct ultrasounds and determine which lizards were pregnant.

After returning to the lab, researchers measured the stress hormone cortisol in the lizards' collected blood samples.

"Behavioral responses to noise pollution often translate into stress responses, as loud noises increase cortisol levels in several species," the study authors wrote.

Cortisol is typically released in the minutes following the onset of a stressful situation, and the study participants found that the whiptails' blood concentrations of cortisol skyrocketed immediately after the military flyovers. 

So how did those stressed-out lizards respond to the high levels of stress? The way so many of us do: by eating.

Researchers found that the whiptails moved around less and ate more following the aircraft disturbances, in an apparent effort to replenish the energy they lost while stressing about the noise. 

"Compensatory eating would allow individuals to maintain their energy levels during a stressful event. This is important because metabolism, physical activity, investment into reproduction, and hormonal responses require energy," Layne Sermersheim, a master's student at Utah State University and a study author, said in a statement.

While comparable studies found similar "freezing" responses among other animals during moments of high stress and loud noise, the discovery of the whiptails' eating response is particularly "novel," according to the study authors. 

In order to help the lizards thrive, the study's authors recommended that pilots avoid flyovers in heavily populated whiptail areas during the species' breeding season, and suggested flying high enough to keep the noise level below 50 decibels on the ground.

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