Lizards stress-eat from noisy US Army flyovers

Lizards exposed to noise pollution from low-flying fighter jets have resorted to stress-eating. More specifically, Colorado checkered whiptails, striped and patterned lizards that live only in southeastern Colorado, are an all-female species that reproduce asexually. Given their location, these lizards must endure constant, considerable noise from US Army flyovers and have begun stress-eating in order to cope with the loud noise.

The noise

Noise disturbances may have dramatic impacts on wildlife. In fact, light and noise pollution are amongst the fastest growing, but least understood, anthropogenic stressors on the planet. (source)

“In skies over grassland habitats that the checkered whiptails (Aspidoscelis neotesselatus) call home, military aircraft are a frequent presence. The lizard’s range extends into the US Army’s Fort Carson Military Base in Colorado Springs, which covers 212 square miles (550 square km) and contains several populations of the lizard.  Fighter jets and transport aircraft soar overhead, along with Black Hawk, Apache and Chinook helicopters, often within 20,000 feet (6,100 meters) above the ground, according to the study.

At times when there were no flyovers, ground readings registered no higher than 56 decibels (dB), about as loud as a refrigerator’s hum. By comparison, ground readings during flyovers surged to 112 dB — louder than a jackhammer and just above the average pain threshold for humans.” (sourcesource)

Study overview

Researchers examined blood samples from these lizards and detected elevated stress levels from the din. The lizards also had a coping strategy for dealing with the loud noise: They moved less and they ate more.  The scientists hypothesize that by snacking during noisy flyovers, the lizards are likely replenishing energy that has been lost during metabolic responses to stress.

“During checkered whiptails’ reproductive season in 2021, the scientists observed dozens of lizards during flyovers. They caught, weighed and measured the lizards, collecting blood samples from 82 females. The researchers also checked to see if lizards were carrying eggs, using a portable ultrasound device to determine egg size and number before marking and releasing the animals.

Analysis of the blood samples showed elevated levels of the stress hormone cortisol and increased production of ketones, which are energy-burning compounds associated with heightened stress. Flyovers also boosted the lizards’ interest in food, with lizards hunkering down and spending more time eating than they did when aircraft were absent.”  (sourcesource)

stressed lizard 2

What can be done?

Scientists say that stress to lizards from the flyovers  could be reduced if pilots avoided locations where lizards gather during breeding season. Another remedy could be flying high enough to lower noise at ground level to below 50 dB.

Journal reference: Kepas, M.E., et al.  Behavior, stress and metabolism of a parthenogenic lizard in response to flyover noise.  Frontiers in Amphibian and Reptile Science, 29 March 2023,
Section: Behavior, Evolution and Ecology, Volume 1 – 2023 |