Flyovers Affect Colorado Checkered Whiptails Physiologically

Researchers looked at how noise from low-flying military aircraft affected the behaviour and health of rare Colorado checkered whiptails (Aspidoscelis neotesselatus).

Flyovers Affect Colorado Checkered Whiptails Physiologically

Although lizards are small, they usually have good hearing. Researchers looked at how noise from low-flying military aircraft affected the behaviour and health of rare Colorado checkered whiptails (Aspidoscelis neotesselatus).

This was carried out at the US military installation of Fort Carson, which is close to Colorado Springs and frequented by Apache, Chinook, and Blackhawk helicopters that transport aircraft as well as F-16 fighter jets that fly over the whiptails’ habitat.

Frontiers in Amphibian and Reptile Science published the findings. The US Army’s active cooperation in the study, the authors emphasised, was a necessity.

“Here, we demonstrate that Colorado checkered whiptails are physiologically affected by noise disturbance. We also demonstrate that they are somewhat resilient and that they may adjust their feeding and movement patterns to some extent as a form of compensation “said the first author, doctoral candidate at Utah State University Megen Kepas.

The US Army classifies A. neotesselatus as a “species at risk,” and Colorado Parks and Wildlife classifies it as a “species of special concern.” The species only consists of triploid females that reproduce asexually and is native to shrubland and mixed grassland along dry rill beds in southeast Colorado.A. neotesselatus populations exist on the 550 square km of land belonging to Fort Carson, including the 0.05 square km of ‘Training Area 55’ (TA55).

Aircraft regularly fly over TA55 at altitudes below 6km, and Kepas, Sermersheim, and colleagues conducted an experimental study in 2021. On flyover dates, noise readings at ground level ranged from 33.9 to 112.2 dB, while on non-flyover dates, they ranged from 30.1 to 55.8 dB.

The researchers watched unmarked people for three minutes in the morning and early afternoon, then caught as many as they could. There was only one capture per female.

The lizards were weighed and measured; blood was drawn to measure hormone levels; and portable ultrasounds were used to identify which females were pregnant and, if so, to count and measure the size of the developing eggs. Females caught were marked in accordance with IACUC-approved protocols.

The researchers measured the concentrations in preserved blood samples of the stress hormone cortisol, glucose, ketones, and reactive oxygen metabolites (ROMs) released by the mitochondria under oxygen stress.

They found that Colorado checkered whiptails at Fort Carson show a stress response to aircraft flyovers, even after accounting for individual differences in body size and reproductive investment. However, glucose, ROMs, and ketone concentrations weren’t affected by flyovers.

The findings demonstrate that the lizards’ increased blood cortisol and ketones levels in response to flypast noise are signs of a stress response that quickly releases more energy reserves.

Cortisol levels increased more frequently in females who had more developing eggs, suggesting that these females may be more sensitive to noise disturbance. The whiptails’ behaviour showed the most obvious effects: when exposed to flypast noise, they spent less time moving around and more time eating.

“Through compensatory eating, people could stay energised throughout a stressful situation. This is significant because energy is needed for metabolism, physical activity, investment in reproduction, and hormonal reactions, “Sermersheim said.