Researchers at Florida Atlantic University’s Charles E. Schmidt College of Science have conducted a study examining whether higher nest temperatures impact the cognitive abilities of loggerhead sea turtle hatchlings. The research, published in Endangered Species Research, is the first to test if incubation temperature affects how well these turtles can learn and adapt.
The study focused on eggs collected from Palm Beach County beaches during 2019 and 2020. Hatchlings were incubated at two female-producing temperatures, 88 F and 91 F, then tested using a Y-maze with visual cues. In the initial phase, turtles learned to associate a food reward with a specific pattern. In the reversal phase, researchers switched the rewarded pattern to see if hatchlings could adapt to new information.
Results showed no significant differences in learning ability between groups incubated at different temperatures. In both years, hatchlings completed both acquisition and reversal tasks successfully. Notably, in 2020 they learned faster during the reversal phase than during initial training.
“Not only were the post-hatchlings capable of suppressing previously learned behaviors to form new, more advantageous associations, they were able to do so with remarkable speed – often requiring fewer trials than the initial learning phase,” said Sarah L. Milton, Ph.D., senior author and chair and professor in the FAU Department of Biological Sciences. “This surprising level of behavioral flexibility suggests that these young turtles may be better equipped to navigate and adapt to rapidly changing environmental challenges than we previously understood. Such adaptability could prove crucial for their survival in an increasingly unpredictable world.”
Despite this finding, higher incubation temperatures had negative effects on physical traits. Hatchlings from warmer nests had shorter incubation periods, lower hatching success rates, slower growth after hatching, more frequent shell anomalies (scute defects), and smaller body size—factors that could hinder swimming performance and predator avoidance.
“The concern remains very real,” said Ivana J. Lezcano, corresponding author and a doctoral candidate in FAU’s Department of Biological Sciences. “Elevated incubation temperatures are known to produce smaller, less physically resilient hatchlings and cause a significant decline in overall hatching success. Together, this can pose serious risks to population survival. However, our finding that cognitive ability and learning may remain largely unaffected, at least in the short-term, by these higher temperatures offers a hopeful perspective. It suggests that, despite other developmental and physical challenges, these turtles may retain the mental flexibility needed to adapt to their changing environments. This resilience gives us one of the first glimpses of how incubation temperature may affect behavioral traits, though ongoing research is essential to fully understand the long-term implications.”
The study only examined temperatures up to 91 F; however, sand temperatures on South Florida nesting beaches have already exceeded 93 F and reached nearly 96 F—levels known to further reduce hatching success and potentially affect brain development.
Researchers emphasized that current models for nest success typically focus on emergence rates but should also consider both physical quality and behavioral adaptability of hatchlings.
“The hatchlings in our study were able to swiftly adjust to new information despite developmental stressors,” said Milton. “This behavioral adaptability is not just a survival mechanism – it’s a critical evolutionary advantage that may enable them to cope with the complex challenges posed by their shifting habitats. Conservation efforts must prioritize not only the preservation of hatchling populations but also the environmental conditions that support their ongoing cognitive development and resilience.”
The research was supported by Florida Atlantic University’s School of Environmental, Coastal, and Ocean Sustainability within its Charles E. Schmidt College of Science.
