A sea turtle boom may be hiding a population collapse

A sea turtle boom may be hiding a population collapse Skip to content Subscribe today Every print subscription comes with full digital access Subscribe Now Menu All Topics Health Humans Anthropology Health & Medicine Archaeology Psychology View All Life Animals Plants Ecosystems Paleontology Neuroscience Genetics Microbes View All Earth Agriculture Climate Oceans Environment View All Physics Materials Science Quantum Physics Particle Physics View All Space Astronomy Planetary Science Cosmology View All Magazine Menu All Stories Multimedia Reviews Puzzles Collections Educator Portal Century of Science Unsung characters Coronavirus Outbreak Newsletters Investors Lab About SN Explores Our Store SIGN IN Donate Home INDEPENDENT JOURNALISM SINCE 1921 SIGN IN Search Open search Close search Home INDEPENDENT JOURNALISM SINCE 1921 All Topics Earth Agriculture Climate Oceans Environment Humans Anthropology Health & Medicine Archaeology Psychology Life Animals Plants Ecosystems Paleontology Neuroscience Genetics Microbes Physics Materials Science Quantum Physics Particle Physics Space Astronomy Planetary Science Cosmology Tech Computing Artificial Intelligence Chemistry Math Science & Society All Topics Health Humans Humans Anthropology Health & Medicine Archaeology Psychology Recent posts in Humans Health & Medicine A simple shift in schedule could make cancer immunotherapy work better By Elie DolginFebruary 12, 2026 Health & Medicine This baby sling turns sunlight into treatment for newborn jaundice By Elie DolginFebruary 12, 2026 Health & Medicine Antibiotics can treat appendicitis for many patients, no surgery needed By Laura DattaroFebruary 10, 2026 Life Life Animals Plants Ecosystems Paleontology Neuroscience Genetics Microbes Recent posts in Life Oceans Evolution didn’t wait long after the dinosaurs died By Elie Dolgin8 hours ago Animals A sea turtle boom may be hiding a population collapse By Melissa Hobson10 hours ago Ecosystems Food chains in Caribbean coral reefs are getting shorter By Erin Garcia de JesúsFebruary 11, 2026 Earth Earth Agriculture Climate Oceans Environment Recent posts in Earth Oceans Evolution didn’t wait long after the dinosaurs died By Elie Dolgin8 hours ago Earth Earth’s core may hide dozens of oceans of hydrogen By Nikk OgasaFebruary 10, 2026 Animals Some dung beetles dig deep to keep their eggs cool By Elizabeth PennisiFebruary 4, 2026 Physics Physics Materials Science Quantum Physics Particle Physics Recent posts in Physics Physics A precise proton measurement helps put a core theory of physics to the test By Emily ConoverFebruary 11, 2026 Physics The only U.S. particle collider shuts down – so a new one may rise By Emily ConoverFebruary 6, 2026 Physics A Greek star catalog from the dawn of astronomy, revealed By Adam MannJanuary 30, 2026 Space Space Astronomy Planetary Science Cosmology Recent posts in Space Astronomy This inside-out planetary system has astronomers scratching their heads By Adam MannFebruary 12, 2026 Space Artemis II is returning humans to the moon with science riding shotgun By Lisa GrossmanFebruary 4, 2026 Physics A Greek star catalog from the dawn of astronomy, revealed By Adam MannJanuary 30, 2026 News Animals A sea turtle boom may be hiding a population collapse Warming temperatures disproportionately produce female sea turtles even as populations grow A loggerhead turtle heads back towards the sea after nesting. The incubation temperature of her eggs will determine the sex of the hatchlings. The Eizaguirre Lab By Melissa Hobson 10 hours ago Share this:Share Share via email (Opens in new window) Email Click to share on Facebook (Opens in new window) Facebook Click to share on Reddit (Opens in new window) Reddit Click to share on X (Opens in new window) X Click to print (Opens in new window) Print Listen to this article This is a human-written story voiced by AI. Got feedback? Take our survey . (See our AI policy here .) Around the world, many conservationists are celebrating increases in sea turtle population growth. Cape Verde in West Africa now has 100 times as many loggerhead turtle nests each year as there were in 2008. But scientists warn that this apparent success could be hiding an impending population collapse. Using drone surveys and 15 years of nesting data, scientists at Queen Mary University of London report that booming nest counts could be misleading. As global warming causes temperatures to rise, more sea turtle eggs are developing into females. Without enough males, even a seemingly thriving population can collapse. Their findings, which are yet to be peer-reviewed, were posted January 20 to bioRxiv.org. Sign up for our newsletter We summarize the week's scientific breakthroughs every Thursday. “We think that there’s a bit of a mirage,” says Christophe Eizaguirre, a conservation geneticist at Queen Mary University. Conservation efforts, such as marine protected areas, fishing regulations and protecting egg clutches, are helping populations, but may not provide the full picture. As in some other reptiles, such as crocodiles, a sea turtle’s sex is dependent on the egg’s incubation temperature. Eggs that develop in warmer sand become female, while cooler conditions create males. “The way we describe it in my lab is ‘hot chicks and cool dudes’,” says Jeanette Wyneken, a biologist at Florida Atlantic University in Boca Raton, who wasn’t involved in the study. Using drones, the scientists photographed the breeding population and found a 9–1 ratio of females to males. “We can differentiate between females and males by the tails,” says biologist Fitra Arya Dwi Nugraha, also at Queen Mary University. “Males have longer and thicker tails.” It’s believed that a temperature of about 29 degrees Celsius produces a roughly even split between male and female hatchlings. “We don’t know what a perfect population should look like,” Eizaguirre says. The authors hypothesize that the extreme skew toward female loggerheads (Caretta caretta) that go on to lay eggs inflates the nest count, making the population seem healthier than it is. Without enough males to sustain breeding, population growth could quickly vanish, though it’s hard to predict when this tipping point could arrive. Wyneken has concerns about the study’s methods, particularly in determining the ratio. Although adult males can be identified by drone, it’s harder to tell with subadult individuals, which can be comparable in size to females. “It’s possible that they are counting some immature males as females,” she says. “The 9–1 may be more skewed than normal if it’s got that error.” It’s more accurate, she says, to confirm hatchling sex through a laparoscopy surgery. Turtles have evolved strategies to protect against a female bias: Males can mate more frequently than females, females store sperm to maximize how many clutches of eggs they can f