Too-Familiar Refrain About Florida Turtles: 'It's a Girl'

Wildlife experts in Florida keeping watch on sea turtle eggs have had an easy job of late in cataloging the gender of hatchlings—they've all been girls. "Only female sea turtles for the past four years," Bette Zirkelbach, manager of the Turtle Hospital in Marathon, tells CNN. The reason isn't some genetic fluke. Instead, it involves the state's hotter temperatures. While the gender of most animals' offspring is determined during fertilization, it's determined afterward for turtles, explains the National Ocean Service. Specifically, it's all about the temperature of the sand in which they're buried: If it's 88.8 degrees Fahrenheit or higher, the hatchlings will be girls, and if it's 81.8 degrees or lower, they'll be boys. Temperatures in between will result in a mix of boys and girls.

"The frightening thing is the last four summers in Florida have been the hottest summers on record," says Zirkelbach, whose facility is located in the Florida Keys. What's happening in Florida has been observed elsewhere: A 2018 study in Australia found that virtually all sea turtle hatchlings in parts of the Great Barrier Reef were female as well, Newsweek reported at the time. "Over the years, you're going to see a sharp decline in their population because we just don't have the genetic diversity," Melissa Rosales-Rodriguez of Zoo Miami tells CNN. "We don't have the male-to-female ratio needed in order to be able to have successful breeding sessions."

However, Insider talks to ecologist Lucy Hawkes of the UK's University of Exeter, who has been studying the matter for years. She points out that a relatively small number of males is required to fertilize eggs, suggesting that the out-of-whack male-to-female ratio may not be as dire as some fear. "If you ran out of all males, it would threaten the population—but we don't think that's going to happen too soon," she says. Also, some studies have found that wetting the eggs in a hot nest can result in male hatchlings, suggesting a potential way for human intervention to help the situation should it worsen. (More sea turtles stories.)