‘Millie,’ the green sea turtle SCCF encountered most frequently during the 2023 nesting season.

The SCCF sea turtle team has been busy analyzing the nesting data they collected last summer, including data from our nighttime sea turtle tagging project.

From May through July, the nighttime tagging team conducts nightly beach patrols on Sanibel in search of nesting turtles. Each encountered turtle is tagged with flipper tags and a microchip called a Passive Integrated Transponder (PIT) tag if they don’t already have one. Our team chooses a theme each year for “naming” newly tagged turtles, and the theme for 2023 was female musicians.

“These tags allow us to track an individual’s nesting and movement patterns, so we can learn more about sea turtles’ reproductive behavior and identify trends,” said SCCF Sea Turtle Biologist Savannah Weber.

Along with nighttime tagging data, the team also assesses the hatch success (or % of the nest that hatched) for each nest to estimate how many hatchlings were produced from that individual’s nest.

Weber, who oversees the nighttime tagging project, shares some stories below about some of the most unforgettable turtles we encountered on Sanibel in 2023.  

Most Encountered Turtles: Pat Benatar and Cyphoma

Sea turtles typically nest anywhere from two to seven times during a nesting season, and generally return to nest every two to three years.

“The nesting process can take anywhere from one to three hours, and not every turtle is encountered by our nighttime team. The majority of sea turtles that nest on Sanibel are loggerheads, so it’s no surprise that the two turtles we encountered the most in 2023 were both loggerheads,” Weber said.

The first of these turtles, AKA ‘Pat Benatar,’ was first encountered by our team in 2023. She was observed nesting twice and false crawling (coming ashore without laying eggs) six times.

“Unfortunately, one of her nests was depredated by coyotes, but the other nest had an 84.8% hatch success, resulting in 56 hatchlings making it to the ocean!” Weber said.

The other loggerhead encountered most often in 2023 was Cyphoma (named after the sea snail shell), who was first tagged on Sanibel in 2016 and encountered again in 2020. During this past season, SCCF observed her nesting six times and false crawling twice.

“Unfortunately, some of her nests exhibited low hatch success due to coyote depredation and wash-overs from Hurricane Idalia,” Weber said. “Overall, her nests produced a total of 50 hatchlings”

In 2023 we also encountered four unique green sea turtles, with ‘Millie’ being our most frequently encountered green. Millie was first tagged in 2017 and returned to Sanibel in 2019 and 2021. In 2023, she was observed nesting five times, and two of these nests hatched to produce 77 hatchlings.

“The nighttime team doesn’t observe every turtle that comes ashore along the 11 miles of surveyed beach, so it’s possible that these females nested and/or false crawled more often, but were never encountered,” Weber said. “Regardless, we hope to see these nesting female turtles return for another season in the future!”

Highest Number of Hatchlings Produced

The highest number of hatchlings produced was from ‘Fergie,’ another loggerhead encountered for the first time on Sanibel in 2023. We encountered her laying a total of four nests, all of which hatched and collectively produced 212 hatchlings that made it to sea.

The next highest was from ‘Candystick Tellin’ (another shell-themed name), a loggerhead originally tagged on Sanibel in 2016 and observed again in 2018 and 2021. This past summer she laid four nests, which produced a total of 191 hatchlings.

Smallest and Largest Turtles Encountered

“One of our biggest loggerhead turtles, Raspberry, also had high reproductive success this year,” Weber said. “Her two nests had a hatch success of 74.2% and 93.6% and produced 184 hatchlings.”

Raspberry’s shell measured a whopping 112.9-centimeter curved-carapace length, which is almost 4 feet long. She seems to be on a cycle of returning every three years, as she was first encountered in 2017, then in 2020, and now again in 2023.

The smallest turtle we encountered this past summer was a loggerhead seen on Sanibel for the first time in 2023. Her shell measured 75.7 centimeters (around 2.5 feet long), and she was appropriately named ‘Little Mix.’

Little Mix was encountered laying one nest, which had a 93.1% hatch success rate and produced 54 hatchlings.

“By tagging and identifying the nesting female sea turtles on Sanibel, we can track long-term trends among individuals, such as where the turtle chooses to lay a nest, how often they nest, and how successful their nests are,” Weber said.