Sea turtle nesting season: Record-breaking resilience
Sea turtle nesting season begins Again on May 1 following a banner year in 2022.
Story by Amber Kuehn + Photos by Tudor Pearce
The last nest of the 2022 sea turtle nesting season hatched on Hilton Head on October 14. Nest #386 weathered Hurricane Ian’s storm surge with five other nests and was not expected to hatch. Sea Turtle Patrol HHI excavates and performs an inventory on hatched nests (three days after emergence) and on unhatched nests that have been incubating for 70 days, per guidelines set forth by a permit from the SC Department of Natural Resources. Nest #386 incubated for 69 days and hatched with one day to spare with 64 percent emergence success. I am reminded that I will never know it all and that sea turtles will always amaze me with their resilience.
Overall, the emergence success of all 423 nests combined was 76 percent, which is a record for Hilton Head’s beach. In the 2022 season 36,314 hatchlings emerged from their nests. Contributing to this success was the experience of staff and technology behind the relocation of 241 nests (57 percent).
A digital line was added to our GIS map in 2020 to document the king high tide. With this reference we can predict the water level during extreme tidal events. Our beach is constantly changing, and updates will need to be made for the 2023 nesting season, which begins May 1. A full-scale renourishment of Hilton Head’s beach will occur in 2025 to dramatically increase the sandy surface area for beach goers and sea turtle nesting habitat.
The complete analysis includes nests that had less than 50 percent emergence success. The majority of them, 29 nests (58 percent), were laid in approximately one month, July 1 – August 6; 25 percent of 116 nests laid during this time period were affected. This result raises a red flag. My theory suggests a rainfall event on July 14 that “rain bombed” almost 4 inches of rain in a short period of time. When the beach gets saturated, the water pools inside the nest chamber from the bottom up, and nothing can be done. In this case the eggs at the top of the nest will have the best chance of survival. Most of the unsuccessful eggs died in early development, as they had just been laid. Without getting too technical, some parts of the beach “perc” just a little better than others based on compaction.
Unfortunately, hatchlings from 19 nests were affected by artificial lighting. Since the Town Council passed the revised lighting ordinance in March 2021, instances have decreased from 28 nests affected by artificial lighting in 2021. Although the 2022 numbers reflect almost 2,000 hatchlings lost to lighting-ordinance violations, we must look at the silver lining and continue to reduce that number through outreach and education.
We continue to work tirelessly on our LIGHTS OUT campaign that was officially initiated in 2020. We must get the turtles to the water. Only 1 in 1,000 will make it back to nest at the age of sexual maturity in 30 years. Several opportunities to learn more about sea turtle beach etiquette and preservation will be offered and announced on our website (SeaTurtlePatrolHHI.org) in March/April to prepare for the 2023 nesting season. Our training sessions will be free of charge at USCB Hilton Head campus. I hope to see you there.
76 percent hatchling emergence success
423 nests on HHI
Last nest hatched October 14
57 percent of nests relocated to avoid tidal inundation
29 of 50 nests with less than 50 percent emergence success due to rain saturation
Hatchlings from 19 nests affected by artificial beachfront lighting
Hatchling Emergence Success
(Percentage of emergence success of all sea turtle nests on Hilton Head Island)