By Peter Vankevich
In the dark hours of May 4, a loggerhead sea turtle ventured out of her expansive ocean home and crawled onto the beach at the Fort Fisher State Recreation Area just north of Bald Head Island. She was the first sea turtle to nest this year on North Carolina’s 330 miles of sandy coastal beaches.
On Sept. 13, a green turtle crawled onto Masonboro Island, south of Wrightsville Beach, to lay her eggs. She would be one of the last to nest in the state.
In the time between these two nests, 1,955 others were reported in 25 locations, the second highest yearly number since statistics have been kept. The high benchmark was 2019 with 2,358 nests, according to Seaturtle.org, an organization that supports research and conservation of sea turtles.
Ocracoke had 115 nests this year and Hatteras Island had 255. The success of sea turtle nesting these days can be attributed to the involvement of several state and federal agencies, conservation organizations and many enthusiastic volunteers.
Loggerheads lay the majority of nests in North Carolina.
Also this year, there were 39 green, seven Kemp’s ridley and — a rarity for the state — four leatherbacks, which typically reproduce in the Caribbean.
The leatherback nests all failed, and it is not certain at this time whether they were all laid by the same female. Sea turtles will lay more than one clutch of eggs in the same season. A DNA analysis may later reveal this.
The incubation period for sea turtles is about two months and, based on data gathered from the relocation of nests that are in vulnerable areas and that have a likelihood of failure, an average of 114 eggs were laid per nest.
By Oct. 14, 142,831 hatchlings emerged and some more are expected since there are still a few incubating nests.
As impressive as these numbers are, few of them will make it to adulthood due to predators and other dangers. One unverified but frequently cited estimate made several years ago is only one in a thousand hatchlings will make it to adulthood.
Another disturbing trend is warming temperatures.
Information coming out of Florida is that all hatchlings in the last few years are female. The sex of a turtle is determined in the egg in the first 20 or so days and is determined by the surrounding sand.
Warmer temperatures of 88 degrees and above will produce female hatchlings and mostly males when the average is 84 degrees or less. Between those temperatures, a mix of sexes are produced.
With warmer sand temperatures, as is happening in Florida, the result is more females.
This imbalance could ultimately impact the species survival since females must find a male mate for fertilization prior to laying their eggs. Currently, for adult loggerheads there is already a high ratio of females over males.
Are more female hatchlings also occurring in North Carolina?
“Currently, it is challenging to directly categorize sex of loggerhead hatchlings,” said Matthew Godfrey, sea turtle biologist for NC Wildlife Resources Commission, in an email. “They are not sexually dimorphic at that stage, and they do not have sex-specific chromosomes.”
He said most estimates of hatchling sex ratios use nest temperatures of eggs during incubation or sand temperatures at nest depth during the times when eggs are incubating on the beach.
Because the nesting period goes from May into September, the sand temperatures may be cooler in the early season and again in September and those hatchlings may be a mix of male and female.
And weather conditions vary from year-to-year. When there are years with lots of rain, the sand temperatures would be cooler, which could mean more males.
“Currently, we estimate that male hatchlings continue to be produced each year in North Carolina, although the proportion likely varies from year-to-year,” Godfrey said.
If there is a disparate proportion of females for the past several years and onward, the impact of fewer males will not be known for some time. Loggerheads do not begin laying eggs until they are about 30 years old.