By Peter Vankevich
North Carolina’s approximately 330 miles of ocean-facing sandy beaches provides prime nesting habitat for five species of sea turtle: loggerheads, green, Kemp’s ridley, leatherback and the extremely rare hawksbill.
Statewide, a total of 1,723 nests were monitored, slightly down somewhat from last year’s nearly record high number of 1,958 nests, according to Seaturtle.org, an organization that supports sea turtle research and conservation.
The vast majority of these nests are laid by loggerhead sea turtles, but this season did bring some surprises. Green turtle nests increased from 41 last year to 99.
But the big news was six leatherback turtle nests.
Last year there were four leatherback nests statewide with one on Hatteras Island.
None of them produced any hatchlings.
So, it was with a bit of jubilation when on Aug. 28 on Ocracoke Island 71 hatchlings emerged from the 93 eggs laid.
The other five nests were on Cape Lookout National Seashore. According to Jon Altman, Cape Lookout’s supervisory biologist, three nests were impacted by tropical storm erosion or flooding. Of the two nests from which hatchlings emerged, one produced 83 hatchlings.
The other nest hatched but was later destroyed by coyotes.
Sea turtles can lay eggs multiple times in the same year.
It is not yet known whether just one female was responsible for the six nests, but that will be determined later when a DNA analysis is made of eggs and eggshells from each location.
Cape Hatteras National Seashore, comprising Hatteras, Ocracoke and part of Bodie islands, had a total of 378 nests said Meaghan Johnson, chief of resource management and science, in an interview on Oct. 26. From these nests, 20,305 hatchlings emerged.
“This is on a par with last year’s 379 nests,” she said. Ocracoke had 112 of these nests.
Statewide, a total of 108,788 hatchlings emerged. The average for a nest is 114 eggs and incubation is 57 days.
If these numbers seem high, they should be. Once hatchling emerge, they begin a perilous journey including the short distance to the ocean where predators may be lurking, including ghost crabs, gulls, night herons and mammals.
Coyotes contributed to significant nest and egg losses on Hatteras Island and the Core Banks of Cape Lookout.
On Ocracoke, there is one confirmed coyote and coyote tracks have been seen recently on South Point.
“We’ve seen an increase in coyote predation on our sea turtle nests in our nesting shorebirds this season,” Johnson said. “We do have a full-time predator management specialist for the Seashore who’s helping us do trapping throughout the year.”
They also work with USDA for predator trapping and have an agreement with NC State University to do a coyote population study at both seashores to try to understand how many we have.
Once the baby turtles are in the water, a new set of predators await: carnivorous fish and sharks, among others.
One unsubstantiated estimate is only about one in 1,000 hatchlings may make it to adulthood.
In addition to predation, sea turtle nesting failures are caused by bad weather events.
Nests can survive short durations of overwash from extreme high tides or the swells of out-to-sea hurricanes, but if the duration is prolonged, erosion will wipe them out or water will seep into submerged nests and drown the eggs, said Amy Thompson, the NPS biological technician for Ocracoke.
“And this year on Ocracoke is the first time that I’ve realized that not just ocean overwash but frequent periods of heavy rains for a long period of time can actually fill up a nest cavity as well and affect the survivability of those eggs,” she said.
Sea-turtle nests laid too close to the ocean or in a dangerous section of beach are often relocated to safer areas.
With the anticipated overwashes this year, a high number, 100 nests, were relocated closer to the dunes.
By Peter Vankevich