Network for Endangered Sea Turtles 24 HR. HOTLINE 252-441-8622

DNA Study

by Karen Johnson

UPDATED May 2024: Since 2010, N.E.S.T. has participated in a multi-state genetics research project to answer several basic sea turtle nesting questions. By collecting an egg from every nest, biologists can use DNA genetic fingerprinting (CSI for sea turtles) to identify individual sea turtle females, to gather information about sea turtle nesting behavior and habits, and to provide a census of the actual nesting population. In the area monitored by N.E.S.T., over 330 DNA samples have been analyzed with over 180 unique individual female “fingerprints”.

This data gives us a good idea of:

  • The species of the turtle – Loggerhead (our most common), Green, Kemp’s Ridley, Leatherback, or even a surprise Hawksbill
  • How many clutches of eggs (nests) each nesting female lays in a year
  • Whether the turtle is nesting on more than one beach
  • How close together or far apart each individual turtle lays her nests, both within the same summer and from year-to-year
  • The number of turtles nesting in more than one state
  • How often each turtle nests; every two years, three, more, less?
  • How precisely a daughter returns to her hatching beach to lay her own eggs
VDNA sample vial with DNA (turtle egg shell) sample inside
The viral DNA vial shown above uses alcohol as a preservative.  The eggshell from the egg contains maternal DNA.  The embryo is sacrificed and shell is placed in the vial for shipment to the lab.

Cool facts we have learned about turtles in our nesting population (turtles laying at least one nest between Nags Head and the VA/NC state line:


Some turtles have been very site specific, nesting in a very limited range.

  • Ten turtles have nested exclusively between the NC/VA state line and Oregon Inlet and returned more than one season.
  • One turtle laid two nests within a third of a mile of each other in Kitty Hawk in 2012. In 2019, she again laid two nests one-half mile apart in Kitty Hawk in the same area as in 2012! When she returned in 2022, she laid one nest that season in Duck.
  • A 2016 mom laid three nests that were all located in Nags Head within 3 miles of each other. So far, 2016 has been her only nesting season.
  • A turtle in 2020 laid four nests in a 5-mile area in Nags Head; three were less than 2.5 miles apart.
  • A new mom in 2022 laid four nests in Duck, less than 4 miles apart!
  • A turtle laid one nest in her first season in 2015. She returned to lay five nests in 2018, 2020 and 2022; all sixteen nests within a range of less than 7 miles.
  • A Green Sea Turtle who began nesting in 2021 in Nags Head and returned in 2023 has laid all her nests within a 7-mile stretch. Her sister, however, laid her first nest on Bald Head Island and her second just a few miles south of Nags Head at Pea Island. This is very interesting as it is thought that they hatched the same year and maybe even from the same nest.

Some turtles are far less site specific, nesting up and down the coast in multiple states. In NC, the average distance between nests for a loggerhead turtle mom is 81.9 km 51.7 miles) which is more traveling between nests than in other states which show the average distance is only 31.8 km  (19.6 miles).

  • The maximum distance between nests by any of N.E.S.T.’s turtles is 556 miles. In 2017, a turtle began her nesting in Florida laying two nests. She then traveled to NC laying three (possibly four) more nests as far north as Corolla.
  • In 2018, a turtle began her nesting in Florida, traveling up almost to the NC/VA border to lay a nest in Carova – 546 miles from her first nest.
  • It is not as though the turtles just keep moving up the coast laying nests. They tend to jump north and south throughout the nesting season. In 2019, two first-time nesting moms were long distance travelers. One laid her first nest in Vilano Beach, FL, traveled to Corolla for her next nest, and then finished south in Fort Fisher, NC. Another mom had an impressive nesting season laying at least five (and possibly up to seven) nests. She began in Holden Beach, NC, went south to Cumberland, GA, then back even further north to Southern Shores, winding up her first nesting season. A turtle whose first nesting season was in 2019, beginning at Cape Hatteras,  traveled to Northern FL to end the season. She waited 3 years to lay four nests in NC, one nest in the Northern Outer Banks in Carova very close to the NC/Va state line.
  • An impressive turtle who has been nesting since 2011 and has laid over twenty-five nests (eight in the Northern Outer Banks). Up until 2021, she laid four or five nests a season. In 2021, she laid six, maybe seven, nests. She nested in 2011, 2013, 2016, 2019, 2021 and in 2022, when she laid one nest in Cape Hatteras National Seashore.  over the years she has nested on ten different beaches from FL to VA.

Previous studies suggest that individual loggerheads average three to four nests a season and return every two years. Results from our data show interesting variations.

  • To date, turtles have laid one to eight nests in a season in NC; the average number of nests laid by turtles is 3.6 per year. For the entire study area (NC-SC-GA-FL-VA-MD),  the average is over six nests.
  • Nesting in consecutive years is not common but one turtle laid nests in 2012 and 2013! She waited three years before nesting again in 2016. She returned in 2018  laying four, possibly five nests. In both the 2020 and 2022 seasons, she laid six nests!  with the exception of her first nest in 2012, which she laid in Corolla, this turtle lays her nests in a 30-mile area from Nags Head to Salvo.
  • Nesting histories show that turtles may nest every other year, or every 3 years, or 4 years, and some even vary the gap between nesting seasons. For example, a turtle  who began nesting in 2011, returned in 2012, then 2016, skipping seasons to return in  2020, then 2 years later.
  • In the 2021 nesting season, four returning moms had wide gaps since their previous nests – 6, 8, 9 and 10 years! In 2022, three of our Northern Outer Banks turtles  returned after many years – one after 9 years, one after 10 years and one after 11  years! What’s up with that! Another mom, who only nests in the Northern Outer Banks, made a return in 2022 after a 5-year hiatus.

Looking at the DNA analysis from recent nesting seasons, we have learned the following interesting facts and nesting behaviors of sea turtles who nested in the Northern Outer Banks.


Total Number of Nests

Species     NC         Northern OBX    
  2019 2020 2021 2022 2023 2019 2020 2021 2022 2023
Loggerhead 2293 1335 1448 1906 1615 27 35 32 41 31
Green 63 44 40 41 97 0 1 6 4 6
Kemp’s Ridley 2 8 9 7 5 1 0 0 2 0
Leatherback 0 0 0 4 6 0 0 0 0 0


In the 2022 nesting season:

  • The first nest laid in NC was May 4 at Fort Fisher State Recreation Area by a Loggerhead; the first nest laid in the Northern Outer Banks was May 29, also by a Loggerhead.
  • The last nest laid in 2022 in NC was October 29 at Cape Hatteras National Seashore by a Green. The last nest laid in the Northern Outer Banks was laid by a Loggerhead on August 28.
  • Nine new moms in 2022. All nested in NC, except one left for South Carolina to lay two more nests after laying her first nest in Corolla.
  • Nesting histories show that three turtles who returned in 2022 lay nests exclusively in  the Northern Outer Banks. One turtle has been nesting since 2012!
  • The turtle who traveled the greatest distance, over 500 miles from GA, where she laid  her first nest, to Kitty Hawk, to lay her second. She returned to GA to wind up her  2022 nesting season with two more nests.
  • A Loggerhead who has been laying nests since 2011 every 2-3 years, and laying at  least six nests in 2021, returned in 2022 to lay one nest at Cape Hatteras National  Seashore. She has nested on ten different beaches over the years. 

In the 2023 nesting season:

  • The first nest laid in NC was May 6 at Masonboro Island by a Loggerhead; the first nest in the Northern Outer Banks was laid on June 1, also by a Loggerhead. The last nest laid in 2023 in NC was by a Green on December 3 at Cape Hatteras National  Seashore; the last nest laid in the Northern Outer Banks was August 30, also by a  Green.
  • The above-mentioned Green also laid the last nest in the Northern Outer Banks in  2021, the turtle’s first nesting season. Up until that time, only four Green nests had  been laid in the Northern Outer Banks. In 2021, she laid at least three nests, however,  based on crawl patterns to three other nests typical of a Green, that were consistently  laid every two weeks from mid-July to October 2, we think she may have laid six nests  in the Northern Outer Banks! In 2023, she laid four, and maybe five, nests, most of which were located within a 7-mile stretch.
  • Seven turtles were first time moms, all Loggerheads. Six laid three or more nests, and one turtle laid an impressive five, maybe even seven, nests in her first season! Of our  returning moms, one has been nesting since 2011. It is also interesting to note that  she laid her nests 2 years apart in 2011, 2013 and 2015, but she did not return to nest  until five years later in 2020. Three returning turtles nest exclusively in the area  between Oregon Inlet and the NC/VA border.
  • One new mom laid her first nest on the southern end of Hatteras Island, then traveled  north to lay two nests about a third of a mile apart in Nags Head. Her final nest of the  season was laid a mere seven miles south in the Bodie Island area of Cape Hatteras  National Seashore. 

**** N.E.S.T.’s work is done under and is in compliance with Endangered Species Act Permit 22ST10 and complies with all NCWRC permit requirements