Seabrook Island Turtle Patrol - 2016 Analysis of Nesting Patterns

Every year, one of the Turtle Patrol’s more analytical members, Judy Morr, delves into the DNR’s archives and produces an analysis of the nesting patterns of the Loggerheads that visit Seabrook Island’s beaches..

As the Seabrook Island Turtle Patrol gets ready to begin their season on May 7, it was a good time to look back at the results for 2016 based upon the Department of Natural Resources’ DNA data.  One egg from each nest is sent to the DNR so the membrane can be used to identify the DNA of the mother of each nest.  This DNA mapping provides information about the Loggerhead Sea Turtles nesting behavior.  

Seabrook Island has participated in the program since 2010.  Here are some findings from the 2016 data.

·  59 of the 60 nests laid on Seabrook Island in 2016 have been mapped

·  Those 59 nests were laid by 46 unique mothers

·  19 of those 46 mothers had never before been identified in the system, regardless of beach

·  Those 46 mothers laid a total of 156 nests in 2016 on 26 different beaches. 

·  Of the 156 nests, 59 (37.8%) were on Seabrook Island with an additional 41 nests on Kiawah Island, 8 on Botany Bay Plantation, 7 on Folly Beach and 4 on Botany Bay.

Some of the mothers have become "friends of Seabrook Island"

·  Mother CC000530 has laid 17 nests on Seabrook Island since she was first identified in 2010.  Typically, the female turtles lay nests every two or three years.  CC000530 laid on Seabrook Island in both 2010 and 2011 and again in 2015 and 2016.  In both 2015 and 2016, she laid the first nest of the year.  She also laid on Seabrook in 2013. Her only other nests are one nest on Kiawah in both 2011 and 2013.  She averages a clutch size of 140 eggs with a 70% hatch rate.  A successful mother indeed.

·  Mother CC000570 has laid 19 nests since 2010 with the last 14 being on Seabrook Island.   She laid 6 of our 60 nests in 2016. She averages 141 eggs per clutch and an 83% hatch rate.  In 2016, 2 of her nests were on Pelican Beach and 4 were on North Beach. 

·  Mother CC009950 was a new mother to the system in 2016.  She laid 2 nests on Seabrook Island. She didn't lay any other nests in 2016.

·  Mother CC002043 laid 3 nests on Seabrook Island in 2016 after 2 here in 2013.  She laid one on Pritchards Island in years 2011 and 2016. She also visited Fripp Island twice in 2016, Kiawah twice in 2013 and Hunting Island State Park 3 times in 2011.

·  Mother CC002055 laid 7 nests on Kiawah in 2011 and 2013 before moving to Seabrook Island for 2 nests in 16.  Both of her nests were laid on North Beach.

·  Mother CC002058 has laid 4 nests on Kiawah and 12 nests on Seabrook Island since 2010.  In 2016, she laid 3 nests on each. 

Some other fun facts:

·  Mother CC006469 laid nests on 5 different beaches in 2016.  One each on Seabrook Island, Kiawah Island, Hunting Island State Park, Botany Bay Plantation and Folly Beach.  In 2013, she laid on Folly and Kiawah.

·  Mother CC008942 laid a nest on Seabrook Island on May 31 before heading all the way to Cape Hatteras to lay 2 nests in July.

·  Mother CC009122 laid a nest on Amelia Island, Florida on June 11 then laid a nest on Kiawah Island just 13 days later. It was another 31 days until she laid her nest on Seabrook Island.

·  Of the 223 mothers who have laid nests on Seabrook Island since the DNA study began, 78 laid somewhere in 2016.  36 of those 78 laid nests somewhere other than Seabrook Island.

As the years pass and more DNA data is gathered, science is providing us with a better picture of the nesting population of Loggerhead Turtles and their nesting patterns. Thanks again to Judy Morr for providing this analysis and the South Carolina Department of Natural Resources for allowing us to access their data.