Father’s Day Terrapins Reveal Sippican Secrets

Lucky Terrapin 777 Survived Massive Trauma

Patience!  When you take on turtle research, you intuitively expect that patience will be an important virtue to master.  When you conduct a longitudinal study of turtles, with the emphasis on “LONG” in longitudinal, the virtue of patience becomes the cornerstone of success.  So Turtle Journal has learned and relearned through the years … and decades.  Yet, every so often comes a particular turtle and a special discovery that drive home the critical importance of observing activities and maintaining meticulous records over long periods to uncover the secret lives of diamondback terrapins.

Terrapin #777 Nesting on West Shore of Outer Sippican Harbor

In correspondence earlier this week, we had restated our most important goal of discovering where turtles from the Sippican Harbor mating aggregation nest.  We have been following females in this aggregation since 2003; yet, we have been unsuccessful so far in verifying their nesting sites by finding a marked turtle from the aggregation on a nesting beach.  This Father’s Day morning, Don serendipitously diverted his Sunday run  to inspect some scattered beaches on the west shore of Outer Sippican Harbor for signs of nesting activity.  The tide was all wrong, so finding a nesting terrapin was out of the question.  Except there she was!  Tucked away in a quiet spot, mostly camouflaged, lay Terrapin #777 atop her nest.

Massive Shell Injury on Terrapin #777

This lucky lady had sustained massive shell trauma early in her life.  Turtle Journal had captured her in the Sippican Harbor mating aggregation on June 25th, 2005.  Her carapace had sustained significant injury; marginal scutes across the entire front were missing, as well as in the rear, making her very vulnerable.  We marked her “777″ largely because those scutes were still present, but also to signify her good fortune to have survived.  Now, we have been equally blessed by #777, as she is the very first turtle from the Sippican mating aggregation to have been found on a nesting beach.  And it only took a decade of observations during our SouthCoast longitudinal study to discover.  Patience!

Tabor Academy Schaefer Lab Terrapin Tracks

Also serendipitously during today’s run, Don discovered nesting activity at Tenbrook Beach off Tabor Academy’s Schaefer Lab.  This area had been one of the first nesting sites discovered on the SouthCoast by Sue Wieber Nourse when she and her students had confirmed the presence of terrapins in this estuary back in 2003.  As holder of the Jaeger Chair in Marine Studies, Sue had her students document terrapin nesting at the Schaefer Lab site with the Massachusetts Natural Heritage & Endangered Species Program.  Unfortunately, after Sue left Tabor Academy, the nesting beach was converted to a kayak storage area, blocking access for these threatened critters to their natal nesting site.  Reading the tracks this morning, Don noted the turtle had tried several unviable scrapes around the kayaks and then had returned to the harbor without depositing their eggs.

 

Freshly Laid Diamondback Terrapin Nest

Finding nests is another turtle secret that Don oft ascribes to “divination.”  Reading tracks is a fundamental skill gained through patience and practice during a decades long longitudinal study.    The photograph above is “as good as it gets” for identifying a terrapin nest.  Fortunately, we had come across this section of barrier beach shortly after the turtle had concluded her nesting run.  As all terrapins do, she covered it over and disguised the shaft and egg chamber.  The last step for the turtle is to tap down the sand atop the nest, and then crawl away without leaving any detectable foot prints.  Unfortunately for turtles, as they dig and cover the nest, they blend top sand with bottom, and moisture darkens the color of the surface for a few minutes until bay breezes dry the mixture into a common, undistinguishable hue and pattern.  Through patience and long pracitce, it becomes easier for a reasearcher to “read” surface markings like a legendary tracker of old.  Or as Don might say, a researcher learns the dark art of divination.

Top Layer of Freshly Laid Terrapin Eggs Exposed

Brushing the topsoil with the side of his hand and then probing gently with his fingertips, Don found the “sweet spot,” the shaft that leads to the broader egg chamber.  The sweet spot is called sweet because even though it has been refilled with sand, the shaft feels softer than the surrounding soil.  Bright pink eggs, still slightly soft to the touch, indicate an extremely fresh nest.

Don Lewis Excavates Diamondback Terrapin Nest

Like excavating a delicate archeological site, Don continues to investigate with his fingertips and removes eggs from the shallow chamber to relocate them to a more viable location.  This area of barrier beach is regularly patrolled by raccoons, skunks and foxes in search of protein for their young and themselves.  Nests left to their own are depredated at a rate greater than 90%.

Freshly Laid Diamondback Terrapin Eggs

This particular nest held seven extremely large eggs weighing in the range of 10 to 11 grams and measuring between 3.5 and 3.9 centimeters in length.  In total they weighed 74 grams and should produce very healthy baby hatchlings in another 60 to 75 days of incubation in a safe turtle garden.  After they hatch, the babies will be brought back to their natal site for release into the abutting nursery salt marsh.

Rufus Salutes Terrapin #299 on Completing Her Nest

Terrapin #299 has recovered from severe trauma to both forelimbs that  hinders her ability to nest.  So, we watch her each season with great loving concern to ensure that her offspring get a boost toward survival.  We’ve been observing #299 since July 2005 when she laid a nest of 16 eggs in an overwash area of the causeway to the barrier beach.  Those vulnerable eggs were harvested and brought to Tabor Academy’s Schaefer Lab for incubation and study by Sue Wieber Nourse’s advanced marine science class in field studies, an award winning, hands-on science research program now discontinued at the school.   Sue and her students released all 16 babies back in their natal nursery marsh in September 2005.  This year, Terrapin #299 has been crawling around the barrier beach at Aucoot Cove since May 31st trying to deposit her first nest of the year.     This morning, she finally completed her nest and Rufus the Turtle Dog saluted #299 for her outstanding work.

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