Turtle Journal

 

Handsome Male Diamondback Terrapin 

Turtle Journal returned to a very active mating aggregation in Wellfleet Bay on Outer Cape Cod last Friday.  The objective of our sampling expedition was to examine male diamondback terrapins.  While mature female terrapins will be coming on to shore next month to nest, male terrapins never leave the water.  They’re much more elusive and once dispersed after the spring mating aggregation, they are difficult to track and to capture.  So, this Friday we eschewed large females and focused on the smaller males.

Typical Male Diamondback Terrapin Tail

Terrapins exhibit sexual dimorphism.  A polysyllabic word that simply means that they differ in size between genders.  In the case of diamondback terrapins, females are twice as long and wide, and four times as massive as males.  The key distinguishing feature between males and females is the tail.  Females have small thin tails and males, as demonstrated by the specimen pictured above, have long thick tails.

Where the Boys Are: Heading Back to Mating Aggregation

Who said that turtles have no personality?  Whoever they may be, it’s clear they haven’t spent much time with diamondbacks.  Here’s a small array of personalities that we found during our brief sampling adventure.

Shy

Bold

Upset 

Surprised 

Unfazed

Sue Wieber Nourse Juggles Two Females and a Male Terrapin

Turtle Journal visited the principal mating aggregation on Outer Cape Cod Saturday to assess how far along diamondback terrapins have come from winter brumation.  We met up with Barbara Brennessel as we waded into the South Wellfleet cove in search of turtles.

Male Diamondback Terrapin in Shallows of Mating Aggregaton

The water quality at this time of the year is crystal clear without time for algae formation to cloud visibility.  As adult terrapins enter into mating aggregations on the Outer Cape, they pair up at high tide in the dense salt marsh vegetation ringing the shoreline.  Above, you can clearly identify this male terrapin from its large tail as he patrolled the shallows for a mate.

Sue Wieber Nourse and Barbara Brennessel with Turtles

We found turtles at both ends of the age spectrum.  Sue Wieber Nourse holds an ancient female terrapin that measures as one of the largest (and oldest) turtles on the Outer Cape.  Barbara Brennessel shows off an exquisitely beautiful young four-year-old juvenile female which was found hiding in the dense vegetation at the edge of the cove.

Four-Year-Old Juvenile Female Diamondback Terrapin

This posting wouldn’t be complete without a close-up photograph of this beautiful young turtle.

Sampled Terrapins Released Back into Mating Aggregation 

We sampled thirteen turtles from the cove.  Eleven were adults and two were juveniles.  Ten were female and three were male.  Six were recaptures and seven were first-time captures.  All of the females for whom we had nesting records came from the sandy shores of Great Island.

 The Adorable Terrapin Couple (Male Left, Female Right)

Temperatures were cool on Saturday, April 24th, hovering in the mid-50s with a sharp breeze blowing off the Atlantic Ocean.  Still, the sun was shining and with a nothing-ventured, nothing-gained attitude, Turtle Journal waded into Fresh Brook Run south of Lieutenant Island in South Wellfleet in search of emerging terrapins.  We arrived 90 minutes before low tide and zigzaged through the submerged tidal flats before we spotted our first turtle head snorkeling for air.  Don netted a mature male terrapin snoozing on the bottom and camouflaged in a mound of seaweed.  Sue chased down a mature female about a 100 feet away as she swam for safety into deeper, more turbid water.  Together, they make an adorable couple that perfectly illustrates the gender dimorphism of the species with females twice the linear size of males and nearly four times the mass.

12-Year-Old Female Diamondback Terrapin #9055

This gorgeous 12-year-old female, smiling for the camera, had never been captured before.  She received the new identification number 9055, so that Turtle Journal can follow her exploits through the years.  She measured 18.05 centimeters straight-line carapace length and 16.4 cm plastron length with a mass of 1087 grams.  She had mating scars on her 5th (rear) vertebral and also sported a split nuchal scute.

8-Year-Old Male Diamondback Terrapin #9056

The handsome 8-year-old male had also never been seen before.  He received the number 9056.  He measured 11.4 centimeters straight-line carapace length and 9.6 cm plastron length with a mass of 245 grams.  This fellow had raised rear marginal and sported a broad, striped tail.

Release of the Adorable Couple into Wellfleet Bay

In the afternoon chill, neither turtle moved too swiftly on release.  Eventually, after more than five minutes, the female began to trudge into the surf toward Wellfleet Bay.  The male, who Don had found snoozing on the bottom, refused to budge and waited for the tide to come to him!