Previous Page Photo-Diary of a Terrapin Researcher Next Page

Don Lewis, Massachusetts Audubon Society,
Fox Island Wildlife Management Area

A Nesting Homerun — 21 June 2002

Ace intern volunteer Chris Burns returned to the Land of Ooze today after graduating from high school. 
He had hit Lieutenant Island for five minutes when he snagged his first terrapin as he was rushing to the local bait shop to prepare for an afternoon fishing expedition.  Chris found Terrapin 220 nesting at the side of the main island road.  She had dug into the shoulder but came to a quick halt when she hit asphalt under a top layer of sand.

First spotted as a ten-year-old turtle in 1990, #220 was then only 16.8 centimeters long and 700 grams.  Today she’s nearly 20 centimeters and weighed 1325 grams while still gravid.  After quickly processing her, we released her to continue her nesting run.

Chris went off to the bait shop and I found another terrapin nesting on Turtle Point. Not too easy to spot as she blended perfectly among the dune vegetation, Terrapin 1644 was just finishing her nesting (#032-02), tapping and smoothing the surface to disguise its location, as we arrived on the scene.

Probing to confirm the site, I detected the egg chamber and noted that the top egg (and presumably the last to come out) had a distorted white nodule at its tip.  The nest was re-covered and a predator excluder was installed.

But back to the story of Terrapin 220.  As Chris returned with his bait, he rediscovered #220 now nesting along the shoulder of the island causeway.  She hollowed out her egg chamber, deposited her clutch, disguised the nest, and began to scoot back into Loagy Bay when she was recaptured.  We weighed her again to discover she had lost 118 grams (1325 minus 1207).  The nest (#033-02) had been dug in an extremely vulnerable location.  The causeway is one lane, and at this point the shoulder becomes a parking and passing spot for delivery trucks.  So, we relocated the nest to a nearby safe spot, giving us an opportunity to examine and weigh the clutch, which consisted of 14 perfect, pink, and moist eggs.  They weighed — no surprise — 118 grams.

So, we captured Terrapin 220 inbound and weighed her gravid.  We caught her outbound and weighed her again after depositing her eggs.  We found her nest and discovered the clutch size and its total weight.  And now to stretch this research triple into an inside-the-park homerun, we placed the eggs in a new “natural” nest site and covered it with a predator excluder.  With due diligence and a little luck along the way, we hope to see 220’s hatchlings emerge in September.  If so, we’ll be able to weigh the babies themselves to see what percentage of the egg mass gets converted into live hatchlings.  (As a bonus, we have DNA material from 220, and the potential of extracting genetic samples from the hatchlings, too, presents some very exciting possibilities.)

This great day had a perfect finish.  Beautiful weather conditions seduced us into a late evening paddle in Chipman’s Cove, ostensibly to hunt for terrapins at sunset.  Right!  Well, we did find a few turtles.  Kate Hunt, one of our Wheaton interns, hand-captured a 7-year-old female along the southeast shoreline.  A few minutes later, I netted Terrapin 1092, a 9-year-old female first captured on 7 June 2001 in the same area.  A year ago, she measured 15 centimeters long and weighed just 540 grams — a pre-pubescent female.  Today she has increased her length by 1.2 centimeters and her mass by 140 grams to reach sexual maturity, even though she was not palpably gravid this evening.  Still, this recapture helps fill in the model for the growth spurt that occurs on the cusp of puberty.