Posts Tagged ‘Lieutenant Island’

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Tiny Hatchling Beats Cold Front by a Nose

Wednesday, October 22nd, 2008

Three Gram Second-Chance Terrapin Hatchling

“There’s always one more.”  That’s the motto of the Paludal Posse, our terrapin research and conservation team on Outer Cape Cod.  There’s always one more nest to find, one more nest to hatch, one more turtle in the nest, one more hatchling to emerge, one more turtle to save.  In short, there’s always one more.  And so it was proven again this weekend as we prepared our last batch of terrapin hatchlings for release on Tuesday, a promised mild October day.

Terrapin Hatchling and Second-Chance Egg from Nest 996

Sue counted 20 second-chance hatchlings soaking in 70F water to prepare for their sprint to freedom.  Second-chance hatchlings?  What the heck are second-chance hatchlings?  As we harvest emerging nests that have mostly hatched and other nests that have been exposed by predators, we often find a couple of unhatched eggs left behind.  Most of these eggs are in good shape and need only a couple days more incubation.  A few, though, look pretty sad; dimpled, dented, dehydrated, discolored, and so on.  These eggs wouldn’t make it in the wild.  Still, we prefer to give every turtle egg a chance even if it has only a small probability of survival.  So, these long-shot eggs go into our mystical, magical second-chance bucket, filled wtih clean, moist natal sand and warmed first naturally in our sun room until early October and then under a heat lamp in our lab until successfully hatched or all hope is exhausted.  We always have Halloween hatchlings, usually have Thanksgiving babies and occasionally find a pair of cute dark eyes staring up at us on Christmas morning.  (ASIDE:  Can there be a more powerful holiday message?) 

So, as Sue collected the 20 lucky babies for their trip back into the wild, she scanned the second-chance bucket and yelled in exclamation, “We’ve got another one!”  To which I sagely replied, “Yep.  There’s always one more.”

Perfect October Day for Second-Chance Hatchling Release

We made it to Turtle Point on Lieutenant Island while the weather held; 63F, gentle breeze and warming sunshine.  But a careful look at the clouds streaming above reminded us that a storm front approached. 

2nd Chance Hatchling and 20 Siblings Released at Turtle Point

The sand at Turtle Point had baked through the morning and reflected warmth as we sat down to release our 21 charges.  Placing them in a single bunch near the wrack line on the downward sloping dune, we watched as they scattered in random directions and power bursts.  Soon they had all disappeared into the nursery surroundings, some into upland vegetation, others into downland wrack and Spartina salt marsh, and still others burrowed into the warm dune sand.

Last Sailboat Dances with Northeast Blow in Blackfish Creek

Within an hour the weather had closed in.  The cold front arrived with gusts whistling across the narrow Outer Cape peninsula from the North Atlantic.  Clouds massed and grayed; white caps appeared; and we were doused in cold droplets whether from rain or briny spray we couldn’t tell.

“There’s Always One More” Egg in Second-Chance Bucket

Back in our warm, comfortable lab office Tuesday evening we inventoried our terrapin assets.  Tanks empty and ready.  Second-chance bucket filled with potential.  And our hopes high for one more miracle.

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Northeast Diamondback Terrapin Working Group Meets at Wellfleet Bay Wildlife Sanctuary

Saturday, September 27th, 2008

Mass Audubon’s Wellfleet Bay Wildlife Sanctuary hosted the 3rd annual meeting of the Northeast Diamondback Terrapin Working Group on September 27th.  Bob Prescott, sanctuary director, and Don Lewis, the Turtle Guy, welcomed more than 30 participants from New England and New York.  Chuck Landrey coordinated the meeting agenda, and Russ Burke, Hofstra University professor, chaired the meeting.

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Particpants Assemble in Wellfleet Bay Wildlife Sanctuary Auditorium

After registration and coffee, the meeting kicked off at 10:00 am with opening remarks by Chuck Landrey, the northeast regional coordinator, followed by Russ Burke, DTWG chair.  Bob Prescott and Don Lewis welcomed participants to the Wellfleet Bay Wildlife Sanctuary and presented a very brief overview of Cape Cod geography and terrapin populations from the SouthCoast to the Outer Cape.  Russ topped off the opening session with an update on terrapin research activities within Jamaica Bay and the challenges of wildlife conservation within bounds of the 11th largest city in the world.

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Opening Presentations by Chuck Landrey, Russ Burke, Bob Prescott & Don Lewis

As entertaining as these opening presentations were, participants earned a nice break before hearing more research updates by Charlotte Sornborger of Barrington, Rhode Island, and Barbara Brennessel, professor at Wheaton College.  Eric Strauss, research associate professor at Boston College, talked about environmental studies and the ecological field station at Sandy Neck in Barnstable where he and Peter Auger have conducted long-term terrapin research.

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Second Round of Presentations by Charlotte Sornborger, Eric Strauss and Barbara Brennessel

Lunch break offered an opportunity for Sue Wieber Nourse and I to zip over to Lieutenant Island to check for emergence nests.  Three days of pouring rain and the tropical front accompanying Hurricane Kyle presented conditions favorable for late hatching terrapins to emerge through the soften soil.  At the intersection of a one lane dirt road and a driveway on Marsh Road, we discovered an emergence hole with a tiny diamondback terrapin hatchling poking its head out.  Excavating the egg chamber we rescued four live hatchlings and found two premature hatchlings that had been crushed inside the nest by vehicular traffic.

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Saving Turtles for Lunch from a Vulnerable Road Nest

The afternoon session was devoted to an exchange of information and views on a variety of terrapin research issues as enumerated by the following charts.  Topics included headstarting, how do hatchlings know home, list of predatory and beneficial plants, hatchling survival rate, relationship between age and salinity tolerance, unpublished data on diet, terrapins in captivity, legacy data sets, where do hatchlings hang out, starting a basic terrapin conservation program, capture-mark-recapture methods, tracking methods, mating aggregations, nest protector design and temperature, terrapin survey methods, and how do you know what terrapins are doing when not nesting.

Terrapin Research Topics of Interest to Participants

After a very long and productive day, during which Hurricane Kyle had deluged the auditorium windows and walls with rain, the time had come for a soagy field trip.  Participants assembled in the Nature Center and began the trek along Goose Pond Trail to Cape Cod Bay where we would release the female and male terrapins that Sue and I had captured on Wednesday (see The Last Terrapins).  Then, we would walk over to Try Island to check the remaining protected nests and to share an insight into nesting habitat here at the northernmost outpost for diamondback terrapins.

Bob Prescott (with Binoculars) Leads Participants Down Bayside Boardwalk

En route to the bay, we stopped by an exemplar area of salt marsh die-off to talk about this phenomenon on the Outer Cape.  I spotted a large male squareback marsh crab, one of the prime suspects in the die-off, guarding its muddy burrow.  Bob dove into the ooze and bare-handed the critter; a noble feat since we normally use 3-mil plastic gloves for this work due to the ferocious tenacity of these crabs.  Bob showed off his catch to clicks of rain-drenched cameras.

Bob Prescott Shows Large Male Squareback Marsh Crab to Conference Participants

As downpours resumed, we reached a creek leading to the bay and released our turtle guests back into the wild.  Afterwards, we examined the nesting habitat on Try Island and elsewhere along the Goose Pond Trail, arriving back at the Nature Center tired, soaked and completely satisfied with a most informative and fun filled day.

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Hurricane Kyle Field Trip at Wellfleet Bay Wildlife Sanctuary

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Headcount!

Tuesday, September 16th, 2008

Emergence Hole About 1.5 Inches Long x 0.5 Inch Wide

Today brought a cool overcast to the Outer Cape as September’s autumn preview now grips the Land of Ooze.  Hatching had slowed to a crawl as temperatures fell and clouds rose.  So, we expected little from our afternoon rounds that began at Griffin Island where the truly northernmost terrapins in the world reside, stopped by Indian Neck on the north shore of Blackfish Creek and crossed over to Lieutenant Island on the south shore.

Another Emerge Hole, Same Size as Previous

Surprise!  Emergence holes and emerging nests greeted us at every stop.  Two on Griffin Island:  one on the shoulder of an asphalt road and only about five inches deep because mother hit pavement, and the other along a boardwalk leading to the Herring River salt marsh.  Eight live hatchlings emerged from the first nest and four succumbed to maggot depredation.  Sixteen hatchlings escaped from the second nest into the salt marsh.

Camouflaged Emergence Hole

When I spotted the emergence hole for the second nest, I burst into laughter.  A clump of pine needles had obviously been blown atop the hole by a recent storm.  But it looked so carefuly placed so as to camouflage the nest and give emerging hatchlings cover from predators as they bolted into the safety of the Herring River marsh.

I also hadn’t noticed until this posting the near identical similarity in shape of the first two emergence holes pictured above.  Sure, these critters are nearly identically sized at the hatchling stage, ~ 2.7 cm carapace length and ~ 6 grams mass; but after observing the chaos of an emerging nest (see the video clip below), I’m amazed by the twin shapes. 

Count the Heads as They Emerge

We arrived at the Indian Neck nest just as the clutch began to broil.  Heads popped up for a peek of their brave new world and quickly receded again under the dirt … to be replaced by a new set of darting eyes.  Try keeping a headcount as babies appear.  These thirteen lively characters could easily convert this performance art into a comedy circus routine that I would gladly book for a World Tour.

Hatchling Emerges from Nest; Note Pointy Egg Tooth

The shifting dune sand on the Hook of Lieutenant Island makes finding an emergence hole impossible, except immediately after a drenching rain storm.  No such meteorological assist was in the cards.  One hundred percent overcast, but no rain.  Still, luck played in our favor.  We first spotted a collection of hatchling tracks slaloming across the dune slopes.  Tracing these signs back to a convergence point, we ran smack dab into a terrapin hatchling just emerging from the nest.  Behind this baby, three more waited their turn to make a break for freedom.

Nest Completely Depredated by Fly Maggots

While we rejoiced in more than 75 live emerged hatchlings documented during our rounds this afternoon, we did have one sad encounter.  Nest 210, which we had been monitoring since June on the Boathouse dune, had been completely depredated by fly maggots that had consumed all the hatchlings, leaving  behind only a thin layer of each carapace.

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Rescuing Live Hatchlings from Maggot Infested Nests

Wednesday, September 10th, 2008

No, it’s not a pretty thought.  It’s not a pretty sight and it’s certainly not a pleasant experience.  But it is the real world of terrapin conservation and so for the serious naturalist, it’s a necessary learning moment.  Be thankful that the pictures are two dimensional and that there is no smell-vision key on the video clip.

Research from September 2000 revealed for the first time that a significant percentage of diamondback terrapins nests in the Wellfleet Bay system were being destroyed  by fly maggots.  The infestation appears to begin at pipping when hatchlings poke openings in their eggshells allowing the odor of organic material to escape and to attract flies.  Since Outer Cape hatchlings remain in their shells and underground for several days after pipping, maggots have the opportunity to attack an extremely vulnerable prey as the maggots work their way through the cracked shell to devour the exposed hatchling.

Pipped and Vulnerable (Upside-Down) Terrapin Hatchling

In most cases, the maggots begin with the umbilicus and enter the main body of the living hatchling through the yolk sac, hollowing out the baby from within.  Thus, hatchlings and whole nests are destroyed by these insidious predators underground without ever being exposed for counting by researchers like nests preyed upon by more obvious predators.

Maggots Attacking Helpless Hatchling (Rescued)

Observations over the last nine seasons confirm the 2000 discovery and underscore the severe constraint this predation places on the number of live hatchlings that emerge on the Outer Cape each year.  This season (2008) alone has seen more than half of all nests in the critical habitat of Lieutenant Island infested with maggots.

Maggots Consume Hatchling Embryo

Thankfully, the aggressive conservation protocols developed after the 2000 discovery have rescued more and more hatchlings each year from this infestation.  By checking nests as they begin to pip and harvesting them at the first sign of maggots, our efforts have significantly increased the number of live hatchlings entering the system since the turn of the millennium.  Even after the infestation has begun, our actions can save most hatchlings from the most heavily infested nests.  We harvest the pipped eggs and remove all maggots before re-burying premature hatchlings in clean, moist soil to finalize the incubation process.  These efforts have rescued thousands of hatchlings that would never have seen the light of day.

Hatchlings Rescued from Maggot Infested Nest

This particular nest on Turtle Point gave away its location by a concavity on the surface.  As hatchlings pip and squirm around inside the egg chamber, sand gets displaced and this underground activity shows itself as ripples of the surface sand to the most seasoned turtle researcher.  We were able to rescue 10 baby hatchlings from the devouring horde of maggots in this nest, hand-picking tiny maggots from limb cavities and off yolk sacs, then bathing the hatchlings in clean, fresh water for rehydration before release.  So, a good day in the Land of Ooze where we saved an order of magnitude better than our goal of one turtle at a time.

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Tracking Terrapin Hatchlings

Friday, September 5th, 2008

Where do hatchlings go once they flee the nest? Using various methods of inference and observation, we have determined that some hatchlings race to the wrack line for safety, others scramble further into the salt marsh grasses and still others opt to remain upland for at least the first winter of their “hidden” years.

Terrapin Hatchling Track Heads Down Turtle Pass Dune

Let’s follow some clues, some tracks and some hatchlings to test these hypotheses.  The high dune of Turtle Pass seems the place to start as we discover a hatchling track descending from an emergence nest atop the dune and heading seaward.

Tracks Assume Colorful Tints as Sun Dances Behind Clouds

Down we go along the shifting slope that morphs in shape and color as shadows dance through the contours of the dune.

Close-Up with Tail Mark Bisecting Track

Let’s experience the descent as though we were a newborn hatchling on its first ski run down the slopes.

Follow Tracks to Hatchling Buried in Salt Marsh Wrack

So, our first experiment leads to the discovery of a hatchling burrowed into the landward edge of the wrack line, buried under last winter’s deposit of salt hay.

But our day isn’t over as we encounter another set of hatchlings scaling the bearberry covered banks off 5th Avenue and passing through an exquisite clump of sea lavender en route to safety.

Terrapin Hatchling Scrambles to Reach Salt Marsh

These little critters eschew the wrack line, which to them seems like a clear cut jungle of logs, and head directly into the thick matting of Spartina patens in the salt marsh system separating east and west sections of Lieutenant Island.

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