Saturday, June 18, 2011

Meet The Turtle Moms

Snapping turtle laying eggs beside a road in Paul Smiths, NY.

June is egg-laying time for snapping turtles here in the North Country, and on the Paul Smith's College campus and along nearby roadsides, snapper moms are wandering in search of soft sand. 

When one of them finds a good site, she scoops a shallow depression with her back legs and drops a dozen or more soft, white golf balls into it. 

When she's finished, she scrapes the sand back over the hole and heads back to the water, leaving her offspring to take their chances on their own.

Those chances are pretty slim, all in all.  Our local foxes probably find most of those nests, judging from the abundant excavations and the papery shreds of egg shells that litter the ground like candy wrappers.

If the eggs last until August without being eaten, the hatchlings dig their way out and crawl to the nearest water body which, in our case, is Lower Saint Regis Lake.  If they make it past the gulls and crows, they'll still have to face a host of predators in the lake, as well.  Even the water itself can be a threat because snappers are bottom-walkers, and the babies must struggle to swim up through deep water to catch a breath. Considering the risks involved, it's amazing that any of them reach adulthood at all.

But some clearly do, and have been doing so for at least 40 million years, according to evolutionary biologists. 

It hasn't been an easy trip, though.  At least 2 dozen ice ages have repeatedly pushed snappers out of these parts over the last 2 or 3 million years, only letting them crawl back in for 10,000 years or so at a stretch during interglacial warm spells such as the one we're in now.

Today, there's also a new climatic problem for Chelydra serpentina.  Temperature in the nest determines the sex of the embryos, and the atmosphere is warming due to our greenhouse gas emissions.  By the end of this century, it could be as warm or warmer than the last interglacials ever were, and biologists suggest that such a change could skew turtle sex ratios in favor of females (many lizards and crocodilians have the opposite response to warming, producing more males).

At first, that might actually be a good thing up here in the North Country.  Females are more likely than males to be hit by cars when they cross roads in search of nest sites in the sandy shoulders.  Some people even swerve to hit them when they're safely off the pavement, perhaps because they're under the mistaken impression that snappers are dangerous to people or waterfowl (when defending themselves they usually stop short of actually biting you, and they don't eat birds, being mostly herbivorous).  A boost in female births might therefore help to address the presumed population imbalance for a while.

Fortunately, most of us are sympathetic towards, even protective of our local turtle moms. Just the other day, an office worker overheard Kary and me talking about a recent sighting and chimed in with a heart-warming story.  "I was driving near Malone when a police car in the opposite lane suddenly turned around and sped off in the direction it had just come from. 'Someone's about to get a ticket,' I thought."

Hardly. A short distance farther along, the cruiser was parked on the side of the road with lights flashing. "The officer got out, stopped traffic, and then started to nudge something in the middle of the road with his foot."  It was a snapping turtle. "He finally picked it up and carried it back into the weeds where it had come from. I thought that was so cool!"

A good deed indeed, and one that reassures me about humankind in general.  But please take note, if you do decide to help one of these critters across a road; don't pick it up by the tail (the weight can dislocate it), and put it down on the side of the road it was heading towards, not the one it came from (it's likely to repeat the same journey later).

Over the long term, sustained warming will mean that snapper territory may shift northwards on average, unless some mutation ends up adjusting the temperature sensitivity of their eggs.  But the Adirondacks lie near the northern limit of the species' range, so it would take a long time and a massively extreme warming to drive them out of here altogether. 

In light of that, I like to think that snapper moms will be doing their motherly duty around here far into the future. 

And despite the damage done by our cars and climate disturbances, we can at least chalk up one favor that we've done for them as well.  The latest research shows that our heat-trapping fossil carbon emissions will persist long  enough to prevent ice ages from pushing the turtles out of here again for at least 130,000 years.  How generous of us!

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