Monday, March 31, 2014

Nest Exhumation

Nest exhumations are one my favorite things to do with Equilibrio Azul. On my second day, we headed down to Playita, a pristine white-sand beach with no access to the public.

I felt privileged to enter through this locked gate with a "no trespassing" sign.

This beach gets special protection because it's one of the only known hawksbill nesting site in South America. It's also a favorite site for green turtles, and it was a green turtle nest we would be exhuming today.

The Turtle Team preparing to excavate the nest site.

One of my first questions was, how do you know where to dig? The answer is this: every single night during nesting season, a small group of volunteers and park rangers camps out at Playita overnight. Every hour, someone goes on a "night patrol" of the beach to document any nesting turtles. The eggs are counted as they are laid, and nest is marked with a red stick. Two months later, we consider the nest "dead" and dig it up, since the average incubation time for both greens and hawksbills is 60 days.

Arica did the actual digging by hand.

The first eggs we discovered were tiny, round, hollow things. Our mentor, Caro, explained that green turtles often lay these infertile duds in the nest to crate airspace around the real eggs.


Barbara shows off an infertile egg.

Then we started unearthing egg shells of the successful turtlings and whole eggs of the unsuccessful ones. We ripped open the leathery/papery shell of each unhatched egg and recorded both the cause of death and the stage of development at which death had occurred.


Many of the eggs showed the bright green goo associated with fungus.
Others had the white, cheesy texture and rancid smell of bacteria.

The record sheet also had check-boxes for "plant roots," "insects holes," "crab holes," and "flooding." And those are just the threats inside the nest -- the turtles also face hungry birds, dogs, cats, and crabs as they make their journey to the ocean. It's estimated that only 1% of green turtle hatchlings will ever reach sexual maturity.


Some fetuses were at 4/4 development, meaning they were ready to hatch when they died.

It was amazing to feel the leathery flippers and tiny shell.

Dead 4/4 fetuses kept piling up.

Caro said it's normal to see a lot of unhatched eggs, but it was sad to bury the turtlings.

When we were done with the morbid affair, we returned all the refuse to the hole and buried it with sand. As we hiked the twenty-minute path from the beach back to the road, I was filled with unanswered questions. What kind of bacteria infect these eggs? What kind of fungus? I can't wait to take microbiology and statistics courses so I'll be more prepared to take on research projects like these in the future.

2 comments:

  1. What a lot of work it is for Mama Turtle to do all this so that hopefully 1% of her babies will survive. Who she will never fall in love with and get to watch grow up. A different take on the empty nest thing.

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  2. Reminds me of the painted turtle eggs we dug up on the beach by accident at Brant lake.

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