Hello, my name is Mr. Hill. Please join me as I travel to Costa Rica to study sea turtles!

Thursday, February 3, 2011

Day Five: Mid-afternoon

Just back from a tour of the nearby estuary. All kinds of bird life in there (egrets, ibises, herons, kingfishers, torgans: my dad and next-younger sister would have been in heaven) as well as crocodiles and, my favorite, the howler monkey. Enrique, our guide, does a killer monkey call, so, by the time we reached these two massive trees, the branches were literally crawling with howlers. We must have seen at least two dozen, maybe more, including 3-4 babies. When Enrique howled, many of the monkeys responded in kind: a great noise to hear...in the daytime...with others close by. I can only imagine how hair-raising that sound would be at night, especially if one were all by his- or herself!

I had morning beach patrol today. At 5:30, Tera (you've all met her via Skype) and I walked to the south end of Playa Grande beach and then walked back, checking nests along the way. Tracks leading from the first nest to the ocean told us that eggs had hatched during the night. As Tera counted the tracks, I tended to one johnny-come-lately hatchling who was struggling a bit to get to the water. Hard to believe that should this tiny baby leatherback survive, it could eventually weigh 800 pounds; this morning, it fit quite easily into the palm of my hand. (By the way, I heard a day or two ago that the largest leatherback turtle ever found weighed almost 2000 pounds -- one ton. That's a lot o' turtle.) Only one other of the nests we inspected had hatched, and, according to the tracks, about 13-15 baby leatherbacks made a break for the ocean when they reached the surface of the sand. These two nests will now be excavated the day after tomorrow.

Side note: given how hot it has been, I'm betting most of the more recent hatchlings are female. Turns out (another 'Who knew?' moment) the sex of a hatchling is determined by the temperature of the nest: on the cool side, males; on the warm side, females (the heat encourages the production of estrogen in the eggs: hence, females); just right, a near-equal number of each.

I have night duty tonight. High tide's at 3:37 a.m., and we're out from 11:00 until 5:00. I would love to have the chance to be an egg counter at least one more time before I leave on Monday.

To answer a few more of the questions some of you have sent my way:

1. What characteristics do the "survivors" possess that allow them to survive? Or is it all just luck? (Andrew Sobotka) Hey, Andrew. You probably won't be surprised to learn that it's more or less luck. For example, the little guy I mentioned above -- the one I found on duty this morning -- could easily have died had Tera and I not come along to help him on his way. There were all kinds of birds out looking for breakfast; many many crabs scurrying to and fro also scavenging for food; a few unleashed dogs romping around hoping to find a plaything; not to mention the raccoons and coatis that somehow missed this tasty morsel. And even though the hatchling eventually found his way out to sea, there's no telling if it would be safe from the predators awaiting it there -- not to mention those birds, who might have swooped down and plucked our little laggard right out of the water. I gather that once a leatherback reaches maturity (around age 15) it will most likely die only of, as we say about humans, "natural causes." Until then, however, and especially when it's very young, it's the luck of the draw for the leatherback.

2. Will Laird: good questions. I'll speak to the biologists and get back to you with some answers.

3. How much sleep does a leatherback need/get? When were the first sightings of leatherbacks? (Brandon Aguirre) Funny you should ask this first question, Brandon: I asked my patrol partner the same question a couple of nights ago. Turns out a leatherback can hold its breath for about an hour, so, when it wants to rest, it dives down and naps until it needs another breath. I gather that leatherbacks don't need to sleep for an extended period of time: just several minutes of shut-eye every now and then (kind of like the schedule I and the rest of the crew down here are on!). I don't know the answer to the second question, and I'm not sure anyone does. People have been aware of and studying leatherbacks for years, but interest in leatherbacks has stepped up significantly in the past 20-30 years -- and especially in the past 10-15 years -- because of the alarming decrease in the population.

4. What is the role of Earthwatch in providing people, including non-scientists, with the kind of experience you're having in Costa Rica? (Raphael Wolf) Probably best to go right to the source for the answer to your question, Raf, so click on this link: www.earthwatch.org/europe/aboutus/history At this point I can assure you that Earthwatch has made me, and by extension, many of you far more aware of the fate of the leatherback turtle, and, as Tara told you this morning, as a result of this knowledge there are many things you and I can do to help Tara and many others like her with their work. Once I return to New York, I will continue to speak to people about my time down here, and I'm hopeful that the blog, the Skyping with all three divisions, any follow-up presentations I give, the work you guys have been doing with Ms. Bell, the work the lower schoolers have been doing with their teachers, etc. etc. etc. will have the ripple effect Earthwatch lives for.

Speaking of which, Jonah Max wanted to know how one could tell if the fish he or she eats hurts the leatherback's chances of survival. Here's the website Tara mentioned in answering Jonah's question in the US Skype session: http://www.seafoodwatch.org/. Click on "Seafood Recommendations." And, wouldn't you know it, you can download an app so that you have the information readily available when you're at a restaurant or grocery store.

2 comments:

  1. Mr. Hill, great job on the Skype session. It was really interesting and enlightening.

    You mentioned in a previous post that sometimes a nest needs to be relocated to the hatchery because it's found below the high-tide line. Knowing that temperature determines the sex of the hatchling, how do they go about keeping the eggs warm? Are the numbers ever manipulated so that more of one gender is hatched and released than the other?

    Do you guys ever give the turtles names? I think you should name one of the turtles Shelly. Get it?...Because turtles have shells! That's shellarious!

    -Alvin

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  2. Dear Mr. Hill,

    We have some questions for you from 3S City:

    1) How big are the Leatherback eggs?

    2) How much do the hatchlings weigh?

    3) How many hatchlings from each nest usually make it to the ocean?

    4) How long does it take to get from the nest to the ocean for the hatchlings?

    5) How long does it take for an egg to hatch?

    6) How deep is the nest?

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