Monday, February 7, 2011
Halfway to the other end of our section of the beach, we noticed ahead of us what we thought was a turtle track. Once we got closer, however, we realized that what we were seeing was not a turtle track but a band about 3 feet wide of hermit crabs! The band, at least 100 crabs strong, stretched from the water to the vegetation, and the crabs didn't seem to be heading quickly in either direction; in fact, it looked as if they had all decided to meet at this pre-arranged spot just to hang out. We watched the crabs for awhile, but they seemed in no hurry to clue us in as to what they were doing, so, in order to stay on schedule with our sweep, we moved on, hoping that when we passed the crabs on our second trip up the beach, we'd be able to figure out why they were there.
About 40 minutes later, we were walking back towards the northern end of the beach, and we passed the band o' crabs once again: they were still just hanging out, so Tera and I still
didn't know what those little buggers were up to. Once again at the northern end, we looked for the black turtle -- we didn't see her immediately, but we could hear her moving around, and Tera was pretty certain the black was in the process of camoflauging her nest. It took us some time to locate her because she had found her way far into the vegetation and sequestered herself somewhat under a large, discarded beach sign. The sign was in her way, and she was banging one of her flippers against it in a futile attempt to get to the sand and vegetation underneath. Tera moved the sign out of the turtle's way, and the turtle resumed her covering. We had planned to stay to make sure she finished her work successfully, but the call came over the radio that the final nest in the hatchery had hatched, so we hurried back down the beach to help measure and weigh the hatchlings. As we scurried, I asked Tera how many hatchlings we might see: she guessed about 25-30; I figured fewer, about 15-20.
When we arrived at the hatchery, two other crew members were there, and they had separated the -- get this -- 59 Olive Ridley hatchlings into three buckets. As the others finished setting up the measuring and weighing station, I went back over to the nest to see if any more hatchlings had swum to the surface of the sand. In fact, three more had just emerged (62 now), so I placed them in the bucket I had brought with me, and went back to where we were about to collect the data on the hatchlings. The biologists don't measure and weigh all the hatchlings; they take a sampling of 20. They measure the length and width of the hatchling's shell and the width of its head, and then they weigh the hatchling. These baby turtles fit easily in the palm of my hand, so you can imagine just how small and incredibly cute they are. (Watching the hatchlings crawl all over each other in the buckets reminded me of the way the middle school boys often climb all over each other in the Middle School Center.)
Once we finished with the measuring and weighing, the first shift of the night was finished, so we picked up the three buckets of hatchlings and headed back to the station. We handed the buckets over to the second shift: they were going to have the pleasure of taking the hatchlings farther down the beach and releasing them into the water! I was tempted to go on the second shift -- I really wanted to see the release of the that many hatchlings -- but it was the other volunteers' shift, not mine, and I didn't want to steal their thunder. When I got up this morning, one of the late-night volunteers told me 8 more hatchlings had emerged during the night: final tally, 70.
I'm telling you, those hatchlings were something to see. All that new, vigorous, rough-and-tumble life making its way out of the nest and into the ocean -- perfect, absolutely perfect. Can't think of a more fitting way to end my time down here.
See y'all tomorrow. Thanks for reading.
Sunday, February 6, 2011
I had the earlier of the two beach patrol shifts last night -- 7-11:30 p.m. Kim, my partner on the shift, and I had no action on our section of the beach -- even the nests where we might have seen actual hatchlings or least their tracks, seemed to have taken the night off. In fact, had an Olive Ridley not made her way ashore during the second shift, no one would have a chance to work a turtle during the two-shift, 10-hour patrol. The cool thing about last night's Olive Ridley nesting? The biologist let his Earthwatch volunteers work the turtle all by themselves -- one counted the eggs and the other measured the length and width of her shell. (A side note: this particular turtle happened to be wider than she was long. Olvie Ridleys have a very high-domed shell, so the wider-than-long characteristic is not necessarily out of the ordinary.) I was pleased to hear that we volunteers have become so adept at our turtle skills that the experts are now willing to let us play a significant, instead of a token, role in the collection of the data. Yep, I'm a little proud of us!
My final 24 hours here will include another early shift of beach patrol tonight (with Tera, star of the Skyping sessions and the project manager) and then an early-morning, two-hour stint in the hatchery. Before either of those duties occurs, however, the entire crew here -- biologists and volunteers -- will gather at a viewpoint for a Costa Rican sunset and then wend our way to Keke's for our final dinner here. Because the turtles don't know that we're all leaving tomorrow, we really can't become too sentimental/corny/mushy about the end of our time in Costa Rica, though we'd be remiss if we didn't take a moment to celebrate the work we did and the companerismo (camaraderie) we shared. A few brief words, smiles and or hand shakes and or hugs all 'round, a final casado (chicken, beef, or vegetable), and then back to the turtles: all as it should be.
A few more answers to a few more questions:
1. (from Jack Hogan) How do you know when there's a turtle on the beach? If we don't see the turlte emerge from the water (and we often don't), we see see a very wide track in the sand, leading us to the place where the turtle has decided to nest (or, if it's a false crawl, not to nest). Hard to miss these tracks, even if you're night vision isn't all that great: the leatherback track is often 3-4 feet wide.
2. (from Ola) What skills must you use when observing the turtles? I'm going to rephrase the question slightly, Ola: 'What skills must you use when looking for and then observing the turtles?' When looking for the turtles, the 'skill' we use most is...PATIENCE. As you may have noticed in earlier posts, long stretches of time -- sometimes entire shifts -- go by when we don't see a turtle, so we have to be patient each time we hit the beach. When we actually work a turtle -- when we watch her nest, lay, and cover -- we have to make sure we stay behind her head (so that we don't spook her) and do our work (counting, scanning, measuring) in such a way that we don't bother her while she goes about her business. We have that window when she's in her hormonal trance to collect our data, so we have to be somewhat quick and always efficient. Further, the egg counter has to make sure he or she gets close enough to see the eggs but not so close that he or she causes the nest to collapse. Finally, because tourists love to watch the leatherbacks lay eggs, we often have to do our work surrounded by 10-15 people, and many of them want either to get too close to the turtle or for us to answer questions they have about what they're seeing. Negotiating all of the tourist activity while doing what we need to do with the turtle can sometimes be quite the juggling act!
3. (from Will Laird) Are leatherback populations in Costa Rica expected to increase? That would certainly be the hope, Will, but researchers won't know for another leatherback generation or two if the populations are increasing and at what rate. Poaching has all but been eliminated here -- a big plus. Declaring this area national park (which happened, I think, in 1994) -- also a big plus. The biologists following the trends here seem to feel they've been successful at stabilizing the population: it's still way too low from their point of view, but they think they may have arrested, at least for now, any further decrease -- a huge plus. But just what effect their work here is having on future numbers is anyone's guess at this point. One of those 'only time will tell' situations. Is enough being done to help the leatherback turtles? What more needs to be done? In the last 20+ years, quite a bit has been done around here to help the turtles, but no, there's not enough being done yet -- there's always more to do in this kind of work! Tera, the project manager, would like to see more of the area in this part of Costa Rica (and in similar places in other countries down this way) declared national parks. She would also like to see stricter zoning ordinances in place so that people can't build too close to the beach. She figures the next big obstacle to tackle will be the fishing indsutry. People interested in increasing the leatherback population are already figuring out how best to educate fishing communities about the dangers their ways of fishing pose to the turtles. As you can imagine, some of those "ways" go back generations, so trying to persuade some of these communities to use methods safer for the turtles will be a challenge. It's heartening to me, as I hope it is to you, that there are people more than willing to accept that challenge.
Friday, February 4, 2011
By the time we got to the site, the turtle was putting the finishing touches on her egg chamber. She then began to lay her eggs. By the time she finished -- about 8-10 minutes later -- there were 79 eggs in the nest. She then covered the eggs, tamped down the sand with the characteristic Olive Ridley tamping dance, camoflauged the nest with loose sand, turned herself towards the ocean, and quickly crawled back into the water. The whole process took about 1/2 to 2/3 the time it takes the leatherback to do pretty much the same thing, and that, in part, is because the Olive Ridley weighs about 150 pounds -- not even a quarter of what the leatherback weighs -- and digs a nest that's about half the depth of the average leatherback nest (see question 2.6 below).
Olive Ridleys are the only species of sea turtle that comes ashore to lay during the daytime; consequently, we got to see in full daylight a process similar to what we see at night with only red-light illumination. Nice.
Now to answer a few more posted questions from all y'all.
1. (from 4M) If the babies hatch during the day, do they wait until the night to emerge from the nest and head to the water? Most often, yes, but, if they don't make it all the way out of the nest at night, they will most likely be subjected to the heat of the day, and, as you can figure out, that's not good -- they usually end up dying because it's way too hot for them 'up there' and they have no way of cooling themselves off. If you see a hatchling, why not just pick it up and take it to the water? Depending on where the hatchling is in relation to the water, and whether or not there might be predators around, we do sometimes pick up the hatchling and help it on its way. That said, it's important for the hatchling to get itself into the water because, in doing so, it 'warms up' the muscles the hatchling needs in order to take its maiden voyage in the ocean! How do leatherbacks eat jellyfish without being stung? The leatherback is not affected by the toxin of the jellyfish, so that makes it a-OK for a leatherback to scoop up a jellyfish without thinking twice about what its ingesting.
2. (from 3S) How big are leatherback eggs? About the size of a billiard ball. How much do hatchlings weigh? On the average, approximately 45 grams (or just under 1.5 ounces). How many hatchlings make it to the ocean? As you can imagine, that depends on all kinds of factors (temperature of the sand, predation, etc.), but the vast majority of the hatchlings in each nest make it to the ocean. How long does it take a hatchling to get from the nest to the ocean? Tough to say precisely: some nests are closer to the water than others, and some nests hatch closer to high tide than others. How long does it take the eggs to hatch? Approximately 60-65 days. How deep is the nest? Approximately one meter.
3. (Alvin Lee) How does the hatchery keep eggs warm? The hatchery is outside, so the sun and sand keep the eggs warm -- there's no artificial heat or light source in the hatchery here. Is the heat in the hatchery ever manipulated to produce more of one gender of hatchling than the other? See answer to prior question. But to elaborate a bit, one of the biologists is conducting research into the area you ask about, Alvin. Because of global warming, there is concern that eventually, if it hasn't already happened, there will be an increase in the number of females and a decrease in the number of males, so the biologist is watering with varying amounts of water a certain number of empty plots in the hatchery and recording the temperatures of those plots at various times during the day to see how those varying amounts of water could affect the temperature of a nest. Do the bioligists there name the turtles? Why, yes they do -- not all of them, but some of them. 'Bootsy' came ashore last night to make her 11th nest this season. She's called 'Bootsy' because one of her back flippers has a slice in it and the flipper therefore is now shaped like a -- you guessed it -- boot. At the beginning of the nesting season, the first six turtles ashore are entered into an online 'race', and you can vote for which one of those first six you think will lay the most eggs during the season. In order to keep track of which turtle is which, the Big Six are named. This year there's Esmerelda, La Famosa Tom, Esperanza, Tamy, Tamarinda, and Baulitica in the running. Esmerelda's presently winning, though the aforementioned Bootsy has actually been ashore one more time than has Esmeralda and, as a result, has laid more eggs, but Bootsy was not one of the first six, so she can't be in the race. Sorry to disappoint you, Alvin, but there is no turtle named 'Shelly'...
4. (Ben Miller) Do leatherbacks ever nest in the Galapagos? No, they don't. They go there only to eat!
Because high tide is getting later and later (or, depending on how you look at it, earlier and earlier), tonight's the last night of one six-hour shift. Tomorrow, we go to two shifts: 7-11:30 p.m. and midnight to 5:00 a.m.. Can't decide which shift I'd prefer -- but my preference doesn't really matter since Tera makes up the duty roster!
Thursday, February 3, 2011
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.
Wednesday, February 2, 2011
The excavation of the first nest was straight-forward: we found three hatchlings still alive, and the rest of what was left in the nest -- a couple of dead hatchlings; fully hatched eggs; unhatched eggs; SAGs (shelled albumen globules) -- was there in its usual numbers.
The excavation of the second nest, only 3-4 yards away from the first, was a different story. As Kim, the excavator, dug into the nest, we noticed several hatchling heads sticking up. We immediately became excited: it's always a goosebump moment finding live hatchlings in the nest. And find some we did -- six, to be exact. But then the findings started to turn grim: ten dead hatchlings. Sad, but, according to Kim, not too out of the ordinary.
Next, Kim began pulling out the unhatched eggs and the fully hatched eggs. It gradually became apparent to those of us watching that Kim was concerned about the unhatched eggs she was finding. Once Kim had finished the excavation, the team sorted. Out of approximately 88 eggs laid in the nest, only 20 -- less than a quarter -- had hatched. We had pulled out 6 live hatchlings and 10 dead hatchlings, so only 4 had made it all the way out of the nest on their own -- a low number.
Kim then opened the 68 unhatched eggs: 4 were unfertilized (stage 0), and the entirely of the remaining 64 were in the final stage of development (stage 3 -- there were no stage 1 or 2 eggs). What that means is, there were 64 embryos that were 'this close' to being hatchlings, and yet, for some reason (or combination of reasons) they didn't complete the final stage of their development. Kim has been at her job for awhile, and she assured us she had never seen that large a number of stage 3 unhatched eggs. Because she has to break into the shells of the unhatched eggs to determine specifically what's inside, it was enormously disappointing to see these 64 little leatherback turtle almost-hatchlings laid out on the sand. It's a sight I won't soon forget.
Though she can never know for certain what caused such a high number of stage 3's in this nest, Kim is pretty sure two main factors contributed to the arrested development: first, the nest was too shallow, so, second, the nest could never cool sufficiently at night to let the eggs develop fully.
Once we had finished sorting, counting, and recording, we swept back into the hole all of what Kim had dug out. We then filled the hole with large handfuls of sand and tamped the sand down. Kim was clearly shaken by what she had just witnessed, but she assured us that, though rare, such findings are a fact of life for leatherback turtles.
The silver lining to this story? The six surviving members of the ill-fated nest, along with the three from the first nest, that some of our group coaxed into the water tonight. The people who released the nine hatchlings told me it was an exhilarating sight to see those little buggers paddle their way through thesand down to the surf and then ride the waves out to sea. That, too,thank goodness, is also a fact of life for leatherback turtles.
As we were arriving at the spot where our beach patrol shift began, the biologist in our group had a call on his radio that there was a "tortuga" near marker 14. We rushed up the beach and arrived just in time to see the leatherback covering her eggs. No counting of the eggs, obviously, but we did scan and measure the leatherback. (Many of these leatherbacks have a microchip in each of their shoulders -- metal tagging stopped several years ago -- and we scan each shoulder to find out which turtle we're working with at that moment.) Almost as soon as we finished recording the data, the biologist in our team noticed a red light flashing farther up our sector, so we quickly packed up and headed towards the source of the light.
When we arrived, the ranger there pointed to another leatherback who was putting the finishing touches on her nesting pit. We watched her use her back flippers to create a pretty deep trench about 4-5 inches across in thee pit. The most remarkable part of this digging process? The leatherback can turn her flippers into little cups so that she can not only slice into the sand but also bring it up out of the deepening trench and throw it behind her.
As she neared the end of the trench digging, I slid into place, on my stomach, to begin my duty as egg counter. As soon as the first egg dropped, I placed my one hand on the flipper that was covering the eggs and held it to the side so that I could see the eggs. In my other hand I had a counter, and every time an egg dropped into the trench I clicked the counter. I had to be careful not to get my body too close to the edge of the pit, and I also had to make sure I didn't lean on my elbows: both actions could collapse the side of the egg trench, and, for obvious reasons, I wanted to make sure that collapsing didn't occur -- not so easy at it sounds, given my, um, bulk.
Did my holding the one flipper to the side bother the turtle? If it did, she didn't let on: at no point during the time she and I were hand-to-flipper did she try to fight me. Perhaps she didn't even know I was there, since, when the egg laying begins, a turtle goes into an 'hormonal trance' and remains in that trance, more or less oblivious to what's going on around her, until she's finished laying.
The laying takes about 10 minutes on average, and I knew she was finished when started to use the flipper I was holding to begin convering her eggs. At that point, I pushed back away from the pit, got up, and helped the other two in my group scan and measure the turtle.
Luck would have it that as we were in the midst of "working" this turtle, we got a call that a third turtle had come ashore at the south end of our sector. Because we could not leave our turtle, the biologist in our group radioed another group and asked them to "work" the third turtle. They were more than happy to oblige because the two Earthwatch volunteers in that group had yet to see a leatherback.
During a later sweep of our sector, we were fortunate to find this third turtle finshing the covering of her eggs; as a result, we got to watch her make her way back to the water and then swim out to sea. Given everything these turtles go through, it's hard to imagine they have any energy left to get themselves back in the water, but they do, and they do so surprisingly quickly! 8-10 days later, she'll be back for another nesting, and she'll have, on average, about 15 nestings during the season which runs from October to March. No wonder she'll then take 3-4 years off before she nests again!
The second turtle (mine) laid approximately 89 eggs (I write "approximately" because I may have over-counted -- easy to do, given the position one's in when counting the eggs and the erratic way the eggs drop into the trench); the third turtle, approximately 56. The average number of eggs per nesting: 60-65.
Once one has seen multiple nestings, I suppose one becomes used to, perhaps even blase about, seeing leatherbacks lay their eggs. But I won't be here long enough to have that happen to me, and I was quite happy to hear from the biologists that we volunteers should have another 2-3 nights like last night before we pack up and head out on Monday.
As I was lying there counting eggs, I thought, 'This process has been going for over 60 million years That's 6-0. Million. 60,000,000.' Try wrapping your head around that idea! Pretty overwhelming; pretty awesome; pretty cool.
Tuesday, February 1, 2011
1. Why did I choose turtles for my Earthwatch expedition? I was in Costa Rica for the first time this past August, and, during that trip, I had the opportunity to see green sea turtles come ashore on the east coast and lay eggs. It was such an amazing thing to witness that I was more than happy to come back down here, this time to the west coast, and learn more about sea turtles in general and leatherback turtles in particular.
2. Why/How did the leatherbacks become endangered? I'm going to couple this question with another one: What is the biggest predator of the leatherback turtle? The simple, and true, answer to both questions is Human Beings. 20-30 years ago it became a fad of sorts to eat leatherback turtle eggs. Men saw it as a 'manly' thing to do to have a raw leatherback egg with their beer, so the eggs were readily available -- and in high demand -- in bars. Others coveted the eggs as a kind of status symbol, a way to one-up their friends -- "I have something you don't have." Consequently, with no laws in place to protect the eggs, poachers would come out every night during nesting season, take every single egg in the nest, keep a few for themselves, and sell the rest to interested buyers. The poaching didn't cause an immediate problem because there were still plenty of leatherbacks during the time of the poaching, so no one really noticed any change in the leatherback population. Jump ahead a generation or two of leatherbacks and you find, all of a sudden, an incredibly steep decline in the number of leatherback turtles left in the ocean.
Over-fishing in the Pacific has also added to the problem. The increase in the number of fishing boats meant an increase in the number of leatherbacks getting caught in fishing nets which, in turn, meant an increase in the number of fishermen not attempting to free the turtles from the nets but, instead, just cutting the nets loose with the turtles still caught in them. I'm sure you can figure out where that led -- and, unfortunately, still leads.
3. Why can't the leatherbacks survive on their own? They can. In fact, once a leatherback is fully grown, it's at the top of its food chain, so, other than the interference from man, the leatherback has no other serious predator (unless, maybe, the odd shark has a hankering that day for leatherback...). What people here at the research station, and in other similar stations around the world, are trying to do is increase the number of leatherback turtles making it to adulthood -- hence, the focus on the nesting and the hatching.
4. What happens if you (Mr. Hill) fall asleep during beach patrol? We're on patrol with at least one, sometimes two, other people, so we help each rouse ourselves and make the sweeps when it's time to do so. To make doubly sure we don't nod off indefinitely, we have a walkie-talkie with us and periodically check in with the others on patrol on other parts of the beach. It's not easy to stay awake, especially during our breaks, but, so far, I haven't needed to be woken up!
5. How many leatherbacks have you seen so far? I have yet to see any; one of the groups on patrol last night saw one. Maybe tonight -- 11 p.m to 5:00 a.m. duty -- will be my lucky night!
6. Why don't the leatherbacks lay their eggs closer to the water? In order to produce hatchlings, the eggs have to be buried deep in the sand, and they have to be able to 'breathe'. If the eggs were nearer to the water, they would be wet a good deal of the time while they were incubating, and that wetness would prevent the eggs from receiving the oxygen and warmth they need. It's for that reason that some nests are relocated to the hatchery: if a turtle lays her eggs inside the high-tide line, the eggs don't stand a chance, so the biologists here, who have marked where the nest is (that's part of night-time beach duty!) will relocate the nest to the hatchery the next day.
7. How many hatchlings survive? If we take human beings out of the picture, Nature allows 1 out of 1000 hatchlings to make it to full adulthood -- which means one of a thousand live for at least 15 years. Factor in what I wrote about in #2 above and the number of leatherbacks making it to 15 is now far far fewer. I'll find out the approximate number for you and report back. If a leatherback makes it to 15, and, again, we factor out human beings, a hatchling -- now an adult -- will live approximately 80 years, though that number's a very rough approximation since there's no way as of yet to find out just how long most leatherbacks live.
Hope those answers make sense to you! I'll try to get to more of your questions tomorrow.
Here's an interesting piece of information: leatherback hatchlings will eat whatever they can fit in their mouths; once the hatchling's bigger, however, he or she will eat almost nothing but... jellyfish! And the poison which several species of jellyfish have at their disposal doesn't affect the leatherback in the slightest. I wonder if the decline in the leatherback population has led to an increase in the jellyfish population -- that would only make sense, right?
Up by 8:00 (9:00 EST) to get ready to Skype with the middle schoolers. Just finished that, and had a great time seeing the boys on screen and answering a wide range of questions. Tara, the project manager, was by my side, and she had the answers to the questions that were head-scratchers to me. Lower school tomorrow, and, if it all works out, the upper school on Thursday.
Thanks for all of the questions you've been sending. I'm going to put them into the blog as soon as I finish this post. I'm trying to answer your questions in these postings, so look back at earlier posts or stay tuned for later posts!
Time to go to bed for about an hour: we have our next assignment to carry out in about 90 or so minutes.
Monday, January 31, 2011
Another group -- sweeping south Playa Grande beach -- did get to see a leatherback, but, like our black turtle, she executed what they call a false crawl: in; change of mind; back out. These false crawls aren't uncommon, and the chances are good that the same turtle will return either later that night or the next night to lay her eggs.
Night patrol goes out three hours before high tide and stays out for three hours after -- 6 hours total. When high tide occurs before, right around, or very shortly after midnight (as it did last night), two people are assigned to the morning walk shift to see if there was any activity after the night patrol finished its sweeps. I went out this morning with one of the biologists, and we found two little olive ridley hatchlings doing their darnedest to get to the water -- yep, they were stragglers from the same nest that produced the large batch the night before! The biologist and I picked up the two tiny things and helped them get to the water a bit more quickly than they might otherwise have arrived there. They were very cute, I must admit: the one I held (remember: all of 2-2.5 inches long) took the opportunity to use its front flippers to wipe the sand out of its eyes -- a total 'awwww' moment.
This afternoon the project manager will give us a presentation on the leatherbacks, and then at 3:00 we're going to the hatchery to participate in the excavation of a nest.
I have beach patrol tonight, and high tide is later than it was last night, so I will be out from approximately 10:00 p.m. until 4:00 a.m. It's a late high tide (as I think it will be for the rest of the week), so there will be no morning walk for anyone tomorrow.
Some more Turtle Fun Facts 4 U:
- no one knows for sure what the life expectancy is for a leatherback, but they estimate it to be about 80 years
- olive ridleys lay approximately 100 eggs each session, and close to 80% of those eggs will hatch -- that's a higher percentage of hatchlings than the leatherbacks enjoy
- leatherbacks crawl using both front flippers simultaneously -- they more or less 'swim' through the sand; olive ridleys alternate their front flippers, so they crawl -- who knew?
Lower schoolers: thanks for the questions! I will make sure to ask them at this afternoon's session with the project manager. Look for the answers in a later post.
Sunday, January 30, 2011
Each night, some of us will have beach duty (to find any turtles that have come ashore to lay eggs and then to take data on both the turtle and the egg-laying) and some of us will have hatchery duty (to protect them from water or predators, some of the nests are moved to the hatchery, and those of us on hatchery duty get to watch the eggs -- you guessed it! -- hatch). Both beach and hatchery duties last six hours and are scheduled around high tide, so, for tonight, they take place from 9:10 p.m. until 3:10 a.m.; morning beach patrol runs 5-7 a.m. I'll know more about all three once I've been assigned to each -- I think tonight I get to go on part of the beach duty, and then I have beach patrol tomorrow morning.
A few pieces of information I've picked up, some of which I'm betting some of you already know:
- leatherback turtles have been around since the dinosaurs
- a female leatherback will lay eggs every 3-4 years
- she will lay approximately 65 eggs each time she comes on shore
- she will come on shore anywhere from 7-10 times each laying season, and she will do so every 9-10 days
- the laying season here runs from October to March
- she will then return to the Galapagos and environs until it's time for her to lay agai
Time to go have our headlights covered with red cellophane (no white lights near the turtles -- and, therefore, no pictures of them) and then head down to the hatrchery.
Jack Hogan: I found Taco Star! Thanks for the tip!
Friday, January 28, 2011
A big thanks to everyone at Collegiate who pitched in to make this trip possible for me. I hope I do all of you and the school proud!