Looking for Leatherbacks

The main purpose of the trip was to study and help conserve leatherback sea turtles. The largest of all sea turtles, Dermochelys coriacea, may weigh up to a ton, although more commonly they are about half that size. They have been on the planet since before the time of the dinosaurs, yet posess sophisticated structural adaptations that allow them to dive up to 1,2000 m! Guided by a patch of pineal tissue on top of their heads, known poeticaly in Spanish as the "ventana al cielo," leatherbacks cruise the ocean depths searching for their main food source, jelly fish. Their travels will take them from the tropics up to the seas off Nova Scotia, up to 16,000 km per year.

They will start arriving in Pacuare in March to nest and will continue egg laying until early July. Each female will heave its tremendous bulk up the black sand beach, carve a nest in the sand and lay about 80 eggs in a hole almost a meter below the surface. Marking time offshore, these leatherback mommas may return up to eight times in a season to deposit the next generation. Good thing they are prolific. Only 50% of the eggs hatch and only .1% of the hatchlings will return to lay thier own clutch.

One morning after breakfast an urgent call was made for everyone to report to the beach in front of the biology station. About 40 leatherback hatchlings had forced their way out through the sand and were rowing, hell for leather, for the surf. Fortunately, we made a protective cordon for the break-out, as hungry vultures hovered nearby should any unlucky turtle stray from their course. It was gratifying to watch this brood head for the water, a few more individuals to test their chances in the open sea. If one of them came back to nest, it would be an achievement.

Leatherbacks have a hard enough time surviving the natural dangers waiting for them in the ocean. Humans have made their lives almost impossible. Worldwide their populations have crashed in the last 30 years as egg poaching, fishing nets and habitat changes have decimated their populations. They're now listed on the critically endangered list, although some hopeful signs of recovery have been seen on the Atlantic side of their world. Conservation measures here have given some reason for hope. At Pacuare, the fifth most important nesting beach in the world, there were nearly 900 nests in 2007, compared to less than a hundred when the program started in 2000.

A major part of the EPI program is dedicated to preservation of sea turtles and raising consciousness levels among visiting Americans and local Costa Ricans. Members of our team from Bataan knew of turtles being used as food. In nearby Limón, turtle eggs and meat can still be bought in the market and form an important part of the diet, if only for special occasions. It is hoped that this program may help to begin to change this tradition. However, while turtle eggs can fetch up to 50 cents each, and a long, hard day in the banana plantation earns less than $10, the fate of the sea turtles will not be secure.

Reptiles and Amphibians of Costa Rica Trip

For such a small country the biodiversity of Costa Rica is incredible. A Guardian article claims that 5% of the planet's biodiversity is to be found within its borders which only represent 0.1% of the world's land mass (http://www.guardian.co.uk/travel/2007/may/26/saturday.costarica). At the beginning of our trip we visited InBio Parque, run by the no-profit private Instituto Nacional de Biodiversidad ( http://www.inbio.ac.cr/es/default.html). This visit gave us an idea of what lay ahead for us in terms of different species of plants and animals. In the photo above Pedro and Michael are taking a safe close-up view of a boa constrictor.

Costa Rica boasts approximately 100 different types of snakes. Our only sighting was this Green Vine Snake, or Bejuquillo, Oxybelis sp?. The one with poisonous saliva has a white underside and the harmless one has a yellow underside, but I didn't care to get any closer to find out. The students spotted it along the beach and we watched as it climbed into this beach vegetation where it will lie motionless until striking an unsuspecting mouse. The camoflage works very well. Would you know it was there if I didn't tell you?

Amphibians, like the Green-and-Black Poison Dart Frog (Dendrobates auratus) find Costa Rica's moist forests quite attractive, totaling 120 different species. This one was hanging out near a shady pond near our quarters in La Suerte, Limón province. Poison dart frogs pick up their toxic alkoloids by eating ants and termites off the forest floor. While humans should avoid handling them, they are harmless unless you have a cut, in which case an encounter could be a painful experience.

Andrea was able to get this cool photo of a male carrying a tadpole on its back! In one of the more amazing stories of the animal world, these "lower" vertebrates actually take special care of their young. The female lays between 2-5 eggs in a mini-puddle on some leaf and the male fertilizes them. Then HE will return and let the newly-hatched climb up on its back one at a time and carry it off to some suitable mini-pool, perhaps the water that collects among the leaves of an arboreal bromeliad.

The female Strawberry Poison Dart Frog (Dendrobates pumilio) is not as liberated. She does all the work. Since the tadpoles are canabalistic, she will carry each pollywog to a separate bromeliad pool. Then she will make return climbs up the trees to deliver an egg which will feed her hungry hatchlings until they are ready to hunt on their own in 9-15 weeks. No wonder these frogs are so readily seen. Not only are they brightly-colored, but they are really busy. Of course, they can make their rounds with the quiet assurance that their warning colors will keep predators at distance.

Birds of the Costa Rica Trip

The species count for our 12-day trip was 58, a modest total for this birders' paradise. Stiles and Skutch in their guide book, Birds of Costa Rica (1989), report 830 species in an area the size of West Virginia. That is more than are found in all of the United States and Canada combined. The overlapping of South and North American species accounts for some of the diversity, as does the wide variety of habitats. Two coastal plains divided by a chain of mountains running northwest to southeast provide ample opportunities for species differentiation.

Eylen Zuñiga, one of the Ecology Project International biologists who organized our trip, accompanied me on several bird walks around the Pacuare biology station and the lowland rain forest at La Suerte, Limón. Spotting birds in dense jungle vegetation is difficult and requires patience and luck. It is kind of like fishing in that a quiet approach, and a good insect repellant, are key. Pedro Freitas was the only student willing to brave the clouds of moskitoes and join us on our strolls through the rain forest.

One of the best sightings during the trip was the female White-collared Manakin (Manacus candei) pictured above. She had built a chest-high nest in an open shrub behind our bunkhouse and in front of the bathrooms. During the entire week noisy teenagers passed within inches, but she never betrayed herself and the two eggs she was incubating. It wasn't until the final day when Marvin, my Costa Rican colleague, spotted her and pointed it out to me. Such is the value of protective coloration and a behavioral adaptation to keep still in the presence of danger.

Manakins are celebrities among tropical American birds. The brightly-colored males take time off from picking berries for food to gather in leks, communal display grounds, to impress the females with their frenetic dance steps. (Perhaps not unlike males of another species.) They dart between saplings and dance floor in an attempt to woo the females. In the process they snap their wings, producing a sound like that of a breaking twig. Often I tried to find out what was producing that sound, but the constant movements and broad leaves kept it a secret until Eylen filled me in.

Another notable sighting was that of the rare Agami Heron (Agami agami). A lagoon near the South Station is one of the few known breeding sites for this uncommon bird. The lagoon was the destination of a nature walk we made during a visit to larger of the two Pacuare biology stations. We saw about 10-14 birds perched in trees along the water's edge, while others flew out or gliding in to roost. Unfortunately, the telephoto lens on my camera doesn't have the power to reach them, so I include a photo by Ricard Garrigues that I found on the web.

Views from Pacuare & La Suerte

First day lunch at Villa El Zurqui, outside of San José.






Ecology Project International biologist Andrea Monge giving an explanation at InBio, Heredia, Costa Rica



Boat ride to Pacuare Biology Station







Caribbean beach at Pacuare

Pacuare

Pacuare Biology Station


Front row (left to right): Humberto Ibarrzabal, Michael Moraskie, Chris Dickson.

Back row (left to right): Pedro Freitas, Bob Jones, William Dickson.

The day after school ended six students and I traveled to Costa Rica to work with Ecology Project International on a marine turtle conservation program on the Caribbean. The site was the Pacuare Nature Reserve, a an 800-hectare park purchased by The Endangered Wildlife Trust in 1989. Together the two organizations invite middle and high school students to work with and learn about the sea turtles that visit their 6 km. beach.

Our focus was on leatherbacks which nest here from March until July. We all made evening patrols to discourage egg poachers and monitor turtle nesting. It wasn't easy waking up in the middle of the night to walk 6 km. on the beach, but everyone took part with a minimum of complaining. During our five nights at Pacuare the group observed three female leatherback turtles and one green laying eggs.

Besides night patrols, students studied the life histories of marine turtles through lectures and small group research. One particularly successful activity was to have teams come up with a question about leatherback habits at Pacuare. Then using the scientific method, they proposed a hypothesis, a possible answer to their question. Afterwards, they consulted this year's data for nesting leatherbacks to record actual results and come up with a tentative answer to their original question. I've taught the scientific method for years, but have never seen it presented as simply and with as much meaning.

Working with researchers was another important part of the visit. One Pacuare scientist (in photo) was studying temperature differences in the nest and how they affected hatching success. Our group helped her retrieve some of her equipment during excavation studies on the beach. We also counted unhatched and opened eggs. Here was a case where math took on relevance in helping us study animal behavior. In this nest 50% of the eggs were successful.

Thanks to Andrea Monge for the photo of me stalking baby leatherbacks.