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Wednesday, May 31, 2023

Scientists Study and Protect Turtles at Hatchery

PLAYA CALETAS – On a moonlessnight, the beach was uniformly gray, treetrunks were indistinguishable from thesand, and spotting turtle tracks seemedunlikely.They are a dark line of disturbed sandfrom the water’s edge, up the sloped beach– you’ll see them if they’re there, DavidPalange said. Palange is a turtle biologistwho works with the Costa Rica-basedMarine Turtle Restoration Program (PRETOMA),and has left his own tracks on thisstretch of coast most nights for the pastfive months.He prods through the sand with a polearound the bed – the telltale disturbed sandmarks around the nest – looking for eggs,then carts them covered in their antibacterialgoo back to camp in a backpack. Whenhe stumbles across a turtle, he measures itsshell and clips metal tags to its flippersbefore it returns to the sea.“You put a stick in it, poking, feelingfor a soft spot, then you dig it up,” Palangesaid. “At first I would spend 40 minuteslooking for a nest; now it’s just about twopokes.”No signs of turtles on the first leg of thepatrol.Hordes of olive ridleys and hundreds ofmassive leatherbacks don’t swarm thisbeach like they can at Playa Grande, on thenorthern Pacific coast, but Playa Caletas,near the southwestern tip of the NicoyaPeninsula, is considered the second mostimportant nesting site for leatherbacks inthe eastern Pacific.“Here we get about 15 turtles a night.Studies show that solitary beaches like thishave a much higher hatch-out rate thanthose where thousands come in a night.But poachers hit these beaches harderbecause nobody cares about them,”Palange said.After turning back at the river, a distantflashlight blinked on and off – eitheranother patrol had spotted a turtle, or thenew volunteers were goofing around.He picked up the pace to one nearlyimpossible to match. “It’s about a kilometeraway,” he said, and might have added,“meep, meep!” because he vanished in hisown cloud of dust. The flashlight signalpersisted.It was a turtle. Some of the young scientistsfrom the PRETOMA camp, mostrecent college graduates, huddled aroundan olive ridley, frustrated.The turtle swished her back flipperspathetically in the sand, trying to dig a holefor her eggs, but some biological mysterykept her from backing up her efforts withany force.They dug a hole for her under her backend, but she seemed onto the trick andrefused to lay. Finally, after stringing a tapemeasure along the length and width of hershell, and clamping a steel tag onto herupper flipper, the team left her and optedfor sleep before the next patrol at daybreak.Seeing the failed mother, instead of oneof the scores of successful egg-layers thatplod up that beach, was both a rarity andfitting.Rare, because so many turtles abandontheir future offspring to their fates on thatbeach; olive ridleys lay 300-600 nestsevery season, each laying an average offour nests. Far fewer leatherbacks come –this year only two have arrived – and eachlays about six times, some up to 10 ormore.Fitting, because the turtle’s reproductivefailure was an example of the environmentalminefield her species confrontsfrom conception to adulthood.Studies show that only one in 1,000 hatchlings will survive – most are pickedoff by birds as they make their first run tosea after hatching, and by underwaterpredators when they reach the sea.“We don’t know if our efforts increasethat number,” Palange said. “We give thema head start – we protect them from predatorson the beach, but once they reach thewater they’re on their own.”A day at the research camp confirmsthe hazards that threaten the beasts, evenbefore they hatch. Duds – infertile eggs orpartly formed turtles that died, some invadedby insects, others for causes unknown –are found in every nest.But the hatch-out rate this year is awhopping 80%, double that of last year,thanks to the addition of a roof of palmleaves over the hatchery, Palange believes.This year, PRETOMA scientists useglorified thermometer boxes to take thetemperature of the nests.“The temperature of the sand affectsthe sex ratio,” Palange said. “If it’s above32°C (90°F) they’ll all be females, and ifit’s below 29°C (84°F) they’ll all be males,so we want to keep it between the two tokeep an equilibrium.”The hatchery is a rectangle of roughhewnposts sunken in the sand and woundwith wire mesh to keep out prowlers. Thenests’ animal enemies include dogs, skunksand poachers. In spite of the protection,some raiders have entered – raccoons, judgingby the footprints – and dug up a fewnests, leaving eggshells as evidence.The scientists are volunteers who comefrom around the world to work for a fewmonths on the beach; others who work inthe camp are hired from nearby towns.René Cortés is one such case, hired tohelp in the hatchery and to talk with peopleabout the dangers of poaching.“Every day you learn something more,and that stays with you as a life experience,”Cortés said.He talks with people who visit thebeach on the weekends, and with thosefrom his own community, some of whomhe knew were egg poachers when he wasyounger. Most are receptive, he said, andagree the eggs should be protected.The turtles that come here are allendangered species, but the leatherback,the largest of all of them, is the most atrisk.“The most important thing about thisbeach is that leatherbacks come here,”Palange said.Back at PRETOMA headquarters inSan José, beach projects directorAlexander Gaos rattled off the figures: a90% drop in the leatherback populationworldwide in the last 20 years, and in thePacific, 95% of them have been destroyed.Now, scientists estimate there are only2,500 nesting females in the easternPacific. Researchers have studied theCaletas turtles for only the last three years,but the numbers from Playa Grande andsurrounding beaches are staggering. Morethan 1,300 leatherbacks arrived in 1989;only 68 arrived in 2002.Eyes light up when the leatherback ismentioned at this camp. Mireya Gracia, abiologist from Spain, said they ran twokilometers with stomachs full of rice andbeans when they heard a baula, as it iscalled in Spanish, had arrived.“We took the eggs before she coveredthem,” she said. “She lays them in a tranceand doesn’t notice anything.”Days at the camp are spent checkingthe nests and lounging in hammocks recoveringfrom nights broken by two-hourhikes in search of turtles. This beach iswild and mostly left alone by people. Thescientists have contended with scorpions,ants, flies and an errant pig that ran throughthe camp. Crocodiles lurk in the estuarieshemming in the beach.“This is pure Costa Rica here,” U.S.biologist Tanya Buxton said from herpalm-shaded lookout on the sand andwaves.When the nests hatch, the babies nudgetheir miniature turtle beaks out of the sandand are gathered together until they are allreleased to their likely doom in the sea.As they approach and enter the water,they whip into a plodding and swimmingfrenzy, propelling themselves far out tosea. There, they drift along currents anddigest the yolk of the egg they hadabsorbed into their bellies while stillinside.“You look at all the little hatchlingsscurrying to the water and wonder which,if any, will live to come back to lay eggshere,” Buxton said.Anybody can visit the camp and take anight hike with the scientists looking forturtles. The olive ridley season ended inDecember, but the leatherbacks could continueto lay eggs through February.Donations are welcome.PRETOMA raises most of its moneythrough volunteer programs at its researchcamps. For information, to volunteer or tomake donations, call 241-5227, fax 236-6017, e-mail orvisit


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