The 2007 Leatherback Program was the 13th consecutive year in which specific monitoring activities have been conducted in an effort to learn more about this critically endangered species.
The Research Assistants arrived in early March. They formed a typically diverse group with representatives from Australia, Costa Rica, Mexico, Spain and the U.S. Among them was Archie Carr’s granddaughter, Jennifer Carr, on her first trip to Tortuguero!
Although the nesting season started quite slowly, with few females coming ashore during the first weeks of the program, there were a total of 776 leatherback nests recorded during track surveys conducted from March to June (see figure at right) along the entire 22 miles of beach.
In addition, 150 green turtle and 19 hawksbill nests were also counted during these surveys. Although poaching activities were still observed, the level of illegal take was lower in 2007 than in recent years; 9.3% of leatherback, 4% of green turtle and 15.8% of hawksbill nests were observed to have been taken. Unfortunately, one leatherback female was killed by humans. Her body was encountered by Research Assistants during a morning survey on May 30. Such senseless killing of turtles simply to remove their eggs is very rare in Tortuguero and this is a worrying incident that hopefully will not be repeated.
From March to June, the Research Assistants, led by Field Coordinators Dagnia Nolasco and Xavier Debade, logged a total of 977 hours of night patrols on the beach. They recorded 127 leatherback, 25 green and 7 hawksbill encounters during those patrols. Of the 93 individual leatherback females observed 34 were new recruits to the population and 59 were encountered with tags. The majority of these turtles had been tagged in previous years in Tortuguero; the oldest was first observed in 1989. Others were originally tagged in Parismina, Pacuare, Gandoca and Mondonguillo, all of which are sea turtle projects along the Caribbean coast of Costa Rica, south of Tortuguero. Such movement between nesting beaches is typical of leatherbacks. They are generally less faithful to their natal beach than other sea turtle species. We also found four leatherbacks with tags from the CCC project in Chiriquí Beach, Panama!
The Research Assistants also participated in several educational activities with students from the village schools in Tortuguero. They gave presentations about the benefits of recycling and wrote a story about the life of “Maripili” the leatherback turtle and the dangers she faced. They also created several educational games to highlight the plight of sea turtles and introduce the students to different species of flora and fauna found in Tortuguero National Park, as well as, educating them about the need to conserve their natural resources.
During the 3 month Leatherback Program, the Field Coordinators and Research Assistants all worked incredibly hard, walking many miles throughout the day and night, often in extreme weather conditions. CCC would like to take this opportunity to thank them all for their efforts, and also to acknowledge the support of our program participants who assisted the research team in their activities.<
During her monthly visit to Tortuguero in June, Scientific Director Emma Harrison took the opportunity to lead a nightly tagging patrol. The team encountered a female leatherback that bore some unusual markings on the center of her carapace. Having attached several satellite transmitters to leatherbacks, Emma immediately wondered if this turtle had been fitted at some point with a transmitter harness. When the leatherback’s tag was checked, it turned out that Emma was correct; the leatherback was one of two that were satellite tracked by CCC from Tortuguero in 2003. “Chica Tica” had returned to nest. She had been originally flipper tagged on Mondonguillo beach along the central Caribbean coast of Costa Rica, during the early part of the nesting season in 2003. She nested again in 2003 in Tortuguero, where CCC researchers, including Emma, attached a satellite transmitter. In 2005, she returned to nest in Parismina (between Tortuguero and Mondonguillo), where she was encountered by researchers still wearing her harness, which they removed.
While the markings on her carapace were the result of the harness, she has healed perfectly. There appears to have been no detrimental effect from the harness as she has proven twice that she is perfectly capable of completing her extensive migration to feeding grounds outside the Caribbean, and returning to mate and successfully nest.
In July, Field Coordinators Dagnia Nolasco and Xavier Debade were presented with a tag that had been recovered by Tortuguero National Park Rangers. They studied various databases to determine when and where tag number C3340 had been applied. The tags that CCC applies all have a return address in Gainesville, Florida, so that if somebody finds a flipper tag from a turtle, they can return it to CCC with information about where they found the tag. This tag was definitely not a Tortuguero flipper tag. It had a Cuban return address.
Their search was unsuccessful. CCC has contacted sea turtle biologists in Cuba to learn more about the history of the tag. There is, however, a rather sad twist to this tale. The green turtle carrying the flipper tag C3340 had survived crossing the Caribbean Sea, presumably from feeding grounds around Cuba, evading numerous dangers en route to reach her nesting beach, only to be dragged off the beach while attempting to lay her eggs! The park rangers found the tag in the flipper of a turtle that had been killed and dragged off the beach by a jaguar, a rather unfortunate ending after such an incredible journey.
The night of August 2, 2007 should be called “Golden Oldies Night” in Tortuguero. During tagging patrols on the beach just north of the CCC field station, two rather special female green turtles were encountered the same night. These two old ladies were both originally tagged back in 1982, 25 years ago, breaking the record of ‘Old Faithful’ for the longest nesting history of a green turtle in Tortuguero! What is even more incredible is that both turtles chose to nest on the same night and within a quarter of a mile of each other.
The female green with tag #23897 was first tagged on July 30, 1982. Since first being tagged, she has been seen on 27 subsequent occasions; three additional times in 1982, three times in 1984, four times in 1986, six times in 1988, three times in 1990, once in 1992 and in 1997, four times in 2004, and once in 2002 and 2005. She seems to have a favorite stretch of beach for nesting between mile markers one and two. The female green with tag #24436 was first tagged on August 14, 1982. She has been encountered 22 times since then; twice more in 1982, four times in 1986, three times in 1988, four times in 1991 and in 1996, once in 1999 and in 2002, and three times in 2005. She was also encountered just a quarter of a mile away from where she was originally tagged in 1982, suggesting an amazing knowledge of her nesting beach and a strong preference for a particular section.
Unfortunately, neither of the two turtles had their shell length measured in 1982, so it is impossible to calculate how much they have grown over the 25 years. It is very encouraging to see that they have managed to survive the innumerable threats they face not only in Tortuguero, but throughout their lives as they migrate from place to place in search of food, mates or a place to nest. Hopefully, they will continue to swim safely and return for many more nesting seasons.