REPORT ON THE 2012 GREEN TURTLE PROGRAM AT TORTUGUERO, COSTA RICA

Transcription

1 REPORT ON THE 2012 GREEN TURTLE PROGRAM AT TORTUGUERO, COSTA RICA Submitted to Sea Turtle Conservancy (Formerly Caribbean Conservation Corporation) and the Ministry of Environment, Energy and Telecommunications of Costa Rica 25 July, 2013 by Catalina González Prieto, Field Research Coordinator Juan Daniel Guerrero, Education and Outreach Coordinator Dr Emma Harrison, Scientific Director With assistance from Katherine Ambrose, Research Assistant Jessica Ponce Quezada, Research Assistant Fernando Campos Calderón, Research Assistant Raúl Ramírez Barragán, Research Assistant Angela Chévez Herra, Research Assistant Alan Rosenthal, Research Assistant Jordan Donini, Research Assistant Daniella Rubiano Ciodaro, Research Assistant Jennifer Drenth, Research Assistant Melissa Ussa, Research Assistant Raúl García Varela, Research Assistant Luis Valero-Barrios, Research Assistant Antonio Montemayor, Research Assistant Georgina Zamora Quílez, Research Assistant Schuyler Olsson, Research Assistant Kari Gehrke, Intern Marjorie Pinzón Arias, Research Assistant Lizette Guzman-Zaragoza, Intern Jorge Ivan Ramos, Track Surveyor Address: Apartado Postal NW 13 th St. Suite B-11 San Pedro Gainesville, FL COSTA RICA USA Phone: INT INT Fax: INT INT emma@conserveturtles.org info@conservereturtles.org Webpage:

2 Table of Contents TABLE OF CONTENTS... I LIST OF TABLES... II LIST OF FIGURES... II ACKNOWLEDGMENTS... 3 EXECUTIVE SUMMARY INTRODUCTION METHODS Preparations Track Surveys Dead Turtles Tagging of Nesting Sea Turtles Biometric Data Collection Fibropapilloma Assessment Determination of Nest Survivorship and Hatching Success Physical Data Collection Collection of Human Impact Data Satellite Tracking Project Community Activities RESULTS Preparations Track Surveys Dead Turtles Tagging of Nesting Sea Turtles Biometric Data Collection Fibropapilloma Assessment Determination of Nest Survivorship and Hatching Success Collection of Human Impact Data Satellite Tracking Project Community Activities DISCUSSION Preparations Track Surveys Dead Turtles Tagging of Nesting Sea Turtles Biometric Data Collection Fibropapilloma Assessment Determination of Nest Survivorship and Hatching Success Physical Data Collection Collection of Human Impact Data Satellite Tracking Project Community Activities REFERENCES APPENDICES i

3 List of Tables Table 1. Turtles encountered alive following attempted poaching Table 2. Mean CCLmin of green turtles Table 3. Mean SCLmax of green turtles Table 4. Precision of carapace measurements for green turtles in the same encounter Table 5. Precision of carapace measurements for green turtles between different encounters Table 6. Mean carapace length and clutch size of hawksbill, leatherback and loggerhead turtles Table 7. Precision of carapace measurements for hawksbill, leatherback and loggerhead turtles Table 8. Fate, hatching and emerging success of marked green turtle nests in Table 9. Summary of excavation data for green turtle nests marked in 2012 data combined from Tortuguero and Jalova Table 10. Incidence of albinism, twins and deformed embryos in Table 11. Hatching and emerging success of nests from females observed or not observed by tourists during Table 12. Summary of hawksbill nest excavations from Table 13. Summary of rainfall data January to December, Table 14. Summary of air temperature January to December, Table 15. Mean monthly sand temperature in Table 16. Number of visitors to the STC Natural History and Visitors Center Table 17. Number of paying visitors to Tortuguero National Park, Table 18. Number of tourists participating in turtle tours each month; July October, Table 19. Summary of hatchling disorientation events in Table 20. Summary of the veterinary clinic November List of Figures Figure 1. Temporal distribution of green turtle nesting at Tortuguero in 2012, as determined from weekly track surveys Figure 2. Green turtle nesting trend at Tortuguero, , as determined by weekly track surveys of the entire beach Figure 3. Spatial distribution of green turtle nesting at Tortuguero in 2012, as determined from weekly track surveys Figure 4. Results of daily track surveys of the northern 5 2/8 miles of beach in Figure 5. Results of daily track surveys of the southern three miles of beach in Figure 6. Illegal take of green turtle nests and females in 2012, as determined from daily track surveys of the northern 5 2/8 miles of beach Figure 7. Summary of monthly light surveys conducted during the 2012 Green Turtle Program ii

4 Acknowledgments The 2012 Green Turtle Program was conducted under a research permit from the Tortuguero Conservation Area (ACTo) of the Ministry of Environment, Energy and Telecommunications (MINAET) of Costa Rica, detailed in resolution N o ACTo-GASP-PIN This report was made possible thanks to the dedication of the 2012 Green Turtle Program research team; all the data presented here were collected by Field Research Coordinator (FRC) Catalina González Prieto (Colombia), Education and Outreach Coordinator (Juan Daniel Guerrero Blanco (Spain) and the dedicated team of Research Assistants (RAs): Katherine Ambrose (USA), Fernando Campos Calderón (Costa Rica) Angela Chévez Herra (Costa Rica), Jordan Donini (USA), Jennifer Drenth (USA), Raúl García Varela (Spain), Antonio Montemayor (USA), Schuylere Olsson (USA), Marjorie Pinzón Arias (Colombia), Jessica Ponce Quezada (Mexico), Raúl Ramírez Barragán (Mexico), Alan Rosenthal (Argentina), Daniella Rubioano Ciodaro (Colombia), Melissa Ussa (USA), Luis Valero-Barrios (Venezuela) and Georgina Zamora Quiílez (Spain). They were assisted by two interns from The Science Exchange program; Kari Gehrke (USA) and Lizetter Guzman-Zaragoza (USA) and students from the Colegio Técnico Profesional de Guácimo (Horacio Madrigal Diaz and Walter Vega Morales). We also gratefully acknowledge the support of numerous program participants and staff and volunteers from Global Vision International who facilitated monitoring activities close to Jalova. The weekly track surveys of the entire beach were conducted by Jorge Ivan Ramos, whose considerable efforts we very much applaud. The dedication of all the John H. Phipps Biological Station staff was integral to the 2012 Green Turtle Program. Station manager Randall Torres Brenes provided logistical support; Indira Torrez administrated the Visitor Centre; boat captain Jorge Ivan Ramos safely transported researchers; Juanita Fernández made sure that everyone was well fed; Jacqueline Brandt was responsible for keeping the station clean and ensuring that everyone had clean clothes; and the station was kept secure by various security guards. Ms. Elena Vargas Ramírez, Ms. Sara Zúñiga and the park rangers of ACTo are due acknowledgement for their continuing efforts to protect sea turtles in Tortuguero National Park (TNP). We also acknowledge the continued support of the tour guides and all of the Tortuguero community during the 2012 Green Turtle Program. Our outmost gratitude is extended to National Director Roxana Silman and her assistant Maria Laura Castro in the Sea Turtle Conservancy (STC) office in San José, who provided logistical support throughout the Program. The help of STC staff in the Gainesville, Florida office is also recognized, for providing necessary equipment and help when requested. For financial assistance we would like to thank the Bay & Paul Foundation, the Firedoll Foundation, the Marisla Foundation, the USFWS-Marine Turtle Conservation Fund and all the 2012 Green Turtle Program Eco-Volunteers. 3

5 Executive Summary Monitoring and Research Activities Conducted 1 During 2012, a total of 52 track surveys were conducted along the entire 18 miles of beach between Tortuguero river mouth and Jalova lagoon. 2 Green turtle nesting was observed regularly between May and November; with the first nest recorded on 10 March. 3 Peak nesting was recorded on 18 August; 3,459 green turtle nests were counted in a single night. 4 An estimated 172,760 green turtle nests were laid during This equates to a population of 28,793 61,700 nesting females. 5 A total of 25.6% of all green turtle nests recorded during track surveys were deposited between Tortuguero river mouth (mile 2/8) and mile 5, and between mile 15 and the Jalova lagoon. 6 Jaguars killed a minimum of four green turtles in Hawksbill nesting density was very low throughout the season, with seven nests recorded from April November. 8 During daily track surveys conducted by the FRC and RAs between 8 June and 1 November a total of 27,769 green turtle nests and 30,191 green turtle false crawls were recorded between the Tortuguero river mouth and the mile 5 marker. Surveys between mile 15 and the Jalova lagoon recorded 15,692 nests and 6,148 false crawls. 9 Twelve leatherback, 32 hawksbill and three loggerhead nests were recorded (0.5%) green turtle nests were recorded as poached during daily track surveys. 11 Twenty-two adult green turtles were poached from the beach. 12 Illegal poaching activity was observed on 48.9% of surveys. 13 Nine green turtle nests were depredated by dogs in the northern five miles of beach. 14 Sixty-nine dead green turtles were encountered; all were killed by jaguars. 15 Three green turtles were found alive, following poaching attempts; all were successfully released. 16 2,087.6 team hours of night patrols were conducted from 6 June 31 October; 1,588.3 hours in Tortuguero and hours in Jalova. 17 A total of 1,622 green turtles were newly tagged, 740 green turtles had tags, and 343 females were encountered more than once during night patrols of the previously tagged turtles had been originally been tagged in Tortuguero more than 10 years ago and 10 more than 20 years ago. 19 The longest nesting history for a turtle observed in 2012 was a turtle that was originally tagged in 1984, 28 years ago. 20 Twenty-five green turtles were encountered in 2012 with tags from other projects; four were tagged 4

6 at Pacuare Nature Reserve, 16 at Caño Palma and five at Parismina. 21 One turtle was encountered with tags from locations outside of Costa Rica; from an in-water project in Bocas del Toro, Panama. The turtle was originally tagged there in Newly tagged green turtles had evidence of old tag holes or notches in at least one front flipper in 14.0% of cases. 23 Green turtles encountered during night patrols nested in the open zone in 31.7% of cases, 56.9% were located in the border zone and 10.5% in the vegetation zone. 0.5% of turtles were encountered during a false crawl emergence. 24 Seven newly tagged hawksbill turtles were encountered during the 2012 Green Turtle Program. 25 One newly tagged leatherback turtle, four previously tagged and four renesters were encountered during the 2012 Green Turtle Program. 26 Two loggerhead turtles were observed in 2012; one in Tortuguero and one in Jalova. 27 Overall carapace length for green turtles was 105.3cm (CCLmin) and 99.5cm (SCLmax Tortuguero) and 98.7cm (SCLmax Jalova). 28 Mean clutch size for green turtles was eggs; with a range of eggs. 29 Precision of CCLmin and SCLmax measurements of green turtles was the same within a single encounter; 0.4 cm. For turtles seen more than once, SCLmax measurements were more precise. 30 Mean carapace length for hawksbill turtles was 87.5cm (CCLmin) and 83.2cm (SCLmax). 31 Mean clutch size for hawksbill females was eggs. 32 The mean CCLmin for leatherback turtles was 155.7cm (CCLmin). 33 Mean clutch size for leatherbacks was 78.2 eggs. 34 Mean carapace length for loggerheads was 99.6cm (CCLmin) and 95.5cm (SCLmax). 35 Mean clutch size for loggerheads was eggs. 36 None of the 180 green turtles carefullyfor fibropapiloma had tumors present. Other types of tumors were observed on 53 turtles. 37 A total of 243 green turtle nests were marked and the fate was determined for 191 nests. 38 Overall mean hatching success was estimated at 73.5% and overall mean emerging success at 70.7%. 39 Mean depth for undisturbed green turtle nests at excavation was 60.3cm (n = 146) from the sand surface to the top egg and 76.0cm (n = 145) to the bottom of the egg chamber. 40 A total of three albino, three sets of twins and 15 deformed embryos were observed in unhatched eggs, accounting for 0.115% of eggs. 41 Seven hawksbill nests were monitored and the fate was determined for six nests. Mean hatching and emerging success was 75.8%. 5

7 42 Two loggerhead nests were monitored and the fate was determined for one of them; hatching and emerging success was 50.0%. 43 Rainfall was monitored from January December 2012; February was the driest month (118.6mm) and November was the wettest month (1,163.9mm). 44 Air temperature was monitored from June December 2012; November was the coolest month (23.7 ºC) and August was the warmest (26.8 ºC). 45 Sand temperature in the vegetation zone ranged from ºC, in the border zone it ranged from ºC and in the open zone from ºC. 46 A total of 25,240 people visited the STC Visitors Center in 2012; an average of 69 people per day. 47 Tourist visitation to Tortuguero National Park (TNP) declined in 2012, to 117,341 paying visitors. Entrance fees to TNP generated a total of 366,904,896 (~ US$733,810). 48 A total of 28,537 tourists were issued permits to go on guided turtle tours during the official green turtle season (July - October) in 2012; an average of 221 tourists per night. 49 The problem of artificial lights visible on the beach continued in 2012; on four occasions hatchlings were encountered disorientated by the lights, two of which occurred in front of the Balcon del Mar Cabinas. 50 One green turtle was tracked using satellite telemetry; she swam 1,741 miles (2,811km) to coastal waters off Nicaragua. 51 The eighth veterinary clinic took place in November, 2012; 116 animals were treated, of which 42 were spayed/neutered. To date, 437 animals have been spayed/neutered since Recommendations 1 The collaboration of STC with Global Vision International should continue in the future, to increase monitoring activities at the southern end of the nesting beach. 2 Adequate training of RAs in all aspects of the monitoring protocol is essential to ensure that they are tagging and collecting data effectively and accurately; increased practical sessions should be scheduled during the orientation period, with on-going supervision throughout the program. 3 Regular updates of program results should be made available to TNP staff and tour guides throughout the season; including interesting turtle encounters and nesting distributions. 4 More regular reports should be submitted to TNP staff regarding observations of illegal take of turtles and eggs, both from the nesting beach and near-shore waters. 5 A more effective long-term solution to the control of dog populations should be sought; MINAET should take a more active role in helping to reduce the influx of animals into the area. 6 Collection of physical data should continue on a daily basis throughout the year, to monitor changes in environmental conditions in Tortuguero and provide a baseline for possible studies into the effects of climate change on sea turtles and their habitats. 7 The Turtle Spotter Program should continue in future years and STC should remain responsible for the evaluation of the program activities and further studies to monitor potential negative impacts on 6

8 turtles and their nests. It is important that STC remains an integral part of the committee responsible for overseeing the development and implementation of the program activities. 8 A more detailed study should be conducted to investigate the impact of tourist activities on hatching success of nests of female turtles observed by tour groups. 9 A carrying capacity study should be conducted to determine the maximum limits related to tours to observe sea turtle nesting on the beach at night; to include the total number of people permitted per night or per section of beach, the total number of people permitted to observe each turtle, and establish a minimum distance between turtles being observed to prevent crowding. 10 MINAET should increase their presence on the beach at night to ensure that tour guides and turtle spotters follow the TSP rules regarding the management of tour groups. 11 A revegetation program should be initiated to replace native vegetation between the beach and village buildings, to help reduce the problem of artificial light that is negatively impacting sea turtle hatchlings. 12 The satellite tracking project should continue in future years; it is a great way to find out the migration routes of turtles nesting at Tortuguero, to determine what possible threats turtles may face during migration and also know where their feeding areas are located. 7

9 1. Introduction Dr. Archie Carr began studies of green turtles (Chelonia mydas) in Tortuguero in 1954 (Carr et al. 1978). Since 1959, the Sea Turtle Conservancy (Formerly Caribbean Conservation Corporation), STC, has implemented the annual Green Turtle Program. Prior to the 1998 nesting season, STC staff and the Scientific Advisory Committee revised the Green Turtle Program monitoring protocol. The new protocol defines that the Green Turtle Program is conducted in order to fulfill STC s scientific mission in Tortuguero: STC will provide the scientific information necessary to conserve the populations of sea turtles that nest at Tortuguero, Costa Rica, so that they fulfill their ecological roles The 2012 Green Turtle Program represents the fifteenth consecutive year of implementing the revised monitoring protocol. The objectives of this report are to summarize and discuss the results of the 2012 Green Turtle Program and provide recommendations for future sea turtle programs, conservation efforts and research activities in Tortuguero. 2. Methods 2.1 Preparations Prior to the start of monitoring activities at Tortuguero in 2012, STC signed an agreement with Global Vision International (GVI), a volunteer organization that has a project in Tortuguero National Park. The agreement detailed how GVI staff and volunteers would be trained by STC and assist in monitoring activities close to the Jalova lagoon. At the start of the 2012 Green Turtle Program the Research Assistants (RAs) completed an extensive orientation and training program; they received lectures about sea turtle biology and conservation, and the Green Turtle Program monitoring protocol was explained in detail and conducted training patrols at night. They also learned about the history of the National Park, environmental laws relating to sea turtles, and the historical development of Tortuguero. They were also taken on a canal tour to learn about the flora and fauna of the park. In addition to the practical and theoretical training the RAs checked the position and condition of the beach markers in the northern five miles of beach (from the river mouth to the mile five marker); any missing markers were replaced and all markers were repainted white, with the mile numbers in black. GVI staff and volunteers replaced and repainted mile markers from mile Track Surveys Weekly track surveys Track surveys were carried out approximately weekly during the entire Green Turtle Program. The track surveyor conducted surveys between the Tortuguero river mouth (mile -3/8) and Jalova lagoon (mile 18). The surveys commenced at dawn at the Tortuguero river mouth, or at Tortuguero village, and finished at Jalova lagoon. If the survey started at the village, and the section between Tortuguero river mouth and the village had not been surveyed in the morning, the same person surveyed that beach section upon completing the other part of the survey. 8

10 Only tracks from the previous night were recorded and for each track the following information was recorded: Species Mile Nest or false crawl If the nest and/or turtle was poached If the turtle was depredated by jaguars A nest was recorded as poached if there were signs of human disturbance, including footprints around the nest, poke holes from a stick, evidence of digging, an empty egg chamber or fresh broken egg shells close to the nest. A turtle was considered poached when there was no down track heading back to the sea and there was evidence that she had been flipped over and dragged off the beach (either through the vegetation or to a boat). Dead turtles were considered depredated by jaguars (Panthera onca) when they were surrounded by jaguar tracks or showed characteristic jaguar injuries, such as extensive bites marks to the neck Daily track surveys In addition to the weekly track surveys of the entire 18 miles of nesting beach the FRC and RAs conducted daily track surveys along the northern 5 2/8 miles of beach (from the Tortuguero river mouth to the mile 5 marker) and the southern three miles at Jalova (from Jalova lagoon to mile 15) from June - October. These surveys commenced at 6.00am each morning. Only tracks from the previous night were counted, and for each track the following information was recorded: Species Mile Nest or false crawl Once a nest had been recorded two lines were drawn through the track to ensure that it was not counted on future surveys Illegal take and nest predation During track surveys researchers also recorded the level of illegal take of nests and nesting turtles, and nest depredation. For each nest the following information was recorded: Species Mile If the nest and/or turtle was poached by humans If the nest was predated Identify the predator if possible 2.3 Dead Turtles Any dead turtles encountered during track surveys or other monitoring activities were examined and an attempt was made to determine the cause of death. For each turtle the following information was recorded: Species 9

11 Mile Sex if possible to determine If the turtle was killed by a jaguar Cause of death if possible to determine Presence of flipper tags numbers recorded if present Other pertinent observations 2.4 Tagging of Nesting Sea Turtles Tagging teams patrolled the beach every night from June - October. The northern part of the beach was divided into two sections: Boca - from the river mouth to the field station (at mile 2 5/8) and Park - from the field station to the mile 5 marker. Separate teams patrolled each section during two shifts: 8pm - 12am and 12-4am, when the number of researchers and volunteer participants allowed. Trained GVI staff and volunteers conducted additional patrols in the southernmost three miles of beach, between mile 15 and the Jalova lagoon. Female turtles encountered during the patrol were tagged after finishing oviposition or when returning to the sea. Leatherbacks (Dermochelys coriacea) were tagged in the rear flippers; hard-shelled species were tagged axillary, close to the first scale on the front flippers. All turtles were double-tagged to allow identification even if one tag was lost between nesting emergences. For each encounter the following information was recorded: Date Mile marker (to the north of the turtle) Species Tag numbers of existing tags and/or evidence of old tag holes or notches Name of the person applying the tags The location of the nest was classified into one of three groups: Open open beach with no vegetation and no shading Border nest partially shaded by vegetation for some part of the day Vegetation dense vegetation completely shading the nest throughout the day Green turtles Inconel #681 tags were used to tag a minimum sample of 1,000 green turtles not carrying old tags. Every effort was made not to mix Inconel and Monel tags on the same individual. Thus, if a turtle was encountered carrying one Monel tag this was removed and two Inconel tags were applied. If it was not possible to remove the Monel tag for some reason, a second Monel tag was applied to the other flipper Hawksbill turtles Hawksbill (Eretmochelys imbricata) turtles were tagged with Inconel #681 tags. Due to the very low level of hawksbill nesting at Tortuguero, and the fact that they are listed as critically endangered, researchers always remained with the turtle until she returned to the sea and then they thoroughly erased the track afterwards, to minimize the possibility of the nest being taken by poachers Leatherback turtles Leatherback turtles were tagged in the rear flippers using Monel #49 tags. 10

12 2.5 Biometric Data Collection Green turtles Biometric data were collected from a sample of nesting green turtles. An attempt was made to count one clutch of eggs per night in each of the two northern beach sections (Boca and Park) and at least one clutch per night in the southern beach section (Jalova). Eggs counts were conducted as the eggs were laid, by a person wearing a plastic glove so as not to contaminate the nest. Eggs were counted using an egg counter; any yolkless eggs were counted separately. All egg counts were conducted after midnight, when there were no tour groups present on the beach. All tagged turtles were measured after they had finished nesting, if possible. Curved carapace length minimum (CCLmin), from where the skin meets the carapace by the nuchal notch to the posterior notch between the supracaudals, along the midline, was determined to the closest millimeter using a fiberglass tape measure. Straight carapace length maximum (SCLmax), from the anteriormost edge of the carapace to the posterior tip of the longest supracaudal, was determined, to the closest millimeter, using a set of calipers. Both CCLmin and SCLmax measurements were taken three times by the same person, whose name was recorded in the field book, in order to determine the precision of the measurements. Precision is defined as the difference in centimeters between the longest and the shortest of the three measurements. Precision for females encountered more than once during the 2012 season is defined as the difference between the shortest and the longest of all measurements taken from the same turtle over the course of the season Hawksbill turtles CCLmin and SCLmax measurements were taken for all hawksbills encountered during night patrols. As for green turtles, the same observer measured the turtle three times for each measurement, to allow the precision to be calculated. Whenever possible the clutch was counted, if the hawksbill had not already started to lay eggs when encountered Leatherback turtles For leatherbacks, CCLmin (from where the skin meets the carapace by the notch of the neck to the posterior end of the caudal projection, next to the central ridge) was measured using a 300cm fiberglass measuring tape. Each turtle was measured three times to determine an average CCLmin. No SCLmax measurements were taken as the calipers were not sufficiently large enough to measure a leatherback turtle. 2.6 Fibropapilloma Assessment For a minimum sample of 100 green turtles, those for which clutches were counted, an examination for the presence of fibropapilloma tumors was also conducted. All soft body parts, including the cloacal region, were inspected, using a flashlight with a red filter. The following data were recorded for each assessment: The presence or absence of fibropapilloma tumors Location of fibropapilloma tumors observed Size of any tumors detected The name of the person examining the turtle Any evidence of fibropapilloma tumors on turtles for which the clutch was not counted was also recorded during the season. 11

13 2.7 Determination of Nest Survivorship and Hatching Success A sample of green turtle and hawksbill nests was marked during oviposition. These nests were located between Tortuguero river mouth (mile -3/8) and the mile 5 marker at the northern end of the beach, and between mile 15 and the Jalova lagoon at the southern end of the beach. The nests were marked using three pieces of flagging tape that were attached to vegetation behind the nest. While the turtle was laying eggs the distance from the centre of the egg chamber to each of these tapes was measured to the nearest centimeter, so that the location of the nest could be determined at the time of excavation using triangulation. Three marker tapes were used to compensate for the loss of any tapes as a result of camouflaging turtles, insects or persons removing the tapes intentionally; if one marker tape was lost it was still possible to locate the nest using the other two tapes. The distance to the most recent high tide line was also recorded at the time of oviposition. To assist in the positive identification of the marked nest during excavation a small piece of flagging tape with the nest code written on it was deposited in the egg chamber during oviposition. In addition, the morning after a nest was marked the measurements were checked to ensure that they crossed; any discrepancies were re-checked by the researchers responsible for marking the nest the previous night. In this way, erroneous measurements, or errors during the recording of data in the field books could be identified and corrected immediately. All of the marked nests were inspected daily. Evidence of depredation, poaching or beach erosion were noted and resulted in termination of monitoring for that nest; if the evidence was inconclusive, monitoring continued as normal, but the date of the observed disturbance was recorded, so that any resulting anomalous excavation data could be accounted for. Also, it was recorded if the nest had been washed over or inundated by the tide during the previous 24 hours. If evidence of hatching was observed, the date was noted and the nest was excavated two days later. If no depression or hatchling tracks were recorded, the nest was excavated after 65 days (75 days for any leatherback nests). After 65 days, or sooner if signs of emergence had been recorded, the nest was excavated, once the distances from the marker tapes had been re-measured to confirm that it was the original nest. Nests that had no obvious depressions were located by carefully probing for soft sand using a wooden stick (only after 65 days, when it was presumed that hatching and emergence had occurred), and this technique greatly aided in locating several of the marked nests for which hatching had not been recorded. The excavation was discontinued if the researcher encountered a large number of hatchlings in the nest; in such cases the hatchlings were re-buried and the nest excavated at a later date. If a few hatchlings were encountered, they were placed in a shallow hole close to the nest site and covered with sand so that they could reach the sand surface and emerge the following night. For each nest the following information was recorded during the excavation: Nest code Mile marker Name of persons conducting excavation Date laid, hatched (if available) and excavated Number of empty shells only shells corresponding to more than 50% of the egg were counted Number of hatchlings alive or dead Number of unhatched eggs - these were categorized as o Without embryo no visible embryo observed o Embryo an embryo at any stage of development was present o Full embryo a fully developed embryo was present Number of pipped eggs embryo had broken the shell but failed to hatch 12

14 Number of predated eggs Number of deformed embryos including albinism or multiple embryos in a single egg Number of yolkless eggs If the nest identification tape was found Any other pertinent information In addition, the depth from the surface to the top of the egg chamber (to the first egg encountered), and the bottom of the egg chamber (after the last egg was removed) was measured to the nearest centimeter. If a nest could not be found when excavated, an additional attempt was made the following morning by a different research team. If after two attempts the nest could not be found, researchers tried to determine the fate of the nest. Nests were considered poached if an empty egg chamber was encountered. Nests were assumed dug-up by another turtle if broken eggshells and/or the nest code tape from within the egg chamber, and a new body pit were encountered where the original nest was supposed to be located. Nests were considered depredated if a large number of opened eggshells were found in close proximity to the location of the marked nest, and there were signs of digging by animals, or tracks. An attempt was made to identify the predator if possible. If human footprints and digging was observed at the location of the nest, the nest was considered dug-up by tour guides or other persons to show the hatchlings to tourists. Nests for which the fate could not be determined with certainty or which were not excavated entirely were excluded from the subsequent analysis of nest survivorship and hatching success. 2.8 Physical Data Collection Throughout the 2012 Green Turtle Program several environmental variables were monitored on a daily basis at the John H. Phipps Biological Station in Tortuguero. Rainfall was collected in a gauge that was emptied each day at 9.00am and recorded to the closest 0.1mm. Air temperature was recorded at 9.00am; the minimum and maximum values for the previous 24 hours, and the current temperature were noted. Sand temperature was measured using data loggers buried at 30, 50 and 70cm depth in the open, border and vegetation zones of the beach in front of the STC station. The data loggers were set to take a temperature reading every hour. The data were downloaded at the end of the 2012 Green Turtle Program. 2.9 Collection of Human Impact Data Visitors to STC Visitors Centre The number of visitors paying to enter the STC Natural History and Visitors Center was recorded each day during 2012 by the Visitor Center Administrator Visitors to Tortuguero National Park Staff at the Tortuguero National Park headquarters at Cuatro Esquinas provided information on tourist visitation to the park during

15 2.9.3 Turtle tours The number of tourists going on guided turtle tours during the 2012 Green Turtle Program was determined from the permits issued to tour guides by ACTo. In 2012, the Turtle Spotter Program (TSP), the visitation system introduced in 2004 that aimed to reduce negative impacts of tourism on nesting sea turtles, was implemented along the northern five miles of beach where tourism is permitted (from the Tortuguero river mouth to the mile 5 marker). Turtle spotters patrolled the beach searching for nesting turtles, and reported their location to the tour groups waiting with their guides at designated areas behind the beach. When the turtle was close to laying eggs, guides led their group to her location using a path behind the beach, thus reducing the number of people walking along the beach who could potentially disturb other turtles as they came ashore to nest Artificial lights To assess the level of impact of artificial lights on the Tortuguero nesting beach a light survey was conducted each month. Dates as close as possible to the new moon were selected when natural light levels on the beach were minimal. The beach was surveyed from the Tortuguero river mouth to the mile 5 marker, commencing at 8.00pm. For each survey the following data were recorded: Date Beach section Boca or Park Name of observers Mile section Number of lights visible from the beach Light source (if possible to determine) To avoid duplicate recording of the same light source in more than one 1/8 mile section of beach, only those lights that could be seen while viewed perpendicular from the beach were recorded in each 1/8 mile Hatchling disorientation Any evidence of hatchling disorientation was recorded, for marked or unmarked nests. Where possible the light source causing the disorientation was noted, in addition to the number of disorientated hatchlings encountered (dead or alive) and the number of hatchlings that reached the sea successfully Satellite Tracking Project Continuing the satellite tracking project that has been conducted by STC within the Caribbean region since 2001, in 2012 one satellite transmitter was available for attachment to a green or hawksbill turtle during the Green Turtle Program. This turtle was included in the 2012 Tour de Turtles; an on-line education event run by STC to raise awareness about sea turtles, their migration behavior and threats that they face. The transmitter was attached during the middle of the nesting season; the data would provide information on inter-nesting behavior between nesting emergences and also post-nesting migrations to feeding grounds away from Costa Rica. The turtle was selected by researchers depending on her size, physical characteristics of the carapace (to aid attachment by not having any deformities or irregularities in the scutes) and distance from the field station (to facilitate their relocation to the station where they were retained overnight). 14

16 The following morning the transmitter attachment process began at 6.00am, following the protocol of Coyne et al.(2008). Visitors from the lodges and cabinas, and members of the community were invited to observe the attachment procedure and subsequent release of the turtle. STC researchers were available to answer any questions about sea turtles, satellite telemetry or the work of STC. Data from the transmitter were used to produce migration maps which were regularly updated on the Tour de Turtles website ( Community Activities Veterinary Clinic In response to concerns in 2007 from STC, local guides and National Park staff about the level of dog predation of turtle nests and the increasing population of dogs in the village, a committee was organized comprising representatives from interested groups and individuals to coordinate a veterinarian spay/neuter clinic and educational program in 2008 with the aim of reducing the dog population and also providing advice to local residents on how to care for their pets. In 2012, one clinic was conducted and STC remained closely involved in the organization committee. 3. Results 3.1 Preparations The agreement between STC and GVI facilitated collaboration between the two organizations; GVI staff and volunteers assisted in the collection of data for the 2012 Green Turtle Program, and the additional personnel allowed beach patrols to be conducted in the section of beach close to Jalova which typically is only monitored at night during the Leatherback Program from March June. The RAs arrived in Tortuguero on 4 June, During the first two weeks of the 2012 Green Turtle Program the RAs received an intensive training program and general orientation. This included lectures about sea turtle biology, conservation, tourism in Tortuguero, and the history and structure of STC. There was also a detailed explanation of the Green Turtle Program monitoring protocol. In addition to theoretical instruction they also received practical training in flipper tagging, nest marking and other data collection procedures from the FRC and Scientific Director (SD). Training patrols were conducted on several nights along sections of beach close to the field station (between the Tortuguero river mouth and mile 5), during which the FRC/SD demonstrated field techniques and supervised RAs tagging and measuring turtles, and recording data in the field books. To help build a better relationship with the turtle spotters (who look for turtles for tour groups during the green turtle nesting season), joint training sessions were conducted with the RAs and spotters to practice how to manage tour groups and also how Eco-Volunteers could collect data from a turtle being observed by tourists. Tour guides were also invited to participate in these practical sessions, but no-one attended. To have a better understanding of TNP and Costa Rican environmental laws, RAs received a talk from park rangers. They also had an opportunity to speak to members of one of the founding families of Tortuguero to learn about the history and development of the area. To facilitate the environmental education program there were also visits to the school and high school in Tortuguero, and the school in San Francisco, so that the directors and teachers could meet the EOC and RAs before they started activities with the students. 15

17 During the first week of the program the mile markers on the beach between the Tortuguero river mouth (mile -3/8) and the mile 5 marker were replaced and/or repainted as necessary, to ensure that there were three markers at each 1/8 of a mile; GVI personnel checked the markers between miles These markers were put in the same locations as those positioned at the start of the 2012 Leatherback Program. 3.2 Track Surveys Weekly track surveys Fifty-two weekly track surveys were conducted from 7 January to 29 December, The first green turtle nest was recorded on 10 March, 2012, with regular nesting observed from May November (See Figure 1). Peak nesting was observed on 18 August, when 3,459 nests were recorded in a single night. Using the methodology of Troëng & Rankin (2005), it was estimated that 172,760 green turtle nests were laid along the entire 18 miles of beach during the 2012 nesting season (See Figure 2). This equates to a population of between 28,793 61,700 nesting females. As observed in previous years, green turtle nesting density was found to be highest away from the river mouths that mark the end of the beach; the least stable area of nesting habitat (See Figure 3). Increased nesting was observed within TNP, between miles 4 14, but there was no defined peak as in previous years. Nests laid between the Tortuguero river mouth and the mile 5 marker, and between miles in Jalova, where nightly beach patrols were regularly conducted, accounted for 25.6% of all nests laid on the entire beach (See Figure 3). Six green turtle nests were recorded as poached during weekly track surveys, between June and July. Five green turtles were reported as poached; four on 27 October and one on 3 November. All the turtles taken on 27 October were within TNP, between miles

18 17 Figure 1. Temporal distribution of green turtle nesting at Tortuguero in 2012, as determined from weekly track surveys

19 Figure 2. Green turtle nesting trend at Tortuguero, , as determined by weekly track surveys of the entire beach 18

20 19 Figure 3. Spatial distribution of green turtle nesting at Tortuguero in 2012, as determined from weekly track surveys

21 Seven hawksbill nests were observed between April and November, One nest and one turtle were recorded as poached. A detailed discussion on the temporal and spatial distribution of leatherback nesting in 2012 can be found in the 2012 Leatherback Program Report Daily track surveys Daily track surveys were conducted by the FRC and RAs between 8 June and 1 November (except 12 and 15 June, 4 and 18 August, 20 September and 4-5 October). Partial surveys were conducted 8-11 June for RA training. On 17 and 28 August surveys were abandoned due to storms on the beach. A total of 27,769 green turtle nests and 30,191green turtle false crawls were recorded between the Tortuguero river mouth and the mile 5 marker (See Figure 4a and 4b); successful nesting was observed in 47.9% of green turtle emergences. Figure 4a shows the spatial distribution of green turtle nests and false crawls for the northern 5 2/8 miles of beach. Nesting density per 1/8 mile was greater within the National Park (past 3 3/8). However, the overall number of nests laid north of the limit to TNP was very similar to that laid inside; 13,602 (49.0%) compared to 14,167 (51.0%), respectively. As in previous years, nesting density was lowest close to the river mouth (mile -2/8) and in front of Tortuguero village (miles 2 7/8-3 2/8). The temporal distribution of nesting for the 2012 Green Turtle Program is shown in Figure 4b. Peak nesting activity was recorded on 11 September, when 652 green turtle nests were counted from the previous night. Nesting activity was much higher than in 2012, and on almost every night in August and September more than 200 nests were recorded. Six leatherback nests were counted at the start of the 2012 Green Turtle Program; the last was observed on 1 July. Hawksbill nesting activity was observed throughout the program; the first two nests were recorded on 13 June and the last on 23 October. A total of 13 nests and 15 false crawls were recorded during track surveys. One loggerhead (Caretta caretta) nest was reported on 7 July. Daily track surveys were conducted by the GVI staff and volunteers between 1 June and 31 October (except 2, 9, June, 4, 11, 21, 24, 28, 29 July, 2, 3, 14, 18, 24, 25 August, 7, 8, 15, 20 September and 6, 13, 19, 20, 26, 27 October). A total of 15,692 green turtle nests and 6,148 green turtle false crawls were recorded between mile 15 and the Jalova lagoon (See Figure 5a and 5b); successful nesting was observed in 72.0% of green turtle emergences at the southern end of the beach. Peak nesting was recorded on 2 September; 443 green turtle nests were counted from the previous night (See Figure 5b) In addition, six leatherback nests and one false crawl were recorded during daily track surveys close to Jalova; the last nest was on 6 July. Hawksbill nesting was observed from June September; a total of 19 nests and 10 false crawls were registered. Two loggerhead nests were observed; 7 and 19 June. On both occasions the turtles were encountered during night patrols, so species identification was verified. 20

22 Figure 4. Results of daily track surveys of the northern 5 2/8 miles of beach in 2012 a) Spatial distribution b) Temporal distribution 21

23 Figure 5. Results of daily track surveys of the southern three miles of beach in 2012 a) Spatial distribution b) Temporal distribution 22

24 3.2.3 Illegal take and nest predation During the daily track surveys researchers also noted the level of illegal take of both eggs and female turtles (See Figure 6a and 6b). In total, 134 green turtle nests (0.5% of the total number laid) were taken from June October. No leatherback or hawksbill nests were recorded as poached. Twenty-two green turtles were also taken from the nesting beach. From Figure 6a it can be seen that nest poaching occurred along the entire five miles of beach surveyed, but there were two peaks; one close to the Tortuguero river mouth, between mile -1/8 and mile 2/8, and the other close to the village and within TNP, between miles 2 4/8 and 3 3/8. There was no one are with more turtle poaching; it was registered between mile -1/8 and 4 2/8(See Figure 6a). From 8 June - 1 November, poaching (of either nests or turtles) was observed during 69 of 142 (48.9%) track surveys (See Figure 6b). The highest number of poached nests was recorded on 21 July and 7 August, when eight green turtle nests were taken in one night (See Figure 6b). Poaching of nests and turtles was observed throughout the nesting season, although the poaching of nests was more prominent from July August (See Figure 6b). A total of nine fresh green turtle nests (0.03%) were reported as predated by dogs from June October in the northern five miles of beach close to Tortuguero village; on another occasion a dog was observed eating a hatchling. There were many nests that were destroyed by other nesting females, too many to make an exact count. Only one green nest was reported as poached during the surveys of the three miles of beach close to Jalova from June October; on 31 July. No turtles were taken and no green turtle nests were reported as predated by dogs close to the Jalova lagoon. 23

25 Figure 6. Illegal take of green turtle nests and females in 2012, as determined from daily track surveys of the northern 5 2/8 miles of beach a) Spatial distribution b) Temporal distribution 24

26 3.3 Dead Turtles Turtles killed by jaguars A total of 69 turtles were reported killed by jaguars during the 2012 Green Turtle Program (See Appendix 1); the majority were found during the weekly track surveys of the 18 miles of beach. Only turtles from the previous night were counted during these surveys, so this value should be considered as a minimum number of turtles killed by jaguars Turtles found flipped over In addition to the turtles that were reported as poached during the daily track surveys, three green turtles were found flipped over and alive during track surveys and nest check activities. All were helped to the beach and returned to the sea; none of these individuals were encountered stranded afterwards, and so it was assumed that they survived. Table 1. Turtles encountered alive following attempted poaching Date Mile Time Species Sex Comments 12 August am Cm Female Found flipped over and tied up; tag # September am Cm Female Found flipped over in the vegetation 2 November am Cm Female Cm = Chelonia mydas Green turtle Found flipped over in the vegetation; tag #s / Tagging of Nesting Sea Turtles Tags used during the 2012 Green Turtle Program (in Tortuguero and Jalova) were National Band & Tag Company Monel #49 tags VC4302-VC4303 and Inconel #681 tags , , , , , In the northernmost five miles (Tortuguero), a minimum of one night patrol was conducted from 6 June 30 October, 2012 (except 8, 9, 13 and 17 June; 4 and 27 October); a total of 1,588.3 team patrol hours were logged. At the southern end of the nesting beach (Jalova), night patrols were conducted on 6 June 31 October, 2012 (except 8, 15, 29 and 30 June; 6, 20 and 28 July; 3, 4, 16, 17, 24 and 25 August; 6, September; 6, 12, 17, 19, 20, 23 and 26 October); a minimum of team patrol hours were logged. Data from both sections of the beach are combined for subsequent analyses, unless indicated Green turtles A total of 2,705 green turtle encounters were recorded in the two sectors at either limit of the beach (Tortuguero in the north and Jalova in the south); 2,060 in Tortuguero and 645 in Jalova (See Appendix 2). These encounters included 2,362 individual females; 1,622 (68.7%) initially observed without tags and 740 (31.3%) who had tags. In addition there were 343 encounters with turtles observed more than once during the 2012 nesting season. During the 2012 Green Turtle Program, 25 green turtles tagged at other nesting beach projects in Costa Rica were encountered; 16 were tagged by researchers from the Caño Palma turtle monitoring project 25

27 (north of the Tortuguero river mouth), five in Parismina and four in Pacuare Nature Reserve, which are all beaches south of TNP. The SD is awaiting confirmation of original tagging dates from researchers working at that beach. In addition there was one female encountered with tags from countries other than Costa Rica. She had tag number MM144 and was originally tagged in July 1995 as part of the in-water project coordinated by Drs. Anne and Peter Meylan in Bocas del Toro, Panama. This turtle was also encountered nesting at Tortuguero in The other females that had tags were all originally tagged in Tortuguero. There were 173 individuals that had been tagged more than 10 years previously; of these, 10 were tagged more than 20 years ago. The turtle with the longest tagging history for 2012 was observed on 17 August; the female with ID#28301 was originally tagged in She was observed in eight other nesting seasons in the intervening 28 years; 1988, 1991, 1995, 1998, 2001, 2004, 2007 and Of 1,572 newly tagged green turtles checked for the evidence of old tag holes or notches when encountered for the first time during the 2012 Green Turtle Program, 220 (14.0%) had evidence in at least one flipper. It is interesting to note that the percentage of turtles with evidence of tags in Tortuguero was much higher than in Jalova (19.0% compared to 4.2%, respectively). Beach zone was recorded for 2,687 green turtles encounters; 31.7% (n = 851) of those females nested in the open zone, 59.6% (n = 1,530) were located in the border zone, 10.5% (n = 282) in the vegetation zone and 0.9% were encountered while making a false crawl (n = 24) Hawksbill turtles Seven hawksbill encounters were logged during the 2012 Green Turtle Program (See Appendix 2); all were newly tagged individuals and none had evidence of old tag holes or notches. Four of the seven hawksbill nests (57.1%) were laid in the border zone, two (28.6%) in the open zone and one (14.3%) in the vegetation zone Leatherback turtles Nine leatherback encounters were recorded during the 2012 Green Turtle Program; one was newly tagged, four were previously tagged and four were observed more than once during the nesting season (See Appendix 2). The last leatherback encounter was on 5 July. Seven of the eight nests (87.5%) were laid in the open zone and one in the border zone (12.5%); one female did not nest successfully. 3.5 Biometric Data Collection Green turtles Table 3 shows the mean curved carapace length (CCLmin) of green turtle females measured during the 2012 Green Turtle Program. An initial analysis compared carapace length between newly tagged and previously tagged turtles encountered in Tortuguero and Jalova; no significant differences were found and so data from Tortuguero and Jalova were combined for subsequent analyses (Mann-Whitney test: U = , p = and U = , p = 0.811, for newly tagged and previously tagged turtles, respectively). A second analysis was conducted to see if there was any difference in CCLmin between newly tagged and previously tagged turtles; results showed a significant difference (Mann-Whitney test: U = , p <0.0001). A further analysis compared CCLmin of newly tagged turtles with and without evidence of previous tags; results indicated a significant difference (Mann-Whitney test: U = , p = 0.000). Thus, data from previously tagged and newly tagged turtles were analyzed 26

28 separately and newly tagged turtles were divided into two groups (with or without evidence of previous tags See Table 2). To ensure independence of the data, only the first CCLmin measurement taken for each individual was included in the analysis. Table 2. Mean CCLmin of green turtles Sample N CCLmin / cm x ± S.D. Newly tagged females no OTH/OTN 1, ± 4.8 Newly tagged females OTH/OTN ± 5.2 Previously tagged females ± 4.7 All 2, ± 4.9 OTH = Old tag hole, OTN = Old tag notch The overall mean CCLmin was 105.3cm (Range = cm). Newly tagged females with no evidence of previous tags were slightly smaller than newly tagged females with evidence of previous tags, and previously tagged females (See Table 2). Table 3 shows the mean straight carapace length (SCLmax) of green turtles. An initial analysis compared carapace length between newly tagged and previously tagged turtles from Tortuguero and Jalova. Results indicated a significant difference for newly tagged females, but not for previously tagged individuals (Mann-Whitney test: U = , p = and U = , p = 0.811, respectively); therefore data from Tortuguero and Jalova were analyzed separately. A second analysis compared SCLmax between newly tagged turtles with or without evidence of previous tags; results showed a significant difference (Mann-Whitney test: U = , p = 0.003) and so data from the two groups were analyzed separately. A final analysis compared SCLmax between newly tagged and previously tagged females; results showed a significant difference (Mann-Whitney test: U = , p < ), thus data for these two groups were analyzed separately (See Table 3). To ensure independence of the data, only the first SCLmax measurement taken for each individual was included in the analysis. Mean SCLmax in Tortuguero was 99.5cm (Range = cm) and in Jalova it was 98.7cm (Range = cm). Table 3. Mean SCLmax of green turtles Sample Tortuguero Jalova n x ± S.D. N x ± S.D. Newly tagged females no OTH/OTN ± ± 4.4 Newly tagged females OTH/OTN ± ± 4.1 Previously tagged females ± ± 4.5 All 1, ± ±

29 There was no significant difference between clutch size for females in Tortuguero and Jalova (Mann- Whitney test: U = , p = 0.145), therefore data for both sites were combined. An analysis of the number of eggs laid by newly tagged and previously tagged turtles also indicated no significant difference (Mann-Whitney test: U = , p = 0.479), so data from the two groups were combined for analysis. Overall clutch size ranged from eggs for all nests counted ( x = eggs, n =192). If the three nests in which the female laid fewer than 50 eggs are excluded from the analysis, mean clutch size becomes eggs. On 46 occasions females were observed to lay yolkless eggs; the number ranged from one to 32. For green turtles there was a slight difference in the precision of measurements of CCLmin and SCLmax taken by RAs and Eco-Volunteers, and the precision of the two different carapace measurements taken during a single encounter was almost equal (See Table 4). Table 4. Precision of carapace measurements for green turtles in the same encounter Observer CCLmin / cm SCLmax / cm n x ± S.D. Range n x ± S.D. Range RAs 1, ± , ± Eco-Volunteers ± ± Total 2, ± , ± For females encountered and measured on two or more occasions in 2012, SCLmax measurements were taken with a higher level of precision than CCLmin measurements (See Table 5). For both CCLmin and SCLmax measurements there were occasions when the difference between the length measurements on subsequent encounters with the same female was greater than 10cm (See Table 5); if there was an error made when recording the tag number during the second encounter it is possible that in fact it was not actually the same female. Table 5. Precision of carapace measurements for green turtles between different encounters CCLmin / cm SCLmax / cm Encounters n x ± S.D. Range n x ± S.D. Range ± ± ± ± ± ± Other turtle species Carapace measurements were taken for all hawksbill. leatherback and loggerhead females observed during the 2012 Green Turtle Program (See Table 6). For hawksbills, CCLmin ranged from cm, SCLmax from cm and clutch size was between eggs; for leatherbacks CCLmin ranged from cm and clutch size varied from eggs, and for loggerheads, CCLmin ranged from cm and clutch size was between eggs. 28

30 Table 6. Mean carapace length and clutch size of hawksbill, leatherback and loggerhead turtles Species CCLmin / cm SCLmax / cm Clutch size / eggs n x ± S.D. n x ± S.D. n x ± S.D. Hawksbill ± ± ± 9.0 Leatherback ± ± 4.8 Loggerhead ± ± 40.3 Precision of SCLmax measurements of hawksbill and loggerhead females was slightly higher than that of CCLmin measurements (See Table 7). A species comparison shows that the precision of CCLmin and SCLmax measurements was very similar for all species (CCLmin = 0.3 = 0.8cm; SCLmax = cm); for both species for which SCLmax measurements were taken, the precision was slightly higher than CCLmin measurements (See Table 4 and Table 7). Table 7. Precision of carapace measurements for hawksbill, leatherback and loggerhead turtles Species CCLmin / cm SCLmax / cm n x Range n x Range Hawksbill ± ± Leatherback ± Loggerhead ± Fibropapilloma Assessment A total of 180 green turtles were subject to a thorough examination for the presence of fibropapilloma tumors; no individual was recorded to be affected with the disease. In addition to the females who were checked specifically for the presence/absence of fibropapilloma, tumors were also recorded if observed during the routine check for physical abnormalities conducted on all females encountered; three individuals were found to have fibropapilloma tumors. All these turtles had tumors on the flippers or neck. Tumors ranged in size from 1 5cm. Researchers encountered a further 53 turtles that had other types of tumors; they ranged in size from 1 7cm, and up to eight tumors were recorded on a single female. 3.7 Determination of Nest Survivorship and Hatching Success Green turtles A total of 243 green turtle nests were marked between 16 April and 28 September, 2012; 127 nests were marked in the northern five miles of beach and additional patrols at the south of the beach allowed 116 nests to be marked close to the Jalova lagoon. Six of these nests were marked during the 2012 Leatherback Program. 29

31 For various nests the fate could not be determined with certainty; either they were not encountered at excavation (n = 13), or the ness were possibly disturbed by another turtle (n = 9), the measurements were not recorded correctly (n = 1), it was not possible to finish the excavation as the nest was flooded (n = 1) or because there were hatchlings in the nest at the end of them program (n = 1). For another 18 nests the excavation could not be conducted as a fresh nest was found close to the location of the marked nest; this included a nest of eggs that had been found close to the STC station that were relocated by STC personnel. Nine excavations included eggs from two different nests. All of these nests (n = 52; 21.4%) were therefore excluded from subsequent analysis, leaving a sample of 191 green turtle nests monitored from the date of oviposition until their fates could be determined. Table 8 lists the fate of all of the green turtle nests marked in Fate Table 8. Fate, hatching and emerging success of marked green turtle nests in 2012 Tort n Jal n Total n % of total Hatching success (%) Emerging success (%) 1. Undisturbed Disturbed by another turtle Destroyed by another turtle Depredated Unhatched Partially eroded Eroded Poached Disturbed by animals Relocated Total Calculated as the mean of all 191 nests Nests not included in analysis Tort n Jal n Total n Possibly disturbed by another turtle Could not find at excavation Incomplete excavation as new nest encountered Excavated two nests Measurements recorded incorrectly Hatchlings in nest at end of Program Incomplete excavation as nest flooded Relocated nest new nest encountered Total Tort = Tortuguero (northern five miles); Jal = Jalova (southern three miles) A summary of the excavations of the 191 green turtle nests monitored throughout the incubation period is summarized in Table 9. 30

32 Table 9. Summary of excavation data for green turtle nests marked in 2012 data combined from Tortuguero and Jalova Fate * n Hatchlings Unhatched eggs Empty Pipped Live Dead shells eggs No Full Embryo embryo embryo Depredated eggs Destroyed eggs Yolkless eggs , Total , , * For fate code descriptions see Table 8 31

33 From Table 8 it can be seen that the majority of nests included in the analysis (78.0%) remained undisturbed during the incubation period (n = 149).The majority of disturbed nests were affected by another nesting turtle (8.4% - either disturbed or destroyed) or were poached (3.7%). Poaching was only recorded in the northern five miles close to Tortuguero. Overall hatching success was calculated as 73.5% and overall emerging success was estimated as 70.7% (See Table 8). These values were determined as the mean of all 191 marked nests for which the fate could be determined. One nest contained eggs that were confiscated by MINAET personnel; the success of this nest was presented in the report entitled Informe del Proyecto del Manejo y Monitoreo de Huevos de Tortugas Marinas Decomisados (Report on the Project for the Management and Monitoring of Confiscated Sea Turtle Eggs Project Sea Turtle Conservancy, 2012). Average clutch size (determined from egg counts conducted at the time of oviposition) was eggs with a range of eggs (n = 201); this value includes nests that were subsequently excluded from the analysis of hatching and emerging success. The distance between the sand surface and the top eggshell at the time of excavation for undisturbed nests (n = 146) ranged between 19-93cm with a mean of 60.3cm. The distance between the sand surface and the bottom of the egg chamber (n = 145) varied between cm with a mean of 76.0cm. Incubation period, for nests for which hatching was observed (n = 64) ranged from days, with a mean of 58 days. Unhatched eggs that contained albino, twin or deformed embryos accounted for only 0.115% of all eggs laid in the 191 excavated nests (See Table 10). Of the deformed embryos there were malformation of the flippers, carapace, eyes and head, and several had two heads. The albino embryo was also deformed; it had no eyes. Table 10. Incidence of albinism, twins and deformed embryos in 2012 Type of abnormality n % of total Albino Twin embryo Deformed embryo Total Evaluation of the impacts of tourist activities on green turtle nest success Staff from Tortuguero National Park (TNP) requested the help of STC to evaluate if the presence of tour groups observing nesting turtles has any impacts on the hatching and emerging success of green turtle nests. During the 2012 Green Turtle Program we conducted a study to compare the success of nests from females observed by tourists to those nests that were marked in the presence of STC researchers only. All nests were marked using the same methodology as described in section 2. 7 above. A total of 36 nests were marked while the female was observed by groups of tourists (up to a maximum of 20 tourists with one female, following TNP regulations). Of these nests, 12 were 32

34 excluded from the subsequent analyses; depredated (n = 1), eroded (n = 2), poached (n = 1), unhatched (n = 1), not found (n = 1), new nest found on top during excavation (n = 4), measurements recorded incorrectly (n = 1) and hatchlings in nest at the end of the Program (n = 1). Table 11 shows hatching and emerging success of nests of females observed or not observed by tourists. Table 11. Hatching and emerging success of nests from females observed or not observed by tourists during 2012 Category n Hatching success (%) Emerging success (%) Observed by tourists Not observed by tourists As can be seen from Table 11, nests from females that had not been observed by tourists were more successful. There was a significant difference in hatching and emerging success between the two groups (Z = , p = and Z = , p = , respectively) Hawksbill turtles Seven hawksbill nests were marked between 14 April 31 August, 2012; of these two were marked during the 2012 Leatherback Program. One nest was excluded from the determination of hatching and emerging success because the excavation could not be completed as a fresh nest was found close to the location of the marked nest. The results of the excavations from the other six hawksbill nests are summarized in Table 12; data from Tortuguero and Jalova are combined. Mean hatching and emerging success was 75.8% (See Table 12); these values were determined as the mean for all six nests. Evidence of hatching was observed for only one nest; the incubation period was 61 days. The mean distance between the sand surface and the top eggshell at the time of excavation for undisturbed hawksbill nests (n = 4) was 47.1cm (Range = cm). The mean distance between the sand surface and the bottom of the egg chamber was 58.9cm (Range = 51-73cm) Loggerhead turtles There was a possibility to mark two loggerhead nests; unfortunately, one of the nests was destroyed by another turtle and the other was partially depredated; hatching and emerging success was only 50.0% Leatherback turtles The hatching and emerging success of leatherback nests laid at Tortuguero during 2012 is discussed in detail in the 2012 Leatherback Report. 33

35 Table 12. Summary of hawksbill nest excavations from 2012 Fate 1 n Empty shells No embryo Unhatched eggs Embryo Full embryo Depredated eggs Hatching success % Emerging success % Total For fate code descriptions see Table 8; 2 Calculated as the mean for all six nests 34

36 3.8 Physical Data Collection Rainfall Rainfall was recorded daily from January December, 2012, during the Leatherback and Green Turtle Programs (See Table 13). Table 13. Summary of rainfall data January to December, 2012 Month Total rainfall mm/month x rainfall mm/24 hours 1 January February March April May June July August September October November 1, December Total 5, Data for 48 hours: October, November; 72 hours: August, 29 September-1 October, 2-4 October, November; 120 hours: 1-5 June; 144 hours: December; 168 hours: 28 April-4 May; 192 hours: October The driest month was February, with a total of 118.6mm of rain recorded; the wettest month was November, with 1,163.9mm of rain recorded (accounting for 22.7% of the rain for the entire year). July and December were also very wet months, with over 700mm of rain (See Table 13). The total amount of rain recorded at the station during 2012 was 5,131.7mm; an average of 14.0mm per day. Average daily rainfall each month ranged from 4.1mm to 38.8mm per day (February and November, respectively). The highest rainfall recorded for a single 24 hour period was on 21 November, with 191.4mm Air temperature Air temperature was measured from June to December 2012 (See Table 14). The thermometer measured only the current temperature, which was recorded every day; it did not record the daily minimum or maximum temperatures. Air temperature ranged from C; mean monthly temperature was very similar from June October ( C). Temperature dropped in November and December, when the monthly mean temperature was less than 24 C. 35

37 3.8.3 Sand temperature Table 14. Summary of air temperature January to December, 2012 Month Mean air temperature / C Range / C January N/A N/A February N/A N/A March N/A N/A April N/A N/A May N/A N/A June July August September October November December Total Unfortunately it was not possible to record sand temperature until May 2012; Table 15 shows mean monthly same temperature from May November in the vegetation, border and open zones. Table 15. Mean monthly sand temperature in 2012 Zone Vegetation x temperature / ºC Border x temperature / ºC Open x temperature / ºC Depth/ cm May N/A N/A N/A June N/A July N/A August N/A September N/A October N/A November N/A Total N/A N/A = No datalogger at that depth in that month; 1 From 3 May; 2 From 2 June In all months, and at all depths, the temperature in the vegetation zone was lower than in the border and open zones. In all zones, monthly mean temperature did not fall below 24.3 C, or rise above 31.7 C. Temperature in the vegetation zone ranged from C, in the border zone from

38 25.2 C and in the open zone from C. 3.9 Collection of Human Impact Data Visitors to STC Natural History and Visitor Centre The number of visitors registered at the STC Visitor Center in 2012 increased to 25,240 visitors (See Table 16); 1,711 people more than in This is the first time that visitation has increased at the center since Table 16. Number of visitors to the STC Natural History and Visitors Center Month Total x / day Total x / day Total x / day January 3, , , February 3, , , March 3, , , April 2, , , May 1, June 1, , , July 2, , , August 1, , , September October November 2, , , December 2, , , Total 24, , , The pattern of visitation was similar to that observed previously; most visitors came in January March, with a significant decline in April. A slight increase in visitation was observed in July; this coincides with increased green turtle nesting, which is the major tourist attraction in the area. There was a dramatic decrease in September, with an average visitation of just 18 people per day (See Table 16). In each month there were more visitors in 2012 than in 2011, with the exception of May and October. Mean daily visitation was 69 visitors, with a range of 18 (September) to 149 (March) Visitors to Tortuguero National Park The number of people visiting TNP decreased slightly in 2012 (See Table 17). A total of 117,341 tourists were registered as paying the entrance fee to the park in 2012; this is almost 500 less visitors than in The number of Costa Rican visitors included 12,623 people from the local community (tour guides, boat captains, etc). Admission fees to TNP in 2012 raised 366,904,896, which is approximately $733,

39 Table 17. Number of paying visitors to Tortuguero National Park, Year Costa Rican visitors Foreign visitors Total no. of visitors ,643 59,026 67, ,545 71,912 81, ,292 77,291 87, ,257 80, , ,898 92, , , , , ,632 90, , ,592 89, , ,753 91, , ,769 90, , Turtle tours Data from Moya Calderón, 2013 Since 2005 the Turtle Spotter Program (TSP) has been implemented along the entire 5-mile stretch of beach (from the Tortuguero river mouth to mile 5) where tourism is permitted by MINAET. In 2012, STC continued to be part of the TSP committee, along with representatives from ACTo, the Tortuguero Development Association, the Tour Guide Association, the Turtle Spotter Association and the local hoteliers. In 2012 there was no TSP Coordinator; daily supervision of the turtle spotters and program activities was provided by one of the committee members. Fifteen turtle spotters were hired for the official green turtle season (1 July 31 October). Of these 15, one was designated as the Supervisor, who helped oversee the other turtle spotters on the beach and one was assigned to maintenance of the trails and tourist waiting areas. Two additional people were hired to receive donations from the tour guides and to manage the sale of brochures. TNP staff registered that a total of 28,537 tourists participated in turtle tours during the months that the TSP was running (See Table 18); this represents a decline of 3,662 people compared to 2011, and continues the tendency observed since An average of 221 tourists per night participated in tours during these four months (See Table 18); this estimation does not include any additional nights when tours might have been permitted in November. There were various nights in 2012 when more than 600 tourists participated in the tours. Table 18. Number of tourists participating in turtle tours each month; July October, 2012 Month Number of tourists Average per night July 11, August 11, September 4, October Total 28, Data from Moya Calderón,

40 As in the last two years, in 2012, following the studies conducted by STC investigating the impact of tourist activities on nesting behavior of green turtles, a limit of 20 tourists (plus guides) was imposed per turtle. Unfortunately, there were various occasions during the 2012 Green Turtle Program that STC researchers observed more than 20 people around a single turtle Artificial lights Three light surveys were conducted during the 2012 Green Turtle Program between June and October. The results from these surveys are summarized in Figure 7. As in previous years, most of the lights visible on the beach were from Tortuguero village, between miles 2 6/8-3 3/8; these included cabinas, restaurants, houses, street lights and the school. In addition, clusters of lights were also visible from the lodges located north of the village, including some located on the opposite side of the river. As Figure 7 clearly shows, there are no artificial lights within TNP, due the absence of any buildings past mile 3 3/8. During 2012 the Tortuguero Development Association (TDA) put forward a proposal to illuminate the football field in Tortuguero village. The STC was opposed to this proposal, due to the potential negative impact to nesting turtles and hatchlings. A copy of the letter sent to the TDA can be seen in Appendix 3 (translated from the original Spanish version) Hatchling disorientation Evidence of hatchling disorientation was recorded on four occasions during the 2012 Green Turtle Program (See Table 19). Date Mile Light source 18 Sep 3 2/8 19 Sep 2 7/8 21 Sep 3 2/8 Table 19. Summary of hatchling disorientation events in 2012 Balcon del Mar Cabinas Street and house lights Balcon del Mar Cabinas # of hatchlings # of dead hatchlings # of live hatchlings # of hatchlings that reached the sea Sep 2 7/8 Street lights On 18 September there were hatchlings from three different nests that emerged at the same time and became disorientated; the hatchling that died was attacked by a dog and killed. On all four occasions STC researchers found the hatchlings during night patrols; they ensured that they reached the sea successfully. All four cases of disorientation were observed in front of the village; twice the lights from the same small hotel (Balcon del Mar Cabinas) were impacting hatchlings. 39

41 Figure 7. Summary of monthly light surveys conducted during the 2012 Green Turtle Program Tortuguero Village Limit to TNP Tortuga Lodge Laguna Lodge Mawamba Lodge STC Field station Light sources in Tortuguero village San Francisco Village Ilan Ilan Lodge Wild Ginger restaurant Miss Junnie s Cabinas Tortuguero School Cabinas Princesa del Mar Miss Miriam s Cabinas Miss Miriam s #2 Icaco Cabinas Cabinas Balcon del Mar Gecko Cabinas House lights Street lights 40

42 3.10 Satellite Tracking Project One satellite transmitter was successfully attached to a green turtle encountered nesting close to the STC field station in mile 2 4/8 on 13 July; she measured 98.7cm CCLmin. The transmitter was attached the following morning and her sponsor (Holbrook Travel) named her Shelldon. Her cause in the Tour de Turtles (interactive activity that allows anyone interested to follow on-line as different turtles race during their migrations, and each turtle has a different cause to raise public awareness about threats that sea turtles face and help fund raise) was the negative impact of eating sea turtle meat. Following her release Shelldon stayed close to the nesting beach until September; she was monitored travelling south, almost to Limón. She was tracked for 323 days, during which time she swam a total of 1,747 miles (2, 811 km); when her transmitter stopped sending signals in June 2013 she was location in coastal waters in Nicaragua, presumably in sea grass habitat (See migration map in Appendix 4) Community Activities Veterinary clinic STC continued to be an active member of the organizing committee for the veterinary clinics in 2012, with representatives from MINAET and ProParques and support from several local residents from Tortuguero and San Francisco. Veterinary support was provided by the Costa Rica Humane Association for Animal Protection. In 2012 one vet clinic was conducted; 3-4 November. Vets held clinics in Tortuguero (3 November) and also in San Francisco (4 November). As in previous years, the Tortuguero clinic took place at the park ranger station, and at the school in San Francisco. STC SD, Emma Harrison helped with logistical support for the clinic in Tortuguero; RAs helped during the clinic when necessary and STC also provided board and lodging for the vets at the field station. Table 20 summarizes the results from the November clinic; since the start of the clinic program in 2008, a total of 437 animals have been spayed/neutered. Place Table 20. Summary of the veterinary clinic November 2012 # animals treated # animals spayed/neutered # animals deparisitized 1 Tortuguero San Francisco Total Includes animals previously spayed/neutered at another clinic and animals whose owners declined to castrate them 4. Discussion 4.1 Preparations The agreement with GVI for a third year continued to allow additional patrols to be conducted at the southern end of the beach, close to the Jalova lagoon. The involvement of GVI staff and volunteers helped to increase the amount beach that could be patrolled on a daily basis, and also allowed nests to 41

43 be marked and monitored in this part of the beach. The intensive training and orientation program given to the RAs by the FRC is important for them to learn the monitoring protocol in detail, and to give them the opportunity to practice various important skills, such as tagging, carapace measurements and nest marking. Even for RAs with previous experience working with sea turtles these theoretical and practical sessions ensure that everyone collects data according to the STC protocol. Obviously, it is also important that all members of GVI receive adequate training and have regular contact with the FRC to address any issues that may arise. Constant supervision throughout the program is also very important; the FRC should work with all the RAs regularly to evaluate the standard of data collection, and bring to their attention any errors that are being made at the soonest opportunity to ensure a high level of accuracy in the data being collected. It is not only important that the RAs learn the monitoring protocol, but also that they are taught how to correctly manage volunteer groups when working with a turtle, and how to interact with tour groups, spotters and guides on the beach. This type of training will help eliminate problems when the RAs need to work a turtle in front of a group of tourists. Such practice sessions should be continued in the training program for future years. Fortunately the majority of the beach markers placed at the start of the 2012 Leatherback Program were still in excellent condition at the start of the 2012 Green Turtle Program; the FRC and RAs replaced an occasional missing marker and repaint3e those still in place. This activity, though somewhat time consuming, is important as it provides the opportunity to teach the RAs the need to familiarize themselves with the beach and the markers to facilitate the night patrols. 4.2 Track Surveys Green turtles Green turtle nesting was observed regularly from June to October, with a peak in August. The pattern of nesting in 2012 was similar to recent years; few nests were observed before June, the peak of the season was in the middle of August and nesting dropped rapidly in October (See Figure 1). The estimate of 172,760 green turtle nests laid during the 2012 season was more than double the number calculated for 2011, when only 78,852 nests were estimated. It was expected that 2012 would be a higher season than 2011, as we had seen this pattern previously in Tortuguero (a low year followed by a high year); for example , and (See Figure 2). It is important to mention that these nesting values for green turtles are estimates; it would be impossible to do a total count for the whole beach every day, which would be the only way to guarantee real counts and not estimates. At Tortuguero, the key is to ensure that standard methodology is used every year, so that the data are comparable. Having the same person conduct the weekly track surveys helps standardize the data, by reducing observer variation. Overall spatial distribution of nesting along the beach was similar to that seen in recent years, with a distinct increase in nesting noted between miles 4-13, with a peak in the middle of the beach (See Figure 3). The two extremes of the beach, as always, had less nesting, presumably as these are the least stable sections of the beach. The daily track surveys conducted by the FRC and RAs from June - November between the Tortuguero river mouth and the mile 5 marker require considerable effort but provide invaluable data relating to spatial and temporal nest distribution, level of illegal take of nests and females, and dog predation. In 2012, as in the last two years, it was possible to conduct daily track surveys of the 42

44 southern three miles, between mile 15 and the Jalova lagoon (mile 18). The number of green turtle nests laid in the northern five miles of beach and the southernmost three miles was more than double that observed in 2011; 27,769 compare to 12,420 and 15,692 compared to 6,618, respectively. It was interesting to note that there was a big difference in the proportion of false crawls at the two extremes of the beach; in Tortuguero 52.1% of the tracks were false crawls and close to Jalova it was just 28.2%. This could be a reflection of the difficulty of identifying false crawls and nests with the very high level of nesting; therefore it is important to ensure good training for all the RAs and GVI personnel. The temporal distribution of nesting observed from the daily track surveys showed a difference to weekly track surveys (See Figure 1, 4b and 5b); peak nesting was in August and September, respectively. At the two extremes of the beach there was a gradual decline in nesting at the end of September (See Figures 4b and 5b). It will be interesting to monitor the differences in nesting patterns in future seasons. Illegal take of nests and turtles was observed infrequently during weekly track surveys in 2012; however, it was discouraging to see that there were several turtles reported taken from within TNP. As in 2011, there was an obvious difference in the levels of illegal take of turtles and nests recorded at the northern and southern limits to the nesting beach; close to Tortuguero poaching was observed throughout the nesting season, while close to Jalova only one nest was poached and no turtles were taken in the three miles of beach monitored. Patterns of poaching were similar to those observed in previous seasons, with poaching in Tortuguero concentrated in two sectors; the first 3/8 of a mile near to the river mouth and the mile in front of Tortuguero village between miles 2 4/8 3 4/8 (See Figure 6a). The section of beach close to the river mouth is a designated protected area (Archie Carr Natural Refuge), so it was very discouraging to see that there is insufficient vigilance from MINAET to ensure the protection of nesting females in these miles. Hopefully these data will be useful to ACTo, as justification to request the additional resources necessary to improve turtle protection in this zone, and the rest of the Tortuguero nesting beach Other species of turtles A comprehensive discussion of leatherback nesting is included in the 2012 Leatherback Program Report. Leatherback nesting density continues to decline in Tortuguero, which is worrying for STC and other organizations involved in leatherback conservation efforts along the Caribbean coast. Few hawksbill nests were observed during the weekly track surveys of the entire nesting beach in 2011; just seven hawksbill nests were observed from April November. However, daily track surveys of the northern five miles and the southern three miles reported 32 nests; fewer than in It is possible, however, that the large number of green turtle nests obscured the hawksbill tracks and so they were not seen during the daily surveys. It was unusual and interesting to record loggerhead nesting at both ends of the beach in The SD has been in contact with researchers at other projects along the Caribbean coast and various people also commented that they had seen loggerheads nesting at their beaches. 4.3 Dead Turtles Predation of turtles by jaguars increased again in 2012, compared to levels seen in 2011; during weekly track surveys 69 turtles were recorded from January December (See Appendix 1). Once again there was a report of a leatherback killed by jaguars. Jaguars were active along the majority of the 43

45 beach south of Tortuguero village; as evidenced by their tracks on the beach. The numbers of turtles reported during the weekly track surveys should be seen as a minimum, as only those turtles killed the previous night are recorded. The track surveyor also observed jaguars on the beach on numerous occasions during Tagging of Nesting Sea Turtles Green turtles The goal of 1,000 newly tagged green turtles was reach in September of 2012; 1,622 green turtles were tagged during the Green Turtle Program. The FRC and RAs conducted additional patrols between miles 5 and 9 to ensure that the objective was met. A total of 2,705 encounters with green turtles were recorded in 2012, considerably more than in The proportion of tagged turtles was very different at the two extremes of the beach, as in 2011; close to Jalova only 7.0% of turtles had tags, while in Tortuguero 33.7% of females were encountered with tags. This could reflect high site fidelity by green turtles, especially given the fact that very few individuals have been tagged close to Jalova in previous years. There were only a couple of turtles that were encountered in both sections of beach over the course of the season. The overall proportion of turtles encountered with tags was similar to that in other years; around 30% of individuals seen. For another consecutive season there were many turtles that had been tagged originally more than 10 years ago; 173 females were first seen at Tortuguero more than a decade ago. Additionally, there 10 turtles that were originally tagged more than 20 years previously. The turtle with the longest nesting record observed in 2012 was a female first encountered in 1984, 28 years ago. As always it is good to see that there are a considerable number of older females that return to nest each year, and that there are still plenty of new (untagged) females being encountered; which suggests a balance of different age classes within the Tortuguero nesting population. Turtles encountered with tags from other countries are always exciting, and in 2012 there was one green turtle with tags from Panama; she was tagged as part of an in-water project 17 years previously. These type of encounters demonstrate the connectivity that exists between countries in the region with regard to sea turtles. They use different locations to nest, feed and migrate and, therefore, it is important that there is good collaboration to ensure the protection and conservation of turtle populations and their key habitats Other species of turtles The number of hawksbill encounters (n = 7) was at the lower limit of the range observed in other seasons. The number of encounters was similar at the north and south sections of the beach; four in Tortuguero and three in Jalova. None of the hawksbills encountered had tags. Given the low nesting density of this species at Tortuguero, it is important that the RAs realize the importance of every encounter with a nesting hawksbill during night patrols as they provide very valuable information on the species. The protocol to not show hawksbill turtles to tour groups (first implemented in 2008 following a request by the SD to the TSP committee) was continued in 2012; but unfortunately on at least one occasion groups of tourists observed a hawksbill nesting. It is very important that all of the spotters receive adequate training to be able to correctly distinguish between green turtles and hawksbills, and that they follow the Park rules for the TSP, and minimize the impacts of tourist activities. 44

46 It was exceptional to tag two loggerheads in one season; normally females of this species nests very infrequently at Tortuguero, one individual every two or three years. Every encounter with this species is an opportunity to increase our knowledge about the nesting population using Tortuguero. The 2012 Leatherback Program Report includes a detailed review of the tagging of leatherback turtles at Tortuguero in Once again, however, there was an encounter with a leatherback turtle in July, during night patrols for the 2012 Green Turtle Program; normally, leatherback nesting finishes in June or early July, so it was quite unusual to encounter a female of this species nesting later in the year. 4.5 Biometric Data Collection Green turtles The overall mean curved carapace length (CCLmin) was 105.3cm and the mean straight carapace length (SCLmax) was 99.5cm (Tortuguero) and 98.7cm (Jalova). These measurements are consistent with those obtained from the Tortuguero green turtle population in previous seasons, and they also show a typical range from very small to very large individuals ( cm CCLmin; cm SCLmax). In addition, the mean clutch size of 111 eggs was very similar to that determined in other years. RAs were slightly more precise than Eco-Volunteers when taking CCLmin and SCLmax measurements (See Table 5); but the difference was less than that observed in other seasons. However, it is important that all Eco-Volunteers receive good training before taking part in night patrols, including sufficient practice in taking carapace measurements; the RAs are also responsible for properly overseeing all data collection by volunteers during night patrols, both when working directly with the turtle, or when recording data in the field books. In 2012, the FRC implemented a new training program for the Eco-Volunteers; on the first day they received a general introduction to the program and observed the data collection process during their first night patrol. The following day they received a practical session on how to take the different measurements. This change helped the Eco-Volunteers to feel more comfortable around the turtle (they knew their movements during the different phases of the nesting process) and they were more confident when taking the measurements. Unfortunately, there was considerable variability in the measurements taken of the same female when she was observed on more than one occasion (up to 18.9cm), and so more care should be taken during training sessions, with RAs and Eco-Volunteers, to ensure that everyone is measuring the carapace in the same manner, using the same reference points. For the turtle with a difference of 18.9cm it is quite probable that there was an error at the moment of recording the measurements, or possibly an error in recording the tag number, and that in actual fact it was not the same individual on the second encounter. One option to assist with the training would be to create a video of someone taking measurements on the beach at night; this is a suggestion for future programs CCLmin and SCLmax measurements were taken with the same degree of precision, and it is suggested that both measurements continue to be taken for a sample of females nesting at Tortuguero Other species of turtles Carapace measurements obtained for hawksbill turtles during the 2012 Green Turtle Program were within the range observed in previous years; mean CCLmin was 87.5cm and SCLmax was 83.2cm. There are so few data available for loggerheads that it is not possible to say if the females encountered in 2012 were of a normal size for individuals of this species at Tortuguero; mean CCLmin was 99.6cm and SCLmax was 95.5cm, but these values are within the range presented in the available literature for other sites. CCLmin and SCLmax measurements were taken with the same degree of precision for all 45

47 species. The mean clutch size for hawksbills (149 eggs) was in the range observed in other years; it was the first loggerhead clutch counted at Tortuguero. The 2012 Leatherback Program Report summarizes biometric data collected from leatherback turtles nesting in Tortuguero in 2012 from March to June. For the females observed during the 2012 Green Turtle Program, the CCLmin was 155.7cm; within the normal range for this species at Tortuguero. 4.6 Fibropapilloma Assessment No turtle examined specifically for the presence of fibropapiloma (FP) in 2012 showed evidence of the tumors related to this disease. However, during the routine revision of each turtle worked, three turtles were reported to have the FP tumors. This is typical for the green turtle population in Tortuguero, where we have reported very low levels of incidence of fibropapilomatosis. It is encouraging to see that there has been no increase in the prevalence of this disease in Tortuguero. The examination of turtles for these kinds of anomalies is important and should continue to be part of the protocol in the future. 4.7 Determination of Nest Survivorship and Hatching Success Green turtles A total of 243 green turtle nests were marked during the 2012 Green Turtle Program; 127 in Tortuguero and 116 in Jalova. From these it was possible to determine the fate for 191 (78.6%); it was disappointing that the fate of more than 20% of marked nests could not be determined, though there were various reasons why successful excavations could not be conducted, such as the presence of new nests that impeded the excavation, which indicates the high density of nests in some sections of the beach. There were 13 nests that could not be found (5.3% of the total); this is less than the perecentage that were not found in previous years. There was considerable focus during the RA training of the importance of closely checking all of the marked nests each day during the incubation period, to have a more thorough record of factors that might possibly affect the survival and success of the nest. During 2012 the great majority (78%) of marked nests remained undisturbed and hatched successfully; the major cause of loss of nests was due to disturbance or destruction by other females, poaching (in Tortuguero), erosion and depredation (See Table 8). Nests close to the predicted emerging date should also be carefully inspected for signs of hatching (depressions or hatchling tracks); in 2012 the incubation period could only be determined for several nests in Jalova. Although depressions and hatchling tracks can be quickly eliminated by heavy rain or strong winds, it should be possible to detect evidence of hatching if RAs are more conscientious. Overall hatching success of marked nests was lower in 2012 than in 2011, 73.5% compared to 77.2%, respectively; the same pattern was observed for emerging success, 70.7% and 76.1%, respectively. For undisturbed nests (n = 149) emerging and hatching success were very high, 88.6% and 84.6%, respectively (See Table 8). The estimations of overall hatching and emerging success were affected by nests that were destroyed by other nesting females, poached, eroded or depredated (such nests had a hatching and emerging success of 0%, obviously). Very few deformed, albino or twin embryos were recorded; as in previous years. The study to compare hatching and emerging success between nests from females that were observed by tour groups and those observed only by STC researchers was very important, because it can help to manage the TSP, that has as one of its principal objectives the reduction in negative impacts to sea turtles caused by tourist activities. As can clearly be seen in Table 11, hatching and emerging success 46

48 was much lower in nests from females that had been observed by tourists (79.8% and 78.3%, respectively, compared to 89.3% and 85.0% for nests from females that had not been observed by tourists). These values are statistically different, which implies that, for whatever reason, nests from females that have been observed by tourists are less successful. There are several factors that could impact nest success, but obviously it is a little worrying to detect such differences in success for nests that may be a direct result of tourist observation; therefore it would be very interesting to continue this study in the future, improving the design, to be able to detect why nests are less successful Other species of turtles It was possible to mark and monitor six hawksbill nests during Hatching and emerging success of undisturbed nests were high (89.8%), higher than the values for this species in Overall hatching and emerging success was affected by nests disturbed by other nesting females, which all had very low success. It is hoped that the policy to not show hawksbill turtles to tour groups will allow STC personnel priority access to this species, and that in future more nests will be marked and followed during the incubation period, to gain a further insight into the survivorship and hatching success of this critically endangered species at Tortuguero. Unfortunately, only one of the two loggerhead nests that were marked during the 2012 Green Turtle Program showed evidence of emergence; hatching and emerging success for this nest was 50.0% A discussion of leatherback nest survivorship and hatching success in Tortuguero during 2012 can be found in the 2012 Leatherback Program Report. 4.8 Physical Data Collection Rainfall The pattern of precipitation observed in 2012 was different to that seen in 2011; the months of June and July were wet, while August, September and October were very dry. As in previous years, November was the wettest month, with 1,164mm of rain registered; 191mm recorded within a single 24 hour period. It is interesting that rainfall patterns appear to change each year, and this is one of the reasons why it is important that STC continues to collection data on rainfall in Tortuguero as part of the standard monitoring protocol, to evaluate potential impacts on nest survivorship and hatching success, and to provide long-term trends in precipitation Air temperature The thermometer was replaced in June, so it was possible to measure air temperature for the last six months of Temperature varied between C, but the mean temperature for the first four months (June October) only varied by 1.4 C; in November and December there was a very pronounced decrease in temperature, which could have been related to the increase in rainfall registered in those months. As for the rainfall data, it is important to ensure that air temperature is recorded daily as part of the standard monitoring protocol in future programs Sand temperature During 2012 we saw the same pattern for sand temperatures as in other seasons; temperatures in the open zone were higher than in the border or vegetation zones. It was disturbing to see temperatures rising above 30 C in the border zone, where the majority of the green turtle nests were located. It is 47

49 possible that there is a very high percentage of female hatchlings emerging from the nests of this species in Tortuguero. It would be very interesting to conduct an analysis of the sand temperature data collected over the last 10 years, to see if there are any visible trends for different zones of the beach. In future programs it is important to continue to monitor sand temperatures at Tortuguero, as for the other physical data that are recorded each day, this information will allow the detection of any changes to the nesting habitat environment that could be a result of global climate change. 4.9 Collection of Human Impact Data Visitors to STC Visitors Centre It was encouraging to observe an increase in the number of tourists to the STC Visitor Center in 2012; it was the first increase in visitation since In 2012 we changed the video for a new version, which contains updated information about the activities STC conducts in Tortuguero, including the community environmental education program. There were various comments from the tour guides about the new video, some positive and some more critical. In 2012 we also made various changes to the Visitor Center, primarily the inclusion of a guided tour by an RA, to explain the different exhibits and provide more information about the STC program and our activities, and some new exhibits with up to date content. Also, the Education and Outreach Coordinator worked hard to improve the tourist experience to the Visitor Center. Unfortunately, there are still some tour guides that do not want to enter the Visitor Centre with their groups; but now, with the new video the excuse that there is nothing new to show them has been eliminated. Therefore, a priority for the next couple of years will be to continue the process of improving the Visitor Center so that we can fulfill the objective to not only provide information to tourists about sea turtles, but also to demonstrate the importance of STC s work, and show how visitors can directly support our program by entering the Visitor Center Visitors to Tortuguero National Park The data from ACTo show that in 2012 there was a slight decrease in the number of people paying the entrance fee to TNP; but the difference from the previous year was only 500 people, the majority foreign tourists, as the number of national visitors was very similar to the number registered in 2011 (See Table 16). Park entrance fees generate a lot of funds (more than $733,000); but unfortunately not all of this money is reinvested in TNP, which results in a serious lack of financial resources and insufficient staff each year to conduct basic activities to adequately protect the flora and fauna in TNP (including sea turtles) and effectively implement Costa Rican environmental laws Turtle tours The number of people that participated in turtle tours during the official 2012 green turtle season (July October) decreased for another consecutive year in 2012; more than 3,600 fewer people participated in tours than in However, there was still an average of 221 tourists per night on the beach between July and October; on many occasions the number of tourists surpassed 500 people in a single night. This information, together with the results from the study to evaluate hatching success of nests laid by turtles observed by tour groups is worrying, as it suggests that there is a high probability that tourist activities in Tortuguero are having potentially serious negative impact on the sea turtle population; this is in complete contradiction to the idea of a sustainable ecotourism initiative. 48

50 As we have requested for the past few years from MINAET personnel, it is imperative that a detailed revision of the TSP is conducted, to establish very clear guidelines with regard to the management of tour groups on the beach. However, it is not enough to simply establish rules, it is vital that MINAET increases its presence on the beach at night, so that the spotters and tour guides follow the regulations. STC is very concerned that, at present, the limited regulations currently in place are being openly ignored, to the detriment of the endangered sea turtles that the tourists are coming to Tortuguero to observe. This issue should be considered a priority for MINAET and the TNP administration; STC, as always, is willing to share information and provide technical assessment where necessary to help protect Tortuguero s sea turtles. The TSP committee also continued their discussion about the possibility of making the purchase of a brochure mandatory for all tourists participating in turtle tours, to ensure that sufficient funds are generated to cover program expenses and also provide additional money for donations to TNP and community projects. The legal issues associated with this change from a voluntary fee are still being explored by MINAET Artificial Lights The problem of artificial lights visible on the beach continues (See Figure 7); the strip of vegetation in front of buildings in the village and the hotels close to the beach plays and important role in protecting turtles and hatchlings from the lights, thus it is important to try to increase the quantity of plants and trees in this zone in the future. The proposal to illuminate the football field is very worrying due to the enormous potential negative impacts of these lights, not only for sea turtles but also, due to the proximity of the football field to TNP, to the other species of nocturnal fauna. STC is not opposed to the idea of increasing the number of activities open to the young people in the village, but we can t support this specific proposal by the TDA Hatchling disorientation It was disappointing to observe evidence of hatchling disorientation on four separate occasions in 2012; caused by artificial lights visible on the beach. It is important that STC works closely with MINAET and the community in the future to reduce the number of lights that can negatively affect nesting females and hatchlings. A reforestation project between the buildings and the beach could be a way to solve the problem; another would be to use red bulbs in locations close to the beach, and try to educate people about the very real problem caused by lights in Tortuguero Satellite Tracking Project The turtle fitted with a satellite transmitter during the 2012 Green Turtle Program will provide valuable information about the migratory behavior the Tortuguero green turtle nesting population. It was interesting to be able to follow this female during the inter-nesting period, during which she remained close to the beach for a period of several weeks; she travelled almost to Limón during this period. Once she had finished nesting for the season she left the area and traveled north to the Pearl Lagoon in Nicaragua (See map in Appendix 4). Once she arrived at her chosen feeding ground she remained within a defined area for almost one year. Satellite telemetry is a very useful tool for researchers to use to study migration behavior of sea turtles once they leave the nesting beach, and to determine the location of foraging sites, and the potential threats they may face on route to the feeding area, or once they arrive there. Also, it can be a powerful 49

51 educative tool, providing a means to reach the public and teach them in an entertaining way about science and conservation initiatives. This turtle was part of the Tour de Turtles on-line event, organized by STC, which allows the general public an opportunity to follow the turtles during their migrations, and at the same time, raise awareness about a variety of different threats to sea turtles and their habitats, through each turtle s campaign in the competition. At Tortuguero, hundreds of people, local residents and visitors, could observe the attachment of the transmitter and the subsequent release of the turtle back to the ocean. The project, therefore, was very successful, both from a scientific perspective as well as the public outreach opportunity it provided Community Activities Veterinary clinic The clinic held in November 2012 was, once again, very successful; more than 100 animals were treated in Tortuguero and San Francisco. The veterinary clinic program has been very successful, with 437 animals spayed/neutered in five years. However, there are still a lot of dogs in both communities, but at least the proportion of castrated animals is increasing with each clinic conducted. 5. References Carr, A., Carr, M.H. & Meylan, A.B The ecology and migrations of sea turtles, 7. The west Caribbean green turtle colony. Bull. Amer. Mus. Nat. Hist. 162, Moya Calderón, M Informe de visitación turística Parque Nacional Tortuguero, Puesto Operativo Cuatro Esquinas y Jalova Unpublished report. Pp. 18. Sea Turtle Conservancy Informe del proyecto del manejo y monitoreo de huevos de tortugas marinas decomisados Unpublished report presented to MINAET. Pp. 9. Troëng, S. & Rankin, E Long-term conservation efforts contribute to positive green turtle Chelonia mydas nesting trend at Tortuguero, Costa Rica. Biol. Conserv. 121, Wetherall, J. A Analysis of double-tagging experiments. Fish. Bull. 80,

52 6. Appendices Appendix 1. Turtles killed by jaguars, June November 2012 Date Mile Species Comments 6 Cm 9-Jun 9 4/8 Cm 5 4/8 Cm 16-Jun 9 Cm 10 Cm 22-Jun 4 7/8 Cm 23-Jun 8 4/8 Cm 4 1/8 Cm Tag# Jun 4 7/8 Cm Tag #s / Cm Tag # Cm 30-Jun 8 4/8 Cm 9 4/8 Cm 5 Cm 6 Cm 7-Jul 6 4/8 Cm 14 Cm 11-Jul 4 6/8 Cm 8 Cm 9 4/8 Cm 14-Jul 10 Cm 10 Cm 11 4/8 Cm 9 Cm 21-Jul 9 4/8 Cm 14 4/8 Cm 28-Jul 30-Jul 4 7/8 Cm Tag #s / Cm 11-Aug 8 4/8 Cm 9 Cm 4 6/8 Cm 13-Aug 4 6/8 Cm 4 7/8 Cm 5 Cm 9 4/8 Cm Tag#

53 Appendix 1. Continued Date Mile Species Comments 4 4/8 Cm 16-Aug 4 4/8 Cm 19-Aug 4 7/8 Cm 6 6/8 Cm 8-Sep 8 4/8 Cm 12 Cm 4 Cm Tag #s / Sep 5 Cm 14-Sep 4 6/8 Cm 7 Cm 15-Sep 12 4/8 Cm 16 4/8 Cm 24-Sep 4 2/8 Cm 4 2/8 Cm 29-Sep 9 Cm 3-Oct 4 4/8 Cm 5 Cm 6 4/8 Cm 6-Oct 8 4/8 Cm 16 Cm 7-Oct 4 4/8 Cm Tag # Oct 13 5/8 Cm 15-Oct 4 2/8 Cm Tag #s / /8 Cm 20-Oct 13 Cm 14 Cm 6 Cm 9 Cm 3-Nov 12 4/8 Cm 14 Cm 8 4/8 Cm 10-Nov 13 Cm 16 Cm 17-Nov 8 4/8 Cm Cm = Chelonia mydas Green Turtle 52

54 Appendix 2. Nightly sea turtle encounters for the 2012 Green Turtle Program a) Encounters in the northernmost 5 miles of beach (Tortuguero) Date Leatherback Green Hawksbill New REM REN Total New REM REN Total New REM REN Total 6-Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul

55 Date Appendix 2a. Continued Leatherback Green Hawksbill New REM REN Total New REM REN Total New REM REN Total 12-Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug

56 Date Appendix 2a. Continued Leatherback Green Hawksbill New REM REN Total New REM REN Total New REM REN Total 19-Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep

57 Date Appendix 2a. Continued Leatherback Green Hawksbill New REM REN Total New REM REN Total New REM REN Total 26-Sep Sep Sep Sep Sep Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct STT One newly tagged loggerhead encountered on 7July 56

58 57 Date Appendix 2. Continued b) Encounters in the southernmost four miles of beach (Jalova) Leatherback Green Hawksbill New REM REN Total New REM REN Total New REM REN Total 5-Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul

59 Date Appendix 2b. Continued Leatherback Green Hawksbill New REM REN Total New REM REN Total New REM REN Total 13-Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug

60 Date Appendix 2b. Continued Leatherback Green Hawksbill New REM REN Total New REM REN Total New REM REN Total 21-Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep

61 Date Appendix 2b. Continued Leatherback Green Hawksbill New REM REN Total New REM REN Total New REM REN Total 29-Sep Sep Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct STJ Total Key to table 2 & 3 One newly tagged loggerhead encountered on 6 June and she returned on 18 June. New Turtles that had no tags on first encounter in 2012; REM Remigrant turtles that had tags from previous years/other projects on first encounter in 2012; REN Renester turtles that were encountered on more than one occasion during 2012; STT Sub-total of encounters for Tortuguero; STJ Sub-total of encounters for Jalova; Total Combined total of encounters from Tortuguero and Jalova. 60

62 Appendix 3. Translation of letter sent to the Tortuguero Development Association regarding the proposal to illuminate the football field Sea Turtle Conservancy (Antes Caribbean Conservation Corporation) Apartado Postal San Pedro Costa Rica Tel: Fax: San José, 9 May, 2012 Mr. Enrique Obando Vargas President Tortuguero Development Association Dear Mr Obando Vargas, We would like to take this opportunity to respond to your letter of 24 April, 2012, in which you request support for the project proposed by the Tortuguero Development Association (TDA) to illuminate the football field in Tortuguero. While the STC obviously supports the initiative of the TDA to encourage the youth of Tortuguero to be involved in sport, to try to avoid them becoming drawn into undesirable pastimes which are commonplace in the community (such as underage drinking or drug use), we have some fundamental concerns about this project, with regard to the potential negative impacts that the artificial lights may cause to sea turtles and other wildlife in the area. Tortuguero is the most important nesting beach for green turtles (Chelonia mydas) in the Western Hemisphere, with an estimated average of 112,179 nests each season in the last 10 years; which equates to a population of nesting females between 20,000 44,000 individuals. The beach also supports two other critically endangered turtle species; there is a regionally important nesting population of leatherbacks (Dermochelys coriacea), with an estimated average of 470 nests per year in the last 10 years, and occasional nesting by hawksbills (Eretmochelys imbricata), less than 50 nests per year. The long-term monitoring program that has been conducted by STC since the 1950 s indicates that leatherback nesting occurs from January thru July (with one nest recorded in November 2010), though peak nesting is typically from March to June (See Appendix 1a). Green turtles have been observed nesting from April thru November; however, typically peak nesting occurs between June October each year (See Appendix 1b). However, hatching of nests takes place approximately two months after the eggs are laid; thus hatchlings are emerging thru November and into December (at low levels). Therefore, when it states in your letter that the TDA and the community will promise not to use the illumination on the football field from 1 July 31 October and will respect the dates of turtle nesting there is no consideration for either the leatherback nesting season or the hatchling of green turtle nests laid from September onwards. 61

63 Appendix 3. Continued Furthermore, in the Regulations for Public Use of Tortuguero National Park, published in La Gaceta Nº 73, 16 April, 2010 it states in Capítulo V: Para la observación del desove de tortugas marinas, se establecerán las siguientes disposiciones: Artículo 12. Según lo dispuesto en la Ley de Conservación de la Vida Silvestre Nº 7317 del 30 de octubre de 1992 y con base en las Normas Protección Desove Tortuga Verde, Parque Nacional Tortuguero, Decreto Ejecutivo Nº MIRENEM del 7 de enero de 1991, se definirán las siguientes temporadas para la observación de tortugas marinas: a) La temporada de observación de tortuga baula (Dermochelys coriacea) y tortuga verde (Chelonia mydas), se permitirá a partir del 1º de marzo al 31 de octubre. Cuando estudios científicos indiquen que las especies están siendo impactadas negativamente, el Área de Conservación Tortuguero de acuerdo a su criterio técnico y jurídico podrá modificar el período de observación, vía resolución administrativa, la cual será divulgada en la página Web acto.go.cr que para tal efecto tiene el Área de Conservación Tortuguero. b) La temporada de observación de nacimientos de tortuga baula (Dermochelys coriacea) y tortuga verde (Chelonia mydas), se permitirá a partir del 1 de abril hasta el 15 de diciembre. Los permisos de observación se extenderán con base en estudios científicos a criterio del Área de Conservación Tortuguero. Thus in Tortuguero the official sea turtle nesting season, as declared by MINAET, is 1 March 31 October, and they also recognize that there are hatchlings present through 15 December. Nesting density varies considerably along the northern five miles of beach, with fewer nests laid in front of Tortuguero village (miles 2 6/8 3 3/8), and increased nesting within Tortuguero National Park (TNP). However, nesting of both species is recorded, even at low densities, in every 1/8 of a mile section (See Appendix 2). The reduced density of nests in front of the village may, in part, be due to an increased number of artificial lights (See Appendix 3); although there is historical evidence that suggests this pattern was also evident before the village had electricity. However, it is definitely possibly that the observed pattern is also in response to the increased level of light pollution along this section of beach. It is acknowledged by sea turtle conservationists and researchers that artificial lights visible on nesting beaches can cause significant negative impacts to both nesting females and hatchlings. Adult turtles may alter their nesting behavior in response to artificial light; however it is not always possible to observe the impact of the lights through a simple examination of the ratio of nests to false crawls in a given area, because often they will simply choose not to come ashore where there are lights. If they do try to nest they may abandon the nesting process before laying their eggs. However, many females choose to lay nests in an area with high levels of artificial light; there is a high probability that these hatchlings will be subject to high levels of disorientation, in which they are attracted to the light when they leave the nest and so crawl towards it rather than to the sea, and so often die or are subject to increased levels of predation (Witherington & Martin, 2000). At Tortuguero there have been reported incidents of hatchling disorientation over the years, often as a result of artificial light from a building being visible in an area with limited vegetation 62

64 63 Appendix 3. Continued cover; ie. in front of the village, or where there are hotels located behind the beach. To date, these have been isolated incidents; however, in the last year it has become apparent to the STC that the protective vegetation barrier behind the beach has been cut down in several locations (ie. between the STC field station and the village, and also in front of the football field). The STC has worked closely with the Costa Rican Electrical Institute (ICE) over the last couple of years to try and solve the problem of light pollution on the nesting beach at Tortuguero. Technical staff from ICE and STC have conducted patrols at night of the stretch of beach in front of the village, to highlight problematic public lights; which have subsequently been screened by ICE to reduce the amount of light visible on the beach. While the results have been substantial, there are still some public lights that can be seen at night, and also numerous lights from private residences or businesses that are continue to be a problem. It is discouraging that after such a concerted effort by STC and ICE to reduce this serious problem, the proposed plan for illuminating the football field, would completely negate any of the positive results that have been obtained. What is of most concern with regard to this proposal is the quantity and intensity of lights that would be used and the height at which they would be positioned to provide adequate illumination. Information received from ICE suggests that a total of 24 lights would be needed; each high-pressure sodium (HPS) light would have an intensity of 1,000W, and would reflect light for 360º. This type of light (HPS) is known to be highly disruptive to sea turtles (Witherington & Martin, 2000). Furthermore, because the lights would need to be placed on high posts (~13m) they would be above the vegetation line and so directly illuminating the beach. The minimum distance for which these lights would be visible is 1km (0.6 miles); thus at least 1.2 miles of beach would be directly impacted. It is not appropriate only to consider the potential impacts on nests that are laid directly in front of the football field, which as mentioned above, is a small number. On the figures shown in Appendix 2, the bars in red are those in the zone that could be affected by these lights; it is clear that the area of impact would extend within the limits of PNT (from mile 3 3/8). It should be noted that the red bars indicate the minimum distance that could be affected, it is possible that the distance might be greater than 1km. Light pollution is perceived as a significant problem from sea turtles; indeed, in Florida, USA, for example, there are specific ordinances that relate to lighting in buildings close to nesting beaches. People are encouraged to turn off, or shade their lights during sea turtle nesting and hatching season and can face fines if they do not follow the rules. In addition to the studies focused on determining the impacts of artificial lights on sea turtles, there has also been considerable research conducted into how the effects of lights can be minimized or eliminated, through the use of different types of bulbs, lighting fixtures or shading options. That being said, STC has some recommendations that we would like to suggest that would hopefully mitigate any negative impacts, should the plan to illuminate the football field be approved: 1) Limited period of use: Prohibit the use of the lights at night from 1 March 30 November; this time period covers the leatherback and green turtle nesting seasons, and the majority of the green turtle hatching season. 2) Re-vegetate the area in front of the football field with native plants; this would improve the vegetation cover and help minimize the amount of light visible on the beach. It is also proposed

65 Appendix 3. Continued to plant native species not only in front of the football field, but along the entire stretch of beach in front of the village of Tortuguero, which has been severely diminished in recent years. 3) Use of appropriate light fittings; with technical support from ICE, procure light bulbs that have a wavelength that provides sufficient illumination, but which have a wavelength that has minimal impacts on wildlife. STC can provide additional technical information if necessary. Also, position the lights in such a way to minimize the area of impact, ie. use lower posts, create a netting screen to shield the lights, etc. We would like to reiterate that STC is fully supportive of the proposal by the TDA to provide the youth of Tortuguero with an alternative activity, we appreciate that there are limited options for the younger generation in the community, and so many become involved in undesirable activities at an early age. However, STC strongly opposes the plan to illuminate the football field, not only for its obvious potential negative impacts on the endangered sea turtle populations that nest at Tortuguero, but also on other nocturnal species of mammals, birds, reptiles and insects that inhabit TNP and could also be affected by these artificial lights. If you require any further information please do not hesitate to contact STC. Atentamente, Dra. Emma Harrison Directora Científica Caribbean Conservation Corporation Roxana Silman Directora Nacional Caribbean Conservation Corporation Cc. Mr Luis Rojas Director del Área de Conservacion Tortuguero Miss Elena Vargas Ramírez Administradora del Parque Nacional Tortuguero Literature cited: Witherington, B. E & Martin, R. E Understanding, assessing and resolving light pollution problems on sea turtle nesting beaches. 2nd ed. Rev. Florida Marine Research Institute Technical Report TR p. 64

66 Número promedio de rastros Número promedio de rastros Appendix 3. Continued Appendix 1. Temporal distribution of sea turtle nesting at Tortuguero, a) Leatherback turtles ene 15-ene 29-ene 12-feb 26-feb 12-mar 26-mar 9-abr 23-abr 7-may 21-may 4-jun 18-jun Nido 2-jul 16-jul Fecha Media luna b) Green turtles 30-jul 13-ago 27-ago 10-sep 24-sep 8-oct 22-oct 5-nov 19-nov 2-dic 16-dic 30-dic ene 15-ene 29-ene 12-feb 26-feb 12-mar 26-mar 9-abr 23-abr 7-may 21-may 4-jun 18-jun Nido 2-jul 16-jul Fecha Media luna 30-jul 13-ago 27-ago 10-sep 24-sep 8-oct 22-oct 5-nov 19-nov 2-dic 16-dic 30-dic

67 Número promedio de rastros Número promedio de rastros Appendix 3. Continued Appendix 2. Spatial distribution of sea turtle nesting in the northern five miles of beach a) Leatherback turtles Tortuguero village TNP /8-1/8 1/8 3/8 5/8 7/8 1 1/8 1 3/8 1 5/8 1 7/8 2 1/8 2 3/8 2 5/8 2 7/8 3 1/8 3 3/8 3 5/8 3 7/8 4 1/8 4 3/8 4 5/8 4 7/8 Milla Nidos Media lunas b) Green turtles TNP Tortuguero village /8-1/8 1/8 3/8 5/8 7/8 1 1/8 1 3/8 1 5/8 1 7/8 2 1/8 Nido Milla 2 3/8 2 5/8 Media luna 2 7/8 3 1/8 3 3/8 3 5/8 3 7/8 4 1/8 4 3/8 4 5/8 4 7/8 66

68 Número promedio de luces / censo Appendix 3. Continued Appendix 3. Spatial distribution of artificial lights in the northern five miles of beach Tortuguero village TNP /8-1/8 1/8 3/8 5/8 7/8 1 1/8 1 3/8 1 5/8 1 7/8 2 1/8 2 3/8 2 5/8 2 7/8 3 1/8 3 3/8 3 5/8 3 7/8 4 1/8 4 3/8 4 5/8 4 7/8 Milla 67

69 Appendix 4. Photographs of satellite transmitter attachment, release of the turtle and the migration map of the green turtle tracked using satellite telemetry in 2012 Photographs Juan Mata-Lorenzen Attaching the transmitter using fiberglass resin Local residents came to observe the attachment process and learn about sea turtles 68

70 Appendix 4. Continued The turtle returned to the sea, observed by a large crowd of tourists and local residents The turtle reached the sea to start her migration 69

71 Appendix 4. Continued The turtle remained close to Tortuguero (yellow circle) until 12 September, travelling close to Limón. She then headed north where she stayed close to the Pearl Lagoon in Nicaragua (area covered by the green circle) until 2 June, 2013 when her transmitter stopped sending signals. 70