PRETOMA Report 2014 - cremacr.org › ... › 01 › PRETOMA-Report-2014.pdf · By#Madeleine#Beange,#Maike#Heidemeyer,#andRandal# Arauz# # During# the# 2014

By Madeleine Beange, Maike Heidemeyer, and Randal Arauz During the 2014-‐2015 nesting season, PRETOMA monitored sea turtle nesting at four beaches on the southern Nicoyan Peninsula of Costa Rica: Caletas, Costa de Oro, San Miguel, and Corozalito. In total 5567 solitary olive ridley nesting events were recorded, and 3 arribada nesting events occurred at Corozalito of estimated sizes of 3300, 12900 and 6900 events. In addition, 917 nests were protected in project hatcheries, and 65718 olive ridley hatchlings were released into the Pacific Ocean.

P R E T O M A . S a n J o s e , C o s t a R i c a . w w w . p r e t o m a . o r g

PRETOMA Sea Turtle Conservation Beach Project 2014 Report

PRETOMA Sea Turtle Conservation Beach Project 2014 Report 2

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These Projects Were Made Possible with the Support of:


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Table of Contents

1. INTRODUCTION ................................................................................................................................. 4 2. PROJECT SITES ................................................................................................................................... 5 3. METHODS ............................................................................................................................................. 7 3.1 NESTING ACTIVITY MONITORING ................................................................................................................... 7 3.1.1 Sector Markers ............................................................................................................................................ 7 3.1.2 Solitary Nesting Survey Protocol ........................................................................................................ 7 3.1.3 Arribada Survey Protocol ....................................................................................................................... 8 3.1.4 Data Analysis ............................................................................................................................................... 9

3.2 HATCHERY ........................................................................................................................................................... 9 3.2.1 Preparation .................................................................................................................................................. 9 3.2.2 Maintenance and Monitoring ............................................................................................................... 9 3.2.3 Data Collection and Analysis ............................................................................................................. 10

3.3 IN SITU NEST EXHUMATIONS ....................................................................................................................... 11 3.4 DEAD TURTLE STRANDING RECORDS ......................................................................................................... 11 3.5 PHYSICAL DATA COLLECTION ....................................................................................................................... 11

4. RESULTS ............................................................................................................................................. 12 4.1 OLIVE RIDLEY NESTING ................................................................................................................................. 12 4.1.1 Solitary Nesting ....................................................................................................................................... 12 4.1.2 Arribada Nesting ..................................................................................................................................... 18 4.1.3 Biometric Data ......................................................................................................................................... 19 4.1.4 Tagging Data ............................................................................................................................................ 19

4.2 HATCHERY SUCCESS ....................................................................................................................................... 21 4.2.1 Caletas ......................................................................................................................................................... 22 4.2.2 Costa de Oro .............................................................................................................................................. 23 4.2.3 San Miguel .................................................................................................................................................. 23

4.3 COROZALITO IN SITU NEST SUCCESS .......................................................................................................... 24 4.4 GREEN TURTLE NESTING .............................................................................................................................. 24 4.5 LEATHERBACK NESTING ................................................................................................................................ 24 4.6 DEAD TURTLE DATA ...................................................................................................................................... 25 4.7 TEMPERATURE DATA ..................................................................................................................................... 25 4.7.1 Caletas ......................................................................................................................................................... 25 4.7.2 Costa de Oro .............................................................................................................................................. 27 4.7.3 San Miguel .................................................................................................................................................. 27

5. DISCUSSION ....................................................................................................................................... 30 5.1 SOLITARY OLIVE RIDLEY NESTING ACTIVITY ............................................................................................ 30 5.2 POACHING AND DEPREDATION .................................................................................................................... 31 5.3 TEMPORAL DISTRIBUTION OF SOLITARY OLIVE RIDLEY NESTING ....................................................... 32 5.4 COROZALITO ARRIBADA NESTING ............................................................................................................... 33 5.5 TAGGING STUDY .............................................................................................................................................. 34 5.6 HATCHERY TEMPERATURE AND SUCCESS .................................................................................................. 35 5.7 COROZALITO IN SITU NEST SUCCESS .......................................................................................................... 36 5.8 GREENS AND LEATHERBACK NESTING ....................................................................................................... 37


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6. CONCLUSIONS ................................................................................................................................... 37 7. RECOMMENDATIONS ..................................................................................................................... 38 8. REFERENCES ..................................................................................................................................... 39 9. SUPPLEMENTARY MATERIAL ..................................................................................................... 40

1. Introduction PRETOMA started monitoring sea turtle nesting activity on the southern Nicoya Peninsula (SNP) of Costa Rica in 1998, when it entered San Miguel to help the local effort of protecting turtle eggs by moving them to a hatchery. Since then PRETOMA has created turtle conservation and monitoring projects on three other nesting beaches in the area: Caletas, Corozalito, and Costa de Oro. With these four projects combined, PRETOMA protects a total length of 13 km of nesting beaches. Sea turtles face several direct threats on SNP nesting beaches, the greatest being egg loss through poaching by locals who sell the eggs to supplement their low incomes. Although selling them is illegal, sea turtle egg consumption is a part of Costa Rican culture because of the traditional belief that they have aphrodisiac properties. Another large cause of egg loss on the beaches is through animal depredation. Unlike poaching depredation is limited by predator satiation, but there are many species that visit the beaches to feed on the eggs such as raccoons, skunks, hermit crabs, dogs and coatis. Sea turtles also face indirect threats on the SNP beaches, such as development and climate change, which could destroy the beaches that the turtles rely on for reproduction. Although the beautiful SNP is currently relatively uninhabited, tourism is slowly growing in the area, and with it hotel and vacation home development. Coastal development can cause both light pollution, which deters nesting turtles from visiting the beaches, and beach erosion, which decreases the available area on the beaches to leave their nests. Climate change can contribute to this decrease in nesting area with rising sea levels, which combined with coastal development results in beach squeeze (Fonseca et al. 2009). Another potential cause of climate change is higher sand temperatures, which affects nest incubation and could result in higher proportions of female sex ratios or even nest fatality (Fish et al. 2009). The primary objective of the four PRETOMA a beach projects is to protect sea turtle eggs from poaching and depredation through nightly beach patrols, protected hatcheries, community education, and sustainable tourism development. The secondary objective is to gather scientific data of sea turtle nesting activity and to use this information for both designing conservation methods at the beach projects, and working with local stakeholders to protect the area’s delicate ecosystems.


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Caletas, Costa de Oro, San Miguel, and Corozalito are primarily olive ridley (Lepidochelys olivacea) solitary nesting beaches. Although olive ridleys are classified as vulnerable on the IUCN Red List of Threatened Species, they are the most abundant of the 7 species of sea turtles and thus the lowest priority for conservation funding (IUCN 2014). For this reason olive ridleys are the least studied species of sea turtle and there are many aspects of their biology that aren’t understood, such as the specie’s unique polymorphic reproductive behavior. Olive Ridleys nest not only solitarily like all sea turtle species, but also in arribadas, a behavior unique to the Lepidochelys genus in which up to hundreds of thousands of turtles nest in synchrony over a few days. The majority of research that has been done on olive ridleys has focused on arribada nesting behavior because they are unique and involve such a massive number of individuals. However it is important to consider that solitary nesting is much more widespread and the levels of the two nesting behaviors are potentially equal worldwide (Bernardo et al. 2007). For instance, the eastern Pacific olive ridley population nests from the coasts of Mexico to Ecuador, and only eight beaches along this stretch of coast are arribada nesting beaches. Therefore, solitary nesting plays a fundamental part in maintaining olive ridley populations and needs to be studied to understand how polymorphic reproductive behavior contributes to the overall fitness of the species. The SNP also sees occasional nesting of three other species of sea turtles, all of which the eastern Pacific populations are classified as endangered or critically endangered on the IUCN Red List: the leatherback (Dermochelys coriacea), green (Chelonia mydas), and hawksbill (Eretmochelys imbricate). Although these appearances are rare, accounting for less than 1% of the total beaches’ nesting activity, they are significant because the critical statuses of the populations. The objectives of this report are to summarize the results of the 2014-‐2015 season of the PRETOMA nesting beach projects, to assess the accomplishments and shortcomings of the conservation and research efforts, and to provide recommendations for future nesting seasons.

2. Project Sites The four PRETOMA project beaches are located along 30 kilometers of the southern Nicoya peninsula and are each delineated by rocky outcrops, estuaries, river mouths, wetlands, and mangroves (Figure 1). During the rainy season, which coincides with the nesting season, the estuaries flow into the ocean, releasing brackish, nutrient-‐rich water. This is a common feature of olive ridley nesting beaches and may play a role in the nesting process, such as in navigation or as nesting queues (Bernardo et al. 2007). The wetland and mangrove ecosystems behind the beaches are delicate and have seen degradation due to rice farming,


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cattle ranching, and development. The individual beaches are described below in geographical order, from south to north.

Figure 1. Map of the southern Nicoya peninsula area showing where the four PRETOMA turtle nesting beach projects are located.

Caletas is a 5 kilometer beach within the Caletas-‐Ario National Wildlife Refuge. The beach is enclosed by a rocky outcrop at the northern end and the Bongo River at the southern end. Playa Caletas is uninhabited and isolated, with the closest towns being San Francisco de Coyote, 5 km north, and Quebranando, 5 km northeast. The beach is steeply inclined and has large grained, dark sand. The Caletas project was initiated in 2002 because large numbers of leatherbacks had been reported to be nesting on the beach. In the first couple of seasons 23 and 45 leatherback nesting events were recorded, consecutively. Since then the number has gradually decreased, and no nesting events have been observed in the last couple of seasons. This decrease reflects the general trend of the eastern pacific subpopulation, which has declined 97.4% during the last three generations (IUCN 2014). Despite this discouraging leatherback population collapse, PRETOMA continues to monitor olive ridley nesting activity at Caletas, which varies between 500 and 1500 events per season. Costa de Oro and San Miguel are neighboring beaches separated by the Jabilla estuary. Costa de Oro is 4.6 km long with the Coyote estuary on the southern end, and San Miguel 2.5 km long with Punto Bejuco on the northern end. The two beaches have similar medium-‐coloured, fine-‐grained sand; shallow incline; large tidal flows with low tides exceeding 200 m; and a line of palm trees as vegetation. The beaches also are similarly developed, with mostly vacation houses that are vacant the majority of the year, and small communities of roughly 100 year-‐round


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residents. San Miguel is the oldest of the PRETOMA beach projects, and has had an average of 360 olive ridley nesting events per season since 2004. In contrast, the Costa de Oro project only started three years ago, and there is not enough data to determine the beach’s typical nesting activity level. Corozalito is only 800 m long, and is defined by rocky outcrops at each end and an estuary in the south. The beach is heterogeneous in incline, sand composition, and vegetation. Corozalito is not inhabited but there is a small town 4 km inland from the beach. Although Corozalito is the smallest of the project beaches, it has the highest level of nesting activity. Since the project started in 2008, there has been an average of 1660 solitary nesting events per year. In addition, Corozalito occasionally has nights of exponentially higher than usual nesting activity, which could be described as “mini-‐arribada” events. The erratic nature of these mini-‐arribadas has made studying them difficult. They have varied drastically in estimated size, from 300 to 5000 participants, and have unpredictably occurred between September and January, sometimes skipping years. More data needs to be collected from future events to properly characterize these mini-‐arribadas and understand how they fit in to solitary and arribada nesting phenotypes.

3. Methods

3.1 Nesting Activity Monitoring

3.1.1 Sector Markers At the beginning of the season beach sectors were measured and marked by painting trees or wood posts. Caletas, Costa de Oro, and San Miguel were divided into 50, 46, and 25 100 m sectors respectively. Due to the higher nesting density Corozalito was divided into 15 50 m sectors, and then further subdivided into 12.5m subsectors (ex. 1, 1A, 1B, 1C).

3.1.2 Solitary Nesting Survey Protocol One or two 3-‐hour patrols were conducted each night, depending on the number of participants available at the projects, to record all tracks of emerged sea turtles and biometric data from those encountered. Daily morning surveys were conducted to record tracks from turtles that came up after night patrols, and check whether in situ nests were destroyed by poaching or depredation. Beach patrols were conducted in Caletas from June 27th to March 30th, Costa de Oro from July 12th to December 6th, San Miguel from July 1st to December 15th, and Corozalito from August 3rd to December 13th.


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When tracks from an emerged turtle were encountered date, time, sector, zone, and species, and nesting activity category were recorded. Zones were characterized by below average high tide line (1), above average high tide line (2), and above line of vegetation (3). Nesting activities were categorized as the following:

1. Successful: a clutch of eggs was laid a. Protected: the nest was unharmed b. Poached: humans took the eggs c. Depredated: animals ate and/or destroyed all the eggs d. Partially depredated: some eggs were eaten by animals, but a portion

of the clutch was left unharmed 2. Unsuccessful: a clutch of eggs was not laid

a. False crawl: a turtle emerged from the ocean, walked up the beach, and returned to the ocean

b. Aborted nest: a turtle began the process of laying a nest, clearing a nest bed or digging an egg chamber, but stopped and returned to the ocean before laying eggs

When nests successful nests were encountered, the eggs were counted while using a latex glove in order to avoid contamination. When possible, nests were moved to a project hatchery. If a hatchery was not available, the nests were left in situ, or relocated to a safer position of the beach. When nesting turtles were encountered, they were measured and tagged after they had started depositing eggs, when they were least responsive to disturbances. Over-‐the-‐curve measurements were taken with a non-‐stretchable measuring tape. Curved carapace length (CCL) was measured from the midpoint of the nuchal scute, where the skin touches the carapace, along the midline, to the notch between the last two supercaudal scutes. Curved carapace width (CCW) was measured from the widest part of the carapace, perpendicular to the long axis. Flippers were checked for old tags, or evidence of pre-‐existing tags. New tags were applied on the second large scale from the inside posterior edge of the fore flipper, the left flipper getting the lower tag number.

3.1.3 Arribada Survey Protocol Night patrol surveys switched to arribada protocol if there were more than 50 turtles nesting on the beach in synchrony. The instantaneous count method described in Valverde et al. 1999 was used for the arribada protocol. The number of females laying eggs was counted in each sub-‐sector every 2 hours. An estimate for the total number of turtles that nested during the arribada was calculated by using the following equation:

M =nHht


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Where M is the estimated number of females that nested, n is the number of egg-‐laying females counted, H is the total survey period, h is the average time females take to lay eggs, and t is the number of sampling times. An arribada event was defined as a series of nights in which the estimated number of nesting females was greater than 1000. Nights were included in the events if over 100 turtles nested.

3.1.4 Data Analysis For calculating the numbers of nightly solitary and arribada nesting activity, and inter-‐nesting intervals, the date was defined as the date that the night started. For instance, if a nesting event occurred at 3 am of September 12th the date of September 11th was used. When calculating the average inter-‐nesting interval for turtles encountered twice during the nesting season, an unsuccessful nesting event was only used if it occurred more than a week before or after a successful nesting event. If there was an unsuccessful nesting that occurred within a couple days of the successful nesting event, the date of the successful nesting event was used.

3.2 Hatchery

3.2.1 Preparation The pre-‐existing hatchery locations were used in San Miguel and Caletas. In San Miguel all old sand was exchanged for new sand from the beach. At Caletas the old sand was mixed and sifted to remove new roots, garbage, and eggshells from the previous season. The Costa de Oro hatchery was built in a new location. No hatchery was built in Corozalito due to the higher nesting density and distance of the project station house from the beach. The capacities of the San Miguel, Caletas, and Costa de Oro hatcheries were 168, 200, and 70 nests respectively (Figure 2).

3.2.2 Maintenance and Monitoring The project hatcheries contained nests for the following periods:

1. Caletas: 29-‐06-‐14 to 31-‐03-‐15 2. Costa de Oro: 25-‐07-‐14 to 19-‐12-‐14 3. San Miguel: 04-‐07-‐14 to 20-‐12-‐14

Nests were relocated to the hatcheries in rounds of every second quadrat, from northwest to southeast of the ocean-‐ to land-‐side rows. Nests protected in the hatchery were monitored throughout the incubation period. After 40 days of incubation, a basket was placed around the nest so the hatchlings would be contained upon emergence. If an animal managed to enter the hatchery and


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depredate a nest, an estimate was made of the number eggs eaten. Depredated hatchlings were categorized separately as dead outside nest.

Figure 2. Diagrams of the San Miguel, Caletas, and Costa de Oro hatcheries.

When the hatchlings emerged, they were counted and moved to a bucket. If any were found dead outside of the nest, from overheating or predation, they were recorded. The hatchlings were released in alternating sectors of the beach at least 4 meters before the tideline so they could naturally make their way to the ocean. When nests were exhumed all the sand from the egg chamber was removed, and new sand was used to fill the holes to avoid future contamination.

3.2.3 Data Collection and Analysis Exhumations were preformed on the nests the day after they were observed hatching to determine the hatching success. The contents of the nest were sorted into dead hatchlings, live hatchlings, empty shells, and un-‐hatched eggs. Un-‐hatched eggs were opened and categorized as the following:

1. SD: no signs of development 2. Stage 1A: first signs of blood and tissue present 3. Stage 1B: embryo can be distinguished, but doesn’t have any pigment 4. Stage 2: embryo has pigment, but is not fully developed


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5. Stage 3: embryo is fully developed 6. Pipped: embryo has broken a hole in the shell, but hasn’t emerged 7. NI: the contents of the eggs cannot be identified because they have

decomposed or maggots have eaten them. Two different success rates were calculated. Eclosion or hatching success was the portion of the hatchlings that emerged from their eggs. The total number of hatchlings that were encountered emerged from the sand, dead outside the nest, dead inside the nest, and alive inside the nest was divided by the eggs relocated. Release success only took into account the hatchlings that were found alive and released to the ocean. For overall hatchery success the total numbers of eggs relocated to the hatchery and hatchlings produced over the season were used. For successes in different sections and rounds of the hatchery, the average success of each nest was used. Only data from olive ridley nests were included in the results presented in the Hatchery Success section (4.2). Excavation data from leatherback and green nests are presented separately in sections 4.4 and 4.5 respectively.

3.3 In Situ Nest Exhumations As there was no hatchery in Corozalito, in situ nests were exhumed and identified using the same categorization method described in section 3.2.3. Two nests per night located during oviposition were marked and identified by two-‐point triangulation. For each nest, measurements were taken of lines from the closest sector markers to the point where they intersected over the nests. A piece of labeled flagging tape was then inserted into each egg chamber. Nests were checked regularly for signs of depredation or poaching, and after 45 days they were monitored for signs of hatching.

3.4 Dead Turtle Stranding Records When dead sea turtles washed up on the beaches, a record was taken of the date, time beach sector, species, curved carapace measurements, sex, and degree of decomposition. The turtles were examined for indications of cause of mortality, such as injuries from hooks or nets.

3.5 Physical Data Collection Precipitation counters were placed in the centers of the San Miguel and Caletas hatcheries and checked daily at 7am and 7pm. Daily precipitation levels were found by adding the two measures taken each day. Onset HOBO Pendant temperature loggers were used to monitor nest temperatures in all three project hatcheries. The loggers were sanitized with alcohol and placed in the middle of nests. The loggers recorded temperature every hour throughout the


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entire incubation period. For the figures representing nest temperatures, only every 6 hours were plotted. Previous studies with olive ridley nest incubation have shown that temperatures above 35°C and below 26°C result in increased nest mortality (Valverde et al. 1999). To make it clear when nest temperatures increased above this fatal level, 35°C was marked as a red line in all graphs. The pivotal temperatures was assumed to be an average of 30.5°C during the second trimester of incubation (McCoy et al. 1983, Wibbels et al. 1998). At pivotal temperature a 1:1 sex ratio develops. Above this temperature more females develop, and below this temperature more males develop.

4. Results

4.1 Olive Ridley Nesting

4.1.1 Solitary Nesting

4.1.1.1 Nesting Activity Caletas, Costa de Oro, and San Miguel, and Corozalito had 2381, 430, 537 and 2219 olive ridley nesting events respectively (Table 1). The variation of these numbers partially reflects the duration in which the beaches were monitored. San Miguel and Costa de Oro had the same level of nesting, with an average of 3 events per night. Caletas and Corozalito had much higher levels of nesting, with averages of 9 and 17 events per night, respectively.

Beach Project Caletas Costa de Oro San Miguel Corozalito Days of Monitoring 276 147 167 132

Total Nesting Events 2381 430 537 2219 Successful Nesting 1908 80% 378 88% 458 85% 1931 87%

Protected 502 26% 187 49% 422 92% 1749 91% Poached 299 16% 184 49% 32 7% 70 4% Depredated 949 50% 5 1% 2 0% 93 5% Partially Depredated 158 9% 1 0% 2 0% 19 1%

Unsuccessful Nesting 453 19% 46 11% 76 14% 259 12% False Crawl 154 34% 38 83% 49 64% 173 67% Aborted Nest 299 66% 8 17% 27 36% 86 33%

Unidentified 20 1% 6 1% 3 1% 29 1% Table 1. Numbers of solitary olive ridley nesting events in each nesting category recorded at Caletas, Costa de Oro, San Miguel, and Corozalito during the 2014 monitoring season.

In the past nesting levels have oscillated independently at the three beaches without a uniform trend of nesting level change (Figure 3). However, this year all four


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nesting beaches saw the highest levels of nesting ever recorded. It is difficult to compare nesting levels between seasons because of variations in monitoring durations (Table S1). Generally San Miguel and Corozalito are monitored for the same amount of time, while Caletas is open for a couple extra months and Costa de Oro is open for one less month. Considering these general differences in season lengths, Caletas and San Miguel have had similar nesting levels most years (Figure 3). However 2008, 2009, and this past season were exceptions to this trend when Caletas had much higher nesting levels. The 2014 season nesting level was by far the highest the beach has seen, as there were almost 1000 more nesting events than in 2008, the second-‐highest nesting year at Caletas. Corozalito has always had the highest nesting levels, with 3-‐4 times more than those at the other beaches. Finally, in the three seasons that Costa de Oro has been monitored it has had levels similar to those at San Miguel.

Figure 3. Number of olive ridley nesting events recorded in past monitoring seasons of Caletas (red, square), Costa de Oro (purple, circle), San Miguel (green, triangle), and Corozalito (blue, diamond).

4.1.1.2 Poaching Levels During the 2014 season San Miguel and Corozalito had the lowest portion of nests lost through poaching, with 7% and 4% of nests taken respectively (Table 1). Since the two projects were started, poaching has decreased over the years from 30% in San Miguel and 25% in Corozalito (Figure 4). Conversely, poaching has gradually increased in Caletas where 16% of nests were taken in 2014 compared to 6% in 2003. Since monitoring started in Costa de Oro, it has had the highest level of poaching of the four beaches. This season an alarming 49% of nests were poached at Costa de Oro.

4.1.1.3 Depredation Levels


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Neither San Miguel nor Costa de Oro, both developed beaches, experienced egg loss due to depredation, which is consistent with past seasons (Figure 4). Nest depredation in Corozalito was also low, which is surprising considering the higher levels seen at this beach in past seasons. Conversely, depredation was an enormous problem in Caletas this season, where 50% of nests were completely destroyed by animals (Table 1). Another 9% were partially depredated. The uneaten eggs in these nests were poached (3%), relocated to the hatchery (4%), or left on the beach (2%). This level of depredation is drastically higher than past levels observed in Caletas.

Figure 4. Poaching and depredation levels during past monitoring seasons of Caletas (red, square), Costa de Oro (purple, circle), San Miguel (green, triangle), and Corozalito (blue, diamond).

4.1.1.4 Seasonal Time Distribution For the 2014-‐2015 season nesting levels were highest at the four beaches between August and November (Figure 5). In Caletas and San Miguel, where monitoring started earliest, nesting activity was low for the first couple of weeks of July and then started to increased to peak levels by the first week of August. This was an earlier start to the season than 2013, when nesting levels didn’t peak until September. Nesting decreased at Costa de Oro, San Miguel, and Corozalito for the last three weeks of monitoring in December. In Caletas, where monitoring continued to the end of March 2015, nesting appeared to be decreasing at the end of December. However, it picked up again in January and finally decreased in February. Monitoring in Corozalito didn’t begin until August, at which time nesting levels were already very high. In the middle two weeks of August and first week of September there were very high levels of solitary nesting that didn’t progress to arribada nesting. In later September, October, and November solitary nesting levels were lower because nights of high activity progressed into arribada nesting events. Because precipitation was only recorded at the San Miguel and Caletas projects, the onset of the rainy season can only be compared to that of the nesting season at these


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two beaches (Figure 5). The peak of the nesting season appears to have coincided with the peak of the rainy season on the four beaches. However the nesting season at Caletas extended to long past the rains, which ended in November. There were 2 consecutive weeks of above 100 mm of precipitation by the beginning of August at both Caletas and San Miguel. Precipitation was the highest in October and halted in December. Between July and December there was a total of 2021.08 mm and 1791.77 mm of precipitation at San Miguel and Caletas, respectively. In the previous season precipitation didn’t reach above 100 mm until the end of August. The most precipitation was in September and the total amount was 1380.70.

4.1.1.5 Nightly Time Distribution Olive ridley nesting activity on all four nesting beaches was characterized by unpredictable nightly fluctuations between no nesting, average nesting, and distinct peak activity nights (Figure 6). The activity of the four beaches was not coordinated, and the peak nights of nesting did not align. Caletas’s two peak nesting nights were on September 17th and 23rd, with 56 and 55 nesting events respectively. San Miguel’s peak nesting night was on October 13th with 12 nesting events. Costa de Oro’s peak nesting night was on September 3rd with 13 nesting events. Corozalito had two nights of solitary peak nesting that didn’t progress to arribadas on August 18th and 20th, with 109 and 105 nesting events respectively. There weren’t any obvious correlations between nesting activity and environmental factors such as rain and moon. In San Miguel the peak nights of nesting occurred three days after the heaviest rainstorm of the season (October 8-‐9th). However, in Caletas the biggest rainstorm of the season on October 15th didn’t lead to any change of nesting activity. There was generally less nesting activity in the days surrounding the full moon, which is consistent to results from past seasons. However, this is not a reliable trend, as can be seen especially with the high nesting around the October 8th full moon.


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Figure 5. Number of solitary olive ridley nesting events per week during the 2014-‐2015 nesting season. Number of nesting events graphed on primary y-‐axis (colored, circles.) Precipitation graphed on secondary y-‐axis in grey columns for Caletas (A) and San Miguel (B). Weeks in which there were arribadas in Corozalito (D) are marked as orange, but numbers of arribada nesters are not included in these counts.


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Figure 6. Daily number of nesting activities from August 1st to November 31st, 2014. Number of nesting events graphed on primary y-‐axis (colored, circles.) Precipitation graphed on secondary y-‐axis in grey columns for Caletas (A) and San Miguel (B). Days of full moon are marked with circle-‐topped lines. Days in which there were arribadas in Corozalito (D) are blocked out in grey.


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4.1.2 Arribada Nesting Three arribadas took place over the 2014 nesting season at roughly monthly intervals in September, October, and November (Table 2). The only other year in which more than one arribada was observed was the 2011-‐2012 season. This is the first season in which there have been three consecutive arribadas, and two of these events were the biggest ever observed at Corozalito. The September arribada lasted the longest, but it was more diffused over time, with two nights of over 2000 nests laid, and 5 nights of less than 400 nests. The October event was shorter but more concentrated, with 3 nights of over 4000 nests laid and a couple nights of between 160-‐600 nests each.

Year Duration # Nesting Events

2014 Nov 15 – 17 3300

2014 Oct 18 – 22 12900 2014 Sept 18 – 24 6900 2013 Nov 29 – Dec 1 1300 2012 Nov 10 2000 2012 Jan 5 1000 2011 Sept 24 – 25 5000 2010 Oct 30 120 2009 None -‐ 2008 Sept 26 – 27 300

Table 2. Estimated sizes of arribadas recorded during the monitoring seasons since 2008.

Both solitary and arribada nesting was highest between sector 6 and 8 of the beach (Figure 7). Arribada nesting was concentrated to before sector 11 of the beach, while solitary nesting was more distributed up to the southeastern end.

Figure 7. Corozalito sector distribution of arribada and solitary olive ridley nesting events recorded during the 2014 monitoring season.


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4.1.3 Biometric Data Olive ridley curved carapace measurements and clutch sizes recorded in 2014 were consistent with those of 2013 (Table 3). The data was also constant between the four beaches, with average curved carapace widths of about 64.5 and lengths of about 69 cm. Among the four beaches the CCL’s ranged between 56.2 and 77.0 cm, and the CCW’s ranged between 59.0 and 80.4 cm. In addition, 954 turtles were measured during Corozalito arribadas. These turtles had an average CCL of 64.8 cm and CCW of 68.8 cm, which are almost identical to the average measurements of the solitary nesters measured at this beach.

Season Measurement Caletas Costa de Oro San Miguel Corozalito

2014 No. Measured 296 115 200 815 CCL 64.6 64.6 64.4 64.7 CCW 69.4 69.2 69.1 68.8

2013 No. Measured 144 62 151 486 CCL 65.3 65.6 64.3 64.5 CCW 70.0 71.1 69.1 69.4

Table 3. Average curved carapace lengths (CCL) and widths (CCW) taken of solitary olive ridley nesters at the 4 PRETOMA projects during the 2014 and 2013 monitoring seasons.

The average clutch sizes at the four projects were between 93 and 95 eggs. The smallest clutch was of 10 eggs laid at Caletas. This turtle’s cloaca appeared to be prolapsed. The largest clutches were of 144 eggs, which were laid at both San Miguel and Corozalito.

4.1.4 Tagging Data During the 2014-‐2015 monitoring seasons at Caletas, Costa de Oro, Playa San Miguel, and Corozalito there were 252, 107, 188, and 170 new solitary nesting turtles tagged. Between all four beaches 44 previously tagged turtles were encountered nesting solitarily (Table 4.) Of the 37 turtles tagged and re-‐encountered during the 2014 season, 24 were found on the original beach and 13 were found on different beaches. The turtles that changed beaches switched between the 4 PRETOMA project beaches, Montezuma, Ostional and La Flor. Montezuma is 30 km southeast of Caletas, and Ostional is 50 km northwest of San Miguel. The furthest migration was 160 km northwest between Costa de Oro and La Flor, Nicaragua. The inter-‐nesting interval of the turtles that nested twice during the 2014 season was 23 days. This interval was the same for turtles that nested twice on the same beaches and the turtles that changed beaches. Of the 7 turtles encountered from previous nesting seasons, 4 were seen on the beach where they were originally tagged (Table 4). Three of these turtles were tagged during the previous season, and one during the 2012 season. The other 3 turtles tagged in past years nested on different beaches than they were tagged. The turtle with the oldest tags was tagged 8 years previously in Camaronal.


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Category Tag First Encountered Re-‐Encountered Inter-‐Nesting

Interval Left Right Date Beach Date Beach Same Year, PS652 PS653 Caletas 09/07/14 Caletas 13/08/14 35 Same Beach NY651 NY644 Caletas 03/08/14 Caletas 18/08/14 15 NZ578 NZ579 Caletas 20/11/14 Caletas 12/12/14 22 PS971 PS972 Caletas 11/12/14 Caletas 28/12/14 17 NZ837 NZ838 Caletas 12/12/14 Caletas 03/01/15 22 NZ976 NZ977 Caletas 21/12/14 Caletas 07/02/15 48 NZ886 NZ887 Caletas 12/01/15 Caletas 28/01/15 16 NZ947 NZ948 Caletas 20/01/15 Caletas 11/02/15 22 NO 11581 Caletas 29/01/15 Caletas 03/07/15 37

NY508 NY509 Costa de Oro 13/08/14 Costa de Oro 01/09/14 19

CDO030 CDO031 Costa de Oro 15/09/14 Costa de Oro 21/10/14 36

CDO088 CDO089 Costa de Oro 15/10/14 Costa de Oro 05/11/14 21 NY596 NY597 Costa de Oro 02/11/14 Costa de Oro 20/11/14 18 NY580 NY581 Costa de Oro 05/11/14 Costa de Oro 24/11/14 19 PS152 PS167 San Miguel 06/07/14 San Miguel 03/08/14 28 PS476 PS477 San Miguel 23/07/14 San Miguel 10/08/14 18 NY442 NY443 San Miguel 14/08/14 San Miguel 29/08/14 15 NY486 NO San Miguel 28/08/14 San Miguel 12/09/14 15 NZ449 NZ450 San Miguel 25/09/14 San Miguel 13/10/14 18 SM1427 SM1426 San Miguel 16/10/14 San Miguel 05/11/14 20 NZ647 NZ648 Corozalito 15/08/14 Corozalito 05/09/14 21 NY767 NY768 Corozalito 17/09/14 Corozalito 17/10/14 30 NY837 NY838 Corozalito 02/10/14 Corozalito 17/10/14 15 CZ1212 CZ1213 Corozalito 07/11/14 Corozalito 10/12/14 33 CZ1218 CZ1219 Corozalito 10/11/14 Corozalito 30/11/14 20

Average Inter-‐Nesting Inverval 23 Same Year, NY656 NY657 Caletas 06/08/14 Corozalito 05/09/14 30 Diff. Beach NY647 NY648 Caletas 11/08/14 Corozalito 13/09/14 33 NZ558 NZ559 Caletas 02/11/14 Corozalito 18/11/14 16

PS458 PS459 Costa de Oro 29/07/14 Corozalito 03/08/14 5

CDO004 CDO005 Costa de Oro 02/09/14 San Miguel 19/09/14 17

NY555 NY556 Costa de Oro 06/09/14 San Miguel 26/09/14 20 CDO092 CDO093 Costa de Oro 17/10/14 San Miguel 21/10/14 4 CDO034 CDO035 Costa de Oro 22/09/14 La Flor 23/10/14 31 PS199 PS200 San Miguel 22/07/14 Caletas 09/08/14 18 PS482 PS483 San Miguel 26/07/14 Corozalito 16/08/14 21 NY402 NY403 San Miguel 30/07/14 Caletas 18/08/14 19 PS196 12317 Ostional 13/06/14 San Miguel 18/07/14 35 R515 R516 Montezuma 11/11/14 Caletas 02/12/14 21

Average Inter-‐Nesting Inverval 23 Diff. Year, PS971 PS972 Caletas 04/12/13 Caletas 11/12/14 1 year Same Beach PS903 PS904 Caletas 25/12/13 Caletas 20/01/15 1 year SM816 SM825 San Miguel 07/12/13 San Miguel 24/11/14 1 year CZ1038 NO Corozalito 09/09/12 Corozalito 16/08/14 2 years Diff. Year, NY554 PS079 San Miguel 08/10/13 Costa de Oro 09/05/14 1 year Diff. Beach SM1458 SM1459 Caletas 24/12/12 San Miguel 16/11/14 2 years NP14 NO Camaronal 22/10/06 Corozalito 15/09/14 8 years

Table 4. Previously tagged solitary olive ridley turtles encountered during the 2014-‐2015 monitoring season at Caletas, Costa de Oro, San Miguel, and Corozalito. PS971/972 was listed twice because it was originally tagged last season, and then was seen nesting twice this season.


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During arribadas in Corozalito a total of 48 new turtles were tagged and 29 previously tagged turtles were encountered (Table 5). Nine of these turtles were from ASVO projects and Camaronal, and their original tagging data is unknown. The turtle tagged NY909/910 was seen nesting twice during arribadas with an inter-‐nesting interval of 27 days. All the other turtles were originally tagged while nesting solitarily, and had an average inter-‐nesting interval of 25 days. Of the 17 re-‐observed turtles tagged during the 2014 season, 10 nested both times in Corozalito and 7 changed beaches. Another 3 turtles were tagged in previous years, the oldest having being tagged 6 years earlier in Caletas.

Category Tag First Encountered Re-‐Encountered Inter-‐Nesting

Interval Left Right Date Beach Date Beach Same Year, NZ603 NZ604 Corozalito 03/08/14 Corozaltio 19/09/14 47 Same Beach NZ662 NZ663 Corozalito 18/08/14 Corozaltio 19/09/14 32 NZ676 NZ678 Corozalito 21/08/14 Corozaltio 18/09/14 28 NY705 NY706 Corozalito 29/08/14 Corozaltio 20/09/14 22 NY726 NY727 Corozalito 04/09/14 Corozaltio 20/09/14 16 NY730 NY731 Corozalito 05/09/14 Corozaltio 20/09/14 15 NY823 NY824 Corozalito 29/09/14 Corozaltio 19/10/14 20 NY909 NY910 Corozalito 19/10/14 Corozaltio 15/11/14 27 NY959 NY960 Corozalito 24/10/14 Corozaltio 16/11/14 23 NY994 NY995 Corozalito 30/10/14 Corozaltio 16/11/14 17

Average Inter-‐Nesting Inverval 25 Same Year, NY674 NY675 Caletas 26/08/14 Corozaltio 19/09/14 24 Diff Beach NY687 NY688 Caletas 26/08/14 Corozaltio 20/09/14 25 NZ394 NZ395 Caletas 03/10/14 Corozaltio 21/10/14 18

CDO075 CDO076 Costa de Oro 12/10/14 Corozaltio 16/11/14 35

NY465 NY466 San Miguel 24/08/14 Corozaltio 19/09/14 26 NY415 NY427 San Miguel 17/08/14 Corozaltio 20/09/14 34 436 437 Montezuma 02/09/14 Corozaltio 21/09/14 19

Average Inter-‐Nesting Inverval 26 Diff Year, PS378 NO Corozalito 26/10/13 Corozaltio 19/09/14 1 year Same Beach Diff Year, NY173 NY174 Costa de Oro 20/08/12 Corozaltio 18/09/14 2 years Diff Beach CL321 NO Caletas 10/02/08 Corozaltio 20/09/14 6 years Table 5. Previously tagged olive ridleys seen nesting during 2014 Corozalito arribadas. NY909/NY910 is highlighted because it nested twice during arriabadas.

4.2 Hatchery Success A total of 917 olive ridley nests and 85 333 eggs were protected in PRETOMA beach project hatcheries during the 2014-‐2015 season (Table 6). The Costa de Oro and Caletas hatcheries had the lowest and highest number of protected nests respectively because of the relative amounts of time the hatcheries were active. San Miguel was the most productive hatchery, with the impressive eclosion success of 87%. This is the highest eclosion success of any of the past PRETOMA hatcheries (FigureS1).


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Caletas Costa de Oro San Miguel Nests 465

126

326

Eggs 42252

12088

30993 Eclosed 31081 73% 9297 77% 26949 87%

Released 30525 72% 8731 72% 26462 85% Table 6. The total number olive ridley nests and eggs moved to the project hatcheries during the 2014 monitoring season, and the average number and proportion of the eggs that eclosed and were released.

Costa de Oro had the biggest difference between eclosed and released hatchlings released because of dogs that managed to break into the hatchery and eat 464 hatchlings. In Caletas and San Miguel the hatchlings were mostly lost to raccoon depredation. At all three hatcheries the highest proportion of un-‐hatched eggs showed no evidence of development (Table S3). There were also large proportions of un-‐hatched eggs from the Caletas and Costa de Oro hatcheries showing the first and last stages of development. The following sections present each hatchery separately, to analyze whether there were variations within the season and between sections of the hatcheries.

4.2.1 Caletas The eclosion success of the nests relocated to the Caletas hatchery during the 2014 monitoring season was 73%, a 4% increase from the 2013 season. Lack of shading in the back section of the hatchery was a major factor that brought down the success rate. When the hatchery was built in the beginning of the season a mesh roof was applied over the front part of the hatchery, but the back section was left open. The eclosion success of the front area was high throughout the season. On the other hand, the first two rounds of nests relocated to the back un-‐shaded area had very low success rates of 24% and 48% consecutively (Table 7).

Round Front Back

Start Duration Eclosion Start Duration Eclosion 1 29/06/14 47 82% 17/07/14 45 24% 2 28/07/14 49 88% 07/08/14 46 48% 3 31/08/14 55 76% 25/09/14 53 86% 4 09/10/15 54 86% 10/11/15 48 79% 5 18/12/14 49 78% 18/01/15 47 73%

Table 7. Average Eclosion success and days of incubation for each round of nests relocated to the front and back sections of the Caletas hatchery during the 2014 season. The start date is the date the first nest of each round was relocated to the hatchery.

Roofing was added to the back side of the hatchery on September 23rd when these results were discovered. The next two rounds of nests relocated to the back part of the hatchery after it was shaded had success rates of 86% and 79%. If the two unshaded rounds of nests weren’t considered, the overall hatchery eclosion success was 82%. The eclosion success decreased for the last round of nests, which were


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relocated to the hatchery in the last three months of the project when there was almost no rain and the sand became very dry.

4.2.2 Costa de Oro The eclosion success of the Costa de Oro hatchery was 77% for the 2014 season, a 9% decrease from the previous season. Two nests poached from the hatchery accounted for 1% of the decrease. The biggest factor that accounted for the low hatching rate was the poor success of the first round of nests relocated to the hatchery (Table 8). A mesh roof was applied to the hatchery on October 8th once these results were discovered. By this time the second round of nests were almost through incubation. Despite lack of shading second round nests had a better eclosion rate, probably because of the increase of precipitation during this time. The last two rounds of nests, which were relocated to the hatchery after the roof was applied, had greatly improved average eclosion rates of 85% and 86% consecutively. The duration of incubation increased drastically for the nests that were relocate to the hatchery after the roof was applied.

Round Start Duration Eclosion 1 25/07/14 47 59% 2 21/08/14 49 78% 3 17/09/14 57 85% 4 10/10/14 56 86%

Table 8. Average eclosion success rate and days of incubation for each round of nests relocated to the Costa de Oro hatchery during the 2014 season. The start date is the date the first nest of each round was relocated to the hatchery.

4.2.3 San Miguel Since the eclosion success of the San Miguel hatchery was high throughout the season, no mesh roofing was applied (Table 9). Unlike past seasons when particular sections of the hatchery were more productive than others, this season hatching success varied between sections equally. The average incubation duration for the four rounds of nests were 47, 48, 52, and 49 days consecutively.

Round Start All Front Middle Back

1 04/07/14 88% 86% 88% 91%

2 14/08/14 89% 84% 91% 90% 3 09/09/14 85% 90% 83% 82%

4 11/10/14 86% 90% 84% 84% Table 9. Average eclosion success for each round of nests relocated to the San Miguel hatchery during the 2014 season. The start date is the date the first nest of each round was relocated to the hatchery.


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4.3 Corozalito In Situ Nest Success A total of 134 solitary olive ridley nests were triangulated in Corozalito during the 2014 season. Only 5 of these nests were depredated and one was poached. Forty of the marked nests were encountered and excavated, and 69 were not encountered. Another 18 could not be excavated because there were new nests on top of where the old nests were positioned. Of the 40 marked nests excavated, 26 had more than 10 extra or missing eggs, so a proper success rate couldn’t be calculated. The 14 excavated nests with less than 10 extra or missing eggs had a success rate of 87%.

4.4 Green Turtle Nesting During the 2014 monitoring season 29 green turtle emergences were recorded at the four nesting beaches, of which 12 resulted in successful nesting events. There were 8, 6, 4, 11 events recorded at Caletas, Costa de Oro, San Miguel, and Corozalito respectively. Most of these events occurred between September and November. Three individual turtles were seen re-‐nesting. CDO055/056 was seen 6 times, and nested twice in both San Miguel and Costa de Oro. SM1404/1405 was seen 4 times and nested once in both San Miguel and Corozalito. Finally, NY771/772 was seen nesting 3 times in Corozalito. Five nests were protected in project hatcheries: 1 in Caletas, 2 in Costa de Oro, and 2 in San Miguel. The average eclosion success of these nests was 83%, and a total of 204 green hatchlings were released. One of the nests in Corozalito was excavated and found to have a success rate of 89%.

4.5 Leatherback Nesting Three leatherback nesting events were recorded this season. One event was a false crawl in San Miguel, in which the turtle was not seen. Two turtles successfully nested at San Miguel and Corozalito, on October 1st and November 24th respectively. Neither of these turtles were previously tagged. The Corozalito leatherback measured 149.0 cm CCL and 108.0 cm CCW. Of the 69 eggs that she laid, only 4 hatched and 2 made it to the ocean. The San Miguel leatherback measured 140.0 cm CCL and 96.0 cm CCW, and laid 34 regular eggs and 41 yolkless eggs. The nest was relocated to a safe section of the beach, but since it occurred late in the season it wasn’t excavated and the eclosion success wasn’t determined. This season there were no leatherback nesting events in Caletas (Table S3). In the first five seasons that Caletas was monitored, there were over 15 nesting events each season. Since then leatherback activity has decreased gradually, and there haven’t been any leatherback turtles seen on the beach in the last three seasons.


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4.6 Dead Turtle Data A total of 18 turtles were stranded on the project beaches during the 2014 season, which is a decrease from 39 turtles stranded in the 2013 season. There were 1, 7, 8, and 2 olive turtles found on the beaches of Caletas, Costa de Oro, San Miguel, and Corozalito, respectively. All of these turtles were dead when they washed up on shore. Of the turtles that were fresh enough to determine their sex, 8 were male and 5 were female.

4.7 Temperature Data

4.7.1 Caletas Dataloggers were used to measure the temperatures of seven nests in the Caletas hatchery (Figure 8). The first three nests were relocated to the hatchery between July and September. The first nest (CLN1) was relocated to the shaded front section, had an average incubation temperature (AIT) of 30.992°C, and an eclosion success of 96%. The second two nests (CLN2 and CLN3) were relocated to the back section of the hatchery before a roof was applied to this section. The lack of shade made a large difference in temperatures, as both nests’ AIT’s were at least 3°C higher than CLN1. Although the two nests had almost the same AIT, CLN3 had a much higher eclosion success than CLN2 (75% versus 14%). This could be because CLN2 spent more time above the fatal nest temperature of 35°C during early incubation stages, while CLN3 only reached above this level during the third trimester. Between September and November the fourth and fifth dataloggers were placed in the front and back sections of the hatchery respectively. By this time there was a roof over the back section of the hatchery, so both nests were shaded throughout incubation. The two nests appear to have had ideal conditions, as their eclosion rates were 94% and 95%. Their AIT’s were 29.608°C and 30.408°C, and their temperatures never approached fatal levels. Between December and February the sixth and seventh dataloggers were placed in the front and back sections of the hatchery respectively. Since there was only rain one day during this time period, nest temperatures were constant and gradually increased. The two nests had eclosion rates above 80% and AIT’s of about 32°C. Neither nest crossed fatal temperatures, but CLN6 approached 35°C during the final trimester, which could account for its lower eclosion success. Throughout the season the nests with shading had AIT’s near pivotal temperatures during the second trimesters, and likely developed both females and males. The two nests that didn’t receive shading had AIT’s above 33°C during the second trimesters, and only females would have developed in those clutches.


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Figure 8. Caletas hatchery temperatures from inside nests relocated in the early (B), middle (C) and late (D) monitoring season. Red horizontal lines at 35°C and 26°C represent upper and lower lethal nest temperatures. (A) Table displays the sections of the hatchery the nests were in, the date they were relocated to the hatchery, the eclosion success rates, and the average incubation temperatures (AIT). The average incubation temperatures for the first, second and third trimesters are also shown (labeled AIT T1, AIT T2 and AIT T3 respectively).


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4.7.2 Costa de Oro The temperatures of four nests were measured in the Costa de Oro hatchery (Figure 9). Because the first two nests (CDON1 and CDON2) were relocated to the hatchery when it wasn’t shaded, both nests had temperatures reaching fatal levels throughout incubation. The two nests’ AIT’s were 34.228°C and 32.497°C, consecutively. There was more rainfall during CDON2’s incubation period, which likely accounts for its lower AIT and higher eclosion success (32% versus 74%). A roof was applied to the Costa de Oro hatchery on October 8th, two weeks into the incubation period of the third nest (CDON3). The roof was applied just before the largest rainstorm of the season, which brought nest temperatures down by 6°C. Since the roof’s shading kept temperatures down after the storm, CDON3’s AIT was 3°C lower than the first two nests, at 30.560°C. Its success rate was also much higher, at 86%. The fourth nest (CDON4) was relocated to the hatchery after the roof was applied. It’s temperatures were low throughout incubation, and its AIT was 28.555°C. CDON4 had the highest eclosion success of the four nests, at 89%. The average incubation temperatures during the second trimesters varied drastically between the four nests. Those of CDON1 and CDON2 were above 32°C and likely produced all female hatchlings, whereas CDON4 was about 28°C and likely produced all male hatchlings. CDON3 was closer to pivotal temperature and could have produced sexes.

4.7.3 San Miguel Dataloggers were placed in six nests relocated to the San Miguel hatchery (Figure 10). As there wasn’t a roof applied to the hatchery, temperatures depended on rainfall and shade from trees surrounding the hatchery. The first two nests were exposed to the least rainfall and had AIT’s over 33°C. The third nest (SMN3) was exposed to more rain and had a lower AIT of 32.639°C. The fourth nest had a similar AIT to SMN3 because it was in its final week of incubation when the largest rainstorm of the season occurred on October 9th. On the other hand, the rainstorm occurred earlier in the incubation of the last couple of nests. These two nests had lower AIT’s of 30.515°C and 31.325, consecutively. Despite the AIT’s of the first two nests being quite high, eclosion success was high for all the nests recorded. Although the high nest temperatures didn’t cause mortality, they likely skewed sex ratios towards a female bias. Four of the six nests had average incubation temperatures over 32°C during the second trimester of incubation, and likely produced all females. The last two nests recorded were closer to pivotal temperature during the second trimester, and likely produced both sexes.


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Figure 9. Costa de Oro hatchery temperatures from inside nests relocated in the early (B), late (C) monitoring season. Red horizontal lines at 35°C and 26°C represent upper and lower lethal nest temperatures. (A) Table displays the date the nests were relocated to the hatchery, the eclosion success rates, and the average incubation temperatures (AIT). The average incubation temperatures for the first, second and third trimesters are also shown (labeled AIT T1, AIT T2 and AIT T3 respectively).


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Figure 10. San Miguel hatchery temperatures from inside nests relocated in the early (B) and late (C) monitoring season. Red horizontal lines at 35°C and 26°C represent upper and lower lethal nest temperatures. (A) Table displays the sections of the hatchery the nests were in, the date they were relocated to the hatchery, the eclosion success rates, and the average incubation temperatures (AIT). The average incubation temperatures for the first, second and third trimesters are also shown (labeled AIT T1, AIT T2 and AIT T3 respectively).


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5. Discussion When interpreting the results from these sea turtle conservation beach projects, one of the most important factors to consider is that every year the work is conducted by different voluntary participants. Efforts are made to keep protocols constant through training and supervision, but resources are limited and the accuracy of the work in part depends on the integrity of the participants. In the following discussion the implications of the results will be presented, while considering how human error could affect them.

5.1 Solitary Olive Ridley Nesting Activity The fluctuations of nesting activity seen by the four beaches every year are partially due to changes in monitoring durations and methods. There are a couple key changes in monitoring duration that could have accounted for years of lower nesting levels recorded (Figure 3). First, the Caletas seasons from 2009 to 2013 included patrol data for one month less than other years. Second, in 2008 both Corozalito and San Miguel beaches were patrolled for shorter periods than usual. Conducting morning censuses is a part of the patrolling method that is crucial in accurately recording the number of nesting events each season. If morning censuses are neglected tracks that are missed during night patrols or events that occur after patrols won’t be recorded. Examples of known seasons when project coordinators were vigilant in conducting morning censuses, which could have contributed to increases in recorded nesting activity include Caletas 2008, 2009 and 2014; and Corozalito 2013 and 2014. On the other hand, during the Caletas 2013 season morning censuses were neglected, which contributed to lower recorded nesting activity. In addition to the factors considered above, annual variations in recorded nesting events reflect natural fluctuations in nesting activity. In the past activity has oscillated differently at each beach, not indicating any clear, universal trends for the nesting population. This year however nesting at all four projects increased to record-‐breaking levels. This is a promising sign for the eastern Pacific olive ridley nesting population. Such a sign could indicate that conservation efforts over the last couple decades by PRETOMA and other organizations on the Pacific coast of Costa Rica are having positive effects. Olive ridley turtles take an estimated 13 years to reach maturity (Zug et al. 2006), so enough time has passed for hatchlings released in the early seasons at the San Miguel and Caletas projects to have started reproducing. However, if the increase in nesting were due to a new, younger cohort it would be expected that the carapace measurements would be smaller than recent years. This was not the case, as the


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average ACC and LCC’s were almost identical between the last two seasons (Table 3). It is possible that this is just a higher year of nesting due to optimal ocean conditions, and doesn’t reflect a change in population size.

5.2 Poaching and Depredation For the last four seasons in San Miguel poaching has declined, and this year’s poaching level was the lowest ever recorded at the beach (Figure 4). In the 17 years that PRETOMA has been protecting San Miguel, the organization has tried to end the tradition of egg poaching through creating positive relationships with the community and conducting environmental education activities in the school. This has been a challenging and delicate process, as was seen in 2011, when poaching spiked because of a conflict between PRETOMA and local poachers. However there has been a gradual shift over the years in the community’s attitude towards poaching, and most of the local families have stopped the practice. Although poaching persists, and nests still have to be moved to a hatchery for protection, this change in attitude has contributed to the decrease in poaching at San Miguel. Hopefully this model of long-‐term beach protection combined with community education can be applied to Costa de Oro, which has a similar community dynamic and geography. So far it has been challenging to protect this beach, as poaching has remained at the alarming level of 50% for the three seasons it has been monitored. A similar tactic has been used in Corozalito and although it’s been successful in changing local community actions, poaching has persisted by people from other nearby towns. This year the Corozalito community helped PRETOMA convince the police to start visiting the beach weekly. The police presence created an evident change in the poachers’ confidence, and there was a large decrease in poaching this season. Corozalito is an easy beach for police to monitor because there is only one public-‐access road and the beach is very small. Efforts by the local police to perform these simple patrols at the other projects have been less effective because the beaches are much longer and poachers can easily avoid officers. As Caletas is located on a wildlife refuge, it doesn’t have a community. In the past the lack of human presence at the beach was beneficial, and Caletas consistently had the lowest poaching rate of the PRETOMA projects. However, poaching has gradually increased, likely because the populations of two of the closest in-‐land towns, San Francisco de Coyote and Quebranando, have grown. There have been some environmental education efforts at the schools in Coyote, but since these communities aren’t on the beach, it is harder to develop a sense of ownership of the fate of Caletas wildlife. In addition, police are hesitant to visit the beach because it is so remote. Since Caletas is part of a national wildlife refuge, there should be a park-‐ranger presence on the beach, and this help will be essential if poaching continues to grow.


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The level of depredation in Caletas this year was shocking. Over half of the nests laid on the beach were eaten, and most of this destruction was due to raccoons. Both the high level of depredation and population size of raccoons have never been observed in Caletas. Before 2010 the harmful pesticides from the rice agriculture in the wetlands behind Caletas probably kept the raccoon population at bay. It appears that since these harmful practices have stopped, the raccoon population has rebounded to uncontrolled numbers. Perhaps populations of top-‐predators such as coyotes have not had the time to recover and in future years a more sustainable balance will be reached in the ecosystem. In contrast, Corozalito saw a drastic drop in depredation from 28% last season to 6% in 2014. This could be due to the type of depredation taking place. In-‐situ nests are monitored for depredation the day after they are laid because in the past mostly fresh nests were targeted by predators. However, this year Corozalito team members observed a shift towards depredation occurring to hatching nests. Perhaps the increase in the volume of nests laid on the beach, and therefore the nests hatching on the beach, created this change in predator strategy. In future seasons, a method for monitoring the level of depredated hatching nests should be instigated. Another source of change in the recorded number of depredated nests could be human error in data collection. In order to record in-‐situ nest depredation, nests located on night patrols must be checked the following day. If morning censuses are not conducted, or participants fail to locate the nests, nests will be incorrectly categorized as protected. Human error due to failure to identify poached and depredated nests mostly applies to Corozalito data, where all nests are left in situ. However, this could have occurred at the other projects when nests were left in situ because the hatcheries weren’t available.

5.3 Temporal Distribution of Solitary Olive Ridley Nesting In San Miguel and Caletas, where monitoring started earliest, the 2014 nesting season started about a month earlier than the 2013 season. This season nesting levels were at peak levels by August, whereas last season they didn’t peak until September. This year there were also higher levels of precipitation earlier, which possibly triggered earlier nesting. As precipitation levels have only been measured at the projects for 2 years, there is not enough data to study whether nesting season shifts with the rainy season. In future season this possibility should be further examined. Caletas was monitored until the end of March, and nesting levels remained high until the end of February. At Costa de Oro, San Miguel, and Corozalito the nesting season appeared to be ending when the projects closed in December. However, it is possible that the nesting at these projects increased again in January as it did in Caletas. Unfortunately it isn’t possible to continue monitoring Costa de Oro, San


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Miguel, and Corozalito past December because costs of running the projects are unsustainable during the busy tourist season. It is unknown whether there are certain environmental cues that initiate solitary olive ridley nesting; or if individuals simply nest when intrinsic cues signal that eggs are developed, fertilized, and ready to be released. Although daily nesting levels appear to fluctuate randomly, nesting seasons are characterized by distinct peak nights. It is believed that synchronous arribada events are regulated by extrinsic cues (Bernardo et al. 2007), and it is possible that these cues also initiate peak nights of solitary nesting. Peak nights were not synchronous between the four beaches, which indicates that potential cues would be present in the local environment. It has been suggested that when estuaries at nesting beaches flush into the ocean during the rainy season, olive ridleys time arribadas by using olfaction to sense signals from changing water nutrients (Robinson 1987). The four PRETOMA beaches are close in proximity and normally get the same levels of precipitation annually, but storms in the area can be highly concentrated, and daily precipitation varies drastically between them (Figure 6). In 2013 data indicated that there might be a relationship between peak days of rain and nesting. However, this season there wasn’t any relationship between the two. Therefore, it appears that nesting is stimulated by intrinsic, rather than extrinsic, factors.

5.4 Corozalito Arribada Nesting Three arribadas were occurred at Corozalito during the 2014 nesting season. This was the first year that more than 2 arribadas have been observed during a nesting season at this beach. The arribadas were spaced at intervals of about a month apart. Although the estimates of these arrribadas are not precise, and could contain a scientific error of ±1000 turtles, it is clear that the September and October arribadas were the biggest recorded in Corozalito’s history. The increase in number per season and size of Corozalito arribadas indicates that the beach is growing as an arribada nesting beach. The creation of an arribada nesting beach is a rare phenomenon and hasn’t been well studied before. PRETOMA will have to continue monitoring the beach to see if this trend continues. Because of the unpredictable nature of the mini-‐arribadas, and inadequate project personnel, it has been hard to prepare an affective survey method to accurately estimate the size of these events in past seasons. Data from before the 2013 season is very limited, as the only information gathered were the dates and a rough estimate of size, without any raw data (Table 2). In the last two seasons PRETOMA has been dedicated to improving the arribada protocol and collecting additional useful data. By conducting counts at a fixed interval at every sector, the estimates calculated for the sizes of the arribadas this season were more accurate than past years.


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As this season’s arribadas were much larger than past years, there were new difficulties with the survey protocol. The more turtles there were in each sector, the more time consuming it was to count all the nesting females. It was found that at least three people were required during peak hours to conduct the counts within the two hour time-‐frame. An aspect of the patrols that was time consuming was finding each sector marker. Next season reflective tape should be added to the posts to make them easier to find with red light at night. If arribadas continue to grow in future years, PRETOMA may have to sample random transects of nesting activity, rather than every sector of the beach. The last couple of seasons of conducting counts in each sector have revealed more concentrated nesting during the arribadas than solitary nesting. This result could be caused by the difference in methods of recording the two different types of nesting behaviors. For solitary nesters every single event is recorded, whereas during arribadas only egg-‐laying females are counted every couple of hours.

5.5 Tagging Study Past studies of the eastern pacific population have found that solitary olive ridley nesters have a shorter oviposit cycle, with individuals nesting every 14 days (Kalb 1999). However, more recent studies on Central African Atlantic and western Atlantic solitary nesting populations have found longer inter-‐nesting periods of 17.5 and 22.4 days, respectively (Maxwell et al. 2011 and Matos et al. 2012). The 23 day inter-‐nesting interval found at the PRETOMA projects during the 2014 season supports the longer periods found in the latter studies. A third of the re-‐observed turtles switched nesting beaches, confirming past findings that solitary olive ridleys have low site fidelity. Although the majority of the turtles remained within the 20.5 km stretch of coast that PRETOMA monitors, a few turtles travelled as far as Ostional and La Flor, Nicaragua. As turtle activity isn’t monitored at the majority of beaches on the Pacific coast of Costa Rica, it is likely that there are many unrecorded cases of turtles tagged by PRETOMA nesting on other beaches. This was the first season that PRETOMA checked turtles for tags during arribada events and the results were fascinating: 19 turtles were encountered during arribada events that had originally been tagged while nesting solitarily. A prominent theory among scientists is that olive ridleys either nest strictly solitarily or in arribadas, and arribada nesting turtles are believed to have higher nest fidelity and longer oviposit cycles than solitary nesters (Bernardo et al. 2007). However, these results show that olive ridleys can switch between mass-‐nesting and solitary-‐nesting phenotypes within one nesting season.


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Perhaps olive ridleys displaying both nesting phenotypes are unique to Corozalito “mini-‐arribadas”, which are smaller and less frequent than the events at the well-‐studied arribada beaches Ostional and Nancite. It could be that if Corozalito arribadas become more frequent in future years, these turtles will switch to only nesting in these events. For instance, one turtle was observed nesting in two of the 2014 Corozalito arribadas. This is the first year that this behaviour has been possible, as it was the first season that there have been 2 arribadas a month apart. On the other hand, it could be that olive ridleys are capable of using both nesting strategies throughout their reproductive life cycle. More turtles should be tagged in future Corozalito arribadas to shed light on the proportion of turtles that are nesting repeatedly in arribadas, as opposed to those that are switching between solitary and arribada nesting. The olive ridleys tagged at the PRETOMA projects have a very low re-‐observation rate. Of the 627 turtles tagged solitarily on the four nesting beaches during the 2014 season, 5.5% were re-‐observed nesting solitarily and 2.4% were seen nesting during the Corozalito arribada. Also, of the 4187 olive ridleys tagged in the 8 past seasons at PRETOMA projects, only 10 were re-‐encountered this season. Of these turtles the 2 oldest were from 6 and 8 years earlier. There are several potential reasons why such a low number of tagged turtles are re-‐encountered. First, as discussed previously, it is likely that the turtles are re-‐nesting at other un-‐monitored beaches. Second, the turtles could be dying in fisheries by-‐catch. Tens of thousands of olive ridleys are estimated to die off the coast of Costa Rica every year from large-‐scale shrimp trawling and long line fisheries, and small-‐scale gill-‐net fisheries (Frazier et al. 2007). Finally, the tags could be falling off. This year the tagging method was changed to applying tags to the scales, rather than the skin between the scales, in hope that tag retention would increase. Although there wasn’t a significant increase in re-‐observation rate from last year’s 3.6%, this change could make a difference in the longer term.

5.6 Hatchery Temperature and Success With the nests protected during the 2014-‐2015 season, PRETOMA has protected a total of 8417 olive ridley nests and 772 699 eggs since it began its beach conservation projects. Maintaining productive hatcheries is challenging, and requires a balance of several factors such as keeping the sand clean, deciding when shading needs to be applied, choosing an area that won’t flood, and keeping animals out. This year PRETOMA had its most productive hatchery in history, with San Miguel’s exceptional eclosion rate of 87%. One factor that could have contributed to the increase in success from last season was that the sand was replaced before the season started. However, clean sand can’t explain the difference between the hatcheries of the three projects, as the sand has been replaced in all of them in the


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last couple of seasons. An important factor that contributed to the eclosion success was natural shading. Unlike the other two hatcheries, the San Miguel hatchery has some surrounding palm trees that provided enough shade to kept the temperatures just below lethal levels. The Costa de Oro hatchery was built in a new location this year. An appropriate area was chosen, as there weren’t any problems with flooding like those encountered during the 2012 season. However, there were low eclosion rates in the beginning of the season due to high sand temperatures. Unfortunately, just when roofing was applied to the hatchery Costa de Oro had the biggest rainstorm of the season, and nest temperatures decreased drastically. Average incubation temperatures after this point were the lowest found at the projects and the incubation durations were the longest. In future seasons alternative shading methods should be tested, such as applying roofing at the beginning of the season and removing it when the strong rainstorms begin. Maintaining a productive hatchery in Caletas over the years has been challenging, and eclosion has consistently been lower than at San Miguel. In the 2013 season a brand new hatchery was built on the other side of camp to see if the problem was bacterial contamination in the sand. Unfortunately the success rate remained low in the new hatchery. Experimentation with shading has proved more successful. Over the last couple of season it was found that shading the hatchery brought sand temperatures down to better incubation conditions. The sand at Caletas is much darker than at the other two beaches. This could explain why shading brought nest temperatures just below fatal temperatures in Caletas, when it brought nest temperatures in Costa de Oro too low. In future years PRETOMA plans to shade the entire Caletas hatchery for the whole length of the season. In addition to nest mortality, sex ratio development should be considered when managing hatcheries. In the beginning of the season in both San Miguel and Costa de Oro nest temperatures were high above pivotal temperatures during the second trimester and mostly females were likely produced. On the other hand, after the shading was applied to Costa de Oro, the nest temperatures dropped to the other extreme, and mostly males were likely produced. This is a good example of why manipulation of hatchery conditions should be done with caution. Nest temperatures were closer to pivotal temperatures in Caletas, where shading was applied, and in San Miguel, later in the rainy season.

5.7 Corozalito In Situ Nest Success A result of the incredible number of nests laid at Corozalito over the 3 arribadas was the large proportion of previously laid nests dug up by nesting females. Corozalito is a very short beach, under a kilometer long, and there isn’t enough space for tens of thousands of nests. It is difficult to quantify how many nests were destroyed in this matter, but the in-‐situ nest excavations performed shed some light on the situation.


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Of the 134 nests triangulated throughout the season, only 30% were located, and 60% of the nests located had more than 10 extra or missing eggs. Nest destruction by later-‐nesting turtles makes it very difficult to estimate nest success at Corozalito. However, the high success rate found in the excavated nests, and the high number of hatchlings observed emerging on the beach indicates that the beach is still productive.

5.8 Greens and Leatherback Nesting Southern Nicoyan Peninsula beaches get occasional nesting by green, leatherback, and hawksbill sea turtle, but this accounts for less than 1% of the activity at the beaches. Nonetheless, this small portion of nesting is relevant because of the endangered statuses of these populations. There are important green turtle nesting sites in northern Costa Rica, such as Isla San Jose, which gets over 700 nests per year (Fonseca et al. 2013). Perhaps the greens visiting the PRETOMA beaches are stragglers from this nesting population. In future seasons of the project it would be useful to collect tissue samples from the greens so that DNA analysis could be done. This was the third consecutive year that no leatherbacks have visited Caletas. The two events in San Miguel and Corozalito indicate that although there are still some leatherbacks remaining in the eastern Pacific population, it doesn’t seem likely that there is enough nesting in this area of Costa Rica to maintain the population.

6. Conclusions This season there were record-‐breaking levels of nesting at all four nesting beaches. Long-‐term nest protection, in addition to community environmental education, has been effective in reducing poaching levels in San Miguel and Corozalito. However, poaching is increasing at Caletas, where there is no beach community, and high in Costa de Oro, where the project is new. In addition, a weekly police presence was affective in decreasing poaching at Corozalito. The raccoon population has increased dramatically in Caletas, and depredation will be the primary threat at this beach unless the population is controlled. Nightly solitary olive ridley nesting wasn’t synchronous between the four nesting beaches, and did not appear to correlate with peak rainstorms. There were 3 Corozalito mini-‐arribadas. The increase in frequency and size of these events indicates that Corozalito could be growing as a mass-‐nesting beach.


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The average inter-‐nesting period for the 44 re-‐encountered solitary nesting olive ridley turtles was 23 days. These turtles showed low site fidelity, with only 8% of those tagged this season re-‐encountered and one third switching nesting beaches. Tagged turtles encountered nesting in the Corozalito arribadas had been nesting solitarily when originally tagged, demonstrating that olive ridleys can display both nesting phenotypes. These turtles have an interesting interval of 25 days. Shading from surrounding palms, lighter sand composition, and replaced sand contributed to the high eclosion success at the San Miguel hatchery. Although high temperatures didn’t cause mortality, sex ratio was likely skewed heavily to a female bias. Artificial hatchery shading is required in Caletas season-‐long for appropriate incubation temperatures and successful eclosion rates. Costa de Oro nest temperatures are too high without artificial shading at the beginning of the season, but shading applied during the strongest rains of the season brought the nest temperatures too low.

7. Recommendations Increase research assistant and volunteer participation at Caletas so that more nests can be protected from raccoon depredation. If problems persist with the population size of raccoons, investigate possibilities of control. Record depredation of end-‐of-‐term nests at Corozalito to see if depredation has shifted from newly hatched nests. Install a park ranger at the Caletas-‐Ario Wildlife Refuge to enforce poaching laws. Present high poaching numbers of Costa de Oro to local police and try to arrange regular night patrols to this beach. Continue these patrols at Corozalito. Expand environmental education programs at all project beach communities, including San Francisco de Coyote and Quebrenando. Continue precipitation measurements and Caletas and San Miguel. Apply shading to the entire Caletas hatchery for the length of the season. Experiment with applying shading to the Costa de Oro hatchery at the beginning of the season and removing it when strong rains begin. Continue checking for tagged turtles during arribadas and tag more arribada nesters.


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8. References Bernardo, J. and Plotkin, P.T. 2007. An evolutionary perspective on the Arribada phenomenon and

reproductive behavioral polymorphism of olive ridley sea turtles (Lepidochelys olivacea). In: P.T. Plotkin (ed.), Biology and Conservation of Ridley Sea Turtles. Johns Hopkins University Press, Baltimore, MD.

Fish, M.R., A. Lombana and C. Drews. 2009. Climate change and marine turtles in the Wider

Caribbean: regional climate projections. WWF report, San José, 20 pp. Frazier, J., Randall, A., Chevalier, J., Formia, A., Fretey, J., Godfreay, M., Marquez, R., Pandav, B., and

Shanker, K. 2007. Human-‐Turtle Interactions at Sea. In: P.T. Plotkin (ed.), Biology and Conservation of Ridley Sea Turtles. Johns Hopkins University Press, Baltimore, MD.

Fonseca, A. and C. Drews. 2009. Rising sea level due to climate change at Playa Grande, Las Baulas

National Park, Costa Rica: inundation simulation based on a high resolution, digital elevation model and implications for park management. WWF / Stereocarto Report, San José, pp. 20.

Fonseca, L., Quirós, W., Villachica, W., Mora, Jairo., Heidemeyer, M. y Valverde, R. (2013). Anidación de

tortuga verde (Chelonia mydas) del Pacífico, en la Isla San José, Área de Conservación Guanacaste, Costa Rica (Temporada 2012-‐2013). Unpublished.

IUCN 2014. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>.

Downloaded on 13 April 2015. Kalb HJ (1999) Behavior and physiology of solitary and arribada nesting olive ridley sea turtles

(Lepidochelys olivacea) during the internesting period. Dissertation, Texas A&M University McCoy CJ, Vogt RC, Censky EJ (1983) Temperature-‐controlled sex determination in the sea turtle

Lepidochelys olivacea. J Herpetol 17:404–406 Matos, L., Silva, A., Castilhos, J., Weber, M., Soares, L., Vicente, L. 2012. Strong site fidelity and longer

internesting interval for solitary nesting olive ridley sea turtles in Brazil. Marine Biology (Impact Factor: 2.47). 159(5). DOI:10.1007/s00227-‐012-‐1881-‐1

Maxwell SM, Breed GA, Nickel BA, Makanga-‐Bahouna J, Pemo-‐Makaya E, et al. (2011) Using satellite

tracking to optimize protection of long-‐lives marine species: olive ridley sea turtle conservation in Central Africa. PLoS ONE 6(5):e19905. DOI:10.1371/journal.pone.0019905

Robinson, D. 1987. Two hypotheses on arribada behavior. In Serino, J.L. (Compiler). Seventh Annual

Workshop on Sea Turlte Biology and Conservation. Unpublished proceedings, p.19 Valverde, R.A. and Gates, C.E. (1999). Population surveys on mass nesting beaches. In: Eckert, K., K.

Bjorndal, A. Abreu and M. Donnelly (eds.). Research and Management Techniques for the Conservation of Sea Turtles. IUCN/SSC Marine Turtle Specialist Group. Pub. No. 4, pp. 56-‐60

Wibbels T, Rostal DC, Byles R (1998) High pivotal temperature in the sex determination of the olive

ridley sea turtle from Playa Nancite, Costa Rica. Copeia 1998: 1086–1088 Zug, G.R., Chaloupka, M. and Balazs, G.H. 2006. Age and growth in olive ridley sea turtles

(Lepidochelys olivacea) from the North-‐central Pacific: a skeletochronological analysis. Marine Ecology 27: 263-‐270.


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9. Supplementary Material

Year Study Duration Total

Events Successful Un-‐

successful Start End Days Total Protected Poached Predated

CALETA

S

2014 27/6/14 25/2/15 243 2381 1921 26% 16% 59% 436 2013 01/7/13 28/2/14 242 525 431 73% 15% 12% 92 2012 15/7/12 28/2/13 228 906 730 63% 24% 13% 175 2011 11/7/11 15/2/12 219 690 510 61% 9% 30% 180 2010 15/7/10 15/2/11 215 664 555 81% 8% 11% 109 2009 07/7/09 28/2/10 236 1179 918 87% 5% 9% 261 2008 02/7/08 18/3/09 259 1547 1221 85% 7% 7% 344 2007 01/7/07 31/3/08 274 957 645 89% 5% 6% 208 2006 01/7/06 31/3/07 273 977 697 91% 4% 5% 279 2005 01/7/05 31/3/06 273 1007 752 87% 3% 10% 255 2004 07/7/04 26/3/05 262 784 625 89% 4% 7% 157 2003 15/7/03 15/4/04 275 447 359 69% 6% 25% 88

CDO 2014 12/7/14 06/12/14 147 430 378 49% 49% 1% 46

2013 15/7/13 30/11/13 138 264 228 49% 50% 1% 34 2012 05/8/12 01/12/12 118 264 227 56% 42% 2% 37

SAN M

IGUEL

2014 01/7/14 15/12/14 167 537 458 92% 7% 0% 76 2013 01/7/13 12/12/13 164 336 292 90% 10% 0% 43 2012 14/7/12 13/12/12 152 354 305 87% 13% 0% 46 2011 15/7/11 15/12/11 153 407 329 82% 17% 0% 78 2010 15/7/10 15/12/10 153 509 395 75% 25% 1% 114 2009 16/7/09 19/12/09 156 215 182 80% 17% 3% 33 2008 08/7/08 24/11/08 139 180 165 89% 11% 0% 15 2007 06/7/07 15/12/07 162 418 324 92% 7% 0% 70 2006 07/7/06 15/12/06 161 302 268 84% 16% 0% 32 2005 12/7/05 20/12/05 161 443 368 83% 16% 1% 75 2004 14/7/04 20/12/04 159 443 381 90% 10% 0% 62 2003 15/8/03 15/12/03 122 124 109 77% 23% 0% 15 2002 30/8/02 30/11/02 138 150 137 77% 23% 0% 13 2001 25/9/01 30/11/01 117 116 95 61% 39% 0% 21 2000 20/8/00 31/12/00 133 248 194 69% 31% 0% 54 1999 017/99 01/12/99 153 245 191 70% 30% 0% 54 1998 15/7/98 26/12/98 164 188 145 70% 30% 0% 43

CORO

ZALITO

2014 03/8/14 13/12/14 132 2219 1931 91% 4% 5% 259 2013 27/6/13 13/12/13 169 1772 1577 63% 9% 28% 181 2012 28/6/12 03/12/12 158 1588 1282 68% 11% 21% 164 2011 27/6/11 05/12/11 161 1512 1264 79% 9% 12% 196 2010 01/7/10 15/12/10 167 1888 1544 85% 6% 9% 344 2009 15/7/09 15/12/09 153 1782 1512 70% 10% 20% 209 2008 13/8/08 11/11/08 90 1417 1366 68% 25% 7% 54

Table S1. Solitary olive ridley nesting activity recorded in past monitoring seasons of the Caletas, Costa de Oro, San Miguel, and Corozalito PRETOMA sea turtle beach conservation projects.


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CL CDO SM Eggs 42334 12088 30993

Emerged 28432 67.2% 7729 63.9% 25053 80.8% Alive in the Nest 2093 4.9% 953 7.9% 1355 4.4%

Dead Outside the Nest 252 0.6% 471 3.9% 312 1.0%

Dead Inside the Nest 304 0.7% 95 0.8% 175 0.6% Without Development 4742 11.2% 907 7.5% 2157 7.0%

Stage 1A Development 1592 3.8% 269 2.2% 254 0.8% Stage 1B Development 435 1.0% 60 0.5% 63 0.2%

Stage 2 Development 704 1.7% 133 1.1% 163 0.5%

Stage 3 Development 1269 3.0% 571 4.7% 371 1.2% Pipped Dead 826 2.0% 116 1.0% 361 1.2%

Pipped Alive 310 0.7% 49 0.4% 54 0.2% Depredated 160 0.4% 27 0.2% 14 0.0%

Unidentified 767 1.8% 221 1.8% 368 1.2% Table S2. Data from exhumations of the olive ridley nests relocated to the Caletas, Costa de Oro, and San Miguel hatcheries during the 2014 monitoring season.

Figure S1. Past eclosion success of the Caletas (red, squares), Costa de Oro (purple, circles), and San Miguel (green, triangles) hatcheries.


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Year Leatherback Green Hawksbill

Caletas

2002 23 0 0 2003 45 9 0 2004 17 2 0 2005 15 7 1 2006 18 4 0 2007 1 9 0 2008 8 0 1 2009 6 5 0 2010 3 4 0 2011 13 3 0 2012 1 16 0 2013 0

0 7 0

2014 0 8 0

San Migue

l

1999 2 0 0 0 0 0 0

2000 3 0 0 2001 1 0 0 2002 0 0 0 2003 0 1 0 2004 0 0 0 2005 1 0 0 2006 2 0 0 2007 1 3 0 2008 0 0 0 2009 0 1 0 2010 0 7 0 2011 0 0 0 2012 0 1 0 2013 1 1 0 2014 2 4 0

CDO 2012 0 0 0

2013 0 3 0 2014 0 6 0

Corozalito

2008 0 3 0 2009 0 11 0 2010 0 10 0 2011 0 8 0 2012 0 6 0 2013 0 5 0 2014 1 11 0

Table S3. Past leatherback, green, and hawksbill nesting events recorded at Caletas, San Miguel, and Corozalito PRETOMA sea turtle beach conservation projects.

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