Loggerhead Nests Research Articles

Do costal erosion and urban development threat loggerhead sea turtle nesting? Implications for sandy beach management

Nest beach selection by sea turtles at a regional scale may depend on upper shore environmental cues. Thus, the variability of sandy beach conditions, including coastal erosion rates and urban development can affect their nesting ecology. Almost half of worldwide sandy beaches are suffering from erosion and most of them are located in highly developed areas. This can lead to shore stretches with coastal squeeze and loss of habitat for beach-dependent species such as sea turtles. Understanding whether an endangered species, such as the loggerhead sea turtle Caretta caretta (Linnaeus, 1758), selects certain beaches to nest is the first step in devising mitigation strategies for human activities and climate change impacts. We predicted that the occurrence of loggerhead nests along 62 km of sandy beaches in southeastern Brazil is negatively related to higher urbanization levels and extreme erosion. A total of 731 nests of the loggerhead sea turtle were recorded in the 2022-2023 nesting season. Only 6% of those nests were found on beach sectors with severe and extreme erosion. The probability of laying a nest was negatively related to erosion rate. Also, approximately 50% of nests were found on low-urbanized beaches; thus, the higher the urbanization, the lower the probability of a turtle laying a nest. Nature-based solutions to recover the beach-dune system are recommended in order to mitigate coastal erosion where loggerheads are avoiding nesting. This should be coupled with management planning of the protected areas where nests are laid and must include nest relocation and monitoring as priority actions.

Modeling the impacts of temperature during nesting seasons on Loggerhead (Caretta caretta) Sea Turtle populations in South Florida

Loggerhead sea turtles (Caretta caretta) are a threatened sea turtle species that nests on beaches along the northwestern Atlantic Ocean. Loggerhead nesting in Florida accounts for approximately 80% of the loggerhead population in the Atlantic Ocean, yet the underlying ecological mechanisms behind their population dynamics are understudied. C. caretta are largely inaccessible since they spend most of their early life in open ocean habitats. Consequently, their nesting and hatchling production offer quantifiable insight of their population dynamics. Emergence success, the proportion of eggs laid that produce offspring which successfully leave the nest, is the source of all later life stages. Yet the abiotic factors that drive emergence success trends have not been fully described. This study explores the relationship between air temperature and emergence success across multiple nesting seasons to better understand the potential impact of anthropogenic climate change on subsequent loggerhead populations. Here we investigate the effect of changing emergence success on the juvenile and adult life stages. After exploring numerous aspects of temperature and precipitation metrics, we determined that the mean of the maximum daily temperatures for each trimester of the eggs’ incubation periods related most closely to the variation in emergence success (the proportion of hatchlings that make it out of the nest) across nests. A novel feature of our approach to modeling the impact of temperature on the later life stages is through connecting a statistical model into a discrete mechanistic population model. Our population model has two parts, one with eggs and hatchlings on a daily time scale in the nesting season and the other with juveniles and adults on an annual time scale. The statistical model enables us to illustrate the effect of temperature changes across these life stages. The decline in the adult population follows from the decline of the hatchling emergence success. Using predicted increases in temperature due to climate change, we illustrate a corresponding prediction for the population classes.

Ghost crab predation of loggerhead turtle eggs across thermal habitats

The reproductive success of sea turtles is highly influenced by the environmental and biological conditions of the nesting beach. Maio Island, Cabo Verde, one of the main nesting sites for the Northeast Atlantic loggerhead subpopulation, displays marked heterogeneity of sand coloration, with dark, mixed and light sandy beaches, resulting in different thermal habitats. Considering that sand temperature can influence both sea turtle embryo development and predatory activity by ghost crabs – the main predators of clutches and hatchlings at Cabo Verde – we surveyed loggerhead nesting beaches at Maio Island, with three sand colorations (‘beach type’), to assess: 1) the density and size of ghost crab burrows, as a proxy for ghost crab density and size, and 2) ghost crab predation on 70 loggerhead nests. We further assessed nest site selection, by considering the number of nesting activities and clutches laid across beach type. There were no evident trends in the distributions of ghost crab density and size between years or beach type. We found that ghost crab predation is a major source of mortality in Maio Island, affecting 67.8% (n = 59) of the nests. Ghost crab predation was variable between beaches, but generally, at the warmer dark sand beaches, clutch mortality was mostly caused by ghost crab predation (53.2%, n = 17), while at the mixed sand beaches mortality by predation was low (7.5%, n = 18), compared to mortality due to other causes (49.9%), indicating that other factors can also significantly impact clutch survival. The mixed sand beaches had more nesting activities and higher nest density (2.29/m2; 1.25/m2, respectively), compared to the light sand (0.72/m2; 0.35/m2) and the dark sand beaches (0.73/m2; 0.27/m2), suggesting a possible predation-free nesting preference. Our findings show that some beaches are in need of nest protection, thus we recommend both in situ nest protection and egg translocation to safe hatcheries, depending on the threats identified, to enhance clutch survival at such heterogeneous nesting areas as Maio Island.

Abundance Trends and Nesting Biology of Green Turtles Chelonia mydas (Testudines: Cheloniidae) During Ten Consecutive Breeding Seasons (2012-2021) at Akyatan Beach, Turkey.

Data obtained from long-term survey studies are valuable for assessing the population status and trends in critical populations of threatened species, like sea turtles. Akyatan Beach is one of the most important green turtle nesting beaches in the Mediterranean and has been monitored since 2006 without interruption. The beach is 22 km long and more than 100 m wide at some points, and both loggerhead and green turtles nest on the beach. However, loggerhead nesting is very limited compared to green turtles. A total of 3866 C. mydas nests were recorded over ten consecutive years at Akyatan Beach, with a mean of 387 ± 127 nests (range = 201-559). The average nesting density was 17.6 nests km-1 (range = 9.1-25.4 nests km-1). In the 3309 nests, a total of 355,259 eggs were counted. The overall mean clutch size was 112 ± 26.10 eggs. Of these eggs, 50.80% hatched (depredated nests included), and 78.07% of them were able to reach the sea. The overall mean hatching success was 73.07 ± 26.20%. The overall mean incubation duration was 51.4 ± 3.5 days. The clutch sizes and hatching success differed between years, and there was a significant decreasing trend in mean incubation duration over the ten years of the study. A total of 1585 green turtle nests (41.02% of nests) were totally or partially depredated by golden jackals and wild boars, while other predators depredated 20.5% of hatchlings. The nesting data obtained since 2006 showed strong annual fluctuations ranging from 170 (in 2007) to 562 (in 2006) with a slightly increasing but statistically insignificant trend (r = 0.94, p > 0.05). The main threats to the population were depredation by jackals and wild boars.

Temperature-based modeling of incubation period to protect loggerhead hatchlings on an urban beach in Northwest Florida

Sea turtle hatchlings face many natural and anthropogenic threats during their short journey to the water after emerging from nests. Reducing hatchling mortality is critical to population recovery of imperiled sea turtle species; however, protecting hatchlings is particularly challenging on beaches degraded by human development and disturbances, including artificial lighting. Managers need practical methods to reduce hatchling mortality without harming their natural behavior or development. To address this need, we describe an approach to reduce mortality of loggerhead hatchlings that relies on prediction of clutch incubation length and knowledge of hatchling emergence patterns. We developed models to predict incubation length utilizing sand temperature and nest depth data from 133 loggerhead nests laid on an urban beach in Northwest Florida from 2013 to 2020. Incubation length was predicted to within 2.2 days using mean sand temperatures measured just outside of the clutch. Predicted accuracy improved to 1.9 days using a 2-parameter model incorporating sand temperature and measured depth to the topmost eggs. Hatchlings emerged almost exclusively at night in a single large group with no evidence of asynchronous emergences. Emergence times were skewed toward the early evening, in contrast to loggerhead nests on the Florida Atlantic coast which tend to hatch near midnight. Using these prediction tools, monitoring efforts could be focused on days and times of expected emergence to enable protection of hatchlings emerging naturally from nests left in situ. The method used here, while not a substitute for recovery of degraded nesting habitat, provides a way to protect hatchlings that avoids disturbing the eggs with instruments or restraining the hatchlings with cages or screens.

A test of the use of gray wolf (Canis lupus) urine to reduce coyote (Canis latrans) depredation rates on loggerhead sea turtles (Caretta caretta) nests

Loggerhead sea turtles (Caretta caretta) are currently listed as vulnerable, with a decreasing population trend, by the International Union of Conservation of Nature. From 2015 to 2019, coyotes (Canis latrans) depredated 24.12% of loggerhead nests on the night they were laid on South Island beach at the Tom Yawkey Wildlife Center, near Georgetown, SC, resulting in an estimated 3816 eggs lost each year. Over that time, a South Carolina Department of Natural Resources Turtle Technician Team patrolled the beach at dawn every morning to cage and catalog loggerhead nests and eggs but were unable to cost-effectively protect the nests the night the eggs were laid. To test a new method to dissuade coyote depredation, we used dispensers filled with gray wolf (Canis lupus) urine to simulate wolf activity on seven sections of the beach and left seven sections untreated as controls. We observed a significant reduction in depredation rates where urine was present relative to control areas (G-test adjusted with the Williams correction, G = 5.749, df = 1, p = 0.0165). The results suggest this may be an example of exploitative competition in the absence of interference competition. With daily teams already patrolling the beaches, using wolf urine as a deterrent could be an inexpensive, non-invasive way to reduce coyote depredation on loggerhead and other sea turtle nests elsewhere.

Cayman Islands Sea Turtle Nesting Population Increases Over 22 Years of Monitoring

Given differing trajectories of sea turtle populations worldwide, there is a need to assess and report long-term population trends and determine which conservation strategies are effective. In this study, we report on sea turtle nest monitoring in the Cayman Islands over a 22-year period. We found that green (Chelonia mydas) and loggerhead (Caretta caretta) nest numbers increased significantly across the three islands since monitoring began in 1998, but that hawksbill nest numbers remained low with a maximum of 13 nests recorded in a season. Comparing the first 5 years of nest numbers to the most recent 5 years, the greatest percentage increase in green turtle nests was in Grand Cayman from 82 to 1,005 nests (1,126%), whereas the greatest percentage increase for loggerhead turtle nests was in Little Cayman from 10 to 290 nests (3,800%). A captive breeding operation contributed to the increase in the Grand Cayman green turtle population, however, loggerhead turtles were never captive-bred, and these populations began to increase after a legal traditional turtle fishery became inactive in 2008. Although both species have shown significant signs of recovery, populations remain at a fragment of their historical level and are vulnerable to threats. Illegal harvesting occurs to this day, with multiple females taken from nesting beaches each year. For nests and hatchlings, threats include artificial lighting on nesting beaches, causing hatchlings to misorient away from the sea, and inundation of nests by seawater reducing hatch success. The impacts of lighting were found to increase over the monitoring period. Spatial data on nest distribution was used to identify critical nesting habitat for green and loggerhead turtles and is used by the Cayman Islands Department of Environment to facilitate remediation of threats related to beachside development and for targeted future management efforts.

Effects of supplemental watering on loggerhead (Caretta caretta) nests and hatchlings

The influence of environmental conditions during sea turtle egg development makes the ongoing threat of climate change particularly concerning. The nest environment greatly influences several aspects of sea turtle hatchling biology, including developmental rate and sexual differentiation. Various studies examine the effectiveness of watering nests as a mitigation strategy for high temperatures and dry conditions but few have rigorously identified the impacts across multiple nesting seasons and weather conditions. This study experimentally examined the impact of increased moisture on loggerhead turtle (Caretta caretta) hatchling sex ratios and hatching success across three nesting seasons. Supplemental water was added to experimental treatments while control treatments received only ambient water as rainfall. Sand moisture and nest temperature were measured throughout incubation. Overall, watering nests lowered nest temperatures and increased nest sand moisture. Watered nests had significantly higher hatching success; however, nests that received the highest treatment amounts had similar hatching success as controls. After hatchlings emerged, nests were inventoried and a sample of hatchlings from each nest was collected and their sex was verified. Only nests watered with the highest water volume treatment produced significantly more males. Watering nests may mediate the effects of high temperatures and desiccation associated with climate change. However, as temperatures continue to increase, watering nests may not prove effective in mitigating for entirely female-producing beaches.

Assessing the effectiveness of different sea turtle nest protection strategies against coyotes

Depredation of sea turtle nests, where a nest is either partially or completely predated by a predator, is particularly detrimental to the reproductive output of sea turtles and consequently a concern for sea turtle conservation efforts globally. To minimize depredation of sea turtle nests, several protective strategies have been trialed against different predators. However, although information on their effectiveness exists, information on the effectiveness of strategies aiming to mitigate depredation by coyotes, which is an issue at loggerhead turtle, Caretta caretta, nesting beaches in Florida and globally is inexistent. To inform future management of sea turtle nest depredation by coyotes, this study evaluated the effectiveness of three nest protection strategies (self-releasing metal cage, self-releasing plastic cage, and self-releasing metal screen). Further, to obtain insights into coyote behavior during depredation activities and inform management strategies, we used infrared camera surveillance to monitor sea turtle nests. Self-releasing plastic cages were found to be the most effective strategy at mitigating coyote depredation on loggerhead nests. Our findings provide important information for consideration when developing depredation mitigation strategies in the region and globally.

Predation of loggerhead sea turtle eggs across Georgia’s barrier islands

Nesting beach management is a vital element of the population recovery efforts for the vulnerable loggerhead sea turtle (Caretta caretta) across the globe. In the southeast United Sates, turtle nests are threatened by numerous anthropogenic and natural threats, including predation of eggs by native and non-native predators. We analyzed loggerhead nest predation and other egg; loss using an exceptional 10-year data set (2009–2018) that covered nesting beaches on 12 islands on the Georgia coast. Our objectives were to 1) determine which predators cause the greatest loss of loggerhead sea turtle eggs, 2) evaluate whether non-native species have a higher; rate of predation than native species, and 3) compare predation rates to other major sources of egg loss across these islands. Our results show that under current strategies for nest management: 1) non-native feral hogs and native raccoons have the greatest impact as predators on sea turtle eggs; 2) non-native predators have caused significantly more egg loss across Georgia’s coast than native species, but the impact varies greatly by species; and 3) losses to predation are similar in magnitude to post-management losses from tides and storms over the last decade. We recommend the continued use of multiple management techniques, including nest screening and; targeted predator management, but caution that predator controls should be focused on those demonstrated to cause significant losses in order to prioritize conservation funding.

Brightness of the Night Sky Affects Loggerhead (Caretta caretta) Sea Turtle Hatchling Misorientation but Not Nest Site Selection

Sea turtles in the Gulf of Mexico, which are listed as either threatened or endangered under the US Endangered Species Act, face numerous threats but are particularly susceptible to the negative effects of light pollution on nesting beaches. Light pollution affects the distribution, density, and placement of nests on beaches, and disrupts seafinding in hatchlings emerging from nests; often leading to their death. Rapid urban growth near Gulf Islands National Seashore (GUIS), Florida, USA, over the last century has contributed to increased light pollution on its beaches. There is concern that light pollution is causing females to lay nests in at-risk locations subject to erosion and flooding, and is causing the observed high rates of hatchling misorientation. From 2015-2016, we measured brightness of the night sky, horizon profile, and lunar variables at GUIS at loggerhead (Caretta caretta) nests to assess the effects of brightness on laying of at-risk nests and hatchling misorientation. In addition, we quantified the effects of relocating at-risk nests on nest success. We found that contrast in brightness between the landward and seaward directions at GUIS was partially responsible for high rates of hatchling misorientation, and there was a strong moderating influence of lunar fraction and lunar altitude on hatchling misorientation: larger lunar fractions and lower lunar altitudes reduced misorientation. We did not document an effect of artificial light, horizon profile, or lunar fraction on the propensity of loggerheads to lay nests in at-risk locations, and found no evidence that relocating nests at GUIS reduced loggerhead nest success. Rather, we found nest success was improved and hatchling misorientation rates were reduced for relocated loggerhead nests.

Impact of the fire ant pesticide AMDRO on loggerhead turtle nest productivity and seafinding orientation

Invasive fire ants prey on a variety of organisms in the southeastern USA, including the pipped eggs and hatchlings within sea turtle nests. The granular fire ant bait AMDRO® (active ingredient hydramethylnon) is currently used at some rookeries to protect nests, but no studies have been conducted to determine if the pesticide negatively impacts the eggs or the hatchlings. We examined the pesticide’s effect on loggerhead (Caretta caretta) nests at Juno Beach, Florida, USA, specifically targeting how exposure affected hatching success, hatchling emergence success, and the ability of the turtles to orient visually from the nest to the sea. Pesticide granules were placed within a 30 cm diameter circle on the sand directly above the nest during the final 5-10 days of incubation, representative of its typical application at nesting beaches. Cornmeal granules in soybean oil and untreated natural nests served as controls. AMDRO had no significant effect on hatching success or emergence success, nor did it result in any deficiencies in hatchling orientation accuracy. However, the pesticide and cornmeal control attracted other predators (Atlantic ghost crabs and avian species), in addition to fire ants, to the nest site, thus revealing the nest’s location and potentially increasing its vulnerability. Consequently, we suggest that its usage may not be beneficial at sites where predators other than ants are especially abundant.

Heat, health and hatchlings: associations of in situ nest temperatures with morphological and physiological characteristics of loggerhead sea turtle hatchlings from Florida.

Incubation temperatures, in addition to an embryo’s genetic makeup, are critical in many aspects of adequate sea turtle embryonic development. The effects of high and low incubation temperatures on hatchling quality have been previously examined; however, many of these studies were conducted on relocated or laboratory-reared nests, which do not accurately reflect natural nest temperature fluctuations. To observe the impacts of varying in situ incubation temperatures on loggerhead sea turtle (Caretta caretta) hatchling morphology, various health variables and locomotor performance, temperature data loggers were deployed in 15 loggerhead nests on Juno Beach, Florida, between May and July 2018. Over the course of the study period, 10 morphological traits were measured, blood analytes and heart rate were assessed for the establishment of reference intervals and the self-righting response in seawater was evaluated. Warmer months were associated with smaller body size and higher body condition index, larger umbilical scar size, slower righting time, lower heart rates and higher packed cell volume, hemoglobin, total solids, total white blood cell count, absolute heterophils and absolute basophils. These findings provide evidence that higher in situ incubation temperatures have the potential to adversely affect hatchlings from warmer nests due to increased risk of predation from smaller body sizes, decreased physical responses and overall fitness, altered hemodynamic balance (e.g. dehydration) and potential inflammation and/or stress. With rising temperatures, we predict sea turtle hatchlings may have increasing risks of developing suboptimal physiological features affecting overall fitness and ultimately survival. These results demonstrate that rising environmental temperatures can negatively impact sea turtle hatchlings, thus representing additional stress on sea turtle populations and contributing to our understanding of potential pathophysiological effects of climate change on the delicate life-stage class of the sea turtle hatchling. This information will be useful for formulating effective future sea turtle management plans.

Crude Oil and Dispersant Cause Acute Clinicopathological Abnormalities in Hatchling Loggerhead Sea Turtles (Caretta caretta).

Following the explosion of the Deepwater Horizon MC252 oil rig in 2010, 319 live sea turtles exposed to crude oil and oil-dispersant (Corexit) combinations were admitted to rehabilitation centers for decontamination and treatment. Treatment of oiled sea turtles was guided by expected physiological and pathological effects of crude oil exposure extrapolated from studies in other species and from a single loggerhead sea turtle (Caretta caretta) study. While invaluable starting points, inherent limitations to extrapolation, and small sample size of the experimental exposure study, reduce their utility for clinical guidance and for assessing oil spill impacts. Effects of dispersants were not included in the previous experimental exposure study, and cannot be effectively isolated in the analysis of field data from actual spills. A terminal study of pivotal temperature of sex determination using eggs salvaged from doomed loggerhead nests provided an opportunity for an ancillary exposure study to investigate the acute effects of crude oil, dispersant, and a crude oil/dispersant combination in sea turtle hatchlings. Eggs were incubated at 27.2–30.8°C, and hatchlings were randomly assigned to control, oil, dispersant, and combined oil/dispersant exposures for 1 or 4 days. Contaminant exposures were started after a 3 day post-hatching period simulating nest emergence. Turtles were placed in individual glass bowls containing aged seawater and exposed to oil (Gulf Coast—Mixed Crude Oil Sweet, CAS #8002-05-9, 0.833 mL/L) and/or dispersant (Corexit 9500A, 0.083 mL/L), replicating concentrations encountered during oil spills and subsequent response. Statistically significant differences between treatments and non-exposed controls were detected for PCV, AST, uric acid, glucose, calcium, phosphorus, total protein, albumin, globulin, potassium, and sodium. The principal dyscrasias reflected acute osmolar, electrolyte and hydration challenges that were more numerous and greater in combined oil/dispersant exposures at 4 days. Clinicopathological findings were supported by a failure to gain weight (associated with normal hatchling hydration in seawater) in dispersant and combination exposed hatchlings. These findings can help guide clinical response for sea turtles exposed to crude oil and crude oil/dispersant combinations, and indicate potential impacts on wildlife to consider when deploying dispersants in an oil spill response.

Loggerhead Nesting in the Northern Gulf of Mexico: Importance of Beach Slope to Nest Site Selection in the Mississippi Barrier Islands

Abstract Here we describe the effects of beach morphological features on loggerhead (Caretta caretta) nesting behavior on the barrier islands of the north-central Gulf of Mexico. Our results show that loggerhead crawl length decreases as beach slope increases, and our data comparing nest crawls (resulting in egg laying) versus false crawls (emergence onto the beach without laying eggs) suggest that beach slope and crawl length differ between the crawl types but elevation does not. We infer that loggerheads cue in to beach slope to reach a perceived elevation with reduced risk of inundation, crawling longer distances on flatter slopes compared with shorter distances on steep slopes, but that after this elevation is reached, other environmental variables may ultimately factor into the decision to lay eggs.

Female nesting behaviour affects hatchling survival and sex ratio in the loggerhead sea turtle: implications for conservation programmes

Nest-site selection and the depth at which turtle females deposit their eggs have a decisive influence on temperature in the nest chamber. Thus, female turtle nesting behaviour can influence the sex, fitness and emergence behaviour of their hatchlings. We studied nest-site selection and nest depth in 333 natural loggerhead (Caretta caretta) nests from a nesting population in Cabo Verde. Nest site and depth varied among females and among different nests from the same female. However, female body size only explained a very small part of the variability of nest depth. Nest incubation temperature also varied as a function of depth. To test the influence of nest depth on incubation and embryonic development, 90 loggerhead nests were incubated in standard conditions and at different depths (35, 40, 45, 50 and 55 cm) in a beach hatchery and monitored until hatching. Deeper nests had greater emergence success and lower temperature, and hatched later, affecting hatchling sex ratio. Incubation at 35 cm can lead to 89.4–97.7% females, whereas incubation at 50 cm would produce around 62.4–64.9% females. Survival in nests at 35 cm was lower than at deeper nests. Female turtles that dig deeper nests may have more vigorous offspring, exhibiting faster locomotor abilities. Nest depth did not influence emergence behaviour. However, clutch size enhanced synchrony at emergence, resulting in a higher number of hatchlings emerging simultaneously in smaller nests. Depth at which nests are re-buried should be considered a key factor for the success on nest relocation programmes. Females could reduce the impact of climate warming on embryonic development by nesting at deeper locations.

Invertebrate infestation in green turtle (Chelonia mydas (Linnaeus, 1758)) and loggerhead turtle (Caretta caretta (Linnaeus, 1758)) nests on Alata Beach, Mersin, Turkey

Invertebrate infestation in sea turtle nests (Caretta caretta and Chelonia mydas) was recorded for the first time for Alata beach, Mersin, Turkey. A total of 121 green and 32 loggerhead nests were recorded and 34 (22.22%) of these were examined in terms of the invertebrate faunal composition. The specimens found in the nests were identified to order, family, or genus levels and they were represented as 5 orders. These invertebrate groups are Pimelia sp. larvae (Tenebrionidae; Coleoptera), Elater sp. larvae (Elateridae; Coleoptera), Scarabaeidae larvae (Coleoptera), Muscidae (Diptera), Enchytraeidae (Oligochaeta), Myrmeleontidae (Neuroptera), and Cyrptostigmata (Acari).

Factors Influencing Loggerhead (Caretta caretta) and Green Turtle (Chelonia mydas) Reproductive Success on a Mixed Use Beach in Florida

Abstract Although estimates of sea turtle reproductive success are important to quantify population status and effects from threats, published representative values of these rates are rare. Most assessments involving hatching success have taken place as part of experimental analyses that did not spatiotemporally represent a population. To fill this gap, we analyzed an 11-yr time series (2004–2014) of sea turtle hatching and emergence success data for a 7-km stretch of Florida beach backed by mixed suburban and resort/recreational land use. Our analysis examined potential egg-mortality factors associated with the incubation of these nests. The data set included representative sampling of loggerhead (Caretta caretta) nests (n = 2,543, 34.4% of all nests made during the period) and green turtle (Chelonia mydas) nests (n = 972, 44.7% of all nests). Mean (± SD) annual hatching success was 68.6% ± 35.5% for loggerheads and 59.6% ± 39.5% for green turtles, and mean emergence success was 66.6% ± 35.7% for logger...

Paper-efficient multi-species conservation and management are not always field-effective: The status and future of Western Indian Ocean leatherbacks

Threatened species are dependent on conservation, with strategic approaches underpinned by the principle of complementarity to find efficient solutions. But are paper-efficient designs always field-effective? After 51years of monitoring a 56-km-long overlap of two turtle rookeries, there are contrasting population-recovery trends: Vulnerable loggerhead abundance is increasing; and Critically Endangered leatherback abundance is remaining constant, despite leatherback individuals having a higher reproductive output. This questions the efficacy of the conservation programme (annual monitoring and land–sea protection in a World Heritage Site). We use biotelemetry to test if the disparate recovery is biased by differences in detectability in the monitored section of the rookery, and if the reserve confers equal protection. The species' movement ecology contrasts strongly, with implications for nest-event detectability: ~66% of leatherback nesting is outside the monitoring area, compared to ~12% of loggerhead nesting. The marine reserve also strongly favours loggerheads at 95% protection, versus 25% protection for leatherbacks. We hypothesize that variability in leatherback movement ecology, and nest placement, is from ocean currents shaping their behaviour as hatchlings, potentially also determining the proportion of the population at risk of capture in pelagic fisheries. Efficient multi-species conservation strategies need to be carefully designed and adaptive to be effective.

Distribution and status of sea turtle nesting and mortality along the North Sinai coast, Egypt (Reptilia: Cheloniidae)

We assessed in 2012 the distribution of Loggerhead (Caretta caretta) and Green (Chelonia mydas) Turtle nesting sites and mortality along North Sinai, Egypt, the most important nesting area along Egypt's Mediterranean coast, and compared the results with those from a survey carried out in 1998. We observed a similar number of Loggerhead (N=66) and Green Turtles nests (N=7) as recorded in 1998 (Logger- head N=67, Green Turtle N=7). We confirmed successful nesting for 47 Loggerhead and five Green Turtle nests, with a high nesting success (>90% for both species). We found 68 dead Loggerhead Turtles, which is a significant increase compared to 1998, when only 16 individuals were found. The numbers of dead Green Turtles increased from five in 1998 to 9 in 2012. Despite the similar number of sea turtle nests in 1998 and 2012, the large increase in mortality of sea turtles is very concerning.