SUMMARYIt is generally assumed that leatherback turtles (Dermochelys coriacea), like other species of sea turtle, do not feed while offshore from nesting beaches, and rely instead on fat reserves to fuel reproductive activities. Recent studies, however, provide evidence that leatherbacks may forage during the internesting interval while offshore in the Western Atlantic Ocean and Caribbean Sea. Bio-logging technology was used to investigate the foraging behavior of female leatherback turtles at St Croix, US Virgin Islands. Leatherback gastrointestinal tract temperatures (T GT ) were analyzed for sudden fluctuations indicative of ingestions, and laboratory ingestion simulations were used to characterize temperature fluctuations associated with ingestion of prey versus seawater. Dive patterns associated with prey ingestion were characterized and the proportion of prey ingestion during the day (05:00-18:59h) and night (19:00-04:59h) were compared. A combined total of 111 prey ingestions for seven leatherback turtles were documented during the internesting interval. The number of prey ingestions ranged from six to 48 for individual turtles, and the majority (87.4%) of these events occurred during the daytime. Prey ingestions were most frequently associated with V-shaped dives, and the mean (±1s.d.) maximum dive depth with prey ingestion ranged from 154±51 to 232±101m for individual turtles. Although leatherbacks were found to opportunistically feed during the internesting interval, the low prey ingestion rates indicate that energy reserves acquired prior to the breeding season are critical for successful reproduction by leatherbacks from the St Croix, USVI nesting population.

Physical and biological conditions of nests in which sea turtle embryos develop can vary among and within nesting beaches. Monitoring these conditions and their effects on embryonic development should be considered when assessing conservation efforts to increase sea turtle hatchling production. Sandy Point National Wildlife Refuge (SPNWR), St. Croix, US Virgin Islands, hosts a leatherback turtle Dermochelys coriacea nesting colony that has increased exponentially in the past 2 decades, due in part to an ongoing egg relocation program. We characterized the influence of nest environment conditions (e.g. partial pressures of oxygen, pO 2 , and carbon dioxide, pCO 2 , and temperature) on hatching success of relocated eggs at 3 different sites at SPNWR to evaluate potential intra-beach variation in nest environment conditions and hatching success. Although nest conditions varied significantly among sites, hatching success did not vary significantly among relocation sites. Among all clutches and sites, hatching success varied significantly with minimum pO 2 , maximum pCO 2 , and maximum temperatures measured in leatherback nests. Thus, leatherback embryos collectively affected their nest environment (i.e. decreased pO 2 , increased pCO 2 , and temperature), and appeared to show developmental sensitivity to low pO 2 and high levels of pCO 2 and temperature in nests. Our study shows the importance of considering sea turtle nest environment conditions when designing and executing beach-based conservation strategies such as egg relocation programs.

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The leatherback sea turtle Dermochelys coriacea is a Critically Endangered species that nests on oceanic beaches. Natural disturbance cycles of erosion and accretion maintain nesting habitat on these beaches by controlling dune vegetation and sand quality. The nesting beach at Sandy Point National Wildlife Refuge in St. Croix, US Virgin Islands, is designated 'critical habitat' for leatherback turtles by the US Fish and Wildlife Service. It harbors the largest nesting population (> 800 females) in the USA. It is an important rookery for Atlantic leatherback recovery efforts. For the past 30 yr, the beach has been continuously monitored and managed in order to increase hatchling recruitment and conservation. Our study highlights how a multiyear change in the natural disturbance cycle has affected dune plant growth and leatherback production at this beach. Reduced summer erosion relaxed natural control of Ipomoea pes-caprae, a native dune plant, allowing its seaward spread to cover > 75% of the nesting beach. This spread of vegetation led to both direct and indirect interactions between nesting leatherbacks and I. pes-caprae. Because the beach is managed in order to protect leatherback nests, a dune vegetation control plan was needed. We measured the effects of 3 vegetation management options on nest success: herbicide treatment, aboveground mechanical removal, and undisturbed vegetation. These treatments were compared to nest success at a non-vegetated control site. We found that the spread of I. pes-caprae reduced nesting habitat and nest productivity. Aboveground vegetation treatment did not control root growth into nests. We discuss possible vegetation management strategies to improve leatherback nesting habitat quality and maximize nest productivity while minimizing anthropogenic disturbance to the natural beach dynamics.

Unprecedented increases in air temperature and erratic precipitation patterns are predicted throughout the twenty-first century as a result of climate change. A recent global analysis of leatherback turtle hatchling output predicts that the nesting site at Sandy Point National Wildlife Refuge (SPNWR) will experience the most significant regional climate alterations. We aimed to identify how local air temperatures and precipitation patterns influenced within-nest mortality and overall hatchling output at this site between 1990 and 2010. We show that while the greatest mortality occurred during the latest stages of development (stage three), the rate of embryo mortality was highest during the initial stages (stage zero) of development (approx. 3.8 embryos per day per clutch). Increased mortality at stage three was associated with decreased precipitation and increased temperature during this developmental period, whereas precipitation prior to, and during stage zero had the greatest influence on early mortality. There was a significant decline in overall hatching success (falling from 74% to 55%) and emergence rate (calculated from the number of hatchlings that emerged from the nest as a percentage of hatched eggs) which fell from 96% to 91%. However, there was no trend observed in local temperature or precipitation during this timeframe, and neither variable was related to hatching success or emergence rate. In conclusion, our findings suggest that despite influencing within-nest mortality, climatic variability does not account for the overall decline in hatchling output at SPNWR from 1990 to 2010. Further research is therefore needed to elicit the reasons for this decline.