Nesting ecology of leatherback turtles (Dermochelys coriacea) on Buru island, Maluku, Indonesia

Abstract

Leatherback turtles (Dermochelys coriacea) face significant conservation challengesdue to global population declines and their susceptibility to both environmental and anthropogenic pressures. Fine-scale, site-specific research is critical for understanding population characteristics and developing effective conservation strategies. This study uses beach monitoring data collected over eight years (2017-2024), along with beach characteristic survey data from 2024, to examine the nesting behavior of leatherback turtles, beach characteristics, hatchling production, impacts of seasonality, and threats to eggs at Fena Leisela beach, Buru Island, Indonesia. With over 1434 recorded nests and 178 unique individuals identified, findings show that leatherbacks typically lay five clutches per season, with internesting intervals ranging from 9 to 12 days and a remigration interval of approximately 2-4 years. Based on the number of nests and estimated clutches per female, it is estimated that approximately 36 females nest annually at Fena Leisela beach. Nesting occurs year-round, following a bimodal pattern with two peaks: June-July (dry season) and December-February (rainy season). Nesting activity has increased annually over the last eight years, likely due to the cessation of meat harvesting in 2017, which has allowed more turtles to complete their nesting cycles. However, a declining trend has been observed during the rainy season, suggesting increased pressures during this period. The combination of beach monitoring and beach characteristic data collection in 2024 reveals that artificial lighting, slopes, and beach width are important cues in selecting nest sites. Leatherbacks predominantly nest in areas with minimal artificial light, moderate beach widths (approximately 14.2-26.1 meters), moderate beach slopes (ranging from 11.32% to 15.48%), diggable sand, and sparse vegetation cover. These findings suggest that v leatherbacks exhibit specific preferences for nesting habitats. Interestingly, a few individuals were observed nesting in well-lit areas, indicating that some turtles may tolerate a degree of disturbance. Nevertheless, the presence of artificial light could disorient adults and hatchlings whose potential long-term conservation impact remains unclear. This study also highlights a significant reduction in egg harvesting and predation, largely due to active beach monitoring and increased community awareness efforts involving local citizens, government officials, and traditional and religious leaders. Nests in high-risk areas (“doomed nests”) were relocated, resulting in the successful release of approximately 5,674 hatchlings. However, the hatching and emergence success rates were lower in relocated nests (F(1,671)=3.364, P=0.06 and F(1,671)=4.187, P=0.04, respectively), possibly due to changes in nest conditions such as moisture and temperature. Despite this, seasonal variation did not appear to negatively impact relocated nests, suggesting that nest relocation may be most effective during the rainy season, when the risk to nests is the highest. These findings offer valuable insight into the nesting ecology of leatherback turtles at Fena Leisela beach and provide a strong foundation for future research and the development of site-specific conservation strategies.