Hatching Success of Olive Ridley Sea Turtles in Semi‐Natural Nests: A Pilot Assessment of Microclimate Conditions at Batu Hiu Beach

Olive ridley sea turtles (<i>Lepidochelys olivacea</i>) continue to experience population pressures across much of their global range, underscoring the need to understand how incubation environments influence reproductive outcomes in conservation settings. Semi-natural hatcheries are widely used in Indonesia, yet quantitative assessments of their microclimatic performance remain limited. This pilot study examined the hatching success of three olive ridley clutches relocated from natural nests to a semi-natural hatchery at Batu Hiu Beach, West Java, between January and May 2025. A total of 303 eggs were relocated within 6 h of oviposition, placed into hand-dug nests that mimicked natural nest dimensions, and incubated under conditions designed to replicate beach microhabitats. Microclimate variables, including daily air temperature and relative humidity, were extracted from ERA5 reanalysis data and matched to each incubation period. Hatching outcomes varied considerably among the three incubation windows, with success rates ranging from 41% to 95%. The clutch incubated under cooler, more thermally stable conditions had the highest success, while the clutch exposed to more variable temperatures had the lowest success. Humidity varied slightly among periods and showed no clear correspondence with differences in reproductive output. These findings suggest the importance of fine-scale thermal stability in supporting embryonic development, consistent with broader evidence from tropical rookeries where temperature is a key driver of reproductive success. The results provide preliminary guidance for improving hatchery management through targeted shading, moisture regulation, and timing of nest relocation. This pilot assessment across three clutches emphasizes the need for multi-season monitoring and in-nest data logging to refine conservation strategies for <i>L. olivacea</i> in Indonesia.