52 insular nesting areas with high precision is a statistical challenge. The high financial costs associated with field presence act indeed as a strong hindrance to the collection of core data. This may lead to important knowledge gaps and significant misunderstanding of demographic processes in high-potential habitats (Delcroix et al. 2013; Shamblin et al. 2020; Fretey et al. 2023). The development of efficient and resource-optimized tools is therefore a priority as it could reveal unsuspected major nesting rookeries (Fretey et al. 2023), especially in the South Pacific region that encompasses a multitude of island-rich geographies (Nunn and Mimura 1997; Barnett and Campbell 2010). The loggerhead turtle Caretta caretta (Linnaeus, 1758) is classified as ‘Vulnerable’ on the International Union for Conservation of Nature’s (IUCN) Red List on a global scale. However, the South Pacific subpopulation suffered a strong demographic collapse, showing a loss of over 80% of nesting females over the past three generations. It was therefore classified as ‘Critically Endangered’ in 2015 (Limpus and Casale 2015). Nesting aggregations of this distinct Regional Management Unit (Wallace et al. 2011) are restricted to the western part of the ocean basin and are reported almost exclusively in eastern Australia and New Caledonia (Limpus and Limpus 2003; Read et al. 2015). In Australia, approximately 80% of the loggerhead turtle nesting activities are concentrated at five major areas, each supporting hundreds of nesting females every year (Limpus and Casale 2015). They combine for the greatest concentration of all reproductive individuals in the South Pacific region, as the remainder of the nesting population is dispersed at a large number of small aggregations with 10s or <10 nesting females per year. In New Caledonia, only one important coastal nesting site with several 10s of nesting females every year has been identified on the west coast of the mainland, in the ‘Roche Percée’ beach, commune of Bourail (Limpus et al. 2005b; Barbier et al. 2023). Numerous other smaller nesting beaches have been inventoried on dispersed coral islets along the coastline, forming large aggregations off the northwestern coast of the mainland and in the ‘Grand Lagon Sud’ (GLS) provincial park, at the meridional end of the mainland. Despite the pre identified potential for hosting a significant number of nesting activities, information for those insular rookeries remained sparse and only based on expert opinion because they did not benefit censuses to this date. Given the reported lack of information on the loggerhead turtle demographic status at the national scale (Limpus and Casale 2015), the assessment of those nesting areas could prove critical to a re-evaluation of New Caledonia’s population and its importance within the South Pacific subpopulation. In this study, we chose to give a specific focus on the ‘GLS’ area. It presents strong monitoring logistical constraints, with the requisite coverage of multiple, distant and scattered nesting beaches. We have therefore implemented an exploratory protocol, based on the seasonal survey of 28 islets and supported by an appropriate analytical tool to make up for the scarcity
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