Methods for capturing hatchling crocodylians in mound nests

Collecting hatchling crocodylians from natural environments is challenging due to predicting hatching times, the risk of predation, and the complexities of locating nests. This study describes a novel passive capture method for wild neonate caimans directly from mound nests. The method involves constructing a fence around nests during the incubation period. Developed in the Amazon and Atlantic Forest biomes of Brazil, it was applied to the nests of spectacled caimans (Caiman crocodilus) and Broad-snouted caimans (Caiman latirostris) and refined in 2011, 2018, and 2023. Materials such as wooden stakes, vines, metal plates, aluminum tiles, and nails were utilized, each with specific advantages of durability, cost, ease of installation, and protection from predators. The timing of installation was carefully aligned after the thermal sensitivity period of the eggs. Local knowledge and collaboration were key to optimizing the method, improving its efficiency. Results indicate that this technique not only protects nests from predators but also enables the collection of valuable biological data, including hatching rates, biometric measurements, genetic samples, and health assessments of hatchlings in their natural habitat. This method is recommended for use with other crocodylian species and in broader conservation efforts, it has the potential to enhance the sustainability and effectiveness of wildlife management strategies.