The overall objective of this grant is to generate the first species-specific evidence of mercury contamination in the endangered Black Spider Monkey (Ateles chamek) in the Madre de Dios region of the Peruvian Amazon and to translate these findings into conservation-relevant knowledge. Specifically, the project aims to: 1) Quantify mercury levels in spider monkeys using non-invasive biological sampling to assess current exposure and potential health risks. 2) Identify spatial patterns of contamination in relation to gold-mining influence, particularly along the Madre de Dios River, to determine areas of elevated risk. 3) Link contamination levels in spider monkeys to environmental sources of mercury within their habitat, improving understanding of exposure pathways. 4) Communicate results clearly to local communities, conservation practitioners, and regional and national authorities to raise awareness of wildlife contamination. 5) Provide robust scientific evidence that can support long-term advocacy, policy discussion, and future mitigation efforts aimed at reducing mercury exposure for endangered species and Amazonian ecosystems.