Forensic scatology: insights into the secretive Mediterranean monk seal via a comprehensive molecular analysis of aged and recent fecal samples

The Mediterranean monk seal (Monachus monachus), the only pinniped endemic to the Mediterranean Sea, is among the most vulnerable mammals in the Anthropocene, facing severe pressures from habitat degradation, human disturbance, and climate-driven ecosystem changes. Its elusive nature and use of inaccessible habitats complicate monitoring efforts, with most sightings remaining opportunistic and providing limited biological insight. Addressing these challenges requires innovative, non-invasive methodologies to improve conservation outcomes. Here, we assess the potential of fecal DNA analysis as a tool for monitoring and understanding this species in a rapidly changing world. Eight fecal samples, collected under varied conditions and spanning more than a decade, were examined using a suite of nine genetic assays. Analyses revealed critical biological information, including diet composition (predominantly bony fish, with cephalopod and bivalve mollusks), sex determination, and haplotype identity. Results demonstrated that even older samples preserved in ethanol retained substantial host DNA, though prey DNA degradation was more pronounced. DNA degradation in feces can affect data quality, but at the same time can provide insights into scat age and associated ecological behaviors. By integrating molecular ecology with conservation practice, this study highlights fecal DNA as a ready-to-use, non-invasive, and ethically sound approach to generate essential knowledge on diet, genetic diversity, social structure and, and health parameters (e.g., parasite load) in M. monachus. Our findings underscore the importance of applying emerging technologies to mitigate knowledge gaps and inform conservation strategies, ultimately contributing to the preservation of mammalian biodiversity under accelerating anthropogenic pressures.