Stable Isotope Analysis in Wildlife Ecology and Conservation: Invisible Clues to Diet, Trophic Dynamics and Movement Patterns

Abstract

Stable isotope analysis (SIA) has emerged as an indispensable tool in wildlife ecology, providing an indirect yet reliable means of investigating diets, trophic interactions, migration pathways, and contaminant transfer across ecosystems. This review synthesises global and Indian applications of SIA, tracing its development from early bulk tissue analyses to contemporary high-resolution approaches such as Compound-Specific Isotope Analysis (CSIA) and Bayesian mixing models. A systematic literature search following PRISMA guidelines retrieved 742 records, of which 112 were included in the synthesis. Four major applications dominate the field, which include, diet reconstruction, trophic level estimation, migration, habitat use, and ecotoxicology, supplemented by emerging uses in palaeoecology, conservation forensics, and climate change research. Of the 112 reviewed studies, approximately 45% focused on diet reconstruction, 30% on trophic dynamics, 15% on migration tracking, and 10% on ecotoxicology. Carbon and nitrogen isotopes remain central to diet and trophic studies, hydrogen and oxygen isotopes enable tracking of migratory connectivity, sulphur isotopes enhance resolution of aquatic systems, and strontium isotopes provide geological signatures of habitat use. The field has evolved from largely descriptive studies to a rigorous quantitative discipline that directly supports management and policy decisions. In India, although isotope ecology remains in its early stages, it shows strong promise in priority areas such as hilsa fisheries management and elephant crop-conflict landscapes, where isotopes can help clarify movement, habitat use, and resource dependence. Methodological challenges, including baseline variability, tissue-specific discrimination, and limited regional infrastructure, persist, but advances such as CSIA, isoscapes, and probabilistic modelling are improving analytical reliability. Stable isotope ecology remains a dynamic, interdisciplinary field poised to play a pivotal role in biodiversity conservation and environmental change in the 21st century.