Mapping the applications of stable isotope analysis in rodent ecology: a scoping review protocol

Rodents (order Rodentia) are the most diverse and widely distributed order of mammals, occupying a broad range of terrestrial ecosystems worldwide and playing key ecological roles in food webs, nutrient cycling, and ecosystem functioning. Anthropogenic pressures such as land-use change, agricultural intensification, and habitat fragmentation have altered resource availability and trophic interactions across ecosystems, making rodents valuable indicators of ecological change. Stable isotope analysis has emerged as a powerful and integrative tool for investigating ecological processes, allowing inferences about diet, trophic position, habitat use, movement, and resource integration over extended temporal and spatial scales. Although stable isotopes have been increasingly applied in ecological studies involving rodents, the existing literature remains fragmented across ecosystems, isotope systems, tissues, and methodological approaches, and no comprehensive synthesis is currently available. This scoping review aims to systematically map and synthesize the applications of stable isotope analysis in ecological studies of the order Rodentia across diverse ecosystems. Specifically, it seeks to identify the isotope systems employed, methodological approaches, ecological contexts, and research objectives, as well as to highlight research trends, knowledge gaps, and priorities for future research. This scoping review protocol follows the Joanna Briggs Institute (JBI) methodology for scoping reviews. A comprehensive literature search will be conducted in Scopus, Web of Science, and Google Scholar using predefined search strategies. Studies focusing on the order Rodentia and applying stable isotope analysis in ecological contexts will be considered. Eligible sources will include peer-reviewed journal articles, theses, and dissertations reporting quantitative isotope data. The screening of titles and abstracts will be performed using Rayyan, followed by full-text assessment of potentially relevant studies based on predefined inclusion and exclusion criteria. Data extraction will include information on geographic location, ecosystem type, isotope systems, tissue types, study design, objectives, and main findings. Results will be synthesized using descriptive statistics, tables, figures, and narrative summaries to map research patterns and identify gaps in the literature.