From 12 individuals introduced in 1870 in New Caledonia, hundreds of thousands rusa deer (Cervus timorensis rusa; Groves and Grubb 2011) are now present in this biodiversity hotspot. If rusa deer’s favorite diet seems to be herbaceous monocotyledons whenever available, the important feeding plasticity of this taxa allows it to consume a large range of less preferred vegetal resources, including species with high environmental value, when its favorite diet is not available. Rusa deer impact their habitat by overgrazing, imped vegetal regeneration by eating every sprout, provoke older tree’s death by consuming their bark. It results in a habitat opening and an increased erosion that in turn impacts the water distribution and availability. This invasive species therefore constitutes a main concern for agriculture and ecology. Dental Microwear Texture Analysis, the study of the microscopic wear caused by food during mastication, has proven to be efficient enough in deciphering subtle inter and intra-population variations in diet. This approach, initially developed for paleontological purposes, presents a major potential as a monitoring tool for ungulate management and conservation problematics.10 habitats were identified based on vegetation, climate, degradation by rusa deer, and human impact. 2500 mandibles were sampled on a 1-year cycle to consider seasonal dietary variations. 600 feces samples and 200 rumen samples were collected to explore further the feeding ecology of the very same individuals. The purpose of this talk is to present our dental microwear preliminary results and to initiate interdisciplinary collaborations to better understand the feeding ecology of rusa deer, in order to propose managing strategies that would be adapted to the New Caledonian case.