Feeding Niches Under Threat: Unveiling Carnivore Dietary Patterns on the Sunda Shelf in Southeast Asia

Aim The islands of the Sunda Shelf in Southeast Asia represent a global biodiversity hotspot that is under severe threat from deforestation and agricultural expansion. Despite extensive knowledge of the geographic distribution and diversity of small carnivorous mammals coexisting in different habitats, information on how their feeding ecology relates to their persistence (or extinction risk) is lacking for most of them. Here we studied the past history of ecological functions of Southeast Asian carnivorous mammals in their natural ecosystems. Location Southeast Asia. Time Period Museum collection of specimens at a period between now and > 150 years ago. Major Taxa Studied Small carnivorous mammals. Methods We analysed stable carbon ( δ 13 C) and nitrogen ( δ 15 N) isotope ratios in hair samples from 452 museum specimens of 17 carnivore species, collected over historic times from the Sunda Shelf and mainland Southeast Asia. We estimated dietary niches by calculating isotopic niches for each species and biogeographic region. Results We established general dietary patterns and niche partitioning for 17 small carnivore mammal species from Southeast Asia, which suggests that these species are flexible with respect to their feeding strategies that occur in response to sympatry, environmental heterogeneity and resource competition. Our results revealed significant differences between Felidae and Viverridae in their respective δ 15 N and δ 13 C values, with lower values for both isotopes in the preferentially fruit‐eating Viverridae. Remarkably, species listed as endangered by the IUCN Red List (e.g., flat‐headed cat, Prionailurus planiceps , and otter civet, Cynogale bennettii ) separated in their isotopic niches from those with more favourable conservation statuses, indicating vulnerable feeding strategies. Main Conclusions These findings indicate that endangered species from aquatic environments had a higher degree of niche specialisation than closely related species, emphasising the need for targeted conservation efforts to protect the ecological function of these species and their natural habitat.