Weathering Kangaroo Island’s extremes: insights into captures, health, and diet of introduced platypuses in the Rocky River

The platypus (Ornithorhynchus anatinus) is increasingly threatened by habitat loss, climatic extremes, and genetic isolation. Kangaroo Island hosts the only introduced population of the species outside its natural range, offering a rare opportunity to examine population resilience under environmental stress. We conducted live-trapping surveys in the Rocky River catchment in 2021 and 2022, following severe drought, bushfires, and flooding, and compared results with historical data from 1998 to 2000. Capture rates in 2021–2022 were approximately half those recorded two decades earlier, with declining catch-per-unit-effort (CPUE) observed further upstream, suggesting altered spatial dynamics or reduced abundance. Juveniles were captured in both years, indicating continued reproduction despite recent disturbances. Dietary analysis showed a shift in prey composition, with a higher prevalence of Decapoda in 2022, and blood analyses identified year-to-year differences in red cell counts, haemoglobin, and glucose concentrations. These findings point to a population that remains reproductively active and behaviourally flexible, but potentially vulnerable to ongoing environmental change. Given the catchment’s limited extent, low genetic diversity, and projections of increasing drought frequency and reduced rainfall, this population may face heightened extinction risks in the coming decades. Continued monitoring of abundance, health, and habitat use is essential for assessing long-term viability and informing conservation strategies, both for this population and as a model for managing isolated platypus populations under climate stress.