Reintroduction of platypuses to the Royal National Park: Survival and early establishment dynamics

Conservation translocations aim to improve the long-term viability of species in decline, yet many fail due to problems in post-release survival and establishment. The platypus ( Ornithorhynchus anatinus ), a semi-aquatic mammal endemic to eastern Australia, faces threats including habitat degradation, fragmentation, and hydrological change, contributing to the risk of population declines and local extinctions. In May 2023, ten platypuses were reintroduced into Royal National Park (RNP), New South Wales, where the species had been extirpated 20–50 years earlier. We monitored post-release survival, movements, and establishment behaviours over 12 months. Nine individuals were confirmed alive after one year, with estimated annual survival rates of 0.83 for females and 1.00 for males. Individuals displayed a period of initial exploration, with daily movement distances up to 17 km, before establishing home ranges within 2–3 months post-release. Average daily movement declined after 2–4 months in females and 2–5 months in males. Evidence of breeding—including behavioural patterns consistent with nesting and the capture of a juvenile female—confirmed early reproductive success. Our findings confirm the feasibility of platypus translocation and provide valuable insight into post-release establishment processes for a semi-aquatic mammal in a linear freshwater habitat.