Rescue and return: Translocating a semi-wild platypus (Ornithorhynchus anatinus) population during the 2019 drought

Platypus (Ornithorhynchus anatinus) are an endemic Australian freshwater mammal, impacted by synergistic threats across their range. During the extreme drought of 2017–2019, declining water levels threatened Platypus at Tidbinbilla Nature Reserve (TNR), Australian Capital Territory (ACT), Australia. TNR supports a population of Platypus, occupying interconnected ponds within a predator proof fence. During drought conditions in 2019, Platypuses could not move out of the fenced area to refugia as floodgates were closed due to low water levels. In winter of 2019, eight Platypuses were found deceased resulting from starvation. By December, water levels were extremely low and ponds were continuing to dry. Given these circumstances, a rescue intervention was undertaken to capture stranded Platypuses. They were temporarily relocated and housed at Taronga Zoo, Sydney, until they were returned when conditions at TNR improved. Seven Platypuses were rescued, with five successfully housed at Taronga for 5 months. One Platypus was lost after escaping from its enclosure and another Platypus died when trapped in a crevice. The Platypuses were returned after water levels increased at TNR and were monitored for 500 days post-release, demonstrating successful repatriation. This case study outlines the key stages and considerations required for this intervention, providing critical information for rescue attempts on drought-affected Platypus populations. There is a need to continue developing a decision framework for interventions of climate-affected populations, including quantifying trigger thresholds and conservation prioritisation of populations. This will become increasingly necessary given the trajectories of habitat degradation, coupled with the increasingly frequent and severe droughts, expected under anticipated climate change scenarios.