Safe haven for vulnerable mammals

Population surveys reveal an estimated 550 Nuyts southern brown bandicoots and 530 greater sticknest rats are living on the remote islands of the Nuyts Archipelago.

The monitoring surveys – the first since the early 1990s – confirm the rats and bandicoots, which are the only mammals inhabiting Franklin Islands, have remained resilient.

Greater stick-nest rats are a large herbivorous rodent, comparable in size to a small rabbit. Once widespread across the semi-arid zone of southern Australia, greater stick-nest rat populations declined drastically after European colonisation and were restricted to the Franklin Islands by the 1970s.

The Nuyts southern brown bandicoot – only found on three islands in the Nuyts Archipelago – is distinct from its mainland cousins and much smaller in size. Unlike the dense heathy habitats preferred by southern brown bandicoots on the mainland, the Nuyts population inhabits open semi-arid shrubland on the islands.

Greater stick-nest rats and Nuyts southern brown bandicoots are two of the top candidates for introduction to the Flinders Island Safe Haven, where introduced rodents and feral cats are being
eradicated. Department for Environment and Water Senior Ecologist Randall Johnson said recent surveys showed the importance of protecting sensitive island habitats so that vulnerable species could
prosper.

“Conservation of species has never been more important. As extinction rates increase, we must work tirelessly to save those that we can, while we can,” Mr Johnson said.

“The Nuyts Archipelago and Investigator Group wilderness protection areas are incredibly important areas for biodiversity in South Australia.”

In 2024, the Department for Environment and Water introduced a new management plan for the Nuyts Archipelago and Investigator Group wilderness protection areas. The plan covers 36 remote islands and islets, including Franklin Islands, off the coasts of Ceduna and Elliston. These islands are home to species, including the endangered Australian sea lion, white-bellied sea eagle and eastern osprey.

The management plan prioritises conservation by protecting habitat and wildlife breeding areas, minimising impacts to wildlife sensitive to disturbance, and limiting visitation to daytime only at designated sites to help prevent biosecurity incursions.

While nature-based tourism operators are still able to visit beaches on St Francis and Goat islands, subject to securing DEW permits, access to the Franklin Islands is prohibited to protect its unique and vulnerable inhabitants.
Islands are critically important for biodiversity conservation. Their ‘built-in’ biosecurity protection has enabled the persistence of mammal species that are now extinct on the mainland.

Ongoing biosecurity is critical, as the accidental introduction of feral rats and mice, weeds, invertebrate pests and disease could have disastrous consequences for these animals.

Department for Environment and Water Conservation and Wildlife Director Lisien Loan said the work helped establish a clear process to monitor population health and ensure that any translocations
sourced from the islands were sustainable.

“Our islands are particularly critical for species sensitive to disturbance, including the white-bellied sea eagle with 80 per cent of the state’s population now restricted to islands,” Ms Loan said.

“Many species are also completely dependent on our islands for breeding, including the Australian sea lion, rock parrot, fairy penguin, Cape Barren goose and short-tailed shearwater.”