The last resort: Vulnerable native mammals thriving on island safe haven

What do Nuyts southern brown bandicoots and greater stick-nest rats have in common? 

Well, they’re both adorable, similar in size to a small rabbit, and not widely known compared to other cute Australian mammals like bilbies or quokkas. 

Both listed as vulnerable, they’re also only found in their natural habitat on a few small islands in Nuyts Archipelago off South Australia’s west coast. 

The Nuyts southern brown bandicoot - found on only three islands in the archipelago - is distinct from its mainland cousins and much smaller in size.

The greater stick-nest rat was once widespread across the semi-arid zone of southern Australia ,but their population declined drastically after European colonisation. By the 1970’s they were extinct on the mainland.

In good news, despite their vulnerable status, they are doing remarkably well on the Franklin Islands part of the Nuyts Archipelago. 

Recent population surveys conducted by the National Parks and Wildlife Service (NPWS) – the first since the 1990s – found an estimated 550 Nuyts southern brown bandicoots and 530 greater sticknest rats living on the remote islands. These numbers confirm the rats and bandicoots, which are the only mammals inhabiting Franklin Islands, have remained resilient.

Professor Katherine Moseby was engaged by NPWS to provide her expertise for the population survey.

“The Franklin Islands are the last safe haven, last stronghold of the greater stick-nest rat,” she said.

“There’s no cats on these islands, no rabbits, mice, rats – all those feral animals aren’t here, so native species can really flourish and live naturally. We’re also seeing good bird populations and a range of other native species as well.”

The islands are unassuming to look at – sandy and arid in appearance with low-lying vegetation – yet they are teeming with life. 

They are an important site for fairy penguins, Cape Barren geese, short-tailed shearwaters, osprey, white-bellied sea eagles and barn owls. Given the abundant supply of prey, they’re also densely populated with tiger snakes.  

For millennia the islands have remained virtually untouched by humans, and to ensure their protection, we must keep it that way.  

“One of the risks to maintaining these islands is the biosecurity risk of people bringing things, accidentally or deliberately – stow-away mice, pathogens, weeds – that kind of thing,” said Professor Moseby. 

“These islands are the last safe haven for these species so we need to protect them.”

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.

The management plan prioritises conservation by protecting habitat and wildlife breeding areas, minimising impacts to wildlife sensitive to disturbance, and limiting visitation to designated sites to help prevent the introduction of invasive and feral species. 

Access to the Franklin Islands is prohibited to protect its unique and vulnerable inhabitants.

“We’re lucky in South Australia to have offshore islands, because without them a lot of these species we would have lost forever,” said Professor Moseby.

There’s another thing the greater stick-nest rat and Nuyts southern brown bandicoot have in common. Their strong numbers on the Franklin Islands make them top candidates for introduction to the Flinders Island Safe Haven, where feral rodents and cats are being eradicated. 

If successful, the population and territory of these lesser known mammals will expand, increasing their chance of survival so they can continue to be part of South Australia’s unique biodiversity.