Native bush rats have returned to two pockets of northern Sydney bushland as part of an ambitious University of Sydney-led project aimed at restoring one of the city's overlooked engineers of ecosystem health while testing new approaches to wildlife reintroductions, known as rewilding.

Researchers from the University's Global Ecology Lab and Behavioural Ecology and Conservation Lab have released 104 native bush rats (Rattus fuscipes), known as boguls in the Dharug language, into Twin Creeks Reserve near Turramurra and Allenby Park at Beacon Hill. The project has also been active in strengthening the existing bogul population at North Head, where the bogul was successfully reintroduced more than a decade ago.

The most recent reintroduction was delivered in two phases across Twin Creeks and Allenby Park, with the first release of 24 bush rats taking place in March 2026 and the second involving 80 bush rats in June. Researchers are now in the monitoring phase, tracking how the animals establish themselves in their new homes.

The project forms part of the Sydney Rewilding Initiative,  an exploration of how carefully planned reintroductions can help restore native wildlife and ecological function to urban bushland.

The project was designed by University of Sydney PhD candidate Mareshell Wauchope, whose doctoral research focuses on improving the success of wildlife reintroductions in urban environments. She is supervised by Dr Patrick Finnerty, Associate Professor Thomas Newsome and Professor Peter Banks in the School of Life and Environmental Sciences.

"Cities have lost many native species as urbanisation has intensified, but they can still support surprisingly rich biodiversity," Ms Wauchope said.

"Urban rewilding is about bringing back the native animals that quietly keep ecosystems functioning. Bush rats might not be well known, but they disperse seeds and fungi, support healthy vegetation and even help sustain native wildlife by competing with introduced black rats.

"By returning boguls to these reserves we're not simply reintroducing a species, we're helping restore the ecological relationships that have been missing from Sydney bushland since the species disappeared."

Small mammals; big ecological role

While bush rats rarely attract the attention given to koalas or quolls, they perform vital ecological functions.

“Bush rats aren't the animals that usually make the headlines, but they're some of the hardest workers in the bush,” Ms Wauchope said.

“They're exactly the kind of species we should be bringing back into our cities."

Native bush rats benefit other native wildlife. They compete strongly with introduced European black rats, helping suppress populations of one of Australia's most widespread invasive mammals. Fewer black rats can reduce predation pressure on small reptiles, such as skinks, invertebrates and the nests of native birds.

Unlike these introduced black rats, bush rats feed largely on fungi, seeds, fruit and other plant material. As they move through the landscape they disperse seeds, fungi and pollen, helping to maintain healthy native vegetation. Bush rats were also among the first rodents anywhere in the world to be documented as pollinators.

"Keeping these vital native species a common presence in the bush is one of the most effective ways we can restore ecological function," Ms Wauchope said.

Testing new approaches to rewilding

Wildlife translocations are increasingly used around the world to restore declining species, but many reintroductions fail because animals quickly disperse from release sites or struggle to establish new populations.

Rather than simply releasing animals, the Sydney team has incorporated a series of behavioural experiments into the project.

Across both reserves, researchers are testing whether familiar scent cues can help animals remain close to their release sites, and whether releasing socially familiar groups alongside extra? Accompanying? shelter and feeding improves survival and establishment.

Each animal has been microchipped, shave-marked and monitored using a combination of live trapping, camera traps and radio tracking.

Dr Finnerty said the project addresses one of the biggest challenges in conservation reintroductions.

“This project has reintroduced the native bush rat – a regionally common but locally extinct native mammal – into two urban reserves while testing practical strategies that could improve the success of future wildlife reintroductions into fragmented urban landscapes.

“It will help restore a missing native mammal to Sydney's urban ecosystems while generating evidence-based tools that conservation practitioners can use in future urban reintroductions.”

The research team hopes the project will generate practical evidence that can improve future urban rewilding programs in Australia.

Building healthier urban ecosystems

The project is part of a broader movement to restore ecological processes within cities, recognising an increasing need for conservation in residential areas.

The researchers are working closely with government agencies, councils and conservation organisations to coordinate invasive species management, habitat restoration and long-term ecological monitoring.

More than 30 student volunteers have already participated in fieldwork, gaining hands-on experience in wildlife ecology and conservation science.

The project is a collaboration between researchers from the University of Sydney and Macquarie University, together with Taronga Conservation Society Australia, Local Land Services, the NSW National Parks and Wildlife Service, Anderson Environment and Planning, and the Sydney Harbour Federation Trust.

Local government partners include Mosman, Northern Beaches, Ku-ring-gai, North Sydney, Hornsby, Willoughby and Lane Cove councils.

It has been funded by an Australian Research Council Linkage Grant.

Monitoring of the newly established populations continues, with the research team preparing two scientific papers examining the effectiveness of the behavioural rewilding techniques being tested.

Main photo

A native bush rat (Rattus fuscipes) or bogul on North Head in Sydney.

Declaration

The authors declare no competing interests. Funding was received from the Australian Research Council.