Twenty years ago, the koalas around Mount Gilead near Campbelltown in Sydney's south-west, were considered safe with the area explicitly "not required for urban development under the Metropolitan Strategy".
That was then. Now, as pressures mount to grab ever more land for housing, Sydney's last koala holdouts – making up some of the healthiest colonies of the marsupials in NSW – are facing an increased threat.
Campbelltown Council is awaiting government approval to rezone a 210-hectare area of the Gilead Estate, covering a region where the Nepean and Georges rivers are at their closest point.
The council claims there are about 170 koalas in its local government area, while environmentalists say the number is more like 300.
While koalas are hard to find in the earmarked zone itself, development of the site will almost certainly put paid to wildlife moving between the two rivers without carefully designed and maintained wildlife corridors.
Senior Planning staff met environment groups this week to discuss concerns.
These include how rezoning could get the nod even before the council's draft "Comprehensive Koala Plan of Management" – open to the public for input in May and June last year – has been approved by the government.
"The fact you can rezone without the koala plan is a serious weakness in the planning system across this whole region," Jeff Angel, director of the Total Environment Centre said.
"You should finish an effective management plan and get development to adjust to it, not make the plan adjust to some developer's ambition," Mr Angel said, adding the issue was "totemic of the pressures Sydney's koalas and other native species are going to be under" as the city expands.
"The fact you can rezone without the koala plan is a serious weakness in the planning system across this whole region."Jeff Angel, director of the Total Environment Centre
A spokeswoman for Planning said the relevant planning policy doesn't require a koala plan of management when rezoning land. Even so, the department has asked the council "to undertake further work" on the draft koala plan to address issues already raised by the Office of Environment and Heritage.
"The majority of the existing vegetation on the site will be retained as open space, and a biodiversity corridor has been identified through the site and will be in council ownership," the spokeswoman said.
"This will connect the protected vegetation within the site with the Noorumba Reserve in the north and the Beulah Biobanking area in the south. The biodiversity corridor will also enable fauna, including koalas, to move through the site."
Jim Baldwin, director of Campbelltown city development, said the council accepted the area is a "koala movement corridor".
While there have been few sightings of koalas within the Mt Gilead area itself – much of which has been cleared for cattle farming – reported fatalities included along nearby Appin Road from car strikes point to their presence.
"The rezoning proposal is supported by a biocertification application, which is a state government-supported process that incorporates the use of conservation measures and outlines the proposed wildlife corridors across the site," Mr Baldwin said.
"If a threatened species is located on site during development works at the Mt Gilead site, this would trigger a stop work protocol, and the proponent would be required to contact OEH for further instruction on how to proceed."
Ricardo Lonza, a wildlife rescuer who runs the Help Save the Wildlife and Bushlands in Campbelltown Facebook page, has picked up as many as three koalas killed or disoriented along Appin Road in a single night.
"Development should be done properly, so we don't have to wipe out the koalas to build homes," he said, adding that as many as 2000 houses may go up after the Gilead rezoning.
"We're very lucky to have the koalas, we should be doing more to protect and save their disease-free numbers," Mr Lonza said.
Mark Krockenberger, an associate professor specialising in Australian wildlife diseases at Sydney University, said the Campbelltown region represented a "little island of no chlamydia" among koalas in the state.
Chlamydia is typically painful for the animals, "dramatically" reducing fertility, and shortens their increasingly painful lives, he said.
Some areas had seen a big jump in koala chlamydia, including in previously rapidly growing populations such as near Gunnedah.
The proportion of animals with the disease there had gone from 10 per cent in 2008 to roughly two-thirds now.
An increase in stress, perhaps from big heatwaves that have scorched the region several times since 2009, may have made the animals more susceptible to the disease, Professor Krockenberger said.
The Planning spokeswoman said biodiversity issues including impacts on koalas were "a fundamental part of planning for vibrant and sustainable new communities".
"There are examples across NSW where new housing developments and koalas have successfully co-existed, such as Port Macquarie," she said.
The story, Healthy koala colonies potentially the next victims of Sydney's housing crisis, first appeared on the Sydney Morning Herald.