Residents believe an advertised townhouse development site at Jannali will be a crucial test of Sutherland Shire Council's Greenweb conservation strategy.
Three adjoining properties in Wattle Road, opposite Honeysuckle Reserve and Carina Gully, are being offered for sale in one line.
The properties are zoned R2 low density, where townhouses are permitted, but the area is identified on the council's website as being a Greenweb zone.
Council's Greenweb program identifies key areas of bushland habitat in the shire and establishes corridors to connect them so both plants and animals can move easily between them.
Greenweb operates on both public and private lands, however the main target is private property owners within the Greenweb network.
A real estate ad says: "The Wattle represents a unique opportunity to acquire a rare huge land area suited for a townhouse development with at grade car parking or a childcare development".
However, residents in the surrounding area feel a tighter development zoning should be applied than what is normal for an R2 zone.
There is no development application before the council, but residents want to send an early warning to any developer they will fight any such proposal.
"I am rattled to my core that this type of development is even allowed in an area that is in a Green Zone protection area," said one resident, who is a wildlife children's book illustrator.
"I imagine they will try and cram as many townhouses on the site as they can.
"Honeysuckle Reserve is an important green corridor for wildlife including native bird species such as King Parrots, Crimson Rosellas, Black Cockatoos, Rainbow Lorikeets to name just a few.
"It is also home to many reptile species, whose numbers are already declining due to regular housing and population.
"I hate to even think how a development of this scale will impact the wildlife that rises in the creek and green corridor.
"Honeysuckle Reserve needs to be protected from the impacts of any future developments, not only in long term council plans, but immediately.
"There needs to be clear guidelines for appropriate developments in R2 and protected Green Zones so they are actually protected for future generations and for our local wildlife.
"That is a major reason why residents bought homes here in the first place."
A Sutherland Shire Bushcare volunteer said "this parcel of land forms an important connection between Honeysuckle Reserve and Carina Bay Reserve and is mapped as a Greenweb Corridor on the council's web page".
"I have difficulty in seeing how a development of this nature is compatible with the objectives of Greenweb."
About 30 residents from Wattle Road, Tivoli Esplanade, Honeysuckle Street and Jannali Crescent gathered at short notice for Leader photos and more than 50 signatures of protest were gathered within a few days.
A 91-year-old resident, who fought against older townhouses in one of the streets about 25 years ago was among those showing their concern.
A young family, who have recently moved into Wattle Street, told how they had moved from the inner city "to get away from busy streets and cramped housing and chose this location especially for its peaceful atmosphere and leafy outlook".
Another concern of residents is the impact any large development would have on the narrow roads in the area, which includes St Joseph's Infants and Primary School.
Also, they say when there is heavy rain the sewer pipe that runs through Honeysuckle Reserve can overflow and affect the creek.
"Imagine what would happen if these additional town houses were added in this location," one resident said.
