Land sales would reap millions of dollars,with similar-sized vacant blocks already selling for about $500,000.

The Shoalhaven land is held by Sealark,a company owned by Wollumboola Ltd,the trustee of the Halloran charitable trust. The trusthas four listed beneficiaries,including Scots and the University of Sydney research trust. The other two are the Jervis Bay Maritime Museum and the township of Culburra.

Sealark managing director for land and development Matt Philpott said profits from the land would be paid as dividends to the trust,then distributed to its beneficiaries.

A university spokesperson said it had previously received $10 million in donations from the late Warren Halloran,who established the Halloran Trust.

That money had been used to set up the Henry Halloran Research Trust at the university. The spokesperson said any future donations would be subject to the university’s gift policy and procedures. Scots was also approached for comment.

Australian National University research fellow Kara Youngentob said greater glider numbers had fallen dramatically over the past 30 years,as logging and development cut colonies off from each other.

“They need that connected landscape,” she said. “They need big trees,with big hollows,that take 100 years to grow.”

“They’re a sentinel species. If they are there,it tells you[that place] is a special landscape,an intact forested landscape that’s becoming increasingly rare.”

Philpott said residential blocks in the developments would be cleared of vegetation,but Sealark would try to retain as many trees as possible in other areas. Gliders would be relocated,as would their hollows if possible.

Youngentob could not see how the hollows could be relocated without moving an entire tree. She said gliders would not live in hollows in logs on the ground as they would be vulnerable to attack from other animals.

She said countless animals would die during clearing,even if hollows were checked,because it was not always possible to see every hollow in a tree to before it was felled.

And while there had not been any studies to determine glider survival rates after relocation,she said there was “a very high chance that most of the animals wouldn’t survive that”.

Philpott said the trust,through Sealark,owned more than 2700 hectares of land and more than 2000 of it was to be conserved.

As part of the Culburra and Callala Bay proposals,about 500 hectares would be transferred to the Jervis Bay National Park. Ten per cent of the developments would also be affordable housing.

“Compared to what most developers do,we are well and truly ahead of the game,” Philpott said.

Sealark had also established four biobanking sites nearby from which it could claim offset credits for the habitat that would be destroyed at Callala Bay and Culburra.

The Department of Planning and Environment received 1029 submissions on the Callala Bay proposal,1002 of which opposed it.

Cat Holloway,from the Callala Environmental Alliance,said there was more suitable land in the Shoalhaven to address the region’s housing crisis. Callala Bay and Culburra are about a 20-minute drive from regional centre Nowra.

“People need affordable housing that’s close to transport and health infrastructure,and that’s close to jobs,” she said. “We don’t need more expensive houses for people to come and visit on holiday.”

But Philpott said locals,particularly in Culburra,were supportive of the housing plans and Sealark was working with the council on ways to limit holiday rental properties.

Almost half of all Callala Bay dwellings were empty on Census night in 2021,and 39 per cent were empty in Culburra.

“There will be some holiday purchases,without a doubt. Our coastal towns have always been configured that way,” Philpott said.

“We are talking to council and others about how we can limit Airbnbs,because we know what that can do to our housing supply,and to prices.”

Both sites require further detailed approvals to proceed to construction. Philpott said Sealark hoped to start building within the next three years.

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