Declining wetlands are behind a genetic rift placing south-eastern Australia's vulnerable brolga population at further risk.

The birds, which can grow up to 1.5 metres tall, with a wingspan of up to 2.5m, are known for finding a breeding pair for life, and have an elaborate mating dance.

Brolgas can be found in all mainland Australian states and the Northern Territory, but a closer look at their populations tells a differing story.

In northern Australia, brolga numbers are stable, but in Victoria, where they are listed as endangered, numbers are as low as 1,000 in the state.

A new Macquarie University study into their genetic makeup has found differences between the northern and southern populations, confirming beliefs the two groups had become distinct.

There was little genetic variation among individual birds in Victoria, pointing to increased vulnerability into the future as traits that aid survival become limited.

"One individual could have that genetic makeup that's really good for surviving an event, an extreme event, and can help that population to survive," lead researcher Abby Bryce said.

"If there's less of those individuals and less of that genetic diversity, there's not as much of that diversity to have one or two that could give that slight edge for that population down the line."

Ms Bryce said the reduction of wetland habitat for brolgas to breed and feed was driving the reduction of numbers in Victoria and south-east South Australia.

The loss of wetlands also meant the birds roamed across a smaller area, exacerbating genetic concerns.

"All of these factors, wetland loss, degradation and climate change are all playing a factor and limiting the habitats and conditions brolgas are having to live with."

'Physical protectors'

Brolgas hold a special place for Gunditjmara people. They have long shared a home together in south-west Victoria.

Gunditj Mirring Traditional Owners Aboriginal Corporation's Damein Bell, a Gunditjmara man, says kurout, as they are known in the Gunditjmara language, is a totem for his ancestors.

"They're such a protector of their own family," he said.

"There's a series of pretty well-known photographs of brolgas protecting their nests from swans and from foxes, a very physical protector."

Brolga were once spread throughout swampy wetland areas, but as land was drained for farming activities, their numbers declined.

"For an indicator of country health, our brolgas are very important for down here on Gunditjmara country," he said.

Gundtij Mirring has led water restoration projects at Tae Rak (Lake Condah), which have seen brolgas return to a site used by Gunditjmara people for centuries.

"The landscape has been changed so much that it is expected that our rare and threatened species are not going to be doing so well," Budj Bim Indigenous Protection Area manager Evelyn Nicholson said.

"But what is within our power to do, we will do to support them."

Wetland restoration working

The Nature Glenelg Trust is involved in wetland restoration projects across south-east SA and south-west Victoria.

Director Mark Bachmann said conservation efforts had shown real promise.

Green Swamp, a restored wetland in the Southern Grampians region, had recorded up to 250 birds flocking there at one time.

"Whenever we restore a wetland that may have been drained historically and if it has the right attributes for brolga to utilise, then the birds find those wetlands," he said.

"That shows us that when those birds that have gathered and flocked up each year, then dispersed around the landscape, they're actually pretty good at finding a restored wetland in the landscape."

Mr Bachmann said each wetland restored "to the way it was" made a difference.

"We can make sure that they're here for our kids and our grandkids to continue to enjoy and see in the landscape."