Drying Wetlands Put Southern Australia's Brolgas at Genetic Risk

Brolgas are large, graceful birds that live across Australia, but the ones in southern Australia are in serious trouble. A new study from Macquarie University found that brolgas in Victoria and south-east South Australia have very little genetic variety among them. This lack of diversity makes it harder for the population to survive diseases, extreme weather, or other threats. Scientists say the main cause is the loss of wetlands, the swampy areas brolgas depend on for food and breeding.

Brolgas can grow up to 1.5 metres tall and have wingspans of up to 2.5 metres. They are famous for choosing one mate for life and performing an elaborate dancing display together. While brolga numbers are healthy and stable in northern Australia, the story is very different in Victoria, where fewer than 1,000 birds remain and they are listed as endangered.

The Macquarie University study looked closely at the genetic makeup of brolgas in both the north and the south. Researchers found clear differences between the two groups, confirming that they have become separate and distinct populations over time. Within Victoria, there was very little genetic variation from one bird to the next, which is a warning sign for the future.

Lead researcher Abby Bryce explained why genetic diversity matters so much. She said that one individual bird could carry a genetic trait that helps the whole population survive an extreme event. If there are fewer birds with different traits, there is less chance that any one bird will have just the right qualities to help the group pull through a crisis. That puts the whole southern population at greater risk.

Ms Bryce said that wetland loss is the biggest driver of the problem in Victoria and south-east South Australia. When wetlands dry up or are drained for farming, brolgas are forced into a smaller area. Birds that live in a smaller area are more likely to breed only with nearby relatives, which reduces genetic diversity even further. She added that climate change and habitat degradation are also making conditions harder for brolgas.

Brolgas hold deep meaning for the Gunditjmara people of south-west Victoria. Damein Bell, a Gunditjmara man, said the birds — known as 'kurout' in the Gunditjmara language — are a totem for his ancestors. He described them as fierce and loyal protectors of their own families, noting there are well-known photographs of brolgas defending their nests from swans and foxes. 'For an indicator of country health, our brolgas are very important for down here on Gunditjmara country,' he said.

Gunditj Mirring Traditional Owners Aboriginal Corporation has led water restoration work at Tae Rak, also known as Lake Condah, a site the Gunditjmara people have used for centuries. Since the restoration work began, brolgas have returned to the lake. Evelyn Nicholson, manager of the Budj Bim Indigenous Protection Area, said the landscape has changed so much that it is no surprise rare species are struggling. 'But what is within our power to do, we will do to support them,' she said.

There is real hope coming from wetland restoration efforts across the region. The Nature Glenelg Trust has been working to restore wetlands that were drained long ago for farming. Director Mark Bachmann said the results have been encouraging, with up to 250 brolgas flocking to Green Swamp, a restored wetland in the Southern Grampians region, at one time. The birds have proven very good at finding newly restored wetlands on their own.

Mr Bachmann said every wetland that is brought back makes a difference for the species. Restoring these areas gives brolgas more space to roam, breed, and find food, which in turn helps build up the population. Greater numbers across a wider area can also help improve genetic diversity over time. 'We can make sure that they're here for our kids and our grandkids to continue to enjoy and see in the landscape,' he said.