Dancing Brolgas
by Matthew Herring
Brolgas breed as separate pairs in the wettest season, July to December in southern Australia, and flock together near wetlands in drier months. In Part 1, author Matthew Herring outlines the serious inroads made into southern Australian Brolga numbers by wetland loss, historical persecution and foxes. In Part 2, he reveals important steps for wetland management and key support from southern farmers for Brolga conservation.
This article was published in a special Wetlands edition of Wingspan, former membership magazine of Birds Australia (now BirdLife), Vol. 14:4 December 2004. The original text is reproduced by permission (edited for web by Ozcranes).
Part 1 | A national icon: trouble in the south
I doubt many birdwatchers tire of the iconic Brolga, arguably Australia's most treasured waterbird. Whether a breeding pair calling in unison, a lively group on a wetland dance floor, or a graceful flock sailing overhead, Brolgas seem to capture our attention effortlessly.
Fortunately, it is thought that the total remaining Brolga population may number 100,000 or even higher. The vast bulk of these occupy the extensive wetlands and plains of northern Australia, in core areas such as the Atherton Tableland, the Gulf Country, Mount Isa region, Kakadu National Park and parts of the Kimberley. Smaller numbers occur in (Papua) New Guinea, as well as south throughout most of Queensland, spilling into the far north-east of South Australia and across parts of northern New South Wales. Further south, however, Brolgas are in serious trouble.
Falling southern population Brolgas are considered a threatened species in South Australia, Victoria and New South Wales. Once common enough to be regarded as a widespread pest of crops, the southern population has been reduced to alarmingly low numbers. We now know that in total there are fewer than 1,000 birds scattered across south-western Victoria, the far south-east of South Australia, and the New South Wales and Victorian Riverina. Central New South Wales is almost devoid of Brolgas, largely isolating the southern population from its northern counterpart.
Brolgas are now extinct in the Upper Murray River Region, the plains east of Melbourne through Gippsland and elsewhere in south-eastern Australia. In Victoria, breeding now only occurs as far east as Werribee and Rutherglen. In fact, Brolgas have become near impossible to find east of the Hume Highway, which stretches from Sydney to Melbourne. Landholders report continuing local declines in recent decades. The main drivers behind these southern declines are thought to be wetland loss, historic shooting and poisoning campaigns, and predation of young by the introduced fox.
Poor recruitment As the south-eastern Australian summer slowly dries their ephemeral breeding habitat, Brolgas flock together at non-breeding sites, usually within 40 km. Such sites include a wetland with minimal disturbance and open, shallow water for roosting, surrounded by extensive crop stubble and paddocks for foraging. These spectacular Brolga gatherings provide an excellent opportunity to measure recruitment, simply by counting the flock and the number of immature birds.
← Adult Brolga guards twin chicks, an unusual sight in southern Australia (Ian Montgomery)
Not surprisingly, the count varies from year to year. For example, in the Riverina, in the year 2000 there were six immature birds among a total of 137 Brolgas (4 per cent) but none amongst 123 present in 2003, after a drought. Being such a long-lived species you'd be tempted to think these sorts of figures might be sufficient to maintain a viable population. But frighteningly, recruitment in southern Brolgas is typicaly about one quarter or less than that of Brolgas in the north, where up to 15 per cent is commonplace.
TOPPart 2 | A national icon: hope and action in the south
Creating and managing wetlands for Brolgas Down south, Brolgas usually breed between July and December, in response to winter and spring rainfall. They nest as isolated pairs, each pair typically requiring a large (30-200 ha) ephemeral, shallow (maximum depth about 60 cm) and well-vegetated wetland, with little or no tree cover. In the Riverina, more than 90 per cent of breeding sites are Canegrass (Eragrostis australasica, E. infecunda) or Spike-rush (Eleocharis species) dominated wetlands. Many wetlands of this type have been lost since European settlement.
The management of flooding, grazing and fire regimes at the remaining wetlands is very important, as they have a huge effect on the structure and composition of wetland vegetation. For example, under certain circumstances, Canegrass can form thick rank growth that reaches more than two metres in height, whilst more permanent water regimes benefit other tall, robust waterplants, such as Cumbungi (Typha species). When breeding, Brolgas avoid wetland vegetation taller than about a metre, probably because adults like to maintain a panoramic view of their surrounds. Fortunately (for Brolgas at least), Canegrass and Cumbungi are often burnt or crash-grazed to encourage succulent shoots and palatable growth, promoting the future grazing value for stock.
Promisingly, Brolgas will also breed in small (<5 ha) artificial wetlands – large farm dams – provided there are seasonally flooded shallows about 30cm deep, with a healthy cover of emergent waterplants. Landholders with large storage or recycling dams on their farms are in a good position to create potential Brolga breeding habitat. Simple modifications to farm dams can dramatically increase their value for Brolgas, other waterbirds and biodiversity generally. Earthworks to create seasonally flooded shallows and a reduction in grazing pressure are amongst the most successful techniques.
A species worth focussing on People readily identify Brolgas, and observers (mostly farmers) have played a key role in my research, helping to locate breeding and flocking sites each year.
← Brolga nest with surrounding ‘moat’ (M Herring)
Extensive landholder engagement has revealed that the Brolga is an effective communication tool for promoting wetland conservation. Comfortingly, there is now a great deal of wetland conservation targeted at Brolgas in south-eastern Australia.
Brolgas have become flagship species for wetland biota; deservedly so, because their breeding sites are particularly rich in bird life. Good numbers of species like the Baillon's and Spotted Crakes, Glossy Ibis, Black Swan, Purple Swamphen and Red-kneed Dotterel are commonly found at Brolga sites. Of particular significance, more than a third of Brolga breeding sites in the Riverina support the Australasian Bittern, a rare, cover-dependent species of national conservation concern. And finally, even the near-mythical Australian Painted Snipe has been found at a handful of Brolga breeding sites. A big challenge for the future management of Brolga wetlands is incorporating the breeding habitat requirements of these (and other) species. Striking the balance between too much wetland plant cover and not enough is at the heart of this challenge.
More:
- Brolga wetland project, NE Victoria (Video, 9m 15s)
- Brolga FAQs 2»
About the authorMatt was the founding southern Australia representative for the Australian Crane Network, having completed his Honours degree studying threatened Brolga breeding in the Riverina district, south eastern Australia. He is now undertaking a PhD study on the endangered Australasian Bittern breeding in rice fields in the same area. His wide range of studies, reports and community action can be seen at Murray Wildlife.
