Date: Wednesday, October 21, 2015
笔谤辞箩别肠迟:听Eastern Australian Waterbird Survey
Observer - Richard Kingsford
Overnight thunderstorms and a southerly change had considerably cooled the outback 鈥 surveying in low temperatures out here is always a welcome relief. We went south to inspect the Darling Anabranch Lakes, which fill when there is a good flow in the Darling River and water goes two ways near Menindee, down the main branch of the river and down the Darling Anabranch. As expected, they were dry, given the low flows in the Darling River.
Video 1. River Murray, near Loxton, and its parched floodplains and billabongs
Then west to the beginning of band 3 on the River Murray in South Australia, near the town of Loxton.聽聽Here the sinuous River Murray, with its many billabongs and swamps, winds its way through the irrigation areas that flank the main channel.
Our surveys cover the lagoons within the 30km wide survey band. With limited flooding over the past year, many of billabongs and lakes wetlands which normally have water were dry. There were also a few waterbirds, mainly fish-eating birds such as cormorants and pelicans dotted along the river. Just west of Loxton, we surveyed the evaporation ponds where aquatic macrophytes (types of sea grasses) grow and provide feeding habitat for swans and grey teal.
Our eastern progress was helped by a strong tail wind, as we continued on towards the River Murray. First there were the tired and highly degraded wetlands south of Mildura. These are now become dominated by salt with only the odd black swan and Australian shelduck eking out a living. Karadoc Swamp seldom has water, even in the wettest of years. It is probably no longer a viable wetland.
Photo 1. The River Murray under our plane just south of Mildura.
Near Robinvale, there are three lakes. The Euston Lakes hold water constantly and are not particularly productive waterbird habitats. There was shallow water across Lake Caringay to the west which was brimming with waterbirds of many different species. It really shows what you can make happen with a bit of environmental flooding of wetlands.
Photo 2. Lake Caringay, just west of Robinvale, with its shallow water creating lots of productive areas for waterbirds
On east to the Murrumbidgee wetlands and the magnificent, although degraded Lowbidgee wetlands, near Balranald. As with most other rivers, there is little water here. The Murrumbidgee carries flows and there is water in the almost perennial Lakes Tala and Yanga but little else. A few of the swamps have water, particularly Piggery Lake and Breer Swamp, where there is water probably from environmental flows, supporting hundreds of waterbirds and a diverse community of large and small wading birds and ducks.聽
Video 2. Surveying Piggery Lake, one of the wetland jewels in this dry landscape.
The waterbirds we saw in these pockets reminded me of why this system was once known as 鈥淟ittle Kakadu鈥, one of Australia鈥檚 great wetlands. It is incumbent on us to rehabilitate this magnificent system, particularly the Nimmie-Caira system to the west. There is a wonderful opportunity for policy-makers and managers, supported by the scientific community.
Photo 3. Yanga Lake National Park with its homestead, looking across the Lowbidgee floodplain with the scattered thunderstorms which dogged our survey.
East of the Lowbidgee, our surveys focus on the rice fields and off-river storages where irrigation water is respectively flooding rice growing areas and water is stored for later use. There is more cotton now grown in this part of the Murrumbidgee River. The rarity of rice fields is obvious this year, reflecting the lack of water in the system. These wetlands seldom support many waterbirds, generally just a few waterbirds like herons feeding here and there.聽聽The large off-river storages were a surprise on the waterbird front. Usually, they have few waterbirds but some had hundreds this year, reflecting how little water there is in the landscape. We finish up in Griffith.
Video 3. Crops along the Murrumbidgee are irrigated by water stored in large off-river storages which this year had hundreds of waterbirds.