Day 4, Bourke to Moree
Observers: Richard Kingsford & John Porter
Pilot: James Barkell
We left Bourke early and headed to the northwest to the Paroo River wetlands - this time the Currawinya Lakes in Queensland. These two magnificent lakes are part of Currawinya National Park, and also a centre-piece for conservation as Ramsar-listed wetlands on the free flowing Paroo River. They have extraordinary waterbird communities, spectacular at times. And today was not disappointing. Before we got there, we flew past Yantabulla Swamp which connects Cuttaburra Creek from the Warrego River, to the Paroo River. It is a fantastic wetland when it has water, with tens of thousands of waterbirds. But today, it was dry.
Lake Numalla, the freshwater pair of the two Currawinya Lakes, was drying back, not at full flood, with its northwestern and western parts dry.
Still, the lake had hundreds of waterbirds, including a colony of pied cormorants nesting in the middle of the lake on the tops of the dead trees. There were also good numbers of pelicans, wood ducks and grey teal.
From here it was just a hop skip and a jump west, about three kilometres, across to Lake Wyara, the salt lake of the Currawinya Lakes. This has to be one of the most important wetlands for waterbirds on this continent. Today it was amazing. It was some time since we'd seen so many waterbirds on the lake. It was probably only about 70% full but even from the air, you could see through the clear water to the aquatic vegetation underneath which is the engine room for the incredible biodiversity on this system. This primary productivity drives high numbers of invertebrates, all of which is reflected in the high density, diversity and numbers of waterbirds.
There were up to a 100,000 waterbirds or more on this lake, including thousands of pink-eared ducks, Eurasian coot, hardheads, and black swans with hundreds of cygnets. There was also a colony of up to 50 breeding Australian pelicans on the lake, along with quite a few swan nests.
And then of course there were all the other waterbirds. These included Caspian terns, pied stilts, black duck, grey teal, whiskered terns, and freckled duck. There were hundreds of migratory wading birds swirling around under the plane. These have just arrived from the northern hemisphere where they have bred in China and Russia.
It was a wonderful opportunity to count this amazing lake. Exhausting work but also exhilirating. We were flat out counting as fast as we possibly could with so many waterbirds in such dense numbers.
We headed back to Bourke and early lunch and then flew down to survey band 5. Just southeast of Bourke, there were only a few temporary wetlands, most of which were dry. Then we hopped our way east, from farm dam to farm dam, with the odd creek or river flowing north, such as the Bogan River. None of these provide much habitat for waterbirds.
We finally got to the Macquarie Marshes and our survey involved two approaches. First of all we surveyed the top third of the Macquarie Marshes which is within our 30 km wide survey band, consistently flown since 1983. Our 39th year, if you are counting. So we have excellent data for long term tracking of this indicator of waterbirds across the Macquarie Marshes. Remembering that we are tracking the fish-eaters, plant-eaters and invertebrate-eaters and everything in between.
So we zigzagged backwards and forwards, following the flood patterns and counting the waterbirds. It was so great to see water back in the Marshes. Much of this flooding had come from the unregulated tributary flows; the ones that are going to be stopped by the building of a new weir planned by the NSW water agency at Narromine. There is still a reasonably large quantity of environmental flows held by the State and Commonwealth in the dam. There were all three species of ibis - glossy Ibis, Australian white ibis, and straw-necked ibis. And there were ducks; there were herons; there were cormorants and there were pelicans. The waterbirds were back in the Marshes as expected.
One of the concerns was that generally the numbers of waterbirds were thin across the wetland. There was nowhere where we could see more than a few flocks of tens and twenty waterbirds. There were some good indications that some of the birds were starting to nest, including some magpie geese. These are becoming increasingly common in the Marshes when the floods happen. We visited all of the usual major waterbird colonies but there was relatively little action. The colonially breeding waterbirds, the ibis, egrets and spoonbills are loyal to these sites when conditions are right for breeding. There were a few Australian white ibis nesting throughout the Marshes. They are a species that is much more likely to nest on low flows. The whole system was primed for a big flood which is what it needs to really get it humming. It may be an opportunity to capitalise on the natural flows by using the environmental flows held in Burrendong Dam.
Once we had finished the northern third of the Marshes, we used transects across the Marshes, from north to south. There are 11 of these that run east to west and carve out a 200 metre imaginary east to west sliver of the Macquarie Marshes. We fly at a set height and count and identify all the waterbirds in these transects. From top to bottom of the Marshes, this takes a long time. So we didn't get away from the Marshes for a couple of hours, but it was time well spent and very satisfying.
After this, we headed east towards Narrabri. Along the way, there were quite a few places where there was reasonable flooding this year. And these wetlands had a smattering of different species of waterbirds. The day had already been long by the time we reached Narrabri and so we stopped for a brief stretch. From here, we flew further east along the Namoi River where there were a few wood ducks and also surveyed some of the half empty off-river storages used to hold water to irrigate cotton and they had relatively few waterbirds. We headed north to overnight in Moree.
By Richard Kingsford