Abstract
Australia's largest river, the mighty Murray, slowly makes it way along 1,600 miles from its source to the sea. As the little creeks and streams merge, the Murray slowly widens and deepens and becomes a very beautiful river. It passes through a great variety of country as it meanders toward its mouth in South Australia.
The Murray is an important resource also as its water is used by all the towns along its course. Fruit, sheep, wheat, rice, tobacco, citrus, cattle, and all the agriculture along the Murray use its water for drinking and irrigation.
The swamp birds and other wildlife also depend upon the Murray. When the river floods its banks all the low areas become a huge swamp covering some 300,000 acres with the Murray flowing through its middle. At the little town of Barmah the river banks are high and only about 250 yards wide. This bottle-neck backs the water up into the low areas and keeps the swamps from draining too quickly.
During times of flood (the Murray doesn't flood every year) all kinds of water birds come to the swamps to breed. The environment is suitable for all their requirements. There are great areas of reed beds, vast marshy plains of grasses, and plenty of trees both large and small to nest in. There are also a number of high places that become temporary islands sometimes nearly ten miles long. The ground animals tend to congregate on the islands when they are flooded from their normal homes.
To really study and enjoy the wildlife it is necessary to travel through the swamp by boat. I used a sixteen foot boat that was pushed along by pole. I camped each night on one of the many islands.
Birdlife became evident as soon as I entered the swamp. Ducks were plentiful with the black duck (Anas superciiiosa) and grey teal (Anas gibberifrons) being the most common. It was not uncommon to see one fly out of a hole high up in a tree. Other ducks nested low to the ground in a stump where the eggs were sometimes visible. If the duck was not on
the nest her ten to fifteen eggs could be seen covered with feathers and down. Several clutches of little balls of fluff tried to hide in any cover that was on hand while the mother duck feigned a broken wing and tried to lure me away from the babies.
Almost as plentiful as the ducks were the bald coots (Fulica atra), the dusky moorhens (Gallinula tenebrosa), and the eastern swamp-hens (Porhyrio melanotus). Most of these birds nested in the reed-beds where they made the reeds into very neat nests. Some individuals, however, had forsaken the reed-beds and nested under logs or in small saplings.
The second small island I camped on was already occupied. The rising water had squeezed a few kangaroos up onto the island and they didn't seem to like the idea of company. They didn't like the water either but they compromised by going out into the shallow water just a little ways. There they just sat and looked at me as I sat near my campfire and listened to the night noises.
The frogs make an incredible amount of noise. It sounds like a million different voices each trying to outdo the other. Another rather noisy creature is the beautiful black swan (Cygnus atratus). The swans make a very noisy ritual of their mating. Much honking and flapping goes on all night. The displays were obviously effective, though, for during the next few days I saw nests in all stages of construction, eggs in various stages of incubation, and finally a few babies or cygnets. Nothing is so beautiful as the sight of a graceful swan swimming along with five or six little white bits of fluff following in her wake.
The swans are very adept at building nests of whatever material is at hand. Some build out of bark, sticks and debris found two or three feet under water, others bend the dense reeds into tight nests, still others use cat-tails or grass. Once when I climbed a large tree near the reed-beds I had a good view over a large area and saw three or four swan nests per acre.
Deeper into the swamp I found crested grebes (Podiceps poliocephalus). They are very shy birds quite hard to see. Their nest is a flat affair right at water level, in fact they often float. Sometimes the nest is anchored to sticks or debris. The center of the nest is piled with leaf-mold which has a heat of its own and seems to help incubate the eggs.
Much easier to find were the comorants, They nest in huge rookeries in which there were three species, the yellow-faced comorant (Phalacrocorax varius), the little pied comorant (Phalacrocorax melanoleucos), and the black comorant (Pb alacrocorax sulcirostns). Scattered about in these rookeries were lots of herons, egrets, and two species of spoonbills. It is not pleasant to be in or near these large rookeries as the smell is terrible. Dead fish, dead birds and the cornorant's vomit tend to pollute the area. I put my boat very near a huge rookerie and sat for awhile. When alarmed the cornorants rise to the sky in a panic and circle. When they calm down they all drop slowly down to the rookerie and fight and squabble until each bird finds it own nest. The big black comorant (Phalacrocorax carbo) seems to have much different habits. This species prefers to nest in small colonies of twelve to fifteen nests out in the open or in large trees. The very tops of the large trees, however, were quite often occupied by wedge-tailed eagles (Aquila audax).
There were many pelicans in the area and it was very interesting to watch them fish. They had a good system. They would fly some distance out toward the deeper water then light on it in a staggered line. They then swam toward the shallows driving great schools of small fish before them. The pelicans (Pelecanus conspictllatus) swam with their lower beak or pouch under water and when the water became only about one foot deep one could see how many fish the pelicans were catching-sometimes from fifty to eighty tiny carp per fishing trip.
Day by day as I poled by boat from one island camp to another I saw a great variety of ducks including musk duck (Biziura lobata) which dove and swam very well but almost never flew; blue winged shovelers (Anas rhynchotis); white-eyed ducks (Anthya australt"s) which made a very neat reed nest complete with roof; pink eared duck (Malacorhynchus membranaceus); maned goose (Chenonetta jubata); chestnut breasted shelduck ( Casarca tadornoides); plumed tree ducks (Dendroe ygnaeytone); and some whistling tree ducks along with a number of freckled ducks.