Open pasture has fewer than 5 per cent. Grazing often removes the understorey shrubs and grasses, making remnants less suitable for birds. Birds rely particularly on eucalypt trees, and some 300 bird species live in eucalypt woodlands and forests. But they also need shrubs and grasses to survive. It may seem less obvious that Australian vegetation also need birds.
Birds add natural interest, colour and sound to the bush.
These costs would be similar in Australia if natural predators of scarabs, like magpies, were lost. In cane farms in Queensland, it was found that a pair of native owls could eat around 6 rats per night, saving cane farmers money on rat control and loss of crops. Farmers there encourage the owls by providing nest boxes. Birds reduce insect attacks. Farm birds assist in natural insect control by feeding on insects.