A Tale of Two Cockatoos - Part II
Unfortunately both Carnaby’s and Baudin’s Cockatoos are under threat, especially Carnaby’s. It is estimated that their numbers have dwindled by 50% in the last 50 years. In Perth vast areas of coastal Banksia, Hakea and Grevillea, where they used to feed in winter, have been cleared for urban development. Many birds have resorted to feeding in the Gnangara pine plantations, but now these too are being cleared to help the recharge of the Gnangara aquifer. In the wheatbelt much of the woodland where they nest has been cleared for farming.
Cockatoos are long-lived birds and these are no different, living for 40 or 50years in the wild. So it is likely that with little breeding success lately that they are an ageing population and that numbers are likely to fall even more rapidly. Indeed, there is evidence that on the Swan Coastal Plain numbers have been declining by around 15% per annum in recent years.
Carnaby’s historically have nested in Salmon Gum and Wandoo woodland in the Wheatbelt and Great Southern, but mature trees have become scarcer as they are felled for firewood or because they are unsightly. They face competition for scarce nest sites from invasive species like Galahs, Long-billed Corellas and Honey Bees. Successful breeding requires that they have sufficient food plants within 6 to 12km of the nest site and this is becoming rarer in a drying climate. Efforts are now being made to encourage breeding in the west of the state, with some success on the Swan Coastal Plain.
Around Denmark birds feed on the coastal heathland, targeting banksias and hakeas and also in forests, especially on Marri nuts, they can often be located by listening for the thud of nuts being dropped. With the decline in numbers to the north, our populations of these iconic birds in the south have become even more precious.