By Collis, Brad
From town to town, and farm to farm, David Freudenberger travels Australia's hinterland: a determined evangelist. He carries a ritualistic wooden case containing tiny samples of Australia's vanishing soul.
He displays the preserved remains of wagtails, fantails, wrens, thornbills, whistlers and honeyeaters: little woodland songbirds whose dawn chorus once roused the towns, suburbs and farms of past generations.
But an estimated 90-95% of Australia's woodlands are gone, and Freudenberger's sobering message is that despite the good intentions, Australia's revegetation effort in recent years is a long way short of what is needed to sustain the remnant populations of these species.
`In 1962 the American ecologist Rachel Carson sounded the environmental wakeup alarm when she wrote Silent Spring, a book about the absence of birdsong in the landscape because of the over-use of pesticides. Well we're creating a silent spring through the over application of the bulldozer and the sheep and cow,' says Freudenberger, a researcher with CSIRO Sustainable Ecosystems.
Freudenberger is working with Greening Australia on an ambitious new program to bring the small woodlands birds back into the Australian landscape, while there is still time.
The `rebirding' program is expected to lift the national revegetation debate to a new level because research has shown that many so-called wildlife `corridors' and the scattered patches of natural bush restored by farmers are generally far too small to have much effect.
`Unfortunately we can no longer afford willy-nilly "feel good" plantings,' Freudenberger says. `We have to get specific in terms of minimum area, maximum protection from grazing, and correct plant composition.
`The main problem is that many replanted areas tend to be narrow corridors or small patches of a few hectares. But we're discovering these birds need a minimum of 10-20 hectares for them to reoccupy an area, and perhaps up to 100 hectares to settle and breed.'
Freudenberger is the first to admit it's a `big ask' of landholders, but he's quick to insist it's not a figure plucked from the air.
`I'm afraid if people want to argue they'll have to argue with the birds, and decide if they want birds in their landscape,' he says.
`The purpose of my museum specimens is to show people what I'm talking about, to show what an eastern yellow robin looks like because you never see the woodland birds up close; they are just shadows flitting among the trees.'
The rebirding program has come from research started in the Western Australian wheatbelt in 1995. The work investigated the ecological impacts of over-clearing and sought ways to redress the issue.
CSIRO scientist, Rob Lambeck, came up with the concept of `focal species' as an effective way to measure threatening processes such as clearing, loss of biological diversity, and dryland salinity. (See Ecos 100.)
Rather than try to monitor the health of a wide range of plants and animals, he sought to identify the species that were the most sensitive to particular threats.
Lambeck, and now Freudenberger, have observed that by identifying the so-called `focal species' and responding to their needs it establishes an ecological umbrella under which the needs of many other species may be covered.
This is allowing a far more strategic approach to revegetation, particularly in the denuded wheatbelt of WA, where many farmers are becoming willing participants, particularly as the most common focal species are the small woodland birds.
Freudenberger says one of the reasons birds are useful bio-indicators is that they need a dense understorey, which requires revegetation to be far more comprehensive than just tree-planting.
`We've found that woodland birds tend to drop out of the landscape once the bush becomes fragmented. They need a lot of three-dimensionality; trees and shrubs of varying height and density,' he says. …