I don't know if this is new, but it is currently at the top of the ABC webpage
Across Australia, the bush is falling silent as songbirds disappear. It seems
the tree-planting efforts of the past decade have not been enough. Now we are
learning more about what the birds really want. Brad Collis explores the
re-birding of Australia.
>From town to town, farm to farm David Freudenberger travels Australia's
hinterland; a determined evangelist. He carries a ritualistic wooden case and
inside are tiny samples of Australia's vanishing soul.
Borrowed from a museum, 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 to 95 per cent of Australia's woodlands are gone and David
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 wake-up
alarm when she wrote Silent Spring; 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," said
Freudenberger, a researcher with CSIRO Sustainable Ecosystems in Canberra.
Wildlife corridors too small
Freudenberger is now 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. We've
got to get specific in terms of minimum area, maximum protection from grazing,
and correct plant composition," says Freudenberger.
"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 or 20 hectares for them to reoccupy an area, and perhaps up to 100
hectares to settle and breed there."
Freudenberger is the first to admit it's a 'big ask' of landholders, especially
farmers, 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.
"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."
Woodland birds as bio-indicators
The rebirding program has come out of 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.
A young 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 biodiversity, and dryland salinity.
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
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 also be covered.
This is now 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
Freudenberger says one of the reasons why the birds are useful bio-indicators is
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.
"So a rule of thumb we now use to define habitat quality is if you can see
through it, it isn't a very useful habitat. It usually means the understorey
which these birds need for nesting, feeding and for protection from predators,
has been grazed out.
Free pest control
"The other value of birds is their ecosystem service. We think they provide free
pest control and we think there's a link between the presence of a diversity of
woodland birds and the presence of healthy woodland trees.
"I've been involved in a project near Holbrook north of Albury where farmers
have identified dieback as one of their main environmental problems. In looking
for the underlying causes of dieback, it's been noticed there are no small
woodland birds left to eat the sap-sucking insects that contribute to dieback.
And why are there no birds that eat these insects - because the understorey is
missing; because sheep graze continuously beneath the trees."
This is already leading to a change in Greening Australia's tree-planting
recommendations: "Instead of planting trees, we're encouraging people to plant
fences," says Freudenberger.
"To plant a tree might cost $1.50, but nature will do it for free if you provide
the fence to keep out the livestock long enough for plants to regenerate."
Another reason why researchers have chosen the woodland birds as a focal species
is simple PR: "They are charismatic. We'd have a much harder job getting people
on side if we were using native cockroaches; even though I think native
cockroaches are kinda cool. But a red-capped robin flitting through the
woodlands is a spectacular image."
Freudenberger says the next stage of his research will be to try and quantify
how big a patch of native revegetation is needed to attract particular birds.
"We've been finding that the most demanding species of birds, our focal species,
tend to require really big patches - 100 hectares and more. They are simply not
found in patches smaller than that and this is why nature reserves and state
forests are so important.
"But to ask farmers to create 100 hectares of native woodland is too much, so
for the moment we're having to look for less sensitive species which require
perhaps 10 to 20 hectares.
"This area seems to be a general threshold and we've surveyed the Riverina, the
western slopes of NSW, the WA wheatbelt and central NSW. Below this figure the
bush seems incapable of providing woodland birds with the habitat diversity
Freudenberg's research and the rebirding programs being promoted by Greening
Australia are emerging as important innovations in the overall landcare effort
as results of the past decade's revegetation campaign points to the need for a
more strategic approach in the future.
In the long run, Freudenberger is among a growing list of environmental and
agricultural scientists who are saying that only a 'whole-of-landscape' research
effort aimed at marrying farming systems with biodiversity will ever achieve
Freudenberger has no doubt that 'win-win' situations are possible.
"We have farmers already who are making more money by running fewer sheep
because by redesigning their farm according to its variable landscape and
habitats it has led to less, but more productive farmland.
"We know already we can de-intensify some farmed areas and intensify others. So
the rebirding program is another step towards evolving Australian agriculture
away from the alien system brought from the northern hemisphere."
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