Transcript
Robyn Williams: But the point
about climate change is that the evidence mounts from any number of sources,
such as the population of birds in Australian forests. Alexandra de Blas
reports.
Alexandra de Blas: South
Australia's record November heatwave felt uneasily like the scientists' warnings
that climate change is now tracking against their worst-case scenarios. The
extended drought in south-eastern Australia is taking its toll on both people
and wildlife. As the climate warms and dries, a series of studies in northern
Victoria's box ironbark woodlands has found that birds are disappearing at
alarming rates. And it's not just in the bush remnants, the birds in the
national parks are declining too.
Monash and Deakin Universities ran three major
studies over 13 years, as Professor Andrew Bennett, head of the School of Life
and Environmental Sciences at Deakin, explains.
Andrew Bennett: We were
astonished when we put the results of these studies together, we found that they
were all showing major decline in a whole range of woodland birds across the
last ten years, about 108 species we were dealing with, but two-thirds of
species of all kinds had declined significantly.
Alexandra de Blas: And how much
did they decline?
Andrew Bennett: It varied. It was
both some of the common species and the uncommon ones. So, examples like the
grey shrike-thrush, a 20% decline. Even the laughing kookaburra that everybody
knows, 30% decline. And then some of the other less common ones that people
mightn't know, but the black-chinned honeyeater which is typical of these
woodlands, 66% decline. Crested bell-bird, 65% decline. So quite large declines
of these bird species.
Alexandra de Blas: Do you know
how many birds overall have disappeared?
Andrew Bennett: When I compare
the first two years of surveys to the last two years, there was over 40% decline
in the numbers of individual birds that are recorded there, and when you
multiply that out to a forest of 40,000 hectares, that means more than 150,000
fewer birds in the forest now then there was when I started these surveys. And
that's huge.
Alexandra de Blas: So what was
causing it?
Andrew Bennett: We interpret it
as complex changes resulting from long-term decline in rainfall. So there's been
over ten years of below average rainfall, and that has a range of effects. So
the first is there's less food. So there's less productivity, less insects, less
flowering of eucalypts, and that then flows through to reduced reproduction, so
their nesting is not as successful. And then there are other more complex
effects because the forest dries out and the shrub layer becomes more sparse and
so there's less cover and less suitable areas for nest sites and for refuge. So
it's a whole complex array of factors that are acting to reduce the
populations.
Alexandra de Blas: And what was
going on with the flowering?
Andrew Bennett: The species of
particular interest is the ironbarks. Red ironbark is the one that is a winter
flowering species. They have large flowers, lots of nectar, and this is what the
honeyeaters and the lorikeets and the wattle birds come to, and when you have a
heavy flowering event in winter you can hear where the flowering is occurring,
there's just so many bird species and it's a cacophony of sound. And that's
changed. Normally they're reasonably reliable flowerers but in the last eight
years since 2002, in four out of eight years there's been essentially no
flowering of red ironbarks. So that means that the nectar feeders aren't there,
the nectar feeders that come from southern Victoria each winter don't come. So
there are these wider ecosystem effects off the change in that
resource.
Alexandra de Blas: Do you think
those bird numbers would just bounce back if the rainfall increased?
Andrew Bennett: Some species
probably would if the rain increased, but the issue here is these changes are
occurring on top of 150 years of land use change, and we're talking about the
sheep wheat belt of south-eastern Australia where in many districts we've lost
70%, 80%, 90% of the native vegetation. So it's this compounding of the effects
of habitat loss and fragmentation, isolation with the climate change. And our
concern is that we might be having a whole series of local populations
disappearing one by one from these districts.
Alexandra de Blas: What needs to
happen to help remedy the situation?
Andrew Bennett: The first one
is simply recognising we have a problem and recognising the scale at which we're
taking action now does not match the scape of the problem, particularly loss of
native vegetation. That's been the huge driver of these concerns. So the
challenge now is how can we put it back, how can we restore some of these areas
to large-scale restoration so we have landscapes that have 20% and 30% native
vegetation present within them? And that's a huge challenge.
Alexandra de Blas: Is there
sufficient policy focus and funding to make this happen?
Andrew Bennett: Nowhere near
enough, it just doesn't match the scale of the problem. We look at the Caring
for Country initiative and I think the figures are something like $2.4 billion
over five years, and yet we have an economic stimulus package of $10 billion
just before Christmas last year. We really need to rethink the priorities for
how we spend money and where we spend money and recognise that biodiversity
conservation is something that affects us all and affects the future of
Australia and affects the quality of life and our national heritage and who and
what we are as Australians.
Alexandra de Blas: Professor
Andrew Bennett from Deakin University.
Guests
Andrew F Bennett
Professor of
Ecology and Environment Deakin University Burwood Victoria
http://www.deakin.edu.au/scitech/les/about/staff-profiles/display/index.php?username=bennetta
http://www.abc.net.au/rn/scienceshow/stories/2009/2762248.htm
