THERE are moments when the Tasmanian wilderness achieves pure silence, leaving city ears straining for noise.
Here at Melaleuca, six days' walk from the nearest road, such moments of peace are typically broken by bird calls, including the distinct buzzing of the orange-bellied parrot.
Like many Australian families, orange-bellied parrots reunite every summer at the same idyllic spot by the water. After wintering in coastal Victoria and South Australia, almost every orange-bellied parrot in the wild comes back to Melaleuca to breed.
An object of beauty, critically endangered: the orange-bellied parrot in flight. Photo: Justin McManus
But recent summers have brought dramatic breeding failures, thinning the wild population to between 30 and 50.
Fearing extinction in the wild could occur within three to five years, Mr Holdsworth and his team of experts have started their own migration cycle to Melaleuca to try to save the critically endangered bird.
None of their visits are more eagerly anticipated than the January mission, when an inspection of tree-top breeding boxes reveals the number of chicks that have been born.
Orange Bellied Parrot chicks from Melaleuca in south-west Tasmania. Photo: Justin McManus
With an unfashionable helmet strapped to his head, Mr Holdsworth gingerly steps into the climbing harness. As he starts to winch his way up the tree, he carefully avoids the grease he has rubbed around the trunk to prevent tiger snakes slithering up.
Soon he is perched seven metres above the ground, peering inside one of the boxes. As he lifts the lid, a cacophony of squawk fills the air. In this business, that's the sound of success.
With the mother of these chicks out searching for food, Mr Holdsworth slowly reaches inside and removes the four chicks one by one, carefully lowering them into a pillowcase inside his backpack.
''The chicks are quite naive, so this process is just another part of their life,'' he says. ''They are not aggressive or frightened or agitated in any way.''
Back on the ground, he quickly inspects them, identifies them with leg tags and weighs them for his records.
''It's a nerve-racking period because we are handling these chicks and potentially I'm holding 5 or 10 per cent of the entire world's population of the species, and that from time to time gets to you,'' Mr Holdsworth says.
With long careers as scientists and biologists, there's no doubting the professionalism of Mr Holdsworth and his crew, whose rescue program has the backing of state and federal governments.
But it's hard not to be moved by such an important discovery.
Katrina Jones - one of the volunteers assisting at Melaleuca - says the find has delivered ''something approaching jubilation'' to the camp.
Sadly, few of the nests deliver such joy.
Of the 40 or so man-made breeding boxes at Melaleuca, only four were chosen as nests this summer by female orange-bellied parrots.
Those nests delivered nine new chicks, and it is believed at least three more chicks were born in natural nests nearby.
The 2011 tally of at least 12 new birds matches the 2010 result, which was considered a dreadful failure. Yet Mr Holdsworth finds optimism in the 2011 result, saying at least the pattern of decline had been halted between years.
While several factors have contributed to the bird's demise in recent times, none have been more significant than the widespread destruction of coastal habitat on the mainland, where the birds spend the winter.
Urban myth would blame the giant blades of commercial wind farms, but landscape changes at places such as Werribee and Mount Gambier over recent decades have played a bigger role.
Predation by introduced species, and the recent years of drought have hastened decline.
Despite finding hope in the 2011 breeding result, Mr Holdsworth says he has seen nothing to allay fears the species could be extinct in the wild within five years if left unassisted.
He says it's time to do ''something drastic'' to save the orange-bellied parrot.
''The modelling is suggesting the population will go down the tube anyway, so we are left with a very difficult choice,'' he says.
On the other side of Tasmania, Jocelyn Hockley splits her time between a surly group of Tasmanian devils, and a chirpier flock of orange-bellied parrots.
If all goes to plan, this year's crop of chicks from Melaleuca will spend the winter in captivity here - at the Tasmanian government's wildlife quarantine centre in Hobart - rather than flying to the mainland.
Mr Holdsworth's team will spend February trying to catch as many of the Melalueca chicks as possible, transferring them to Hobart where it is hoped they can invigorate a captive population that has become dangerously in-bred.
It might seem odd to remove the desperately needed new generation from the wild, but Ms Hockley says the parrots can no longer be relied upon to bring themselves back from the brink. ''It's a really fine line unfortunately between leaving them in the wild and risking their survival, or biting the bullet and bringing as many as we can into captivity,'' she says.
Mr Holdsworth says captivity is not a solution in its own right; the plan is to breed a captive population that is big enough for some to be released back into the wild.
If the plan works, Mr Holdsworth could be restocking Melaleuca within two years with birds born in captivity.
That's the plan, but the reality might be tougher.
The last attempt to set up a neighbouring colony to Melaleuca appears to have failed for reasons that remain unclear.
Despite evidence that parrots born in captivity can pick up the migration patterns and other natural skills that keep birds alive, there's no guarantee the team will be able to successfully send birds back into the wild.
THESE little wings are still too weak for flight, but already they carry a colossal burden. Beneath a coat of fluffy grey down, the chicks in Mark Holdsworth's hands are starting to show their true colours. Fluorescent green, yellow and blue feathers have sprouted, yet it's the orange patch on their belly that sets them apart.
Just weeks after they hatched in a remote part of Tasmania, this helpless handful already represent a fraction of the world's wild population of orange-bellied parrots. Nature would have them soon begin their migration to the Australian mainland, but a team of scientists have mapped a different journey for these fledglings in a bid to save a species from extinction.