|Western Ground Parrots - Pic by Perth Zoo|
THIS ARTICLE WAS PUBLISHED IN THE WEEKEND AUSTRALIAN OF 6-7 January, 2018
As the sun sets over Cape Arid National Park on the rugged south coast of Western Australia, the silence is broken by a flute-like cadence. A bird on the brink of extinction welcomes the night with a song of rare purity floating above an expanse of knee-high heath ablaze with wildflowers. Not at all parrot-like, this is the call of the western ground parrot, with a total world population occurring nowhere but within the boundaries of this remote national park.
The western ground parrot was once much more numerous. Its range extended historically hundreds of kilometres west and north of Cape Arid to beyond Perth. The species crumbled in the wake of habitat destruction, raging wild fires and predation from introduced foxes and cats; in recent years it has vanished from most of its remaining haunts.
Alarmed by the parrot's precipitous decline, government authorities responded with what has become a standard strategy in Australia to try to bring endangered wildlife back from the brink. A captive-breeding program was established. Wild western ground parrots were caught and transferred to Perth Zoo in the hope they would breed in captivity. Their offspring would be introduced to the wild with the aim of boosting populations; that at least was the plan.
Even more scarce than the western ground parrot is the orange-bellied parrot. The orange-bellied parrot breeds in the wild in one small area around Melaleuca in south-west Tasmania. This summer nesting season, just 19 parrots returned to Melaleuca from the annual winter migration undertaken by the species from Tasmania to the coastal salt marshes of Victoria. The species was described as “locally abundant” a century ago.
Like the western ground parrot, desperate measures are under way to boost the remnant population of orange-bellied parrots with releases from a captive-breeding program. Yet for different reasons, both programs appear doomed to fail. Critical questions are now being asked about the suitability of breeding programs as a key environmental management tool in Australia. Most disturbingly, it is arguable that poorly executed if well-meaning programs may perversely contribute to extinctions.
Estimates of the wild western ground parrot population are accurate because its distinctive calls are monitored by acoustic recording units deployed at Cape Arid. Twelve parrots - almost 10 per cent of the survivors - have been caught and transferred to Perth Zoo since the captive breeding program was initiated in 2014.
|Western Ground Parrot. Pic by Perth Zoo|
Eight of the 12 captured parrots are dead. One died from injuries sustained during capture; another because it was egg bound. Six parrots died of aspergillosis – a respiratory infection caused by a type of mould. The two parrots caught most recently - both young birds - died of aspergillosis while in quarantine before they could be transferred to breeding aviaries. The zoo has four surviving western ground parrots – three males and a female.
Moreover, not a single nestling has emerged from repeated breeding attempts over four seasons. Ten of 11 eggs laid by the surviving female, Fifi, were infertile; the embryo in one egg died. However, the WA Department of Biodiversity, Conservation and Attractions plans to capture more wild parrots for the program in 2018. The number to be caught will be determined following “monitoring of the wild population”, says a departmental spokersperson.
Perth Zoo fauna supervisor Arthur Ferguson insists the captured parrots have not died in vain. “Much has been learned about factors that contribute to aspergillosis in parrots and husbandry and management practices have been refined considerably to minimise such risks,” Ferguson says. “Perth Zoo are experts at native species breeding, having helped reverse the fate of species on the brink including Australia’s rarest reptile, the western swamp tortoise, and the western quoll.”
The project's poor track record is sobering nonetheless. “We are very disappointed that there has been no success,” says Anne Bondin, chairwoman of Friends of the Western Ground Parrot, a community group trying to raise $85,000 for the project.
Says Perth ornithologist Frank O'Connor: “Without a successful captive breeding program I believe the species is doomed, possibly within a decade.”
On the other side of the Great Australian Bight, the orange-bellied parrot is on an even faster track to extinction in the wild. A long-running captive-breeding program in Tasmania has failed to boost the dwindling stock of wild orange-bellied parrots, notwithstanding an important difference from the western ground parrot experience.
|Orange-bellied Parrot . Pic by Save The Orange-bellied Parrot|
Unlike the western birds, orange-bellied parrots breed well in captivity; about 350 birds are thriving in aviaries. The problem is that the captive-bred parrots are not good at surviving in the wild. They continue to be released at the Melaleuca breeding station – 23 parrots raised in aviaries were freed this season – but the program is faltering.
Out of 62 captive-bred parrots released between 2013 and 2015, according to data seen by Inquirer, just seven were spotted 12 months after their release, having survived the hazardous winter migration to the mainland. In 2016, 23 birds were released but 10 were recaptured and returned to aviaries for the winter; just one of the other 13 returned this season.
Zoologist Mark Holdsworth, who has been closely involved with the program for many years, says on average about half the wild parrots would naturally survive the migration, but the proportion is much lower for captive-bred birds. Holdsworth believes all parrots born at Melaleuca this season – whether or not their parents were captive bred - should be captured. Twenty fledglings were produced last year at Melaleuca but only four returned to the breeding station post-migration. “If nothing is done this season to improve survival then the species is likely to be extinct in the wild by next season,” Holdsworth says.
During the 2015 season, 19 nestlings and one adult at Melaleuca tested positive for the often fatal psittacine feather and beak disease, believed to have originated in aviaries. Of the 19 birds to return this season just three are females, one of which was captured because it was thought to have a disease. Australia's leading authority on native parrots, Joseph Forshaw, says a “total rethink on our approach to saving this species” is needed.
But the Tasmanian Government continues to back the program. Department of Primary Industries, Parks, Water and Environment policy manager Andrew Crane says the parents of one wild-born parrot which returned this season were captive bred. “This is a good example of the significance of the breeding program and one which is not immediately obvious from the raw data,” Crane adds.
|Eastern Bristlebird - northern race|
A rare Australian songbird, the eastern bristlebird, is faring a little better than the parrots; the population of bristlebirds in southern NSW and Victoria, although in decline, numbers several hundred. However, the distinctive northern population of the species is critically endangered, with less than 30 birds surviving in the mountains of the Queensland-New South Wales border area.
A captive-breeding program for the northern bristlebirds began at the David Fleay Wildlife Park on the Gold Coast in 2004 but was discontinued in 2009. Eight birds raised in aviaries were released in the wild. Four that were set free at Spicer's Gap in Queensland in 2008 were dead within 12 months of their release; the fate of another four released in NSW is uncertain.
A second breeding program for the birds was established in 2015 at the Currumbin Wildlife Sanctuary, also on the Gold Coast. The sanctuary says on its website that plans to collect the eggs and chicks of wild birds are under way so captive-bred birds could “provide a sustainable boost to this endangered population”. An English springer spaniel has been trained to track down the handful of nests of surviving wild birds so their eggs and chicks can be removed.
Herein lies the dilemma that is central to the captive-breeding program strategy. When numbers of an endangered species are critically low, might that species be pushed over the brink if the survivors are caught for a breeding program which may not succeed? Or can authorities reasonably assume that a species is doomed to extinction in the wild anyway, and reason that its only chance for survival is captive-breeding?
|Lord Howe Woodhen. Pic by NSW Office of Environment & Heritage|
Breeding programs have had some outstanding successes. The flightless Lord Howe woodhen is found only on Lord Howe Island. After the island's settlement in the 1830s, its population crashed in the face of an onslaught from introduced rats, cats and pigs. By 1980, when a captive-breeding program began, just 15 birds survived on the summits of two mountains.
Three woodhen pairs captured for the program produced 66 chicks. Today, with introduced pests eliminated, the woodhen has recolonised the island. Birds are commonly encountered in the gardens of the island's settlement. The estimated population of 240 is probably close to what it was naturally.
Australia has the world's highest rate of mammal extinctions; birds have only recently begun to catch up. The Lord Howe woodhen was brought back from the brink, as have several endangered species in New Zealand, a world leader in pioneering captive-breeding. Such successes have led to a widespread view by authorities in Australia that breeding programs are a panacea: a solution to arrest the country's appalling wildlife extinction record. That view may in some instances be gravely misplaced.