One of Australia’s most critically endangered bird species has started arriving at Melaleuca, in Tasmania’s south-western world heritage area. By late this week, six orange-bellied parrots had turned up at the remote outpost to breed, having made the weeks-long flight from the mainland, across Bass Strait and down the state’s wild west coast.

Relatively little is known about where the birds go during the winter, other than that it is a hazardous journey for a bird that weighs about 40 grams. In recent years, only about half the parrots that leave Melaleuca, the species’ sole wild breeding site, have returned in spring.

But there has been cause for qualified optimism. After crashing to just 17 in 2016 – a catastrophic level that included just three females and suggested imminent extinction in the wild – the population has gradually increased. By an annual census – held at Melaleuca in December each year – it had risen to 92. It swelled to 172 at the time of the spring northern migration after breeding and the addition of captive-bred birds.

For scientists and volunteers dedicated to saving the species, the next few weeks will be a nerve-racking wait to learn how many survived – and to consider what that might mean for a future that includes the development of a contentious new windfarm on its migratory path.

Map showing Melaleuca location in Tasmania

The parrots’ Melaleuca influx has started slightly later this year, and in smaller numbers than usual. Possibly related: Tasmania has been experiencing an atypically windy and wet spring. On Friday, the south-west suffered through gusts of nearly 140km/h. Annie Phillips, the manager of the Tasmanian government’s orange-bellied parrot program and a trained vet, says it is unclear what effect this is having.

“The wild weather might be impacting them, but they also might use the wind to a degree to assist them, particularly if they’re flying across Bass Strait,” she says. “We just wait, fingers crossed.”

Slump to survival

An orange-bellied parrot is a little bigger than a budgie. Males are a shock of colour – bright green on most of the body, a brilliant royal blue on the wings and in a two-tone band between its eyes, and an oval of bright orange on the underside. Females have similar colouring, but are a little duller.

A male orange-bellied parrot resting in scrub pines. Photograph: Nature Picture Library/Alamy

The species used to summer across a larger area, but the remaining birds now head to Melaleuca, gravitating to feeding tables and nesting boxes installed as supplements to the natural eucalyptus hollows they used for breeding. They are primarily ground feeders, hunting among the button grass, and live relatively close to the coast, preferring scrub and heathlands and salt marshes.

The population has been in decline since at least the 1980s. The survival rate of young parrots during migration has slumped from about one-in-two to one-in-five as numbers have dwindled. By 2020, scientists said the species could be gone within five years. But it has hung on, in part due to captive breeding programs. The most notable is at the Tasmanian government’s $2.5m Five Mile Beach captive management facility outside Hobart, which was developed five years ago.

Mark Holdsworth, an ornithologist and orange-bellied parrot expert, says captive breeding programs have been a clear success. “If we stopped releasing birds, the population is likely to decline quite rapidly,” he says.

There are several major challenges in rebuilding the population to the “several hundred” that Phillips says could be a sustainable level. The remaining parrots are drawn from a reduced gene pool, increasing the risk of a disease outbreak having a species-wide impact. Researchers have a relatively limited understanding of the threats that they face after they leave Melaleuca.

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But they largely agree the risk could increase with the construction of the Robbins Island windfarm, which the federal environment minister, Murray Watt, approved in August. The renewable energy company Acen Australia plans to build about 100 turbines, with a maximum blade height of 212 metres, on the nearly 10,000 hectare island.

‘Rolling the dice’

It is a remarkable place: one of Australia’s best potential wind energy sites at a time when the country needs as much renewable energy as it can get, but also an internationally important site for a long list of bird species.

In 2022, the Tasmanian Environment Protection Authority found operating a windfarm on the island while orange-bellied parrots were migrating would be at odds with the species’ national recovery plan that was signed off by the federal and state governments, and ruled the development could go ahead only if it shut for five months each year. That decision was later overturned by the state’s planning appeals tribunal.

In his federal approval, Watt rejected the EPA position, but required Acen to carry out three years of parrot monitoring before construction and develop a bird and bat management plan – a standard requirement for windfarm operators – that could lead to the “curtailment or shutdown of all or some turbines” at certain times. His decision has been has been opposed by Birdlife Australia, which said the island should be a no-go zone, and sharply criticised by some environment groups and Tasmanian Greens MPs.

Holdsworth says the farm’s approval is “deeply troubling”, and believes authorities are “rolling the dice” on the parrot’s survival while also funding its attempted recovery. He believes a monitoring program would need to run for between 10 and 20 years to give a clear picture of the species’ flight path, but agrees with other scientists that there is evidence that orange-bellied parrots cross the island.

Shorebird habitat at the northern end of Robbins Island, looking south. Photograph: The GuardianRed knots (in breeding plumage) and a sanderling at Robbins Island prior to migration. Photograph: The Guardian

While detection technology exists that can lead to windfarms slowing speed or shutting down to limit the risk to some species, Holdsworth says it is “nonsense” to think it can work for such a small bird. “If a 40-gram bird crashes into a turbine you are never going to find it, so you’re never going to know,” he says. “The commonwealth has seriously failed in its duty of care for threatened species in this case.”

Acen says it is confident the risk to birds can be managed and it has adjusted its plans to address concerns, including reducing the number of turbines by 20%. It argues the farm’s approval after eight years of development shows it can balance “overall impacts and conserving biodiversity with the need for clean energy to address climate change”. The farm is expected to start operating in 2030.

For now, the population of the bird remains so low that even a fleeting glimpse is cherished by those who care for it. Debbie Lustig, a writer and volunteer who runs the group Save the Orange-bellied Parrot, was stunned last month when she was out looking for the species at the Western Treatment Plant, west of Melbourne, and stumbled on 10 birds in one spot.

For a few minutes, she was by herself, watching a collection of parrots feeding on the seeds of a samphire bush. “It was very early morning, and it was very cold, and they were just chittering about like this is a normal thing,” she says.

“It was quite surreal. I just had 10 minutes on my own before someone else came along. It was only later that I realised I’d had this precious moment alone with around 10% of the species’ entire population.”