Unusually, the female of this cockatoo species is more colourful than the male.

He is truly glossy; black as tar glistening in the heat, with a strong circle of red revealed on the tail, most visible when seen from below. But he pales in comparison to his mate.

She is a stunner, with black feathers scalloped in yellow, red and orange that swirl into a broach on her chest and give her sub-species their name — the painted lady.

They belong to one of five sub-species of red-tailed black cockies, spread out across Australia.

The south-eastern red-tailed black cockatoo lives in a small area, completely isolated from its closest evolutionary neighbours by huge swathes of impassable terrain.

These are birds that stand on the precipice of extinction.

But the high-pitched sounds made by fledgling chicks could be key to their preservation.

Rare and ever rarer

Like all black cockies, they're most often heard before seen, calling from the air as they fly, then appearing as a team of black crucifixes in the sky.

They look like a cross between a raven and an eagle: large, solid and dark as night.

They move in forward motion on longer wing strokes than seem physically possible. It's as if, by some miracle of avian biology, they are held aloft more by magic than by wing beats.

A south-eastern red-tailed black cockatoo in flight is a sight to behold. ( Getty Images: Sean Garnsworthy )

They're some of Australia's rarest birds — and although they might've been the mascot for the 2006 Commonwealth Games, in the wild, they are rarer than lions on the African continent, or even pandas.

And they have unusually small beaks.

The south-eastern sub-species of the red-tailed black cockatoos are very picky eaters, and in the now agricultural Australian landscape, that means trouble.

They prefer the freshest capsules — that's the green fruit before it flowers and forms a gumnut — of very specific trees.

They will pluck off a branch in their left foot and split the fruit, delicately eating only some of the seeds, before dumping the rest unceremoniously to the ground, as is the habit of many parrots.

For thousands of years these cockies have eaten tiny seeds from the fruit of the stringy bark and bulokes, in a 18,000-kilometre-square area of land that straddles the border between Victoria and South Australia.

Daniella Teixeira is studying the sounds that black cockies make to identify whether breeding is occurring. ( Supplied: Josh Cooper )

According to Daniella Teixeria, who is studying these birds for her PhD at the University of Queensland, in the past almost all of that space would've been suitable habitat.

But now, the source of their specialised diet is becoming scarce.

"The buloke, I think, has been cleared by 90 per cent — it's really significant," says Ms Teixeira, explaining the vegetation type is now endangered.

"The stringy bark has done a bit better. In Victoria [stringy barks] occur mainly on these historical sand dunes from a long time ago, when the coastline was further inland … beautiful sandy soil with lots of bracken fern and these big stringy bark trees.

"The remaining stringy bark forests … are mostly on state land — they're not protected as national parks.

"This is where it gets very complicated, because of fire management."

There are five species of black cockatoo in Australia, many of them very rare. ( Supplied: Daniella Teixeira )

Previous research has indicated that it takes about 10 years for the trees to recover from fire, and that the level of "canopy scorch" is a significant factor in that recovery, in terms of potential cockie food.

"These stringy bark forests are burnt [regularly], through prescribed burning for bushfire mitigation," Ms Teixeria says.

"So, we need some way to be able to measure how well breeding happens in all these areas — including in areas where there has been burning done, within a certain amount of time.

"We're in a difficult situation at the moment, because we don't really have much data to show that it is actually affecting the population.

"So, although we know that maybe the birds don't feed in the areas after burning — what is that actually doing to the population? Is it actually stopping them breeding?

"We need to be able to show that there is a real effect happening."

This crisis of food supply is part of what is edging this population of cockies towards crisis point.

Ancient paddock trees also disappearing

Total population figures have been relatively stable for a while now — but recent bird counts have revealed some ominous trends.

"The scary part of that is that there are fewer and fewer females and juveniles in those flock that we count," Ms Teixeira says.

"Although the numbers we count in our annual survey might not be going down that much, this increase in males and decrease in juveniles is worrying. That means that the breeding population is getting smaller.

"If there are more males in the population than there are females, those male won't have a mate … if we just keep counting lots of birds, but more and more of those are not breeding because females are fewer, then there is actually a population decline, effectively.

With only about 1,400 of these birds left in the wild, every nest is vital to their survival. ( Supplied: Daniella Teixeira )

"We think there are around 1,400 individual birds at the moment."

Adding to the cockies' problems, the ancient, dead paddock trees that they rely on for nesting hollows have started to fall.

"This season we went out to as many of the historical nest records that we knew of, and the rate that they had fallen over was shocking," Ms Teixeira says.

"And you just go, where are they nesting instead? I don't know — and it worries me.

"I worry that I'm going to do my PhD on something that goes extinct in my lifetime."

Over the last two decades of searching, only about 80 nests have been found.

This is even with the help of a special scheme that financially rewards landowners with nests on their property — whether active or not — run by the south-eastern red-tailed black cockatoo recovery team, Birdlife Australia and the Nature Foundation of South Australia.

Supplementary nests are a potential option, made of PVC pipe and erected in areas where the hollows are lacking.

But nothing beats a 400-year-old stag of a paddock tree, with deep hollows and a view of grazing sheep. That seems to be where the cockie's most like to nest — they show a clear preference for trees more than 200 years old.

Sound to the rescue

Ms Teixeira has been out with song meters, which are scientific sound recorders that are strapped to the bases of huge, greyed old trees within sheep paddocks between Portland and Edenhope in Victoria.

She has taken an immense amount of data from these recordings, more than 150 gigabytes per recorder, and is systematically categorising the cockies' communications, trying to find a way that she can judge whether the rare, endangered, chicks fledge or fail.

The sites where the recordings are taken are a secret. They cannot be given out at any cost, as it could hurt the species.

Poachers lurk in Australia, looking for rare birds — especially rare spectacular birds, like the red-tailed black cockatoos.

But against all odds — despite the lack of food for its parents to eat, the lack of hollows, the disparity of sexes in the population — a chick hatches, and the researchers' song meters are there to record all the sound.

The chick is fluffy and yellow and for the first 10 or so weeks, it does not make a sound. It sits in a hollow, long as your arm, and is fed by its mother, who is in turn fed by the chick's father.

It's only when the chick approaches fledging that it starts to make noise.

It screams incessantly. It wants its parents to feed it, for it has a mighty task ahead — the future of its species.

Loading...

It's only recently, trawling through the recordings from the season just gone, that Ms Teixeria has been able to pinpoint the moment when a nestling fledges.

At a moment that is just right, when the wings are fully clothed in glossy black feathers, it opens its wings and flies.

Its parents join it and together they soar, in a chorus of flight calls.