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NARRATION

We know Australian birds are special and the rest of the world does too. Songbirds like our lyrebird are the most amazing mimics on earth. Our parrots are incredibly smart and adaptable. Our pigeons eat fruit, move seeds and shape entire forests. But for most of the last century, scientists from the Northern Hemisphere assume that our birds are just a second-hand fauna, descended from theirs.

Tim Low

That's where birds had evolved, that's where you had normal birds. What was going on in Australia. It was a bit whacky. And you could get away with that 'cause it was this lost continent in the south.

NARRATION

It was only in recent decades that Australian scientists dared to challenge the orthodoxy from Europe and America. And now at least three different groups of birds have revealed something amazing that rocked the world of science. They all had their evolutionary origin in Australia before spreading to the rest of the world, not the other way around. (Magpie warbles)

Mark Horstman

Knowing that this continent was the birthplace of songbirds, parrots and pigeons, helps to explain their close relationship with Australian vegetation and their extraordinary behaviours, why Australian birds are more likely to be intelligent, aggressive, loud, melodious, socially cooperative, environmentally influential and more important for pollination than anywhere else.

NARRATION

When it comes to unravelling the origins of songbirds, Les Christidis and Walter Boles played a big part in turning the world on its head. Back in the '80s, Les and his colleagues decided to test early DNA evidence by comparing proteins from different birds. He was shocked to find the results redrew the entire family tree of songbirds.

Prof Les Christidis

We didn't get the split of the Australian songbirds and the Old World songbirds, we actually got the Old World songbirds sitting within the Australian songbirds. We just kept looking and thinking, 'Is there an error here? Is there something we're missing?' But, no, that's where they were sitting.

NARRATION

It was an explosive finding that shattered the prevailing dogma. The world's 4,500 species of songbirds, like the jays, thrushes, robins and mockingbirds from the Northern Hemisphere, all had ancestors that traced back to Australia. But, the critics demanded, if this is where songbirds began, where's the fossil evidence?

Prof Les Christidis

The fossils may have been here, but there wasn't actually anyone actively working on them. Very few people working on fossils and certainly no-one on... detailed on songbirds, till Walter Boles came along.

NARRATION

While others searched for carnivorous marsupials and giant platypus, Walter sorted through the rich deposits of Riversleigh for tiny bird fossils.

Dr Walter Boles

You don't know what you're going to look at and start putting things under a microscope and suddenly you say, 'Ah-ha.'

NARRATION

In 1993, he identified a fragment of wing bone from Queensland that set a new world record.

Dr Walter Boles

You can see that's quite a small little thing, probably about the size of a finch. I'm guessing what it lacks in size, it makes up for in significance. Well, this was the earliest record of songbirds anywhere in the world, and by a substantial amount - like 25 million years earlier.

Mark Horstman

And this remains the oldest found.

Dr Walter Boles

It does.

NARRATION

This one's about 54 million years old. He and his students have identified plenty more. They're much older than songbirds from the Northern Hemisphere and too early to have evolved there and then moved here.

Dr Walter Boles

Australia was floating slowly northwards and birds evolving in isolation had not reached close enough to Asia for things to move back and forth. Then, yes, this is where the birds were evolving, the birds were singing.

NARRATION

And not just the songbirds. In the last few years, more DNA and fossil studies have revealed Australia is the ancestral home of parrots and pigeons as well. Drawing all these strands together has led biologist Tim Low on a ten-year journey. He's woven them into a book called Where Song Began.

Tim Low

Then I realised, 'Hold on, if you add all these groups of birds together, you are talking about a majority of individual birds in the world having Australian ancestors, and also that Australia was, in fact, the most important continent for bird evolution, that no other continent could match that.

NARRATION

A good place to see the results of this long history is the Gondwana Rainforests World Heritage Area in northern New South Wales. Tim wants to show me an Australian species that characterises much of what makes our birds distinctive, a type of honeyeater called the bellbird, fuelled by sugar, that so aggressively defends its food source, it loves the forest to death. Calling constantly from dawn to dusk, 365 days a year, bellbirds, or bell miners, create a wall of sound to keep other birds away. (Incessant chirping)

Tim Low

Try just waiting and see if you can get a whole second when you can't hear a call.

Mark Horstman

Yeah, it'll be impossible.

Tim Low

That's right. There's no morning peak, it doesn't get weak in the afternoon, it is just this solid wall of sound. And it's a really clear message to birds. They're basically saying, 'Get out of here!' We speculate that it is globally completely unique.

Mark Horstman

But this is a sound that's very familiar to Australians, but many of us would not be aware of the backstory.

Tim Low

It's completely misinterpreted so that real estate agents will sell blocks of land with bellbirds at a premium, saying, 'Come and listen to the tinkling bells.' And what they're actually selling is forest that's going to die.

NARRATION

This is what the bell miners covet, a sugary cap called lerp, created by a minute sap-sucking bug called a psyllid. The birds actually farm the bugs by removing just the lerp, stimulating the psyllid to make more.

Tim Low

And the birds love this. Almost all the small forest birds will eat it. And the bell miners, they're guarding - this is the resource they're guarding. This is what all the action is about. And, yeah, eat it. Aboriginal people love this food.

Tim Low

I eat it all the time.

Mark Horstman

What's in it?

Tim Low

It's a starch sugar and a little bit of wax. So, I don't think you'll find it very sweet, particularly after the rain last night, but the blandness - it's sustaining. You can get the sense that you're eating something starchy.

Mark Horstman

Well, it tastes... it doesn't taste disgusting. It tastes nutritious, like it's worth eating. And I am getting that sweet aftertaste as well.

NARRATION

But the sugar fix that bell miners jealously guard comes at a cost for the forest.

Tim Low

By keeping all the smaller birds that would also like to eat the sap-sucking bugs, the bug numbers build up. So bell miners are eating some of them but not enough. Trees eventually die, and that's what you can see in this stretch of forest here.

Mark Horstman

It's a dramatic change.

Tim Low

That's right. You got this massive tree death which you can now see on a scale like this in places everywhere between southern Victoria and southern Queensland. There's a particularly bad one here, but this phenomenon is becoming really serious over a large area of Australia. So we're talking about a pretty major phenomenon. Bell-miner-associated dieback - BMAD.

NARRATION

Disturbances like fire, drought and logging may also play a part, but once triggered, dieback is an epidemic driven by bell miners. It's a testament to the power of a single species of honeyeater.

Tim Low

It's very much the case and that's one of the really strong points that can be made about Australia. We have incredibly ecologically powerful birds.

NARRATION

Including one that's the closest alive today to the very first songbird that ever evolved - the lyrebird.

Mark Horstman

They're best known for their amazing mimicry. But I've come to Victoria's Yarra Ranges to see how they change the forest.

Daniel Nugent

The lyrebird is a really important ecosystem engineer because it's turning over significant amounts of litter and fuel. It's able to influence the germination of plants and it's able to influence the whole structure of a forest.

NARRATION

Daniel Nugent and Steve Leonard had a hunch that the foraging of superb lyrebirds reduces the risk of fire.

Daniel Nugent

Following the Black Saturday bushfires, colleagues and I noticed that the fire had often stopped at the margins of gullies with a lot of lyrebird activity.

Dr Steve Leonard

That just got us wondering whether there was some connection there, whether lyrebirds were actually forming, in effect, firebreaks.

Daniel Nugent

Through here is an example of a lyrebird foraging area. You can see that the lyrebirds have intermixed this layer of litter and soil together, and you can see the area extends all the way up past these ferns some 20-odd metres. They're using their big feet and claws to scratch around and look for invertebrates to eat. This is something that they do throughout the year.

NARRATION

Lyrebirds can turn over more than 200 tonnes of soil per hectare a year, an incredible amount of earthmoving. To test their theory about fire, the researches set up fences to exclude lyrebirds and compare the amounts of leaf litter inside and out.

Daniel Nugent

11cm. At one site in particular, we found a difference of 7.5 tonnes per hectare, which is a really significant amount.

Daniel Nugent

Five centimetres.

Dr Steve Leonard

Mm-hm. Over a nine-month period, they found lyrebirds reduced the fuel load by 25%. And when they fed their data into the McArthur fire-behaviour models, for low to moderate fire weather, where there were lyrebirds, there was no fire.

Dr Steve Leonard

Even under extreme conditions, even when we plugged in, you know, 35-degree day with very low humidity and strong winds, the lyrebird effect was still measurable.

NARRATION

Superb lyrebirds change more than the fuel load. Their foraging also uproots seedlings which shapes the forest in a distinctive way.

Dr Steve Leonard

So they prevent the establishment of a mid layer in the vegetation. So you end up with this very open forest floor and then a tall layer of small trees and large shrubs. What's missing is a sort of mid shrub layer, the sort of head-high stuff, and that's really important for fire behaviour because they're the ladder fuel. So it'll lead a fire from the floor up into the canopy where it can develop into a high-intensity fire.

NARRATION

Learning from lyrebirds could help protect the bushland fringes of Melbourne from wildfires.

Dr Steve Leonard

You have more lyrebirds, less likelihood of fire, maybe making people safer.

Mark Horstman

Such capacity to shape their environment is a trademark of many Australian birds in the land where song began. But does that mean our birds sing differently too? In the Northern Hemisphere, female birdsong is unusual. Here it's the opposite.

Tim Low

If you think if a whipbird, 'Whoo-oo-whip, choo-choo.' The 'choo-choo' is the female answering. OK, so why do we have a lot of that? Well, because the eucalypts are not deciduous, we've got evergreen forests. We get a lot of drought and seasonal fluctuation, but it's nothing like the severity you get in the Northern Hemisphere where most of the birds have to migrate. What you have are year-round territories and this seems to facilitate the female actually telling the other females, 'This area is taken.' So we have a lot of females participating in calls here.

NARRATION

The old view that still persists today is that Australian birds are the exception to the rule.

Dr Michelle Hall

I guess Australia gets seen as Down Under but it might actually be the other way around. The way that songbirds do things in Australia might actually be the norm in a sense.

NARRATION

Michelle Hall and her team are tracking the lives of 400 superb fairy-wrens at the Serendip Sanctuary in Victoria.

Dr Michelle Hall

Well, they're territorial during the breeding season. So if you play a song of another fairy-wren on their territory, they'll usually think there's an intruder there and that'll get their attention.

Mark Horstman

She's particularly interested in the female songs.

Dr Michelle Hall

They have quite a complex social system. Because the males spend a lot of time off their territory, the females often sing to defend the territory.

NARRATION

However, Darwin's classical theory of sexual selection focuses only on the males. From his Eurocentric perspective, Darwin proposed that song evolved because the boys with the best repertoire got the girls. That's the male fairy-wren with the bright blue head.

Dr Michelle Hall

There's a fairly pervasive view that birdsong is something that male birds do, and anyone who lives in Australia knows that that's probably not really true.

NARRATION

But no-one had done a systematic survey before to establish how many females actually do sing. So Michelle helped to gather information from a thousand different species around the world.

Dr Michelle Hall

We found the female song occurs in 71% of the species that we surveyed. And in a lot of species, females sing just about as much as males do, and a few species, they actually sing more than males do.

NARRATION

When they mapped the female singers onto the family tree, there's a 92% probability that the ancestor to modern songbirds had female song. These new insights reverse the old assumptions about evolution.

Dr Michelle Hall

Perhaps instead of asking why male birds sing, we should be asking why female birds don't always sing. That might give us a different perspective to the current one.

Mark Horstman

All this leaves me looking at birds in an entirely new light. For tens of millions of years, this continent echoed with the song of their ancestors, as they not only shaped this land, but eventually the birdlife in the rest of the planet. And, like songbirds, parrots were also evolving here long before anywhere else. Although their songs are not always music to our ears, one even makes its own musical instruments. The palm cockatoo of Cape York Peninsula is one of the few animals to use tools. It selects the right branch, strips off the bark and bangs its custom-made drumstick against trees to make a rhythm.

Tim Low

The two groups of birds that overwhelmingly stand out for intelligence are the songbirds and the parrots and we know they both originated in Australia. It's just fascinating - we gave the world intelligent birds. And not only that. The fossil record and the genetic record would imply we had smart parrots and songbirds in Australia at least 10 or 20 - maybe longer - a million years before you had intelligent apes. So, in Australia, you would have had the most intelligent organisms in the world.

Dr Walter Boles

All that, of course, that group would be well out.

Prof Les Christidis

And this is where big issues would start.

NARRATION

Back at the Australian Museum, Walter and Les reflect on what's changed in the last 30 years and what hasn't.

Dr Walter Boles

I helped put that gallery together when it opened in 1980, so it is now 35 years out of date, and it very much reflects the old classification that was in use at the time.

Prof Les Christidis

It's quite good going back in time.

Dr Walter Boles

It is.

Dr Walter Boles

Starting to fill in a lot of gaps in the record now.

Prof Les Christidis

If I was to redo a gallery like this, I'd have song, the evolution of song, and you'd have 35 to 20 million years. The rest of the world is quiet, Australia is buzzing and singing. And then suddenly it starts moving through to the rest of the world.

NARRATION

Wherever we look, from backyards to bushland, our birds continue to inspire.

Tim Low

Birds are very easy for us to relate to. They've got beautiful colours, they've often got beautiful songs. They're doing a lot vocally, more than most animals. They're in our gardens. You can be learning about them when you're just sitting on the back verandah with a beer. You can be learning about them while you're standing at the bus stop. I mean, they're user-friendly nature.