When you went out right this moment, did you see any birds? A galah maybe, or a crow?
If you probably did, there’s an honest probability the chook you noticed lives nowhere however Australia. Out of about 850 species present in Australia, 45% are “endemic”, which implies they’re distinctive to Australia. The solely different nation with extra endemic species is Indonesia.
Thanks to their wings, birds are the world’s biggest travellers. So why is it that such a excessive proportion of Australian birds aren’t discovered anyplace else?
The story begins greater than 45 million years in the past, when Australia first break up from Antarctica and began to go north. It was the occasions that occurred throughout this journey – significantly in relation to our local weather – that led to the variety in Australia’s birds right this moment.
When it first set out, Australia was coated in lush rainforest. As it drifted, nevertheless, the local weather grew to become a lot drier. Our distinctive flora of grasslands and eucalypt woodlands began to unfold throughout the continent.
But this drying pattern wasn’t constant. Particularly within the final million years, dry durations related to the ice ages alternated with wetter instances, such because the Holocene epoch – which is what we’ve had for the previous 10,000 or so years.
But the local weather didn’t simply range over hundreds of years. It additionally diversified, as we all know too nicely, from yr to yr. Australia has lengthy been the land of lengthy droughts, typically lasting a long time, interspersed with flooding rains.
What’s local weather bought to do with birds?
The variety in Australia’s birds arose partly due to the listing of passengers aboard the great ship of Australia. This included historical parrots and the ancestors of what had been to turn out to be the world’s first songbirds: the lyrebirds and scrub-birds. Both teams are extremely adaptable and have greater brains than different birds relative to their dimension.
However, it was in the end the local weather that gave us so many endemic species. Every time the local weather dried, birds that most popular forests had been pushed to the damper margins of the continent, the place they advanced into separate species. In wetter instances, some forests unfold and reconnected – however now there have been two or extra species, not only one.
The identical was true for the arid land birds, which bought divided when it grew to become further dry. One historical group referred to as grasswrens has completely different species in virtually all of the remoted blocks of arid habitat throughout the nation.
The parrots and cockatoos additionally diversified into an enormous vary of species, from tiny budgerigars to large black cockatoos.
But that’s solely a part of the story. You may need heard of the unique supercontinent, Pangaea, which break up into Gondwana and Laurasia about 200 million years in the past. When Gondwana finally break up, a number of the continents moved north and shared their faunas with the areas they bumped into within the Northern Hemisphere.
As Africa and India collided with Asia and Europe, the species from the outdated supercontinents of Gondwana and Laurasia combined. North and South America additionally exchanged crops and animals when their land plenty joined. Australia was completely different. And as soon as once more, it got here all the way down to the local weather.
As Australia pushed north, the shifting tectonic plates threw up islands that acted as stepping stones to Asia. These allowed Australian songbirds to go out into the broader world, the place they did exceptionally nicely. In truth, researchers suppose all of the world’s 5,000 or songbird species got here from Australia.
The query is, why was this visitors a method? Why didn’t Asian and American birds resembling woodpeckers hop on over to Australia? One cause may very well be that by that point Australia was already stuffed with powerful birds that had advanced to deal with a fairly imply local weather.
In distinction, the birds from Asia had advanced in fertile rainforests. Any that did disperse south alongside the chain of islands resulting in Australia would have been ill-equipped to deal with its aridity. They would even have needed to compete with parrots and songbirds that already knew how you can take full benefit of the assets out there.
Just a few did make it, together with a beautiful set of finches, however they’re an exception proving the rule.
Budgies are the perfect
It’s in all probability no coincidence the world’s hottest cage birds come from Australia. Cage residing isn’t for each chook; most birds are delicate creatures that want fixed care if bred in captivity.
In distinction, budgerigars, cockatiels and zebra finches from Australia’s fickle arid zone know they have to do what it takes whereas the going’s good, as a result of the following El Niño could begin subsequent week. And it helps in case you can deal with temperatures that fluctuate from -10°C to greater than 40°C.
Australia additionally shares many chook species with New Guinea. This isn’t stunning, given we’re on the identical continental plate.
The Torres Strait is so shallow that drops in sea ranges throughout an ice age would kind a land bridge that even a cassowary may stroll throughout (which is why cassowaries are shared with New Guinea).
For most different Australian birds discovered elsewhere, resembling shorebirds and seabirds, water isn’t any barrier.
But most of our birds are ours alone. Ours to get pleasure from and ours to take care of – as a result of they haven’t any different dwelling.
Listen to the Albert’s lyrebird: the perfect performer you’ve by no means heard of
Stephen Garnett receives funding from the Australian Research Council. I’m an energetic member of BirdLife Australia.