The mystery of how the unlikely bush blow-in made it in the big city is finally explained.
By Matthew Denby.
There’s no more iconic vision of urban Sydney wildlife than the Australian White Ibis; whether the infamously in-your-face species is delighting snap-happy tourists at Circular Quay, or unsettling office workers by plucking McDonald’s wrappers from city bins.
So, it’s hard to believe the ubiquitous former swamp dweller was rarely seen in the urban area until the 1970s, with first local breeding records not formally lodged until the 1980s. Most recent estimates hold that Sydney now hosts a thriving population of more than 7,000 birds.
The sudden and spectacular transformation of the Australian White Ibis from a shy and obscure species of remote inland wetlands, to a creature capable of not only surviving the city but owning it, has been one of nature’s greatest mysteries. Until now.
Thanks to recent studies, we know more about the ibis than ever, and its secret weapon is clear: it has lost the natural fear that has stopped a suite of similar wild birds from successfully making the jump to big city life. And just how it lost that fear makes for a fascinating question.
‘The White Ibis has been able to adapt by reducing its fear tolerance to people, and therefore being able to access a new and diverse range of food resources,’ reveals Dr John Martin, Research Scientist with Taronga Conservation Society Australia.
‘We haven’t seen other birds that are closely related, like the Straw-necked Ibis and the spoonbills, adapt to situations where they can scavenge from people.
‘It really is that change in their fear tolerance and that learned behaviour of new foraging opportunities, such as, you see someone sit down and have lunch and if you hang around, they might throw you something sometimes.
‘These adaptations take time and they take trial and error.’
It’s hard to undersell just how big, fast and unprecedented the ibis’ behavioural transformation has been. In nature, the species naturally prefers to browse in the water column of inland wetlands for treats like small fish and frogs, and it avoids most of the forage sites Sydney residents now associate it with.
‘It’s the bird you see walking through the water and probing through the mud and weeds,’ Dr Martin says. ‘So, it’s actually quite interesting that we see it’s adapted to the more parklands situation in the urban area.’
While one of the more enduring urban legends in Sydney is the bogus claim that the ibis is a cane toad-style foreign invader – often claimed to be a bird from Egypt that escaped a zoo – the White Ibis is indeed a native Australian bird that has every right to be here.
But there is an apparent connection to their history as former exhibits in zoos that might help explain the ibis’ radical transformation.
In the early 1970s, a range of Aussie zoos and wildlife parks, including Sydney’s Taronga Zoo, experimented with the then vogue for free flight bird exhibits, with the White Ibis the most successful beneficiary. Tame birds were brought in from Victoria’s Healesville Sanctuary to Taronga, as well as sanctuaries at Currumbin in Queensland and Tidbinbilla in the ACT.
Contrasting with the negative way some present-day Sydneysiders regard the ibis, in a 1973 ABC TV report on the free flight experiment, the narrator enthused of the species: ‘They’re among the most graceful and decorative of Australian birds.’
The report noted how the flock of 14 released ibises were encouraged to stay with daily meals of meat and crushed grain, and were already breeding freely in the zoo grounds.
File footage shows the resident birds clearly lacking the fear of humans inherent in their wild swamp cousins – and closely associating people with food.
Asked by the Sentinel if the zoos’ experiment may have been the critical trigger for the ibis’ stunning adaptation to city life, Dr Martin indicated that the question is a complex one.
‘Healesville shared this unique Australian species with these other zoos, who released them into the grounds,’ he confirms.
‘And as you can imagine these were birds that had already learned not to fear humans, because they were coming from an area where they were interacting with people, and they were scavenging food, and they had also learned about different foods they could scavenge. ‘So, did that seed our current urban population? It was 14 birds that were released in the mid 70s and we don’t have breeding records for ibis in the Sydney region for more than a decade later.’
While ibis had been recorded fleetingly visiting the urban area while fleeing inland drought, it was not until the eighties that they began setting up house here. From around 1980 onwards, they began regularly appearing in the Botanical Gardens, the CBD and Centennial Park. From there they dispersed across the entire urban area.
The new populations showed a liking for breeding in exotic date palms, approaching people without fear, and eating human scraps – all behaviours that appeared to be totally new and alien to life in an inland swamp.
So, did descendants of the Taronga birds fly the short trip across the harbor to inherit Sydney, armed with their lack of fear and skilled at harvesting human food? Or was something bigger and more complex at play?
‘The most likely scenario is we have had a change at the landscape scale of the habitat in association with drought in the 1980s, and we had birds from those natural wetlands moving to the coast,’ argues Dr Martin.
‘Then you’ve got this interaction of arguably local (Sydney) birds and visiting birds and what do you do, you learn from each other. There’s a potential that that was a formative experience but we don’t know. It would be amazing to prove that.’
While that question may forever remain unanswered, Dr Martin’s community-based research project, Big City Birds, is allowing Sydneysiders to report their observations of the ibis, as well as other surging native birds, such as the brush turkey, cockatoos and corellas.
Observations of ibises in Sydney have already revealed a wealth of new information about the species – including that some ibis fathers are devoted monogamous partners and very involved dads, while others put in the bare minimum of parental effort before habitually running away with a hot new mate.
And far from subsisting on an unpleasant mix of bin juice and fast food, most ibises have a very balanced diet – foraging in natural areas like gardens and creek lines, as well as their familiar dumpster diving – with some flying up to 35km away from their homes for a good feed.
It seems that ibises have far more complex lives than most people think, with the oldest bird banded believed to be 26 years old.
‘It’s good to have the context that that’s the equivalent of a human living to 105,’ explains Dr Martin.
While the ibis is these days as much loved by Sydneysiders as it is disdained – with the species fast emerging in art, pop culture and memes as a symbol of the city – Dr Martin wants those who are as yet unsold on the delights of the species to get to know them a bit better.
Indeed, those who flinch at the sight of the species dubbed by some as the ‘bin chicken’ or the ‘tip turkey’ might want to think about why they are here. With the ibis all but gone from many of its ravaged inland habitats, the species is a symbol not only of survival, but the affects of human action on the environment.
‘What we see now is very small numbers of White Ibis associating with the inland wetlands,’ says Dr Martin. ‘Drought is a factor, but we also know things like human water retention means we have smaller floods and there’s less habitat.
‘I say the city populations are flying the flag for a huge diversity of species that are declining in association with the loss of our inland wetland habitat. When we see a White Ibis in our city, we need to think that the species has had to change where it lives and its behaviour because where it naturally lives has been degraded by human practices.’
And there is a stark warning from history that gives doubters further reason to take note.
Before their recent ascent as a symbol of Sydney, the ibis was most well known as an icon of ancient Egypt. The Egyptian bird, the Sacred Ibis – which is so closely related to the Australian White Ibis they were once believed to be the same species – was famously venerated for its association with the god Thoth.
Writing in 20 AD, the Greek historian Strabo described scenes from the Egyptian port city of Alexandria that many Sydney residents would find familiar – with large numbers of ibises picking through human rubbish, eating people’s unguarded food and streaking sites with their droppings.
Flash forward two millennia, following untold environmental change and degradation, and the once very common Sacred Ibis is now completely extinct in Egypt.
‘The White Ibises in Sydney are a reminder that our actions have consequences beyond us,’ concludes Dr Martin. ‘They shouldn’t be vilified; they are a native species that need to be understood and appreciated.’
The Big City Birds project aims to engage bird watchers and the general public to report sightings of native birds, particularly the Australian White Ibis, Sulphur-crested Cockatoo, Australian Brush-turkey, Little Corella, and Long-billed Corella. The data collected helps scientists understand these species’ behaviour, movement, reproduction, distribution and habitat use in urban areas.
If you would like to be part of the Big City Birds project, please visit: https://www.spotteron.com/bigcitybirds.
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