In 2015, wildlife biologist Richard Major was walking through Stanwell Park, a leafy suburb about an hour south of Sydney, when he saw something that stopped him cold: a sulphur-crested cockatoo standing on top of a household wheelie bin, using its beak and feet like a pair of hands to pry the lid open and flip it back on its hinges. The bird climbed in, rummaged for food scraps, and flew off. Major, a senior scientist at the Australian Museum Research Institute, had never seen anything like it.
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Four years later, residents in 44 different Sydney suburbs were reporting the exact same trick — cockatoos balancing on bin lids, levering them open, and feasting on leftovers. The birds hadn’t all figured it out on their own. According to a landmark study published in the journal Science, they’d learned it from watching each other, suburb by suburb, in one of the clearest documented cases of an animal culture spreading in real time.
Quick answer
Sulphur-crested cockatoos in Sydney, Australia learned to flip open household garbage bin lids to scavenge food, and the behavior spread from just three suburbs before 2018 to 44 suburbs by late 2019. A 2021 study in Science, led by Barbara Klump of the Max Planck Institute of Animal Behavior, used a two-year citizen-science survey and statistical modeling to estimate that social learning — cockatoos watching and copying other cockatoos — accounted for about 93.9% of the suburbs where bin-opening appeared, rather than birds independently inventing the trick on their own.
A bird on a bin lid in Stanwell Park
Richard Major’s 2015 sighting wasn’t a one-off curiosity to him — sulphur-crested cockatoos are famously intelligent, social, and long-lived, often surviving decades in the wild, so a new foraging trick catching on among them was plausible. But proving that cockatoos were teaching each other, rather than each bird separately stumbling onto the same solution, required actual data, not just anecdotes.
So in 2018, Major teamed up with Barbara Klump and Lucy Aplin, behavioral ecologists at Germany’s Max Planck Institute of Animal Behavior, along with John Martin of the Taronga Conservation Society. They launched an online survey asking residents across 478 suburbs in Sydney and nearby Wollongong a simple question: had they ever seen a cockatoo open a bin? The survey ran for two years and gathered 1,396 reports from 1,322 participants — 338 of those reports, spanning 44 suburbs, described actual bin-opening.
From three suburbs to forty-four
The results mapped out something remarkable. Before 2018, bin-opening had only been reported in three suburbs. By the end of 2019, it had been confirmed in 44. Crucially, the spread wasn’t random — it moved like a contagion, reaching nearby suburbs faster than distant ones, exactly the pattern you’d expect if birds were learning by watching their neighbors rather than each independently discovering the trick. The researchers’ best statistical model estimated that social learning accounted for roughly 93.9% of the suburbs where the behavior turned up — strong evidence that the trick was being transmitted bird-to-bird and suburb-to-suburb, not reinvented from scratch each time.
There was an extra wrinkle that made the case even stronger: cockatoos in different suburbs didn’t all open bins the same way. Of 160 directly observed bin-openings, birds showed distinct, suburb-specific styles — some pried the lid with their beak and walked it open sideways, others levered it up and scuttled around the rim. These regional styles stayed fairly consistent within a suburb, like local dialects — further evidence that birds were copying their specific neighbors’ technique rather than all solving the puzzle independently. The researchers even traced a second, independent origin of the trick in the northern suburb of Narraweena in late 2018, which then spread outward through its own cluster of suburbs, separate from the original southern lineage. The study also found the bin-raiders were disproportionately large, dominant males — suggesting size and social status, not just cleverness, helped determine who got to learn and practice the skill in the first place.
The part most people miss
The Science paper wasn’t the end of the story — it was the opening move in an ongoing standoff. A 2022 follow-up study, again involving Klump, surveyed thousands of Sydney bins and found residents fighting back with bricks, pool noodles, shoes, rubber snakes, spikes, and bungee cords rigged across the lids. The cockatoos adapted. Birds learned to simply shove lightweight deterrents like bricks or rubber snakes off the lid; only heavier countermeasures, like a weight bolted directly to the lid or an object jammed into the hinge itself, reliably stopped them. Researchers described it plainly as an arms race — and as humans upgrade their defenses, there’s every reason to expect the birds, who’ve already proven they can watch, copy, and refine a skill across an entire city, will keep adapting too.
Sources
Barbara Klump, Lucy Aplin, Richard Major, and John Martin’s bin-opening social learning study, published in the journal Science, volume 373, issue 6553 (2021), as summarized by the Max Planck Institute of Animal Behavior and the Australian Museum Research Institute’s ‘Contact tracing of cockatoos reveals spread of foraging culture’ write-up.
National Geographic’s coverage of the study, ‘Wild cockatoos learn to open bins by copying others—first evidence of social learning,’ and Science News / The Conversation reporting on the 2022 follow-up study documenting the escalating ‘arms race’ between Sydney residents and bin-opening cockatoos.
Explore more: More true tales from the wild animal kingdom.
Frequently Asked Questions
Which bird learned to open trash bins in Australia?
The sulphur-crested cockatoo (Cacatua galerita), a large white parrot common across eastern Australia, including the greater Sydney region where the bin-opening behavior was first documented.
How do scientists know the cockatoos learned the trick from each other?
A two-year citizen-science survey mapped exactly which suburbs reported the behavior and when. The spread followed a pattern of nearby suburbs picking it up faster than distant ones, and birds in different areas used distinct techniques — both hallmarks of social learning. A statistical model estimated social learning explained about 93.9% of the suburbs where bin-opening appeared, rather than each bird inventing it independently.
Did the bin-opening behavior stop after the study?
No. A follow-up study in 2022 found residents escalating their defenses with bricks, spikes, and bungee cords, while cockatoos kept adapting to defeat lighter deterrents, turning it into an ongoing back-and-forth.
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