One of the key ways humans acquire new skills is by observing proficient individuals in action: think of a child learning by watching older siblings, or budding athletes emulating the techniques of established stars.
Turns out the same is true of cockatoos, according to a study published Thursday in Science.
A few members of the highly intelligent Australian bird species figured out how to pry open trash cans to forage for food, then rapidly spread the gospel to neighboring groups across the suburbs of Sydney until it became more common knowledge, the paper said.
Lead author Barbara Klump of the Max Planck Institute of Animal Behavior told AFP this phenomenon is known as "social learning," but it's usually hard to document in wild animals, either because the behaviors are rare, or there are other possible explanations like genetics.
The idea for the new research came about when one member of the team, Richard Major of the Australian Museum, made a phone video of a sulphur-crested cockatoo using its beak and foot to lift the heavy lid of a bin, flip it over, and feast on leftover foods.
"We were really intrigued because it's a novel foraging innovation, a novel way to access resources in a city," said Klump.
They realized they had a unique opportunity to systematically study the behavior, "because the birds are everywhere on the east coast of Australia, and the bins are exactly the same everywhere," creating uniform conditions scientists refer to as a "natural experiment."
First, they needed to know if all cockatoos could open the wheeled trash cans.
They ran an online survey in which residents of the Greater Sydney and Wollongong region were asked where they lived, if they'd seen the behavior before or not, and if so when.
The results showed that prior to 2018, trash opening was happening only in three suburbs, but by the end of 2019, residents were reporting it in 44 suburbs.
Further analysis of the data confirmed that the skills spread first to districts adjacent to the original suburbs, then further out over time -- confirming the behavior wasn't popping up at random over the city.
- Cockatoo subcultures -
To understand the phenomenon better, the team went out to some of the suburbs on trash collection day and recorded the birds in action, finding that opening a can is a complex, multi-step task.
Within groups, only around ten percent of cockatoos could open a lid, with the rest profiting from the efforts of the "pioneer."
The task comprised five stages: the initial pry, opening the lid more fully, holding it up, walking along the bin's edge towards the hinge to lift the lid higher, and the final flip.
At each of these steps, the team observed variations, such as whether a bird opened the lid at the handle or the rim, and whether it turned its head upside down in the process or not.
Intriguingly, the specific techniques the birds used differed by where they lived, and were more similar in neighboring suburbs than those far away.
"That really shows us that there are these local subcultures, like local traditions of doing things," said Klump.
Cultural differences have previously been seen in other animals, such as different regional dialects in whales and monkeys, or regional variations in birdsong.
The research adds to the long list of impressive feats the birds are capable of -- which includes solving complex mechanical puzzles and inventing their own dance moves to music -- and sheds light on how cockatoos have adapted to the demands of urban living.
In addition to their big brains, cockatoos are highly social.
Each evening, huge flocks of 50 to 500 come to roost, before dispersing in small foraging parties of five or so during the day.
Sometimes these smaller parties mix with other groups, which is probably where the knowledge transfer takes place, Klump said.
"They actually pay attention to each other, learn from each other and pass this knowledge along.. it's interesting how similar they are in these respects to us," she added.